Hi Leon,
For non-coherent FSK demodulators, you require deviation to be at least
the symbol rate Rs. So for 600 baud 2FSK, thats at least 600Hz shift
(deviation).
The FSK demod is low complexity, and the processing is proportional to
bit rate. So my gut feel is 10 600-baud demods running in parallel
would be no problem on the stm32f4.
- David
On 08/03/18 22:43, Leon Lessing wrote:
Hi guys,
Thought I was subscribed here, found out with a bang that I am not.
Here goes.
Doing investigations into Lora it seems their spectrum utilization
really sucks, in that on 125kHz channel only one device can talk at
240bit/s at a time (class A device). I honestly thought that being
spread spectrum we could have 20 to 30 devices talking at the same time,
very much like the gps signals. (the sx1301 seems to do multi channel
reception but on 8 different frequencies)
One question here is we run 100Hz deviation about 500Hz apart at 300 to
600 baud, how many simultaneous channels could be decoded with a single
stm32f4 or stm32f7 device. Basically running 22k samples per second I/Q
The idea here is basically for aprs, so a digipeater should be able to
decode 10 or more "channels" at a time. And then be able to "talk back"
to a device, very much like sigfox does. The talk back could be a normal
1200baud fsk channel.
Using a si4463 we could conceivably transmit on 70cm with 20 to 100mW
and receive on 144.800/144.390 depending on the region used.
73 de Leon
ZS6LMG
Leon Lessing
雷立安
ZS6LMG/AC9GU
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