Switching between observation channels

Hi,

I know it is not possible to receive from both observation channels at the same time. 

I plan to use the ObsRx1 for calibration and once calibration is done start to receive signal from ObsRx2 while both are using sniffer PLL at the same frequencies. The received signals should be the same at both ObsRx1 and ObsRx2 without a random phase shift after switching. Based on MYKONOS_setObsRxPathSource function, it looks like the switching process it quite time consuming. 

Would you please let me know if this switching can cause a random delay between the observation channels? 

Is there other simpler/quicker switching between the channels?

Thanks

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  • Thanks for your reply.

    In our application, actually it does not matter if the time to receive data after calibration is long, what I want to know is that whether the received signals from ObsRx1 and ObsRx2 are exactly the same after switching or there could be a random delay due to the switching?

    I appreciate it if you could answer this question.

  • +1
    •  Analog Employees 
    on Nov 10, 2020 11:03 AM 3 months ago in reply to mamad2

    Using pincontrol mode, the switching time between the two ORX paths will be reduced as compared to the ARM control mode. But in both the cases, it is not possible to operate both the ORX at the same time instant. 

  • Thanks for your help.

    I did one experiment with interesting results. I send a sine wave from Tx1 to Rx1, ObsRx1 and ObsRx2 continuously. In the API, I firstly choose channel ObsRx1 and received a set of data and then switch to ObsRx2 (could not make the Pin-mode work as you mentioned and so used ARM control mode) and captured another set of data. It looks like when I switch from ObsRx1 to ObsRx2 there is always a constant phase shift between the received signals. For example, in the below figures, the delay between Rx1 and ObsRx1 is 8 samples and between Rx1 and ObsRx2 is also 8 samples, thus with reference to Rx1, ObsRx1 and ObsRx2 have 16 samples delay. I have tried this experiment several times and found out that the delay (of 16 samples) is always constant and it is not a random number. If switching works like a RF switch this could be true, but I want to be sure. 

    Would you please let me know if this experiment shows the fact of a constant delay between ObsRx1 and ObsRx2 after switching?

    Thanks

  • 0
    •  Analog Employees 
    on Nov 11, 2020 9:18 AM 3 months ago in reply to mamad2

    Can you check the phase difference between ORX1 and ORX2 and see if its constant for multiple measurements? Also you should measure the phase difference w.r.t a common trigger for all of the receive paths.

  • Can you check the phase difference between ORX1 and ORX2 and see if its constant for multiple measurements?

    Since I cannot receive both ORx1 and ORx2 at the same time I used Rx1 as a reference. Actually did the measurements for several times, it was constant. 

    Also you should measure the phase difference w.r.t a common trigger for all of the receive paths.

    I am thinking I did measure the phase differences based on the number of samples. Could you please explain how can I do this?

    Thanks