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--- projects:jimbob:frequency [2013/09/04 14:07] – created kevwal
+++ projects:jimbob:frequency [2013/09/04 14:26] (current) – kevwal
@@ Line 1: / Line 1: @@
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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
+  * **434.150Mhz - Good Frequency?**
+  * 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
+  * **434.412Mhz - Good Frequency?**
+  * 434.475Mhz - Internet voice gateway, 25khz
+  * **434.487Mhz - Good Frequency?**
+  * 434.500Mhz - Internet voice gateway, 25khz
+  * **434.512Mhz - Good Frequency?**
+  * 434.518Mhz - Weak interference
+  * 434.525Mhz - Internet voice gateway, 25khz
+  * 434.550Mhz - Weak interference
+  * **434.562Mhz - Good Frequency?**
+  * 434.581Mhz - Weak interference
+  * 434.600Mhz - Repeater input, 25khz
+  * **434.612Mhz - Good Frequency?**
+  * 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.