FSK Modem in RC: Obsolete or a hidden gem? - Page 3 - RC Groups
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This thread is privately moderated by jelle737, who may elect to delete unwanted replies.
May 09, 2018, 04:46 PM
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How to use a FSK Modem Board


This is how to wire the FSK Modem PCB:


This is the above schematic applied to connecting a Omnibus F4 Pro board running iNav with the FSK Modem PCB and with the audio line from the VTX:


The correct setup matching the above wiring is activating LTM telemetry on UART1 with a baud rate of 2400.
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May 13, 2018, 05:38 PM
throw new IOPilotException();
IceWind's Avatar
Is there any alternative to the SMD FX604D4? Seems it is deprecated as well.
I'd like to make a TX module for my wings, but it needs to be quite small, in the ground a thru-hole is fine as there are no size limitations.
May 14, 2018, 10:39 AM
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Quote:
Originally Posted by IceWind
Is there any alternative to the SMD FX604D4? Seems it is deprecated as well.
I'd like to make a TX module for my wings, but it needs to be quite small, in the ground a thru-hole is fine as there are no size limitations.
I actually have that chip around here also because SMD stuff is always better then through hole (in my opinion). But the difficulty is that we set the tone pitch of 1 and 0 with resistors and the tone speed with a crystal. And none of them are standardized use at the moment, since a 4.433Mhz crystal is almost impossible to find. Meaning If you want to cross use them you will have to figure the values out. And if you just want to use that system independently then you still have to draw up a board. The FSK Modem v3 board is actually quite small though. There seems to be adequate wing space to hide such a chip in though. If you design something compatible with the existing system I'm def going to try it out also.
May 14, 2018, 11:29 AM
throw new IOPilotException();
IceWind's Avatar
Well I prefer SMD for size reasons. Smaller, lighter ...plan would be to set this on a 800mm wingspan wing (S800) that I'm cutting down on weight on anything possible to make it fly for as long as possible.

I see what you mean about the cristal usage, meaning that both ends would need to be using the same specs.
May give it a got and convert the FSK Modem v3 board to SMD and see how it goes. I'm no PCB export but should be ok as the part count is low.

PS: if cost + postage for those you have is ok I may get two to test. I'd like to make an mobile app to read the data.
Similar to what immersionRC has. That should pretty much FSK modem as well.


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