text:
A router, switch, or other network node generates reports that contain packet level statistics and other information for a monitored media stream. The media stream reports reduce the amount of bandwidth typically required for sending monitored media stream information back to a central analysis device. However the computation of other media stream analytics, such as long term statistical averaging or quality metric computation, is performed by the central analysis device to remove some of the processing burden from the individual network nodes.
1. A method, comprising:
operating a central media monitor configured to remotely monitor media streams transferred over network paths established between media stream endpoints in a packet switched network, wherein the central media monitor is outside of the network paths established between the media stream endpoints;
requesting, with the central media monitor, multiple different network devices to monitor different associated portions of one or more of the media streams established between the endpoints and periodically generate media stream reports summarizing real-time packet transportation statistics for transportation of media packets over the different portions of the media streams, wherein the multiple different network devices are intermediary nodes positioned at different locations within the network paths used for transferring the media streams, and wherein the media stream reports summarize the real-time packet transportation statistics for the different associated portions of the network paths;
setting up tunnels between the central media monitor and the multiple different network devices; and
receiving the media stream reports with the central media monitor over the tunnels from the multiple different network devices that each contain the real-time packet transportation statistics for the different associated portions of requested one or more media streams,
wherein an Internet Protocol (IP) address of an interface where the one or more media streams are monitored is indicated as a source address for the media stream reports, wherein an actual source address of the media stream report is different from the indicated source address.
2. The method of
requesting monitoring of the one or more media streams from a central monitoring device that is not in a native network path of the media streams;
sending monitoring requests to the intermediary nodes for the one or more media streams located between media stream endpoints; and
receiving the media stream reports for each of the one or more media streams at the central monitoring device from the intermediary nodes over the same tunnels, wherein a same tunnel header encapsulates multiple different media stream reports each associated with a different one of the one or more media streams.
3. The method according to
4. The method according to
5. The method according to
decapsulating the RTP tunneling headers from the media stream reports; and
performing further analytics on the one or more media streams using the decapsulated media stream reports.
6. The method according to
7. The method according to
8. The method according to
9. An apparatus, comprising:
one or more processors; and
a memory coupled to the one or more processors comprising instructions executable by the one or more processors, the processors operable when responsive to executing the instructions configured to:
monitor one or more media streams at an intermediary node located at a particular location in a network path, wherein the intermediary node transports media packets in the media streams between two endpoints;
conduct preliminary packet level analysis on the monitored media streams, wherein the packet level analysis identifies media packet statistics associated with transporting the media packets in the media streams over a particular portion of the network path where the intermediary node is located;
generate reports that contain results from the packet level analysis;
establish one or more tunnels between the intermediary node and a network analysis device located outside of the network path;
send the reports over the one or more tunnels to the network analysis device;
include an Internet Protocol (IP) address of a local interface where the media streams are monitored as an indicated source address for the reports, wherein actual source addresses of the reports is different from the indicated source addresses; and
identify an associated media session by including a destination IP address and port of the monitored media streams in the reports.
10. The apparatus according to
monitor the media streams and generate the reports at an intermediary router or switch node between a media source and one or more media stream receiver endpoints for the media streams encapsulate reports for different media streams in a same tunnel header; and
send the reports at the same time through a particular one of the tunnels to a Network Operation Center (NOC) that is located outside of native network path for the media streams.
11. The apparatus according to
12. The apparatus according to
generate statistics that identify a number of lost media packets in the media streams, time stamps when the reports were generated, and media stream packet jitter; and
include the generated statistics in the reports that are tunneled to the network analysis device.
13. The apparatus according to
receive an ingress or egress interface identifier; and
generate media reports for the media streams at an ingress or egress interface corresponding with the ingress or egress identifier.
14. The apparatus according to
15. The apparatus according to
use a Real-Time Protocol (RTP) session IP address for the media streams as the destination address for the report to identify a corresponding RTP session.
16. A method, comprising:
monitoring one or more media streams at multiple different intermediary nodes operating in a same native media stream path between media stream endpoints;
conducting preliminary analytics on the monitored media streams at each of the multiple different intermediary nodes;
generating reports at each of the different intermediate nodes that contain packet-level statistics derived from the preliminary analytics, wherein the packet-level statistics generated by each of the different intermediate nodes are associated with a different location in the same media stream path between the media stream endpoints;
sending the reports from each of the different intermediate nodes to a Network Operation Center (NOC) not located in the native media stream path;
including in each report an indicated source address, wherein the indicated source address is the address of an interface where a corresponding media stream is monitored, wherein an actual source address of the each report is different from the indicated source address, and
wherein the indicated source address indicates whether the interface is an ingress or egress interface; and
explicitly identify in the report an associated media session by including a destination IP address and corresponding port associated with the monitored media stream.
17. The method according to
18. The method according to
accumulating packet level statistics including a number of lost packets in the media streams, time stamps for the packets in the media streams, or inter-arrival packet jitter in the media streams;
putting the accumulated packet level statistics into the reports; and
tunneling the reports to the NOC.
19. The method according to
20. The method according to
using a Session Initiation Protocol (SIP) to initiate generation of the reports and tunneling of the generated reports back to the NOC; and
using a Session Description Protocol (SDP) to identify which media streams to monitor and how to tunnel the reports back to the NOC.
This is a continuation in part of U.S. patent application Ser. No. 11/748,379 filed May 14, 2007, entitled: REMOTE MONITORING OF REAL-TIME INTERNET PROTOCOL MEDIA STREAMS which is herein incorporated by reference in its entirety.
The present disclosure relates generally to the field of networking.
Fault isolation and diagnosis of real-time Internet Protocol (IP) multimedia streams is difficult because the endpoints of the communication have little or no insight into the causes and sources of impairments. The endpoints only know that packets are being lost or delayed by some element, such as a router or switch, along the media network path.
The problem is exacerbated in the case of multicast real-time sessions where any router or switch in the network may replicate and forward packets along different sub-branches of a multicast tree. Hence the impairment patterns seen by different receivers (endpoints) may be very different. Comparing the patterns seen by different receivers may provide further insight into where the problem lies, but is often insufficient to identify with high confidence the particular router, switch, or link causing the fault.
It may be desirable to periodically or continuously monitor many media streams at the same time to get further insight into possible network problems. However the network devices may not have the available processing capacity or bandwidth to continuously send a large number of monitored media streams to one central monitoring site.
A router, switch, or other network node generates reports that contain packet level statistics and other information for a monitored media stream. The media stream report summary reduces the amount of bandwidth typically required for sending monitored media stream information back to a central analysis device. However the computation of other media stream analytics, such as long term statistical averaging or quality metric computation, is performed at to the central analysis device to remove the majority of the processing burden from the individual network nodes.
Monitoring of multimedia streams in intermediate devices increases the ability to identify and diagnose faults. There are three general classes of such intermediary monitoring facilities. A first class includes intermediaries which join media streams as receivers and process the entire media stream as a normal receiver. Such intermediaries may even include specialized stream analysis hardware and software such as are used for quality testing and assessment. These localized systems in most cases are far too expensive to provide monitoring at every potential point where multimedia traffic passes through an Internet Protocol (IP) network.
Another class comprises intermediaries which capture and dump bulk traffic traces to local or remote storage for offline analysis. These capabilities are provided by Switched Port ANalyzer (SPAN) ports and full Netflow traffic tracing. Such systems work well for forensics but are not well suited to real-time fault isolation and diagnosis.
Another class includes intermediaries which monitor individual multimedia streams and compute some statistics based on observation of the traffic flows. The statistics are typically passed through an assessment filter, and if certain thresholds are exceeded, an alarm may be raised. A proposed Media Delivery Index (MDI) described in RFC4445 falls into this category. Flow monitoring with measurement suffers from a difficult tradeoff between the amount of work required to extract the relevant measurements as the data passes through an intermediary node versus the usefulness of the statistics for fault isolation and diagnosis.
All of these systems need a control scheme for turning the measurement and capture machinery on and off in the relevant network nodes, and some external inputs which decide which points in the network to monitor. Care must be taken when turning on these kinds of monitoring. For example adding a receiver to a multicast session, particularly one near the source, may cause the multicast tree to be recomputed significantly perturbing normal network operation.
Lawful Intercept (LI) or "wiretapping" intercepts packets for identified flows and tunnels the flows to a monitoring point called a "mediation device". The LI systems typically require the intercepted stream to have near perfect fidelity. However, precise fidelity is not always necessary in Quality of Service (QoS) monitoring systems. Conversely, the LI systems do not need to preserve the exact timing of the original media stream. However, accurately identifying media stream timing is very important for multimedia monitoring.
