wiki/ communications/ PSAS AV2c C Band Telemetry System
  1. Telemetry Radio
    1. Requirements
  2. C Band Power Amplifier

In our transition from LV2 to LV2.3, we've moved from S to C band for our telemetry because it's Just Better Up Here - we get smaller antennas, and less noise. More importantly, it gets our amateur TV out of the L band and into the now vacant S band, reducing interference with the also L band GPS. In the amateur radio world, running 802.11x in the amateur radio regulations (FCC Part 97) is called High-speed multimedia radio (HSMM).

Telemetry Radio

Requirements

Our requirements:

Radio

We're currently using the Alfa Network 802.11a/b/g/n/ long-range wieless USB adapter model AWUS051NH which seems to work great.

Choice of Channel

According to iwlist, the adapter supports the following channels:

**Channel 36 : 5.18 GHz**
Channel 40 : 5.2 GHz
Channel 44 : 5.22 GHz
Channel 48 : 5.24 GHz
Channel 52 : 5.26 GHz
Channel 56 : 5.28 GHz
Channel 60 : 5.3 GHz
Channel 64 : 5.32 GHz
Channel 149 : 5.745 GHz
Channel 153 : 5.765 GHz
Channel 157 : 5.785 GHz
Channel 161 : 5.805 GHz
Channel 165 : 5.825 GHz

The adapter literature claims it supports 5.15GHz to 5.35GHz and 5.725GHz to 5.825GHz. That's good, except the high end ought to be a bit higher, like 5.83 GHz to really run in channel 165. Huh.

If possible, we'd like to aim dead set in the middle of one of those two bands, so we have room to move up or down in order to match whatever our actual cylindrical patch antenna center point ends up being. And of course, we like higher frequencies, so maybe aim for channel 157 (5.785 GHz)? Although the higher band has a ± 40 MHz range while the lower channel has a ± 60 MHz range.

After testing the CPA, we found a sweet spot nearest channel 36.

C Band Power Amplifier

Requirements

Power Amplifier

We use the the RF LINX Corporation's now obsolete "ANTENNAFIER 4900-5800 CA SERIES" power amplifier. It has: