 gineer can choose a value that the receiving device might require or prefer. Sometimes the receiving device is required to be calibrated to whatever length of pulse is chosen. In most cases, the 1PPS signal is carried over 50-ohm coax cable (coverage of other options follows). Remember that the length of coax cable that can carry a 1PPS pulse is quite limited, certainly much less than 10 m; however, for high-accuracy applications, the coax cable should be of very good quality and be short (less than 2 m). The 1PPS connector often is the same type as the frequency connectors-on timing equipment, it is very common to see BNC, whereas other devices might support SMB. Cisco routers support 1PPS signals with a DIN 1.0/2.3 jack, the same as the 10-MHz frequency connector (refer to the left-hand side of Figure 9-3, earlier in the chapter). Some network elements also support a form of connector (like SMB and DIN 1.0/2.3) that is known as micro coaxial connector (MCX) or micro-miniature coaxial (MMCX). These are popular con- nectors in Europe (they are specified in an IEC standard) and are commonly used as a GPS antenna connector on devices too small to house an SMA connector (such as handheld navigation devices). With all these types of connectors out there, you can see that it is vitally important to understand ex- actly what is needed SO that you don't arrive onsite with the wrong cable or adapter. A second option for 1PPS is to carry it alongside the ToD running on a different set of pins on a type of serial interface over 100-ohm UTP (see clause 19.1 of ITU-T G.703 for specifications and pinouts). In an RJ-45 form factor, this is a balanced signal (such as ITU-T V.11) with two pins car- rying the positive and negative of the ToD and another two pins carrying the 1PPS. Of course, using the UTP/RJ-45 method to carry a combined 1PPS and ToD is easier from a cabling and deployment point of view than using separate connectors for each signal. But, be prepared to change the pinouts if you are trying to use standard Ethern