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Rx Manual gain setting in AD9364

Question asked by jinojs on Jun 2, 2015
Latest reply on Jun 4, 2015 by jinojs

Hi,

 

I'm using the reference design code from No-OS for AD9364 and testing Rx path of the board.

I'm able to receive the data but the amplitude is less than expected. Hence trying to use MGC gain setting.

 

In the init code, I changed the below lines:

 

/* Gain Control */

  2, //gc_rx1_mode *** adi,gc-rx1-mode

  2, //gc_rx2_mode *** adi,gc-rx2-mode

 

to

 

/* Gain Control */

  0, //gc_rx1_mode *** adi,gc-rx1-mode   --> Changed Rx1 to MGC

  2, //gc_rx2_mode *** adi,gc-rx2-mode

 

I see that the default gain in MGC is 71db. So after initialization, I called the function ad9361_set_rx_rf_gain (ad9361_phy, 0, gain_db); with gain_db set to 0.

The issue I'm having is after this change, the received waveform seems to have 'clipped'. I feel somehow the gain applied is still much higher than required and the data is getting cipped (it looks almost like a square wave instead of sine wave).

 

Can you please help me test and verify the Rx gain correctly?

To start with I want to give no gain and then from command line, I want to change the gain one after the other value to verify the behavior.

 

Please suggest.

 

Thank you,

~Jinoj

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