1 2 3 4 5 6 7 8 9

DECrouter 2000 is a moderate cost ($14,000) unit that would probably be adequate, but some research should be done to determine the best routers for this application.

The modems used should be the Fairchild SM-2800. It is important to verify that the routers chosen will interface properly with these modems. It might also be useful to install a pair of MICOM (or equivalent) multiplexers to allow a couple of voice channels to be multiplexed into the data stream on demand.

The receive system should be based on Icom R-9000 receivers. These receivers would be common to both systems, and would probably accommodate any future link with down- converters. It should be noted that there are many considerations to selecting receivers for this application in addition to simple frequency and bandwidth specifications.

There would need to be an up-converter designed and several copies built - this is to accommodate the 70 MHz input requirement from the modem with the IF output of the receiver at 10.7 MHz. The transmit chain is somewhat more complicated, as it is unlikely that any commercial equipment exists, except for the power amplifier for GOES-2. These transmit systems would need to be designed and built.

The 100 watt amplifier for LES-9 operates at UHF frequencies (300 MHz) and the components are cheap and readily available since there are many commercial 2-way radio services around those frequencies. The GOES-2 amplifier needs to operate at L-Band frequencies (above 1 GHz) and therefore requires the more expensive traveling wave tube (TWT) technology for which there are no equivalent commercial uses.

The specific recommendations for each system are as follows:

1) LES-9

cost $

100 5000 4000
???? 2000

1. Existing receive antenna with RF splitter. 2. Icom R-9000 Receiver with up-converter on IF 3. Fairchild Model SM-2800 Modem
4. Custom Built Up-converter for Transmit 5. Custom Built Power Amplifier (100 Watt) 6. Transmit antenna near the Dome

LES-9 bitrate is expected to be 16-32Kbps. There are likely to be some periods of degraded performance due to various mechanisms which result in signal fading. Assuming 16Kbps, 6 hours daily availability yields 34.5 MBytes/day throughput.

2) GOES-2

1. TVRO type Dish Antenna (approx. 3 meter) 2. Commercial Duplexer
3. Commercial Preamplifier
4. Icom R-9000 Receiver with up-converter on IF 5. Fairchild Model SM-2800 Modem 6. Custom Built Up-converter for Transmit 7. Commercial 100 Watt Power Amplifier

cost $

???? 18000

GOES-2 bitrate is expected to be 56Kbps. It is visible at South Pole for approximately 3 hours, increasing in elevation about 0.6 degrees per year. This yields 60.4 MBytes/day throughput.