Hi All,
Hopefully someone has experience with this or an equivalent. I am attempting to get a simple example working for the AD8339 evalz board, which does frequency demodulation at low (0--50 MHz) frequencies meant for ultrasonic processing. Here's the attached the data sheet for reference, as well as multiple pictures and some code.
Ref sheet:
For reference, I am approximately using Figure 62 of the data sheet as a setup, except that I am trying to use SPI and a raspberry pi. The board itself is older, and the cd that comes with it (yes, cd...) has software that only works on windows XP.
I am only using the first channel as input, my signa gen is a dual channel, so they're inherently synchronized.
The SPI has a 20 bit shift register that allows for enabling of channels 1-4, and for setting phases for the demodulation step (that part is not important for now, since I'm trying to run test where all phases are 0.
Since the bits are fed in reverse, a basic 20 bit word enabling only channel 1 is: 0000 0000 0000 0000 0001
The shift register timing reference is on Figures 56-57. The local oscillator needs to be 4 times the input frequency (4Lo), so I'm running tests with a 50 kHz wave (channel 1) and a 210 kHz 4Lo. The result on the sampled outputs SHOULD be a 10 kHz wave on one of the two channels, and nothing on the other (since the demodulator create IQ data).
4. "signal_gen.jpg" and "gen_osc.jpg" show the generator and o-scope setup. The generator is a 2-channel Rigol, so the input and 4Lo shown in figure 61 of the data sheet are channels 1 and 2 of the generator. Channels 1 and 2 of the o-scope are connected as in Figure 61.
6. From my understanding of Figure 57 and previous things I've done with shift registers, I put together a very simple python script attached ("py_script.jpg") to set shift register states. As such, if I feed in a 50 kHz wave with a 4Lo of 210 kHz with a common phase of 0, I would expect the result to be a 10 kHz wave showing only on one of the two output channels, but I get nothing.
