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AD9361 RX data error In RF loopback

Category: Software

Hi Sir,

Am configured the AD9361 in

FDD mode

DDR

60MSPS

with data clock 30Mhz

FB clock also 30Mhz

1R1T  mode with 2.4Ghz LO

8Mhz Bandwidth

we are NO-OS files  we are  using custom board

We are sending  12bits of  data on Tx data port   with every 40msec  continuesly    we are observing RF loopback   we require same data on RX data port

but we are getting incorrect data on RX data port 

But same operation On BIST loopback we are getting  same data ON RX data port bist is working fine.

Issue with RF loopback please give me the solution...........

Top Replies

  • Can you please check the Tx output in the spectrum and ensure that getting as expected, in similar way feed input to the receiver from the signal generator and verify that you are able to see the data. Once both steps are working fine, try testing with RF loopback.

  • Okk sir ,

    But in the receiver chain rx FIR filter overflow is happening it is observed in 0x5E register 

    And 0xF3 and 0xF4 register filter 16 bit coefficients are not reading  i observed these registers are with 0x00 

    How to solve these issues please let me know sir

  • Please give me an idea on AGC configuration

  • What is your configuration, like an FMCOMMS eval board or custom board? and share the configuration where you are seeing failure, Please ensure to operate the device in automatic gain control mode to verify the response of the receiver and to avoid overflow. 

    Is this overflow are you observing when you feed the signal from the external signal generator to the Rx channel?

    How are you loading the filter coefficients in AD9361 and what process you are following to generate the coefficients, please use the AD936X filter wizard to generate the filter coefficients,

  • Please give me an idea on AGC configuration

    Please refer to the AGC section in UG-570 (AD9361 user manual).

  • My board is FMCOMMS3  eval board configured using Zedboard 

    Yes am working on AGC control mode only yes  I observed it overflow only in 0x05E  register the value is 0x81 instead of 0x80 

    By applying external signal i didn't checked the overflow and about filter coefficients am using what ever ADI provided using same cofficients i didn't changed those cofficients 64 cofficients only am using 

    My input signal is 2Mhz with data rate 30MSPS.

    For this how find filter coefficients is there any changes in cofficients and no.of taps.

  • 0X05E is 0x81 means that the RFIR in the RX datapath is saturating.

    Are you giving a TDD waveform at the TX input and then looping back TX output to RX input? Are you using AGC in fast attack or slow attack mode? Are you using default AGC setting?

    Also, have you generated filter coefficients  from Matlab based filter wizard tool for 30Msps sampling rate? Are you using the same? If not, you can generate a filter with the required input sampling rate and bandwidth , from the below filter wizard tool:

    https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms2-ebz/software/filters 

  • AHi sir Am using FDD mode waveform at TX input and then loopback TX output to RX  input through RF loopback .

    yes sir am Using  AGC configuration in slow Attack mode yes am what ever ADI provided those only am using for AGC settings.

    No sir am not generated Filter cofficients from Matlab based filter wizard..

    Am using 60MSPS sampling rate .

    Present Am using same filter coefficients.

    For 60MSPS input rate what is TX FIR and RX fir filter clocks sir in clock chains 

    Please give clock chains for 60MSPS for TX chain and RX chain

  • AHi sir Am using FDD mode waveform at TX input and then loopback TX output to RX  input through RF loopback .

    Did you verify the Tx output in the spectrum analyzer per your requirement? As I mentioned in a previous reply please do the below things before RF loopback.

    1. Configure the Tx and verify the Tx output in the spectrum analyzer and make sure the output spectrum is as per spectrum.

    2. Feed the input signal to the Receiver from the signal generator and verify the performance, and verify if overflow is happening. 

    3. Make sure to keep the same configuration settings for the receiver and transmitter as per your requirements.

    4. once you are satisfied with step:01  & step:02, proceed to RF loopback and it should work.

    No sir am not generated Filter cofficients from Matlab based filter wizard..

    if you are facing issues, please disable the FIR filter and verify the response, please do this experiment after the above steps if the still problem persists.

    For 60MSPS input rate what is TX FIR and RX fir filter clocks sir in clock chains 

    Refer to the below snapshot for the sampling clock for ADC and ADC, and also clock rates for each step.

  • Sir am using Slow Attack AGC is it ok sir?

    And second thing if we disable the FIR decimation and interpolation is not work then is it TXFIR and THB1 clocks are same  as well as RX FIR and THB1 clocks are is it same?

    And if we disable  FIR filters  is there is no need of filter coefficients ?

    Am tried TX output in spectrum analyser am getting spectrum

    Like this  we are using QPSK the spectrum is as it is same sir.

    But it is not my spectrum, it is downloaded from internet.

    We applied signal from signal generator also but to RX input we are getting good signal on rx data port we are verified on ILA.

    I didn't verified overflow by applying external signal from signal generator. And we can't demodulate that data same as signal generator did modulation.