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AD9361 Problem with Slow attack AGC

Question asked by vbif on Oct 31, 2016
Latest reply on Nov 18, 2016 by vbif

Hi All,

 

We have AGC in slow attack mode with the following parameters:

 

/* Gain Control */
2, //gc_rx1_mode *** adi,gc-rx1-mode
2, //gc_rx2_mode *** adi,gc-rx2-mode
58, //gc_adc_large_overload_thresh *** adi,gc-adc-large-overload-thresh
4, //gc_adc_ovr_sample_size *** adi,gc-adc-ovr-sample-size
47, //gc_adc_small_overload_thresh *** adi,gc-adc-small-overload-thresh
8192, //gc_dec_pow_measurement_duration *** adi,gc-dec-pow-measurement-duration
0, //gc_dig_gain_enable *** adi,gc-dig-gain-enable
800, //gc_lmt_overload_high_thresh *** adi,gc-lmt-overload-high-thresh
704, //gc_lmt_overload_low_thresh *** adi,gc-lmt-overload-low-thresh
24, //gc_low_power_thresh *** adi,gc-low-power-thresh

 

/* Gain AGC Control */
10, //agc_adc_large_overload_exceed_counter *** adi,agc-adc-large-overload-exceed-counter
2, //agc_adc_large_overload_inc_steps *** adi,agc-adc-large-overload-inc-steps
0, //agc_adc_lmt_small_overload_prevent_gain_inc_enable *** adi,agc-adc-lmt-small-overload-prevent-gain-inc-enable
10, //agc_adc_small_overload_exceed_counter *** adi,agc-adc-small-overload-exceed-counter
4, //agc_dig_gain_step_size *** adi,agc-dig-gain-step-size
3, //agc_dig_saturation_exceed_counter *** adi,agc-dig-saturation-exceed-counter
1000, // agc_gain_update_interval_us *** adi,agc-gain-update-interval-us
1, //agc_immed_gain_change_if_large_adc_overload_enable *** adi,agc-immed-gain-change-if-large-adc-overload-enable
1, //agc_immed_gain_change_if_large_lmt_overload_enable *** adi,agc-immed-gain-change-if-large-lmt-overload-enable
10, //agc_inner_thresh_high *** adi,agc-inner-thresh-high
1, //agc_inner_thresh_high_dec_steps *** adi,agc-inner-thresh-high-dec-steps
12, //agc_inner_thresh_low *** adi,agc-inner-thresh-low
1, //agc_inner_thresh_low_inc_steps *** adi,agc-inner-thresh-low-inc-steps
10, //agc_lmt_overload_large_exceed_counter *** adi,agc-lmt-overload-large-exceed-counter
2, //agc_lmt_overload_large_inc_steps *** adi,agc-lmt-overload-large-inc-steps
10, //agc_lmt_overload_small_exceed_counter *** adi,agc-lmt-overload-small-exceed-counter
5, //agc_outer_thresh_high *** adi,agc-outer-thresh-high
1, //agc_outer_thresh_high_dec_steps *** adi,agc-outer-thresh-high-dec-steps
18, //agc_outer_thresh_low *** adi,agc-outer-thresh-low
1, //agc_outer_thresh_low_inc_steps *** adi,agc-outer-thresh-low-inc-steps
1, //agc_attack_delay_extra_margin_us; *** adi,agc-attack-delay-extra-margin-us
1, //agc_sync_for_gain_counter_enable *** adi,agc-sync-for-gain-counter-enable

 

From the generator on input RX0 AD9361 we continiously transmit 10 subframes. (5 messages then 5 empty subframes)  Subframe duration is 1 ms.
The decoder processes each frame, and outputs CRC = 0 on empty frames, and CRC = 1 on data messages.
When the power from the generator -47dbm ...- 50dbm (with a resolution of 1dB), this AGC mode with the current settings provides 2.5% error on the information subframes.
In MGC (manual) mode (with the same gain as Slow attack mode - 34 dB) there are no errors.


What settings should be used in slow attack AGC mode for eliminate error?

 

Regards,
Viacheslav

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