Remote Media Monitoring
The receivers 114 could be Personal Computers (PCs), Set-Top Boxes (STBs), Personal Digital Assistants (PDAs), Voice Over Internet Protocol (VOIP) phones, Internet connected televisions, cellular telephones, or any other device that receives media packets. The packet switched network 106 includes multiple different intermediary nodes 110 that direct media packets from media source 108 to one or more of the different receivers 114. The intermediary nodes 110 may be routers, switches, gateways, or any other network processing device. The intermediary nodes 110 and receivers 114 are all referred to generally as local nodes 125.
A Network Operation Center (NOC) 102 provides a central location for monitoring the operation of different local nodes in Internet network 106. The NOC 102 can be any combination of servers and processors that analyze information transmitted by any combination of different local nodes 110 and/or 114.
A central media monitor 104 operates in the NOC 102 and communicates with one or more local Media Monitors (MMs) 112A and 112B that operate locally in the different local nodes 112 and/or 114. The local MM 112 traps media packets from the real-time multimedia stream 116, clones the packets by copying them, and tunnels the packets over different tunnels 120A and 120B to the central media monitor 104 for analysis.
Sending the captured media packets from local nodes 125 to media monitor 104 allows media analysis to be centralized at NOC 102. This eliminates having to use expensive media monitoring equipment at local node. Further, using novel tunneling techniques, the central media monitor 104 can reproduce the media streams with a fidelity equal to that obtainable by monitoring equipment actually located at the individual local nodes.
The flow classifier 150 is installed in the data path 146 of the router, switch, or receiver 125 for a particular interface identified by the central media monitor 104 (
Since IP multicast is tree-based, there will be only a single ingress interface 144 for a flow. In unicast, equal cost path splitting could result in packets for a flow arriving on multiple ingress interfaces. Thus, it often makes sense to only capture packets on egress interfaces 148. There may also be an advantage to trapping on the egress interfaces 148. For example, a packet may be dropped from an output queue due to congestion. Capturing packets on the egress interfaces 148 allow these dropped packets to be detected and reflected in the media monitoring session.
Packets from media stream 116 that match the classifier 150 on the selected interface are trapped by trap operation 152. In order to capture accurate flow timing, the trap operation 152 assigns and binds an associated timestamp value 139 provided by clock 140 with the trapped packet the instant the packet is trapped. For ingress interface 144, the timestamp value 139 from clock 140 is chosen to be close as possible to the moment the media packet 204 is received from the ingress interface 144. For egress interfaces 148, the timestamp values 139 are as close as possible to the instant when the last bit of the packet 204 has departed the output queue (not shown) for successfully transmitted packets. A good approximation of this instant is when the transmit-done interrupt occurs. For dropped packets, the timestamp 139 is as close as possible to the instant when the queuing system scheduler decides to discard packet 204.
The cloning operation 154 makes a copy of the trapped packet 204. When trapping is completed on an ingress interface 144, the packet 204 is physically cloned since the original packet continues through the normal forwarding circuitry of the router/switch 146, and in the case of multicast, through additional replication circuitry. For a multicast stream 116, the clone operation 154 could perform the cloning using the native replication circuitry of the multicast forwarding system 146 and hence get the cloned packet "for free".
When the ingress interface 144 includes ingress queuing, a queued packet could be discarded at ingress due to congestion or system overload. These discarded packets can be marked by the clone operation 154 to notify the central media monitor 104 that the packet was discarded by the local node 125.
In the case of the egress interfaces 148, it is also possible to physically copy the packet. However, an alternative technique takes the original packet off an output buffer ring (not shown) when a transmit done signal is activated and hand the packet directly to the tunnel operation 156. This simply reassigns the output packet buffer to the tunnel operation 156 rather than recycle the output buffer to an output buffer pool. The packet buffer can be reassigned instead of making a copy for packets being discarded.
These different optimizations may or may not be used depending on the relative cost in memory and processing tradeoffs of making copies versus the cost and complexity of managing the re-assignment of packet buffers. In either case the cloned packets are then handed to the tunnel operation 156.
Referring to
Each media packet 204 includes network headers 206 used for forwarding the media packet through the IP network 106 (
It is not strictly necessary to include any Layer 2 headers (e.g. the MAC headers mentioned above) that may have been on the packet at the time it was trapped and cloned. A UDP payload without the corresponding IP and UDP headers may be provided if the tunnel setup provides the same flow information that the IP header 206B and UDP header 206C would provide.
The media packets 204 may also include media stream headers that are used for identifying the timing and sequence of media for the associated media stream. For example, a RTP header 208 may include a media payload type 208A, a media sequence number 208B, media timestamp 208C, and a media Synchronization SouRCe identifier (SSRC) 208D, among other fields. Finally the media packet 204 includes a media stream payload 210 that includes, but is not limited to, audio and/or video information.
The local media monitor 112 (
The tunnel operation 156 in
Reducing Bandwidth
Whenever tunnels are constructed it is possible to run into Maximum Transmission Unit (MTU) issues due to the tunnel headers adding bytes to the original packets. Using RTP for tunneling adds additional overhead of 40 bytes in the case of IPv4 (RTP=12, UDP=8, IP=20). Since stream fidelity should be maintained, some situations may require using IP fragmentation. These MTU issues can be negotiated as part of tunnel setup. Thus, a need exists for reducing the number of bits in these tunneled media packets.
Both compressing/blocking the headers and eliminating the payload may be particularly useful when monitoring media streams 116 at the subscriber end of access links 117 (
This is particularly effective when the payloads are being suppressed. The RTP header compression can also be used on the tunneled stream to further reduce required bandwidth. The RTP header compression is described in Request for Comment (RFC) 4362, RFC 4170, and RFC 2507 and is therefore not described in further detail. If the media flow being monitored is an RTP flow, the RTP payload 210 may optionally be omitted, the tunneled packet 204 may consist of just the RTP headers 208 for the packets being monitored.
In operation 242, the headers of captured media packets may be compressed and/or the payload contents removed from further tunneling pursuant to monitoring requests from the central media monitor 104. The local media monitor 112 attaches a tunnel header to the remaining portions or each of the captured media packets in operation 243. A tunnel sequence number is added to the tunnel headers in operation 244 that identifies a sequential count for the encapsulated tunneled packets sent from the local node 125 to the NOC 102.
A tunnel timestamp is also added to each of the tunnel headers in operation 245 that is associated with the time at local node 125 when the media packet was actually captured or trapped by the local media monitor 112. Packets that are dropped by the local node 125 may be identified and an associated tag or identifier inserted in the corresponding tunnel header in operation 246. The encapsulated media packets or media packet identifiers are then sent over the tunnel 120 to the central media monitor 104 in operation 247.
Tunnel Setup and Flow Description
Referring to
Any variety of different control protocols can be used to set up the tunnels 120. Control Protocols such as Simple Network Management Protocol (SNMP) can be used to define and control the tunnels 120. A simple transport establishment protocol like Stream Control Transmission Protocol (SCTP) could also be used, with the RTP packets carried as unreliable SCTP segments.
In one embodiment, a session rendezvous protocol specifically tailored to real-time multimedia is used. This could include H.323 and Session Initiation Protocol (SIP). Another alternative may include using a Session Announcement Protocol (SAP) and multicasting for instantiating the tunnel rather than unicast. This allows multiple monitoring stations to join a monitoring session and receive the tunneled data via multicast rather than unicast.
In one embodiment, the central media monitor 104 sends a monitoring message 251 to the local media monitor 112 that identifies the media streams 116 to be trapped via a flow classifier 252. Any number of existing flow classification schemes can be used such as a flexible netflow scheme or a common classification engine. In one example, the flow is identified using a IP 5-tuple 254, and optionally by using an Real-Time Protocol (RTP) Synchronization SouRCe identifier (SSRC) 256.
Techniques such as traceroute and mtrace can be used to identify the routers/switches on the tree for a multimedia flow 116, and the monitoring facility enabled on any subset of those network elements as desired. There may be multiple flows that are closely bound to one another that need to be simultaneously monitored through the tunnel 120. Examples are sessions that consist of separate video and audio streams, or sessions constructed by layered coding with a separate flow for each layer. This information may also be used in many monitoring cases to substitute for actually sending the IP header 206B and UDP header 206C for the tunneled packets 204 (
The monitoring message 251 may also identify where to install the trap. While it is possible to simply enumerate the individual interfaces, this may have disadvantages. For example, the central media monitor 104 may need to know how a given system names interfaces, and need a possibly dynamic way to determine the interfaces associated with the media flow 116.
