PGA460: can the device detect the phase shift?

Hi Armin,

Unfortunately, the PGA460 is not design for Doppler shift applications. The device is primarily intended for time-of-flight measurements.
However, it is possible to implement a systematic workaround to enable a Doppler based output. Here is an example on how to implement Doppler/phase shift:

Because the burst/listen command is disruptive, and will take priority over anything else the PGA460 is handling, you could send a burst/listen command of 32 (max pulse count), and just before the last pulse is transmitted, send another burst/listen command to extend the pulse count by another 64 pulses. The timing of the subsequent burst/listen command must be accurate to ensure the pulse stream at the transducer seamlessly extends from 32 to 64. This process could be repeated to extend the pulse count indefinitely.

On the receiver end, you will not be able to leverage the typical DSP sequence for automatic phase shift. The phase shift detect must be handled by your external MCU. Here are two options on extracting the data from the PGA460:
1) Use the Analog Front End output test mode to leverage the integrated low-noise and programmable amplifier. You will need to connect this output to an external ADC/MCU for post-processing.
2) Use the direct data burst mode to capture the 1MSPS rate output from the ADC, DSP's BPF, or DSP's Rectifier. This will require a SPI connection to the PGA460 with an 8MHz clock. The overhead of this implementation is the large external memory buffer requirement and real-time capture/processing of the incoming data stream at the MCU (assuming you are continuously transmitting and receiving data). The advantage of this approach is that the integrated ADC and/or DSP is leveraged to prevent external noise from coupling onto the AFE's analog output.