Constant DC at RF input for one signal, otherwise works fine
Posted: Thu Jan 21, 2016 5:00 am
I'm trying to sample an ultrasonic transducer using the RF input.
I've hooked an oscilloscope up to the output of the cable I want to use and I'm seeing a noisy DC signal at about 1.15V, except when I trigger the transducer, when I see the signal I want to be able to sample. When I connect that same cable to the RF input of the Red Pitaya, the Red Pitaya only sees a constant DC voltage for the entire buffer (literally buff == buff[i+1] for the entire buffer).
When nothing is connected to the RF input, the Red Pitaya sees a noisy DC signal at about -0.013V.
I swapped to Python and reconnected the transducer and I still saw the perfectly DC signal. I generated a waveform on the RF Output and sampled it on the RF Input using Python, and matplotlib was able to perfectly reconstruct it.
I'm at a loss for what the problem could possibly be. The Red Pitaya is apparently sampling correctly and the output of the cable I want to sample is apparently the correct signal, but for some reason when I plug the cable into the RF input, the Red Pitaya only sees a DC voltage that stays constant down to the smallest decimal place. Has anybody got any ideas?
I've hooked an oscilloscope up to the output of the cable I want to use and I'm seeing a noisy DC signal at about 1.15V, except when I trigger the transducer, when I see the signal I want to be able to sample. When I connect that same cable to the RF input of the Red Pitaya, the Red Pitaya only sees a constant DC voltage for the entire buffer (literally buff == buff[i+1] for the entire buffer).
When nothing is connected to the RF input, the Red Pitaya sees a noisy DC signal at about -0.013V.
I swapped to Python and reconnected the transducer and I still saw the perfectly DC signal. I generated a waveform on the RF Output and sampled it on the RF Input using Python, and matplotlib was able to perfectly reconstruct it.
I'm at a loss for what the problem could possibly be. The Red Pitaya is apparently sampling correctly and the output of the cable I want to sample is apparently the correct signal, but for some reason when I plug the cable into the RF input, the Red Pitaya only sees a DC voltage that stays constant down to the smallest decimal place. Has anybody got any ideas?