The following describes one preferred embodiment used for interface binding. For a unicast flow, the monitoring message 251 may simply indicate ingress or egress in field 258 and let the local node 125 performing the trap-clone-tunnel determine where to put the trap. For a multicast flow, the monitoring message 252 may indicate ingress in field 258 for ingress trapping. Alternatively, field 258 may also give a set of IP addresses of next hops that are branches of the multicast sub-tree emanating from the local node to be monitored.
The same or a separate tunnel description message 262 is used for describing the tunnel itself, the destination IP address and port of the tunnel 120, etc., and may include the RTP payload type mappings. The tunnel description message 262 may also include compression/block type information 260 that identifies which headers and payloads should be passed through the tunnel 120, such as IP and UDP headers or the media payload.
Referring to
The SIP transaction 264 may contain three MIME body parts and include an application/SDP body part 252 that describes the flow to be monitored in operation 282. A text encoded or specifically registered MIME application body part 258 in operation 284 may identify the interface information for monitoring different ingress or egress interfaces as described above.
An application/SDP body part 262 in operation 286 constitutes an SDP offer with a description of the tunnel 120. This SDP body part 262 in operation 288 may be enhanced with some payload-format specific information 260 that indicates which headers to include and whether to include the user payload in the tunneled packets. For example, field 260 in
The local media monitor 112 installing the trap may contain a SIP UAS which attempts to complete the session setup as requested. Standard SIP errors are returned if any part of the operation fails. If the operation succeeds, a SIP "200 OK" response 268 is received in operation 290 with a single MIME body part containing the agreed parameters for the tunnel 120. This conforms to the commonly-used SDP offer-answer methodology documented in RFC3264. At this point the trap-clone-tunnel is in operation and media packets are then intercepted by local media monitor 112 and sent through the tunnel 120 to the central media monitor 104.
Processing Tunneled Media Flows
Further, the tunnel headers 202A indicates that the local node 125 dropped the fourth media packet in the native media stream 116 prior to being trapped and tunneled to the central media monitor 104. The tunnel packets 301 also indicate that one of the successfully trapped media packets encapsulated as RTP tunnel sequence number 5 was lost somewhere during the tunnel transmission from local node 125 to NOC 102.
The media monitor 104 separates the native media packets 204 from the RTP tunnel encapsulation headers 200 and sends the decapsulated media stream 302 to a decoder and/or more sophisticated media analysis engine 300. The decapsulated RTP media stream 302 might be fed into an RTP jitter buffer prior to being processed by decoder 300.
All of the RTP tunnel characteristics identified in the RTP tunnel headers 200 can be accounted for by the central media monitor 104 prior to feeding the decapsulated packets 302 into the decoder/analysis engine 300. For example, the central media monitor 104 can reconstruct the arrival times for the decapsulated media packets as originally seen at the trap point in the local node 125. The original trap point timing is recreated by using the RTP tunnel timestamps 202C to clock the packet delivery through the jitter buffer to decoder 300.
As mentioned above, packets lost during tunnel transmission from local node 125 to NOC 102 are identified by gaps in the RTP tunnel sequence numbers 202B. Assuming there are no packets lost in the tunnel 120 and the media stream 116 stream contains the full media payload 210, the decapsulated media stream packets 302 fed to the decoder 300 should be an identical copy of the media as received by the local node 125, along with the precise timing of when the media packets arrived at the local node trap point.
If the tunneled flow 120 does not include the media stream payload 210 and no reference stream is available, no actual decode and play-out can be performed. However, statistics such as loss/jitter alarms raised, etc. can still be computed.
The tunnel 120 can also identify and report packets which were discarded by the router, switch, receiver, etc. acting as the trap point. For example, tunnel header 202A for tunnel packet 301D indicates the associated media packet was dropped at the local node 125. This information can be fed into the analysis engine 300 to both compute more accurate media stream statistics, and for deeper quality estimation. Thus, the analysis engine 300 knows exactly what media packets were lost due to packet drops at the local node 125 and not simply that something was dropped.
If the tunneled data stream 120 has loss, simply feeding the decapsulated media stream 302 into the analysis engine 300 could produce misleading data. The central media monitor 104 can thus also distinguish loss in the native media stream loss 116 from loss in tunnel 120 by identifying any missing tunnel sequence numbers 202B. Media stream analysis is then adjusted to ignore tunnel loss, and packet statistics adjusted so as not to misinterpret the underlying stream loss and jitter in media stream 116.
To explain further, each successfully tunneled and decapsulated media packet 302A-302D is presented to the decoder 300 in the sequence and at the times T1, T2, T3, and T6, respectively, when the media packets were originally trapped by the local node 125. The sequence for the decapsulated media packets 302 are identified by the associated RTP tunnel sequence numbers 202B and the RTP tunnel timestamp values T1, T2, T3, and T6 are identified in the associated RTP tunnel timestamps 202C.
In this example, tunnel packet 301B arrived at the central media monitor 104 before tunnel packet 301C. However, the tunnel headers 200 indicate that media packet 210 encapsulated in tunnel packet 301C should be supplied to decoder 300 at time T2 before the media packet 210 encapsulated in tunnel packet 301B is supplied to decode 300 at time T3.
The tunnel headers 202A and sequence numbers 202B are also used to distinguish packets lost at local node 125 from packets lost in tunnel 120. As described above, tunnel header 202A in tunnel packet 301D indicates media packet seq=4 was dropped by the local node 125. According, the central media monitor 104 will not send any associated decapsulated media packet to the decoder 300 at time T4.
However, the fifth tunnel packet 301 between tunnel packet 301D (seq=4) and 301E (seq=6) is missing. This indicates the packet was dropped during transmission from the local node 125 to NOC 102. Accordingly, the central media monitor 10 may notify the decoder 300 that a media packet 302 was dropped in tunnel 120 and accordingly should not be considered lost by the local node 125 when performing media stream analysis.
Reference Media Stream
Referring to
Such a stream is referred to as a reference stream 320 because it has very close fidelity to the original media stream 116, and is in the exact format and encapsulation of the native media stream 116 sent through the network 106 to the receivers 114. The reference media stream 320 can then be used in combination with the tunneled media stream 120 received from the local media monitor 112A. The payload from the reference stream 320 can be used when the tunneled media flow 120 does not contain media payloads 210 (
When data is lost upstream of the trap point in local node 110A, as opposed to discarded at the trap point, the reference stream 320 can contain the original dropped media packet. This allows the analysis engine 300 (
In this example, the tunnel packets 352 do not include the media stream payload 210 that were contained in the tunnel packets 301 shown in
The central media monitor 104 conducts the same tunnel decomposition 104A described above in
Referring both to
If any tunnel packets 352 are dropped during transmission from the local node 125 to NOC 102 in operation 378, the corresponding packets from reference stream 320 can be inserted in operation 380. The local media monitor 104 in operation 382 may also distinguish packets lost upstream of the local media monitor 112 from other packets lost downstream of the local trap point. For example, any media packet lost in reference media stream 320 would be lost upstream and also indicated as lost by the local node 110. These upstream losses can be distinguished from downstream packets only lost by the local node.
Referring back to
In this example, the third tunneled packet between tunnel packet 352B and 352C was lost during tunnel transmission and not actually identified as lost by the local node 110. Accordingly, the reference packet 350C associated with the lost tunnel packet 352 is inserted as reconstructed packet 354C.
It is also determined that the media packet with seq=2 was lost upstream of the local node trap point. This is determined by recognizing that none of the reference media packets 350 have a seq=2. Accordingly, no media packet is inserted between reconstructed packets 354A and 354B in reconstructed media stream 354.
It can also be determined that the sixth media packet contained in tunnel packet 352C was received by the trap point in the local node 110 before the fifth media packet contained in tunnel packet 352D. This is determined by comparing the tunnel sequence numbers 202B and timestamp values 202C in tunnel packets 352C and 352D. Accordingly, reconstructed packet 354D with seq=6 is input to the decoder 300 (
Referring again back to
For example, media packets may be indicated as lost by the downstream trap point 112B and identified as successfully received by the upstream trap point 112A. Accordingly, the lost packet may be associated to node 110C. Also, a packet lost in the tunnel 324 may be replaced by the corresponding media packet received in tunnel 120. Of course any other additional detailed forensics can be used for isolating and diagnosing faults.
Thus, a new fault isolation and diagnosis system is provided for real-time IP multimedia systems where trap, clone and tunneling is used to send data to a centralized analysis center. A novel RTP tunneling technique further improves the utility and fidelity of equipment used for analyzing faults and impairments.
The centralized media monitoring is more scalable and provides better economics than analysis equipment installed locally on the network nodes. Simple and efficient schemes are used by the nodes to implement media stream monitoring which do not require any understanding of the underlying media flows. Low bandwidth embodiments also described above can be implemented on home gateways so that impairments on access links can be analyzed in detail without perturbing the receivers.
