We want to use AFE5809 in a ultra sound application, and need the demodulator for envelope detection. I have been playing around with the AFE5809EVM / TSW1400EVM in order to get familiar with the device.
I use a 10MHz as carrier frequency and modulate it with 20KHz on channel 1. Using the demodulator example in the slou338a (User's guide), with the decimation factor M=4 and the predefined filter coefficients i can see the envelope of the signal however, the dynamic range seems to be very low, and also DC offset - as seen on the screenshot below:
I don't understand this behavior. I have set the gain to produce maximum signal after the ADC, so why is signal level so low after the demodulator? Similar behavior is also seen in the example on page 19 in the users guide.
Additionally I want to highlight an issue with the eval. kit / SW. Seems like every time I change some parameters in the demodulator via the GUI, the other settings i.e. the input termination are reset, and need to be set again by the user.
