I'm trying to build simple fsk transmitter and receiver, the transmitter is just an
FPGA with a wire, the logic is quite simple, I mix (with a XOR) the transmission frequency with a lower frequency, thats create some distortions which can be picked up with a simple FM receiver.
The receiver is based on the TDA7000 (yes I know that's obsolete) with a fixed tuning frequency. Here is the received spectrum for two different case, the peak at
1.1 KHz should indicate logic
LOW and the peak at
1.6 KHz should indicate
HIGH, the peaks are about
300mV, but I guess it may vary
Note that there are distrotions at
2.1 Khz and and
How can I feed the signal to an FPGA, which should count and identify the frequency, with a minimal number of parts, I guess
LM741 is too much for that kind of task.
How do I deal with the distortions?
Any other suggestions?