![]() What can be deduced from the already available information is that transmission is purely digital. 1: Normal waveform without echo 2: 16 zeros 3: sync pulse 4: water temperature (?) 5: signal with artificial echoes I'll take it to the lake later today. Here are a few screenies that I obtained by rubbing the transducer and hence fooling the receiver. There is a strange 16 bit 0 value, then a long sync pulse of 6, ms, the echoes - if any - and the water temperature in 16 bit. My suspicion, and also the information in the patent, seem to be what's going on. So, I have received the 433 MHz Receiver and played around. Btw, here are the insides of a wireless unit: the bottom of the PCB is +- unpopulated. I think a lot of people would be interested. Since Dave was in the sonar industry for a while, maybe he has a few hints, or maybe he could teardown one of these units and explain it. However, I couldn't really find any circuit descriptions, but what's worse: I can't find the piezo transducers. Or is this maybe analog modulated an the main unit does it all? If impossible, or at a later step, I'd like to tinker around with some piezo crystals myself. Does anybody have info about how exactly it works? I guess it must be a two way communication, as there are some settings on the main unit about the depth range etc. There are Chinese knockoffs that go by the name "Freecast", which implies, the protocol can be decoded. There is the famous Humminbird Smartcast, which has been taken apart here: Basically, the same thing is available as wireless unit: As a first step, I'd like to tap into the 433 Mhz signal the unit is sending. Hi, I would like to build a simple wireless fish finder.
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