 companies with a completely private network. 3. To provide quality telecommunication connectivity where other means are substan- dard or nonexistent. Regarding reason 3, the author is aware of one emerging nation where 124 bank branches had no electrical communication whatsoever with the headquarters institution in the capital city. 9.3.8.2 Characteristics of Typical VSAT Networks. On conventional VSAT net- works, the hub is designed to compensate for the VSAT handicap (i.e., its small size). For example, a hub antenna aperture is 5 m to 11 m (16 ft to 50 ft) (Ref. 12). High-power amplifiers (HPAs) run from 100 W to 600 W of output power. Low-noise amplifiers (LNAs), typically at 12 GHz, display (a) noise figures from 0.5 dB to 1.0 dB and (b) low- noise downconverters in the range of 1.5-dB noise figure. Hub G/T values range from +29 dB/K to +34 dB/K. VSAT terminals have transmitter output powers ranging from 1 W to 50 W, depending on service characteristics. Receiver noise performance using a low-noise downconverter is about 1.5 dB; otherwise 1 dB with an LNA. G/T values for 12.5-GHz downlinks are between +14 dB/K and +22 dB/K, depending greatly on antenna aperture. The idea is to make a VSAT terminal as inexpensive as possible. Figure 9.21 illustrates the conventional hub/VSAT concept of a star network. The hub is at the center. Figure 9.21 Typical VSAT network topology. Note the star network configuration. The outlying VSAT terminals can number in the thousands. 9.4 FIBER-OPTIC COMMUNICATION LINKS 9.3.8.3 Access Techniques. Inbound refers to traffic from VSAT(s) to hub, and outbound refers to traffic from hub to VSAT(s). The outbound link is commonly a time- division multiplex (TDM) serial bit stream, often 56 kbps, and some high-capacity systems reach 1.544 Mbps or 2.048 Mbps. The inbound links can take on any one of a number of flavors, typically 9600 bps. More frequently, VSAT systems support interactive data transactions, which are very short in duration. Thus, we can expect bursty operation from a remote