Is it possible to avoid the RF AGC setting switching between different levels during all RX time?

Hi Peter,

Thank you for posting your question online.
Let me check on this and I will get back to you as soon as possible.

Best Regards,
OV_Renesas

Hi Peter,

We do not think that this would be a good idea. 
When the RF AGC is set to a fixed setting, the risk is that when the incoming signal is weak, there is too much noise in the I/Q singal.
At the other hand, it would 'clip' when the incoming signal is strong. Both will result in worse or bad ranging performance.
From DA1469x Datasheet: 'The LNA and IF Filter gains are controlled by the AGC. This provides the necessary signal conditioning prior to digitalization.'

Best Regards,
OV_Renesas

Hi OV_Renesas,

Thanks for your quick reply!

We know the risk of the RF AGC  is set to a fixed setting, in fact, we want to use our algorithm to control the AGC and AFC. Now we set same value to RF_AGC_LUT_0123_REG, RF_AGC_LUT_4567_REG, RF_AGC_LUT_89AB_REG, RF_AGC_LUT_CDEF_REG, and set 1 to RF_AGC_CTRL2_REG_AGC_MAX_SETTING of RF_AGC_CTRL2_REG, it seems work well.

Could you tell me the correct way to configure AGC to avoid switching?

Best regards,

Peter

Hi Peter,

Thank you for the reply.
We have reached out to the Radio Team and we will get back to you as soon as possible.
Apologies for any delay, it might take a couple of days.

Best Regards,
OV_Renesas

Hi Peter,

Apologies for the delay.
Did you try to do the following setting?
One can prevent AGC switching with RF_AGC_CTRL2_REG  [AGCSETTING_SEL]

Best Regards,
OV_Renesas

Hi OV_Renesas,

Thanks for your reply!

We need more time to finish testing, will give you feedback soon.

Best regards,

Peter 

Hi Peter,

Thank you for the reply.
Please find below the reply from the Radio Team as well:

With AGCSETTING_SEL at 1, you make sure the AGC is fixed. The gain in the RX path is provided by AGCSETTING_WR.
This is a 4 bit number (0 to 15). 
 
The actual gain of the receiver is defined by the AGC Look-up-table (LUT): 

RF_AGC_LUT_0123_REG - > high gain

RF_ACG_LUT_4567_REG  -> lower gain

RF_AGC_LUT_89AB_REG  -> even lower gain.

RF_AGC_LUT_CDEF_REG  -> lowest gain

So, for example: 

AGCSETTING_SEL = 1 and AGCSETTING_WR = 0, the receiver gain is fixed at the highest gain minus 6 dB

AGCSETTING_SEL =1 and AGCSETTING_WR = 1, the receiver gain is fixed with the highest gain minus 12 dB

etc.

Note:
if one wants to know the exact gain value (in dB), one has to create the RF_AGC_LUT_****_REG table: 

AGC_SETTING, LNA gain, VGA1 gain, VGA2 gain 

0,            0,            0,            1    (highest gain minus 6 dB due to 1*6 dB lower gain in VGA2)

1,            0,            0,            2    (highest gain minus 12 dB due to 2*6 dB lower gain in VGA2

2,            1,            0,            2    (highest gain minus 18 dB due to 2*6 dB lower gain in VGA2 and 1*6 dB lower gain in LNA)

3,

4,

5,

6,

7,

8,

9,

Hope this information helps. 

Best Regards,
OV_Renesas

Hi OV_Renesas,

Thanks for your reply!

Yes, with AGCSETTING_SEL at 1, the AGC can be fixed to a custom level, but the average amplitude of I/Q signals may change unexpectedly when receiving a continuous signal. In our test case, we think the average amplitude of I/Q signals should keep constant. We find a way to fix the issue partially by setting some guessed values to:

RF_LNA_CTRL1_REG,

RF_LNA_CTRL2_REG,

RF_LNA_CTRL3_REG

Could you provide more detailed meaning of following fields of above registers?

RFCU_RF_LNA_CTRL1_REG_LNA_TRIM_GAIN0_HP

RFCU_RF_LNA_CTRL2_REG_LNA_TRIM_GAIN0_LP

RFCU_RF_LNA_CTRL3_REG_LNA_TRIM_CASC

RFCU_RF_LNA_CTRL3_REG_LNA_MODE_GAIN0

Thank you and RADIO TEAM again!

Best Regards,

Peter

PS: With some special process to packet, we can receive treated packet at rate 4mbps with AGC enabled.

PS: Constant average amplitude (I, Q, Demodulated signal)

Changed average amplitude (I, Q, Demodulated signal)

Hi Peter,

Thank you for the reply.
We are in contact with the Radio Team.
Please allow some time for the answers.
We will get back to you as soon as we have a response.

Best Regards,
OV_Renesas