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Frequency Ramblings

Frequency range legally available is 434.04MHz - 434.79MHz according to IR2030.

Point in time analysis using SDR and external collinear:

434.040MHz - Start of legal band
434.046Mhz - Weak interference
434.075Mhz - NTX2
434.078Mhz - Weak interference
434.099Mhz - Weak interference
434.110Mhz - Weak interference
434.112Mhz - Weak interference
434.121Mhz - Weak interference
434.127Mhz - Weak interference
434.169Mhz - Medium interference
434.267Mhz - Weak interference
434.320 to 434.330 - Strong interference
434.330Mhz - Weak interference
434.347Mhz - Weak interference
434.361Mhz - Weak interference
434.369 to 434.379 - Strong interference
434.375Mhz - Emergency Comms
434.392Mhz - Weak interference
434.475Mhz - Internet voice gateway, 25khz
434.500Mhz - Internet voice gateway, 25khz
434.518Mhz - Weak interference
434.525Mhz - Internet voice gateway, 25khz
434.550Mhz - Weak interference
434.581Mhz - Weak interference
434.600Mhz - Repeater input, 25khz
434.613Mhz - Weak interference
434.625Mhz - Repeater input, 25khz
434.650Mhz - NTX2
434.650Mhz - Repeater input, 25khz
434.675Mhz - Repeater input, 25khz
434.687Mhz - Good Frequency?
434.700Mhz - Repeater input, 25khz
434.725Mhz - Repeater input, 25khz
434.737Mhz - Good Frequency?
434.750Mhz - Repeater input, 25khz
434.775Mhz - Repeater input, 25khz
434.790Mhz - End of legal band

Thinking about frequency spacing, to be able to receive multiple transmissions with one dongle:

Typical RTTY bandwidth is 650Hz, we probably want at least 3,000Hz gap to keep audio spectrum separate.

Frequency drift research is very difficult, actual examples found are down at 1.1 or 5.7khz, advice is that they could drift 20khz. 50khz spacing seems a reasonable suggestion to allow for +20khz of one and -20khz of another.

We want to restrict the spacing to the FunCUBE Dongle bandwidth of 192,000hz, 50khz plus drift fits easily within this bandwidth.