The monitoring system can be used with any networking equipment required to have a comprehensive capability to isolate and diagnosis faults in Internet Protocol TeleVision (IPTV) or any other real-time multimedia flow.
The Network Operation Center (NOC) 102 provides a central location for monitoring different media streams 116 at different node locations in network 106. The NOC 102 can be any combination of servers and processors that analyze media stream information sent by any combination of different nodes 110 and/or 114. The NOC 102 communicates with one or more local Media Monitors (MMs) 112 that operate locally in the different nodes 110 and/or 114. In one embodiment, the local MMs 112 are implemented in software executed by a programmable processor but any combination of software and/or hardware logic can be used.
The local media monitors 112 described above in
However, the local media monitors 112 for the monitoring system 400 in
For example, the local media monitors 112 may generate media stream reports 402 that identify the number of lost packets, packet jitter, and timestamp information for media stream 116. An analysis system 406 in NOC 102 uses the packet-level statistics in reports 402 to conduct additional media stream analysis, such as long term statistical averaging and quality metric computations.
In one regard, the local media monitors 112 operate like RTP receivers that send RTCP reports back to the media source 108. However, the monitoring system 400 allows the media stream reports 402 to be generated by non-endpoint intermediary nodes 110 in the media stream network path. The media stream reports 402 can also be sent to the NOC 102 over tunnels 404. This enables the nodes 110 and/or 114 to send media stream reports 402 to a non-endpoint NOC 102 that is not located in the native path of the media stream 116.
This trap-clone scheme substitutes for a join operation in the case of a multicast session, or the insertion of an explicit RTP mixer/translator in the case of a unicast session. This keeps the local media monitors 112 transparent to the media source endpoint 108 and receiver endpoints 114 and avoids problems with perturbing media stream routing by explicit joining of a multicast stream.
In one embodiment, the local media monitors 112 produce basic Real-Time Control Protocol (RTCP) counters/statistics that are similar to those generated by media stream receivers 114 when producing conventional RTCP receiver reports. The local media monitors 112 may perform the same computations as RTCP receivers, with the exception that certain values, such as the lost packet counts, may not be synchronized with report intervals.
If sender reports for the media stream 116 are not available (either because they are not sent by the media source, or are not intercepted by the trap and clone machinery), then the total sent packet count may be unknown to the local media monitors 112. The media monitors 112 may also not have the same jitter buffer as the receivers 114. Thus, discarded packet counts for packets arriving too late for play out might not be identifiable. These differences can be taken into account by the analysis system 406.
Any type of report format and statistics can be generated by the local media monitors 112 and reported back to the NOC 102. However, RTCP type receiver reports may be convenient for incorporating into the local media monitors 112 since RTCP reporting is well established and by using RTCP the metrics reported for the monitored stream may be directly compared with those generated by the normal stream receivers.
Rather than accumulating media stream statistics over long intervals and implementing thresholding and alarming, the local media monitors 112 can use tunneling scheme similar to that described above in
The tunnel set up and monitoring protocol is similar to that described above in
Tunnel setup message 420 can use the same SIP with three MIME bodies as described above. However, one enhancement increases scaling by allowing a single tunnel to carry the RTCP reports for a large number of monitored media streams. One technique uses SIP-based tunnel setup to carry multiple SDP messages 420A-420N each identifying one of the media streams to trap. One additional SDP message 420 then identifies the tunnel for carrying the reports and the interface(s) for installing monitoring traps.
A second tunnel setup scheme carries all the media stream flows in a single SDP as separate m=lines. The advantage of the first scheme is that the integrity and general information is maintained for each media session to be monitored. The second scheme provides more efficient encoding for tunnel setup.
It should be understood that the report monitoring scheme described in
Media Stream Reports
The tunnel 404 also includes one or more media stream reports 402A-402N that can each be associated with the same or different media streams. Each media stream report 402 may contain any statistics or analytic information derived by the network node 110 and/or 114 for the monitored media stream. However, in one example, the reports 402 contain some of the same statistics contained in conventional RTCP reports. The generation and type of information contained in RTCP reports is described in Request For Comment (RFC) 3550 which is herein incorporated by reference.
Each media stream report 402 can be accompanied with an associated RTP tunnel header 432. This allows the NOC 102 to identify any media stream reports 402 that may have been lost during tunnel transmission. As described above in
The IP address 440 of the interface being monitored is used as the source of the reports 402. The RTCP reports when coming from endpoint receivers can be trivially associated with the RTP session received by that receiver. However, the reports 402 may not come from receivers. Reports 402 explicitly identify the associated RTP session by including the destination IP address and port of the RTP stream in field 442.
In operation 486, the local media monitor 112 randomly picks an SSRC 444 similarly as defined in RFC3550. The SSRC 444 will not be subject to the SSRC collision detection scheme in RFC3550. Collision detection is not needed because the NOC 102 can distinguish the media stream reports 402 encapsulated in tunnel 404 from conventional non-tunneled RTCP receiver reports.
The frequency that the local media monitors 112 generate media stream reports 402 can be obtained from a b=RR: specifier 423 in the SDP message 422 provided during tunnel setup. Note that the report intervals 423 could be different from conventional RTCP reports generated by native receiver endpoints for the media stream. The NOC 102 may want more frequent or less frequent media stream reports 402 depending on monitoring needs.
The local media stream monitor 112 derives packet statistics for the identified media streams in operation 488. This could include any of the statistics normally generated in a RTCP report by a media stream receiver. For example, the media stream reports 402 in
Again, these are just examples of the packet level statistics that may be generated by the local media monitors 112 and tunneled to the NOC 102. Other information that may be contained in the media stream reports 402 is listed in RFC 3550, which has been incorporated by reference. As also described above, some of these packet level statistics might not be available if certain media sender reports cannot be received by the local media monitor 112. Other statistics not listed in RFC 3550 could also be derived.
Referring back to
The media stream reports 402 are de-capsulated from the other tunneling information in operation 502 and the statistical information contained in the media stream reports is further analyzed in operation 504. For example, the analysis system 406 in
The analysis system 406 in operation 506 uses the statistical information for display, logging, alarming, thresholding, or any other number of operations. For example, whenever a threshold number of packets from a media stream are identified as lost by one or more media stream reports 402, the NOC 102 may send a notification to a network administrator.
The NOC 102 either automatically, or pursuant to initiation by the network administrator, may initiate full media stream packet monitoring as described above in
Thus, the report monitoring scheme allows the NOC 102 to evaluate the overall network based on periodically received media stream reports 402. Any potential problems in the network can be flagged by the NOC 102 and further more detailed analysis initiated. This eliminates each individual node 110 or 114 from having to provide the alarms, thresholding, etc. normally required for notifying a network administrator or NOC 102 of a media stream problem.
As with the full packet tunneling scheme in
Only moderate bandwidth is required on a per stream basis from each of the intermediate nodes providing media stream reporting. For example, the bandwidth usage required by the nodes 110 and/or 114 may only be around 0.25 Packets Per Second (PPS) per media stream. Thus, hundreds of monitoring points can be established that monitor many media streams 116 at the same time. The data load on the NOC 102 is similarly tractable.
Thus it has been shown that the trap-clone-tunnel scheme can also be used to send packet level statistic reports 402 to a centralized NOC 102. Accordingly, better scalability is provided than computing the complex statistics in the intermediate routers/switches 110 or receivers 114.
Several preferred examples have been described above with reference to the accompanying drawings. Various other examples of the invention are also possible and practical. The system may be exemplified in many different forms and should not be construed as being limited to the examples set forth above.
The figures listed above illustrate preferred examples of the application and the operation of such examples. In the figures, the size of the boxes is not intended to represent the size of the various physical components. Where the same element appears in multiple figures, the same reference numeral is used to denote the element in all of the figures where it appears.
Only those parts of the various units are shown and described which are necessary to convey an understanding of the examples to those skilled in the art. Those parts and elements not shown are conventional and known in the art.
The system described above can use dedicated processor systems, micro controllers, programmable logic devices, or microprocessors that perform some or all of the operations. Some of the operations described above may be implemented in software and other operations may be implemented in hardware.
For the sake of convenience, the operations are described as various interconnected functional blocks or distinct software modules. This is not necessary, however, and there may be cases where these functional blocks or modules are equivalently aggregated into a single logic device, program or operation with unclear boundaries. In any event, the functional blocks and software modules or features of the flexible interface can be implemented by themselves, or in combination with other operations in either hardware or software.
