CCS/CC2652R: How to fix Master LNA gain (SDK4.1)

update IQ picture in the same environment without LNA modification

Hi,

If it was not clear, we fix the LNA gain for a given CTE. I am not sure what you are trying to do but by having a too big gain might saturate the LNA (and get unstable values).

Can you provide some details regarding your test setup? Are you running conducted or non-conducted tests? Are you in a controlled environment (anechoic chamber)? Is the AOA varying? How much distance is there between the two devices?

Best regards,

Hi Clément,

We designed our own antennas with different orientations and wanted to know how far the Tag was by the amplitude changes.

If the LNA gain has a variation, The correlation of amplitude and distance correlation is a problem.

so we hope to lock LNA to high gain or low gain.

We do a radiate test in anechoic chamber, the distance is 60 cm.

We have verified on passive mode in the same environment, (modify urfc.c) it is workable

Hi,

I understand. Can you try the following ideas:

- keep the LNA with fix high gain and significantly decrease the TX Power of the source

- try to set the LNA with fix low gain using this override: HW_REG_OVERRIDE(0x6098, 0x3588)

Best regards,

thx Clément,

about case1, i can't find Tx power setting in SDK4.1 Sysconfig, but it exist in SDK3.4 sysconfig, Do you know how to reduce TX power.

Hi  Clément,

Sorry, The problem is still there.

We can't set Tag to lower power, even the result no jagged .

I measured again with conductive for Master -High gain, Master- normal gain, Passive High gain test, and use the same device to measurement. i think Master - high gain have some problem.

Note: The red and green straight line just help me to discern the ANT switch interval, and i already connect RF cable to RF karkit and the signal will not go through ANT switch, so straight line is useless, don't care it.

Hi,

Can you run the tests with a fixed LNA low gain? I would like to see if in that case too the values measured by the passive are twice bigger than the values measured by the master.

Thanks and regards,

Hi again,

May I ask what is the configuration you are using for the master device? If you are not doing so, can you use "RAW_RF no filtering". Depending how you are controlling the master, this can be done from the python script (aoa_params structure > aoa_cc26x2 > aoa_sampling_control) or from the embedded code (function RTLSCtrl_setAoaParamsCmd()). Let me know if you need further details here :)

FYI, there is a difference in the way the master and the passive are sampling the data. The parameter "aoa_sampling_control" only affects the master (not the passive). By setting aoa_sampling_control to "RAW_RF no filtering", the configuration of the master is closer to the configuration of the passive.

Regards,

Hi Clément,

I am using RAW_RF no filtering for Master and Passive device

I have another filter mode issue on this thread

Hi,

Thanks.I am really trying to understand what can be wrong here.

How did you set the High Gain for the master and the passive? (what files did you modify? Which values did you use?)

Have you the same figure for Passive Normal Gain? (can you share it here please?)

Kind regards,

Hi Clément,

thx for your support.

1.My gain change for Master mode (ble_user_config.c)

   -->copy setting from pOverrides_ble1Mbps and add low gain config

uint32_t pOverrides_xxx_ble1Mbps[] =
{
    // override_ble5_setup_override_1mbps.json
    // Bluetooth 5: Set pilot tone length to 20 us
    HW_REG_OVERRIDE(0x5320,0x03C0),
    HW_REG_OVERRIDE(0x6098,0x35ff),
    // Bluetooth 5: Compensate syncTimeadjust
    (uint32_t)0x015302A3,
    (uint32_t)0xFFFFFFFF
};

const boardConfig_t boardConfig =
{
  .rfFeModeBias  = RF_FE_MODE_AND_BIAS,
  .rfRegTbl      = (regOverride_t*)pOverrides_bleCommon,
  .rfRegTbl1M    = (regOverride_t*)pOverrides_xxx_ble1Mbps,
#if defined(BLE_V50_FEATURES) && (BLE_V50_FEATURES & (PHY_2MBPS_CFG | PHY_LR_CFG))
  // Currently, no overrides for 2M and Coded, so exclude from build.

2.My gain change for Passive mode (urfc.c)

  regOverride_t pOverridesCommon[] = {
    0x00158000, // S2RCFG: Capture S2R from FrontEnd, on event (CM0 will arm)
    0x000E51D0, // After FRAC
    ((CTECONFIG << 16) | 0x8BB3), // Enable CTE capture
    ((CTEOFFSET << 24) | ((CTE_SAMPLING_CONFIG | (CTE_SAMPLING_CONFIG << 4)) << 16) | 0x0BC3), // Sampling rate, offset
    0xC0040341, // Pointer to antenna switching table in next entry
    (uint32_t) antSwitching, // Pointer to antenna switching table
     END_OVERRIDE };

   regOverride_t pOverrides1Mbps[] = {
     HW_REG_OVERRIDE(0x6098,0x35ff),
     END_OVERRIDE };

I have upload low gain picture for Master/Passive. Looks like Passive gain stage have some problem on SDK4.1. but it is normal on SDK3.4