rtl_433
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merbanan
Fish Finder
rtl_433 -X 'n=fishfinder,m=OOK_PWM,s=175,l=575,r=700'
There are three different signals: 20 bits c0000, 16 bits b3cc or b3cc and one long pulse (6.6 ms, shown as {1}0).
Data could be in that b3.. packet, or if those don't vary then the data could be in the timing? Faster signals -> more fish close by? Or what should the signal indicate?
I think the 20bits might be a sync code as this changes when you switch the unit on and off
The 16bits might be the water temperature and the other data packets are the returns
There seems to be a long 6ms sync pulse, but the other signals are PWM
Fish finder sonar: circuits, protocols and transducers
I have now managed to decode the 20 Bits, the first 16 bits are the temperature, strangely the bits are doubled up, odd and even bits are the same. So I needed to extract every other bit to decode the temperature. I still need to calibrate the algorithm to get the correct temperature.