Having described and illustrated the principles of the invention in a preferred embodiment thereof, it should be apparent that the invention may be modified in arrangement and detail without departing from such principles. I/We claim all modifications and variation coming within the spirit and scope of the following claims.
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A method for use in the study and diagnosis of vascular systems in which liquids of a wide range of viscosities and for various purposes may be injected into such a system at constant predetermined rates and volumes.
Claims available in
Description (OCR text may contain errors)
United States Patent James C. Hobbs, II
4384 lngraham Highway, Miami, Fla. 33 133 Mar. 25,1969
Jan. 4, 1972 Continuation of application Ser. No. 531,834, Mar. 4, 1966, now abandoned. This application Mar. 25, 1969, Ser. No. 810,292
Inventor App]. No. Filed Patented METHOD AND APPARATUS FOR INJECTING FLUID INTO THE VASCULAR SYSTEM 24 Claims, 9 Drawing Figs.
US. Cl 128/2 R, 128/218 A Int. Cl A61b 6/00, A6lm 5/00, A61m 5/20 Field of Search 128/2, 2.05,
[56] References Cited UNITED STATES PATENTS 2,602,446 7/1952 Glass et al 128/218 2,627,270 2/1953 Glass 128/218 2,690,178 9/1954 Bickford 128/213 2,896,621 7/1959 Rodriques. 128/218 3,155,090 11/1964 Holter 128/218 3,156,236 11/1964 Williamson... l28/2.05 3,252,623 5/1966 Corbin et a1. 222/59 Primary Examiner-Dalton L. Truluck Attorney--Watts, Hoffman, Fisher & Heinke ABSTRACT: A method for use in the study and diagnosis of vascular systems in which liquids of a wide range of viscosities and for various purposes may be injected into such a system at constant predetermined rates and volumes.
Apparatus to inject radiopaque fluid into a vascular system comprising a syringe, a plunger in the syringe, a catheter connecting the syringe to the vascular system, means to move the plunger in the syringe, and means to measure and control the speed of the plunger in the syringe throughout the period of injection.
METHOD AND APPARATUS FOR INJECTING FLUID INTO THE VASCULAR SYSTEM This application is a continuation of my copending application, Ser. No. 531,834, filed Mar. 4, 1966, now abandoned.
BACKGROUND OF THE INVENTION Heretofore various liquids, including liquids opaque to X- rays, have been injected into the circulatory systems of human beings for the purpose of recording the distribution of the liquid and examining the conditions and changes of conditions in the vascular system from time to time. The apparatus employed heretofore in an effort to accomplish the desired results has not been completely satisfactory so far as I am advised.
THE PRIOR ART The patents which are known to me and which, when employed, would carry out a method most nearly pertinent to the present invenn'on are the patents to Williamson, US. Pat. No. 3,156,236 and to Glass, US. Pat. No. 2,627,270.
SUMMARY The present method and apparatus inventions have been found to be highly satisfactory in contrast with prior methods and apparatus due, primarily, to the ability to control the operating conditions in such a manner as to insure that the injection rates and volumes of injected liquid may be predetermined and accurately repeated time after time and over extended periods of time. The present method has the additional quite desirable result of making it possible to observe, at various times during a long period of time, the progression and regression of a condition peculiar to some particular portion of the vascular system and directly comparing the conditions at different times. Also, the present method makes it possible to observes a locally affected area in the vascular system by delivering the same amount of liquid at the same rate of injection to the same area from time to time. Furthermore, the present method permits the injection of liquids having high viscosities which vary widely under different temperature conditions. Furthermore, the radiopaque liquid is injected by the present method at a controlled rate and in a controlled volume, thereby making it possible to duplicate diagnostic procedures and be able to compare conditions in the patient from time to time.
There are many factors and conditions which are involved in making injections of fluids into the vascular system. For example, none of the prior injectors could be so controlled that, in case the patient was to be exposed to X- rays, the desired amount of liquid opaque to the X- rays would be at the desired location during the desired portion of the cardiac cycle. As a result, X- ray pictures taken of the same patient from time to time were seldom comparable and, hence, the extent of changes would not be noted with certainty.
In other instances where it was desired to observe, over a period of time, the progression and regression of a condition of a particular portion of the vascular system, the prior injectors were incapable of performing in the same way on each occasion and, hence, the results were not directly comparable. In other instances where a locally affected area in the vascular system was to be treated, the prior injectors were incapable of delivering the same amount of liquid to the same area from time to time and, hence, the treatment was somewhat haphazard.
There are several reasons why the prior devices have been incapable of performing as desired including variations in the resistance offered by the equipment including the catheters through which the fluid is passed, variations in the pressure during the injection, variations in the amount of the fluid actually delivered to the desired place in the vascular system and variations in the rate at which the fluid is injected.
The catheters used to conduct the fluid from the injector into the vascular system are prime sources of variable resistance. The catheters vary in length, diameter, materials and internal surface finish, and the flow of fluid through the catheters varies with the variations in the physical configuration of the inlet and outlet ends of the catheters. Moreover, prior injectors have been equipped with various fittings such as stop cocks, check valves, and multiple outlet valves, and the pressure drop through these fittings varies widely. Thus, when all these structural features are taken into account, it is apparent that there is an almost limitless number of combinations of those equipment variables which afiect both the volume and the flow rate of the fluid at the discharge end of the catheter.
Variables are also present in the means used to apply the force to the syringe. Some prior devices have used high-pressure bottled gas as a source of energy to actuate the syringe. That gas was passed through a reducing valve to act upon the piston of the syringe. While such a procedure was a great improvement over the old method of having a manually operated syringe, it was quite difficult to control accurately the flow of gas under pressure at various temperatures and flow rates through small orifices and passageways of reducing valves in a very short period of time. There have also been mechanically actuated syringes activated by a metal spring but uncertain variables were present due to spring fatigue or friction, lubrication and even the temperature of the materials. Other efforts used an experimentally compiled data sheet to select a substantially constant torque to be developed by an electric motor connected to a screw thread to move the syringe. That arrangement produced a substantially constant force acting on the syringe but did not deliver the fluid at the precise rate desired. The arrangement also involved equipment which was large and bulky and often was underpowered, thus necessitating resort to a smaller diameter fluid discharge piston, in order to inject at the high pressures required to get a desirable flow. Such bulky equipment has also been restricted in the position in which it could be used in addition to using up premium space close to a patient that must be accessible to doctors and other equipment and apparatus.
Apparatus embodying the present invention avoids the foregoing troubles incident to equipment by including means which can exert any desired pressure on a fluid to inject any predetermined volume of it at any desired rate through any selected catheter or apparatus offering resistance to flow for any duration of time and for injecting predetermined volumes repeatedly throughout predetermined intervals.
BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood by those skilled in the art from the following specification and the accompanying drawings which form a part thereof and in which:
FIG. 1 is an isometric view of one form of injector embodying the present invention;
FIG. 2 is a fragmentary elevational view, partly in section, of means for raising and lowering the injector on its support post;
FIG. 3 is a side elevation, partly in section, of the syringe assembly, the power cylinder assembly and the motive power assembly of the injector of FIG. 1;
FIG. 4 is an end view taken on line 4-4 of FIG. 3 showing the gear train and the position of the tachometergenerator with respect to the motor;
FIG. 5 is an enlarged partial top view, partly in section, of the syringe assembly and power cylinder assembly of FIG. 3;
FIG. 6 is a fragmentary side elevational view, partly in section, showing details of the volume controls;
FIG. 7 is a fragmentary plan view of parts of FIG. 6;
FIG. 8 is a sectional view taken on line 8-8 of FIG. 5; and
FIG. 9 is a function diagram of the apparatus.
In FIGS. I and 2, A indicates the console assembly, B the syringe assembly, C the frame assembly, and D the power cylinder assembly.
TI-Ie console assembly A includes a base I mounted on casters (not shown), a post 2 extending up from the base, means including a rack 3 fixed to post 2, a pinion 4 having tooth engagement with the rack, a shaft 5 joumaled in pads on the console and a crank 6 secured to shaft 5 for moving the console up and down on post 2.
Control console 10 is a case which houses the electrical wiring and timing and control devices. On its sloping top surface, console 10 carries a powerline switch 1 1, an indicator light 12, a fuse 13, a time delay dial 14, an injection time dial 15, an injection rate dial 16, a master switch 17, a timed operation switch 18, a switch 20, and indicator lights 22. A remote handoperated switch is shown at 23, and 24 is an indicator light to indicate the existence of undesirable stray current or difference in electrical potential.
The console assembly includes an arm 25 hinged to the console and swingable in a horizontal plane with a hinge 26 at its free end carrying a tubular arm 27 rotatably carried on a rodlike extension of hinge 26. The arm 27 may be locked in position by clamp handle 28 and is connected to case 29. This case 29 constitutes part of the frame assembly, houses part of the power cylinder assembly and carries the motive power assembly and the syringe assembly.
The operations of the dial, switches and the like above mentioned as being parts of the control console assembly are as follows:
Main switch 11 controls the power supply into the console. Whenever indicator light 12 is on there is electrical power into the console. An easily accessible fuse of suitable size is mounted at 13 to protect the various assemblies of the injector against overloading. Time delay dial 14 controls the period of time, in seconds or fractions thereof, after the initial start of the injection cycle that will elapse before an auxiliary circuit, such as an X- ray control circuit, will be energized. Injection time dial 15 controls the total time of the injection cycle and, for purposes of illustration, may be established between 0.2 second and 4.0 seconds.
Injection rate dial 16 controls the rate of fluid injection in milliliters per second. The rate of discharge from the syringe is determined by the speed of the drive motor. For example, the rate of injection may be varied between 1 milliliter and 60 milliliters per second.
Switch 17 is one of two master switches that must be positioned properly for operation of the apparatus at a preselected rate. During preliminary preparations switch 17 is put in the Fill" position while the syringe assembly, described later, either is being filled with fluid or discharging fluid and possibly air. When switch 17 is in the "Fill position, switch 19 will control the direction of rotation of the motor by either being in the Load" or Unload position and when operating in either direction the motor speed will be at a slow fixed rate. When switch 17 is in the Inject position, switch 19 is cut out of the circuit and switch 18 is included in the circuit. Switch 18 may be placed in the Timed" position to include time delay dial l4, injection time dial 15, and injection rate dial 16 in the circuit. Switch 18 may also be positioned in the Manual position so that only injector rate dial 16 is in the circuit to control the speed of the motor and thus the rate of injection may be preselected while the period of time of injection is not automatically controlled.
Regardless of the position of switch 18 the injection will not begin until the second master switch 20 is placed in the Armed position. Thus, both master switch 17 and master switch 20 must be set by the technician before other than very slow injection will occur. When all dials have been set and other preparations completed, switch 20 is placed in the Armed" position at which time indicator lights 22 on the console and on the case will be on to indicate that all is ready and also as a warning to exercise precautions against accidental injection.
Remote switch 23 is shown as a handoperated switch although a footoperated switch might be preferred in some cases. Closing switch 23 will begin the injection at the rate selected by dial 16. If switch 18 is in the Timed" position, the injection will continue for the time period selected by dial 15 and then stop unless one of the other safety means described later should come into play. If switch 18 is in the Manual position, the injection will continue either until remote switch 23 is released or one of the other safety means is used.
For timed operation, switch 18 is set in the Timed" position, dials 15 and 16 are set, switch 17 is positioned in the Inject" position, switch 20 is placed in the "Armed" position and immediately indicator lights 22 come on. These lights indicate to the technician that all is ready. When remote switch 23 is closed the injection cycle will begin.
Indicator light 24 indicates the existence of an undesirable stray current or difference in electrical potential in connection with the patient and under such conditions the injection cycle will not begin and, if already underway, then current will be broken and the cycle will be interrupted.
Arm 25, tubular arm 27, and hinge 26allow case 29 to be moved close to the patient without using premium bedside space for either the console or the operator. In addition, case 29 may be raised or lowered by turning handle 6. Thus, it is possible to position the unit exactly as desired for each use.
Motive power assembly E is shown in FIGS. 3 and 4. Motor 30 is mounted within case 29 shown in partial section. Pinion 31 on the motor shaft engages clutch gear 32 which incorporates a spring loaded clutch normally engaged but onethat will slip in the event of an overload. Idler gear 33 acts between clutch gear 32 and drive screw gear 34 mounted on drive screw 35 which is positioned against axial movement by hearing 36. Tachometergenerator 37 is connected to the gear train for a positive drive from motor 30 and generates an electrical signal in proportion to the speed of rotation. The generated signal, as later described, is used to control the speed of motor 30. The slightly offset position of tachometergenerator 37 is more clearly shown in FIG. 4.
Motor 30 is a direct current motor that will have a high starting torque, attain the selected speed very quickly, be accurately controlled at a preselected speed, and may be almost instantaneously stopped by dynamically braking. The motor is large enough to develop whatever power is required to move the plunger 52, later described, at the selected rate.
Shown in FIGS. 5 and 6 and in part in FIG. 3 is the assembled relationship of frame assembly C, syringe assembly 8 and power cylinder assembly D. Frame assembly C is made up of backplate 40 to which is fastened guide tube 41 and two support rods 42 (also shown in FIG. 1). Bushings 43 are mounted on rods 42 and have screwthreaded connection with nuts 44. Heater 45 is to maintain the injection fluid close to body temperature and is made in form of a half cylindrical saddle to conform to the outer surface of cylinder 53 and is carried by straps 46 which are so formed as to fit over rods 42. Lead wire 47 is connected to the heater. Indicator rod 48 is positioned and supported by case 29 as shown in FIG. 1.
Syringe assembly B includes plunger stem 50 on which is mounted nut 51 in adjustable screwthreaded relationship. Plunger 52 is at one end of stem 50 and is slidable within cylinder 53 (shown in FIG. 1) which is supported at one end in a recess of yoke 54 so formed as to be loosely engaged and supported by rods 42. The other end of cylinder 53 engages cylinder head 55 preferably made of a transparent plastic material and supported by nozzle 56 (also shown in FIG. I). As will be seen, nozzle 56 is formed to engage shoulders on the ends of rods 42 to limit axial movement and also has a nozzle tip 57 to connect to a fluid conducting catheter 80 shown in FIG. 3. Fluidtight sealing is maintained where needed by use of O- rings 58 of proper dimensions.
Syringe assembly 8 may be removed from the injector as a unit by loosening nuts 44 and thumb screw 64. The assembly may be sterilized and replaced on support rods 42 as a unit. When this procedure is followed the entire area around nozzle tip 57 that is contacted by the technician while connecting the catheter is clinically clean and sterile and the possibility of contamination of the injection fluid or of the patient is greatly reduced.
Power cylinder assembly D is shown in horizontal section in FIG. 5 and partial elevation section in FIG. 6. Power cylinder 60 is fitted at one end with bushing 61 attached to nut 62. Nut
62 is screw threaded on drive screw 35. The screw thread between nut 62 and drive screw should have a minimum of friction and the ball bearing type of thread has been found to be very satisfactory for this purpose. At the other end of cylinder 60 adapter 63 is connected to and has a recess for one end of plunger stem 50. Thumb screw 64 is threaded into adapter 63 to engage an annular groove in stem and prevent axial movement of the stern out of adapter 63. Indicator pin 65 is connected to bushing 61 and cylinder and extends through an axial slot 75 in guide tube 41. Pin thus prevents rotation of the power cylinder assembly within tube 41 when drive screw 35 is rotating in either direction. Mounted on the outer end of pin 65 is knob 66. Slide post 67 has mounted on its outer end slide knob 68 and is positioned by slide block 69 which engages and slides in groove 75 in guide tube 41. Post block 70 is fastened to slide post 67 under the surface of case 29. Knob 68 may be loosened to allow the post 67 and block 69 to be moved to a desired position along slot and then tightened so as to clamp the knob 68 and block 70 against case 29 for a fixed position. Injection limit switch 71 is mounted on slide block 69 and thus may be moved and positioned axially by means of knob 68. Fill limit switch 72 is mounted on guide tube 41 in a fixed location.
In order to avoid bending and binding of the various parts of the connected assemblies the tension rods 42, plunger stem 50, and nozzle tip 57 are all in the same plane. With this arrangement of parts, the forces developed by drive screw 35 through cylinder 60 to plunger stem 50 and through the fluid against nozzle 56 are resisted by rode 42 in a balanced and symmetrical manner to avoid uneven deflections.
FIG. 7 shows the relationship of injection limit switch 71 and fill limit switch 72 to injection limit scale 73 and injection indicator scale 74 on case 29. The extent and shape of slot 75 in guide tube 41 is also shown clearly in this view. Injection limit pointer 76 is positioned by knob 68 and injection indicator pointer 77 is positioned by knob 66. Limit switch 71 is adjustable along slot 75 by loosening knob 68. The pointer 76 attached to knob 68 is positioned along the indicator scale 74. In operation, when indicator pin 65 advances and trips limit switch 71, the electric power supply will be interrupted to stop the motor 30. When the injector is being filled, post 65 will engage and trip limit switch 72 upon reaching the withdrawn position.
FIG. 8 shows the assembled relationship of the support rods 42, cylinder head 55, and nozzle 56. Also shown is the location of opening 59 with respect to the cylinder head 55. In addition this view shows slots 81 formed to receive the ends of rods 42.
FIG. 9 is a function diagram of the apparatus that shows the operational relationship of the various circuits and switches. If the diagram is used in the manner of the usual flow chart it is possible to trace one of several paths from the main switch 111 to the actuator or motor that drives the injector. FIG. 9 ineludes many of the parts referred to in FIGS. 1-8 and, for FIG. 9, the reference numbers will be the number of the part previously described and referenced plus 100. Thus main switch 11 of FIG. 1 will be referred to as main switch 111 of the function diagram.
It will be apparent from FIG. 9 that one of two principal functional systems may be used to operate the injector unit. Generally speaking, but not necessarily, one system is used for preparatory procedures and the second system is used for the fluid injection procedure.
The preparatory procedure may be traced down the lefthand side of the diagram. First, main switch 111 is closed to energize the injector console with power supply 100. Master switch 120 is placed in the Safe position and master switch 117 is placed in the Fill" position. It will be apparent that both manually operated switches must be properly positioned before the power supply is connected to and available to operate motor 30 of FIG. 1 and move plunger 52 of FIG. 5. Manual switch 119 controls the direction of rotation of the motor and thus the direction of movement of the plunger in the syringe assembly. In either direction of movement the rate control circuits, described later, that function when using the preparatory system, will maintain a low motor speed so the plunger movement will be at a fixed and low rate of approximately 4 milliliters per second. Whenever switch 119 is in the Load" position, the movement of the syringe plunger 152 will continue in the Retract direction until limit switch 172, of the Press to open" type, is tripped. Whenever switch 119 is in the Unload position, the Expel" movement will continue until limit switch 171, also a Press to open" type, is tripped or until adjustable stop nut 151 bumps against part of the syringe assembly and causes the clutch to slip.
When the motor is running and the actuator, comprising the motive power assembly and the power cylinder assembly, is moving the plunger, tachometergenerator 137 generates and sends a feedback signal to the rate control circuit to maintain the desired speed of the motor. The feedback signal is an electrical potential or voltage that is balanced in a conventional manner against a voltage corresponding to the selected motor speed. Any unbalance between the two voltages will result in additional current to the motor if the speed of the motor is low or less current to the motor if the speed is above the desired speed. The injection procedure is traceable down the righthand side of the diagram and includes the use of remote switch 123 as the final link to control power supply 100. Remote switch 123 is manually operated when all is in order for an injection and is the last switch to be closed in this system. Switch 123 is of the Press and hold to close type and thus at any time in the procedure the entire program may be stopped by releasing the pressure on the switch.
Also, as an automatic master control for this system, included is a ground detection and amplification circuit to open a relay and interrupt the power supply in the event of an undesirable difference in electrical potential between the patient and the injector apparatus. When such an interruption happens, indicator light 124 will indicate the existence of the hazard.
After master switch 120 is moved to the Armed position, indicator lights 122, shown as light 22 on both the console 10 and the case 20 of FIG. 1, will be lighted as a precautionary warning to the technician. Placing master switch 117 in the Inject position will make available X- ray delay timer 114 if it is desired to be used to actuate X- ray apparatus either immediately or after a specified delay after injection starts.
Switch 118 may be placed in the Manual" position in which case the injection time period will nonnally be controlled by remote switch 123 or by the later described limit switch 171. When switch 118 is in the Timed" position, a suitable timer is preset to control the injection period. The rate control circuit may be adjusted by variable rate control 116 to set the speed of the motor and thus the speed of the plunger. The use of the timed circuit with the variable rate determines the volume of fluid injected.
During the injection procedure the plunger, unless stopped by one of the abovementioned functions, will continue to expel fluid until either limit switch 171, of the Press to open" type, or adjustable nut 151 stops the plunger.
Throughout the injection procedure tachometergenerator 137 continues to send a feedback signal to be balanced against a signal corresponding to the rate selected and thus maintain the selected actuator speed.
Shown on FIG. 9 are four dash-lined boxes. Each box encloses a functional part or combination of parts that limit the volume of fluid injected. The quadruple duplication of limiting functions provides positive and absolute protection and safety of the patient against an excessive volume of fluid being injected at any one time.
In order to use the injector, cylinder 53 must first be filled with injection fluid. This may be done by tipping the syringe assembly to a vertical or near vertical position with the outlet of nozzle 56 up. Injection fluid is drawn into cylinder 53 by operating motor 30 in a direction to move plunger 41 back into the cylinder. The direction of rotation of the motor is controlled by switch 18 when switch 17 is in the Fill" position. When the plunger is in the full position, slide post 65 will trip limit switch 72 and stop the motor.
While the nozzle is in an upward position opening 59 in the nozzle next to transparent cylinder head 55 will permit a visual observation of the contained fluid to determine the presence of undesirable air bubbles in the cylinder. If air bubbles are present the cylinder may be tapped lightly to shake the air up and out through the nozzle tip 57 or the plunger may be moved slightly to force the bubbles out. When the cylinder is filled in a satisfactory manner, the catheter 80 may be connected and the necessary steps taken to prepare it for use.
Before the injection procedure is started, stop nut 51 should be positioned on plunger stem 50 to limit mechanically the forward or discharge travel of the plunger stern and attached plunger 52. The stop nut is set so that an annular groove on the edge of the nut is in line with the proper index mark on indicator rod 48. Then, should other limit means fail, stop nut 51 will bump against yoke 54 to prevent further travel of plunger 52 and thereby limit, by mechanical means, the volume of fluid injected. When this happens the spring loaded slip clutch on clutch gear 32 will slip and prevent mechanical damage to the unit.
For manual control of the injection program, switch 18 is moved to the Manual" position and switch 17 is moved to the lnject position. The rate of advancement of plunger 52 and thus the rate of injection is determined by the speed of motor 30 because of the positive mechanical connection through gears and screw threads to plunger 52. Tachometergenerator 37 is connected by suitable wiring through arms 25 and 27 to the console and the electric signal from the tachometergenerator is used through suitable circuits connected to dial 16 to regulate accurately the speed of the motor. Dial 16 is set for the desired injection rate. Switch 20 is placed in the Armed position.
After the above settings have been made for manual control, remote switch 23 need only be pressed and held in by the technician. The injection will begin at the rate indicated by dial l6 and continue either as long as switch 23 is held in or until post 65 advances with the power cylinder assembly and trips limit switch 71. When this procedure is followed the volume of fluid injected will be limited by a combination of mechanical and electrical means. lf it is preferred not to use limit switch 71, the technician may observe the advancement of pointer 77 along scale 73 and stop the injection at the desired limit by releasing switch 23.
For time control of the injection program, switch 18 is moved to the Timed position, switch 17 is moved to the Inject" position, dial is set for the length of time desired for the injection, dial 16 is set for rate of injection, and switch is moved to the Armed position at which time indicator lights 22 will come on. When the technician presses remote switch 23, injection will begin with the plunger 52 advancing at the rate selected by dial 16 and continued until the expiration of the time selected by dial 15. By using this combination 'of switches and circuits, it is possible to limit, by electrical means, the volume of fluid injected even though remote switch 23 is still closed and even though post 65 may not have tripped limit switch 71. However, if for any reason, at any point while under automatic control, the injection program may be stopped by the technician by releasing switch 23.
Switch 23 is connected to the console by a lead wire of sufficient length to allow the operator to be away from the console, after the necessary switches and dials are positioned, to permit the technician either to be close to the patient for constant surveillance or to be removed from the general area when X- rays are being made.
Because control switch 23 has full control over the operation of the injector, the procedure may be started and stopped at any instant. This precise control over the injection stroke of the plunger allows the technician to use the injector during the insertion of the catheter into the vascular system. By using a fluoroscope and injecting small amounts for short periods of time or stuttering" of fluids through the catheter, it is possible to follow the progress of the tip of the catheter as it is inserted into the body. Such control over the injection stroke may also be secured by using the rate dial and the time dial set at low range.
The terms fluid and fluids," as used herein with reference to materials which are to be injected into the vascular system and which are opaque to X- rays, mean and include not only liquids of a wide range of viscosities but also gases which are readily absorbed by the blood.
Having thus described this invention in such full, clear, c'oncise and exact terms as to enable any person skilled in the art to make and use the same, and having set forth the best mode contemplated of carrying out this invention, 1 state that the subject matter which I regard as being my invention is particularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or modifications of, or substitutions for, parts of the above specifically described embodiment of the invention may be made without departing from the scope of the invention as set forth in what is claimed.
What is claimed is:
1. The method of injecting radiopaque fluids into the vascular system of a human being which comprises the steps of:
a. placing a quantity of a radiopaque fluid in a syringe having a plunger, connecting one end of the syringe to a catheter to receive fluid expelled from the syringe,
c. inserting the other end of the catheter into the vascular system of a human being,
exerting sufficient force on the plunger to expel the fluid through said catheter and inject the fluid into said vascular system, and
maintaining a preselected constant rate of injection by continuously monitoring and maintaining constant the speed of the plunger advance in the syringe during the time of injection of fluid, said monitoring being the result of a signal automatically generated by control means connected to said syringe. 2. The method set out in claim 1 in which said rate is continued for a predetermined period of time.
3. The method set out in claim 1 in which a predetermined volume of the fluid is expelled.
4. The method set out in claim 1 in which the force is repeatedly applied and interrupted so that the flow of the fluid is pulsating.
5. The method set out in claim 1 in which a signal corresponding to the predetermined rate of injection is generated and a feedback signal corresponding to the actual rate of injection is generated and the two signals are maintained in balance.
6. Apparatus for injecting radiopaque fluids into the vascular system of a mammal comprising:
a. a syringe assembly including a cylinder to contain a radiopaque fluid, a plunger movable endwise therein to expel said fluids,
b. a frame assembly supporting said syringe assembly,
c. a power cylinder assembly operatively connected to said frame assembly and to said plunger,
(1. a motive power assembly including a motor operatively connected to said power cylinder assembly for moving said plunger at a constant predetermined speed, and
e. means operatively connected to said motive power assembly to generate a plunger speedindicating signal to control the speed of the motor whereby the discharge rate of said fluid is maintained constant independently of fluid pressure variations in the syringe assembly.
7. The combination of elements set forth in claim 6 in which the power cylinder assembly includes a cylinder, a threaded rod in and connected to said cylinder and connected at one end to said motive power assembly.
8. The combination of elements set forth in claim 6 in which a stop nut is adjustably screw threaded on said plunger to limit the endwise movement of said plunger in one direction.
9. The combination of elements in claim 6 in which the frame assembly includes at least two rods on opposite sides of said syringe and having the centerlines thereof parallel to and in the same plane as the centerline of syringe to support the syringe assembly and a nut on each rod to engage and clamp the syringe assembly in place.
10. The combination of elements set forth in claim 6 in which the motive power assembly includes a variable speed direct current motor and means for controlling the speed of the said motor.
11. Apparatus for injecting fluid into a mammular vascular system comprising:
a. a syringe assembly including a cylinder to contain a fluid to be injected, a plunger therein, and an endwise movable stern connected to said plunger,
b. a source of electric power,
c. an electric motor operatively connected to said source and said stem,
d. means operatively connected to said motor to monitor and control the speed of said motor at a constant preselected speed while injecting said fluid by continuously varying the power supplied to the motor to maintain a predetermined rate of discharge of said fluid,
e. a manually operated switch to start said motor, and
f. an automatically operated switch to stop said motor.
12. The combination of elements set forth in claim 11 in which said automatically operated switch is adjustable as to location.
13. The combination of elements set forth in claim 11 in which the said automatically operated switch is a relay switch that opens when an undesirable electrical hazard is detected.
14. The combination of elements set forth in claim 11 in which said manually operated switch is connected to and energizes an auxiliary circuit for apparatus to record the distribution of said fluid in said vascular system.
15. The method of injecting radiopaque liquids into the vascular system of a human being which comprises the steps of a. exerting sufficient force on a plunger in a syringe to expel radiopaque liquid from said syringe and into such a vascular system, and
b. maintaining a predetermined constant rate of injection of the liquid by continuously monitoring the forward speed of the plunger to maintain constant the speed of the plunger advance in the syringe during the time of injection of the liquid, said monitoring being the result of a signal automatically generated by control means connected to said syringe.
16. The method set out in claim 15 in which said rate is continued for a predetermined period of time.
17. The method set out in claim 15 in which a predetermined volume of the liquid is expelled.
18. The method set out in claim 15 in which the force is repeatedly applied and interrupted so that the flow of the fluid is pulsating.
19. The method set out in claim 15 in which a signal corresponding to the predetermined rate of injection is generated and a feedback signal corresponding to the actual rate of injection is generated and the two signals are maintained in balance.
20. The method of injecting radiopaque fluids into the human vascular system which comprises the steps of:
a. placing a quantity of radiopaque fluid in a motor driven syringe having a plunger, connecting one end of the syringe to a catheter to receive fluid expelled from the syringe,
inserting the other end of the catheter into the human vascular system, generating a first signal corresponding to the desired rate of flow of said radiopaque fluid out of said syringe, generating a feedback signal corresponding to the actual rate of flow of said fluid, and f. combining the two said signals, said combination of signals serving to o mate the motor of said motor driven syringe so that sat radiopaque fluid IS in ected into the vascular system at a constant rate of flow.
21. The method as in claim 20 wherein said feedback signal is derived by continuously monitoring the forward plunger speed.
22. Apparatus for injecting radiopaque fluids into the vascular system of a mammal comprising:
a. a syringe assembly including a cylinder to contain a radiopaque fluid, a plunger movable endwise therein to expel said fluids,
b. a casing assembly supporting said syringe assembly,
c. a power cylinder assembly operatively connected to said casing assembly and to said plunger,
d. a motive power assembly including a motor, operatively connected to said power cylinder assembly for moving said plunger at a constant predetermined speed, and
e. means operatively connected to said power assembly to generate a plunger speedindicating signal to control the speed of the motor whereby the discharge rate rate of said fluid is maintained constant independently of fluid pressure variations in the syringe assembly.
23. The apparatus as in claim 22 wherein said signalgenerating means is a tachometergenerator.
24. Apparatus for injecting fluid into a mammular vascular system comprising:
a. a syringe assembly including a cylinder to contain a fluid to be injected, a plunger therein, and an endwise movable stem connected to the plunger, an electric motor operatively connected to said stem and adapted to be connected to a source of electricity, means operatively connected to said motor to monitor and control the speed of said motor at a constant preselected speed while injecting said fluid by continuously varying the power supplied to the motor to maintain a predetermined rate of discharge of said fluid, and means operatively connected to the motor to automatically terminate the injection when a condition dangerous to the patient exist within said apparatus.
Patent Citations
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Players will be able to customize their characters with the same kinds of gear found in the original Shoot Many Robots, and more is on the way. While the official release date is still under wraps, interested players can sign up for the closed beta here. Check out a pair of screens – sans any robots that we can see – in the gallery below.%Gallery-160934%
Demiurge Studios Announces Shoot Many Robots: Arena Kings, May or May Not Have Robots in it
Cambridge, MA – July 23, 2012 – From Demiurge Studios comes Shoot Many Robots: Arena Kings, the player-versus-player follow-up to its recently released Shoot Many Robots. The new, standalone title Arena Kings is an online deathmatch that pits players against each other in a game of (porcelain) thrones. In "Royal Flush" the Kings must murder each other to collect their crowns, and flush them down a teleporting golden toilet, naturally. New content and updates are being added to the game weekly, based on feedback received directly from players. Don't just stay tuned to see what happens next – be a part of it!
Arena Kings is a free-to-play title for PC via Steam, and is currently in a closed beta. Prospective Kings and Queens can sign up at http://arenakingsbeta.shootmanyrobots.com – batches of keys are sent out weekly!
"We're taking our favorite parts of Shoot Many Robots and stirring in PvP competition and gameplay that's constantly evolving," says Will Jennings, lead designer on Arena Kings. "It's like a big tasty vegetarian stew with lots of guns in it, but also alive and mutating and fighting other soups. While I've got notebooks full of weapons, special moves, and pants I can't wait to add, what's really exciting is getting to hear from players in the earliest stages of the game's development and giving them what they're asking for, sometimes in the very next weekly update."
Arena Kings still has the zany gear from Shoot Many Robots (Butterfly wings, tighty-whities, deep sea diver helmet? Check, check, check!), and will continue to expand the creative uses of the multitude of equipment. Completing challenges to upgrade your arsenal and unlock achievements is only the beginning of how Arena Kings will continue to build upon its predecessor.
Founded in 2002, Demiurge Studios is one of the leading independent studios within Boston's thriving video game development community, making a name for itself developing creative, new IP for groundbreaking markets and platforms. The studio has been retained by industry leaders like Electronic Arts, Epic Games, Gearbox Software, Ubisoft, and more to help deliver over twenty titles for PC, mobile devices, and every major console since the studio's inception. Demiurge's first original title, Shoot Many Robots, is available for digital download on Xbox LIVE Arcade, PlayStation Network, and PC. For more information please visit www.demiurgestudios.com.