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Original question:

CCS/CC2652R: How to fix Master/Passive LNA gain and Slave TX power

CCS/CC2652R: [RTLS]Some questions about RSSI field

Valery Wu
Expert 1100 points
Part Number: CC2652R

Tool/software: Code Composer Studio

Hi,

I have do a conductive test to check RSSI report.

1.We have 3 ANT path(0,1,2) and connect to Tag with a RF divider

2.add 3db Attenuator both on ANT0 and ANT2 path

3.RTLS Master mode setting:

                        "aoa_slot_durations": 2,
                        "aoa_sample_rate": 4,
                        "aoa_sample_size": 2,
                        "aoa_sampling_control": int('0x11', 16),
                        "aoa_sampling_enable": 1,
                        "aoa_pattern_len": 3,
                        "aoa_ant_pattern": [0, 1, 2]

suggest that scan process and reference signal should have 3db lose.(received by ANT0?)(normal RSSI is -31 or -32, so ANT0/2 should received -34~-35db )

but the RSSI shows -51db on scan procedure.

MASTER  : 58:93:D8:6A:A9:5F --> {'type': 'Event', 'command': 'RTLS_CMD_SCAN', 'payload': {'eventType': 19, 'addrType': 0, 'addr': '58:93:D8:6A:A9:0E', 'rssi': -51, 'dataLen': 14, 'data': '0A:08:52:54:4C:53:53:6C:61:76:65:02:01:06'}}

first 32 index of IQ are reference signal and it should received by ANT0 in my configuration. but it show -32db?

Looks like RSSI of 33~624 index will follow first 32 index and won't update until next frame?

Can i change RSSI measurement setting to keep flush between difference IQ packet?

 {'type': 'Event', 'command': 'RTLS_CMD_AOA_RESULT_RAW', 'payload': {'connHandle': 0, 'bd_addr': [14, 169, 106, 216, 147, 88], 'rssi': -32, 'antenna': 1, 'channel': 31, 'offset': 0, 'samplesLength': 624,

{'type': 'Event', 'command': 'RTLS_CMD_AOA_RESULT_RAW', 'payload': {'connHandle': 0, 'bd_addr': [14, 169, 106, 216, 147, 88], 'rssi': -32, 'antenna': 1, 'channel': 31, 'offset': 192, 'samplesLength': 624, 

{'type': 'Event', 'command': 'RTLS_CMD_AOA_RESULT_RAW', 'payload': {'connHandle': 0, 'bd_addr': [14, 169, 106, 216, 147, 88], 'rssi': -32, 'antenna': 1, 'channel': 31, 'offset': 288, 'samplesLength': 624,

{'type': 'Event', 'command': 'RTLS_CMD_AOA_RESULT_RAW', 'payload': {'connHandle': 0, 'bd_addr': [14, 169, 106, 216, 147, 88], 'rssi': -32, 'antenna': 1, 'channel': 31, 'offset': 352, 'samplesLength': 624,

{'type': 'Event', 'command': 'RTLS_CMD_AOA_RESULT_RAW', 'payload': {'connHandle': 0, 'bd_addr': [14, 169, 106, 216, 147, 88], 'rssi': -32, 'antenna': 1, 'channel': 31, 'offset': 608, 'samplesLength': 624, 

{'type': 'Event', 'command': 'RTLS_CMD_AOA_RESULT_RAW', 'payload': {'connHandle': 0, 'bd_addr': [14, 169, 106, 216, 147, 88], 'rssi': -32, 'antenna': 1, 'channel': 31, 'offset': 512, 'samplesLengt

  • 0
    TI__Guru* 81181 points

    Hi Valery,

    Please don't compare RSSI and dBm values. The RSSI is a measurement of power received but it's not measured in a specific unit.

    Please only compare RSSI to RSSI, and only on one device (e.g. don't compare RSSI received on one device with RSSI received on a different device).

  • 0 in reply to Marie H
    Expert 1100 points

    Hi Marie,

    Sorry for reply lately.

    the RSSI report just use one Master device to measure one slave with conductive RF cable.

    we can just discuss RSSI.

    1. Do you know why RSSI are difference between scan and measurement stage?  -51, -32

    2. Ti report 32 IQ and 1 RSSI value in one measurement packet, i32 IQ include 4 times switch(4Mhz sampling, 2us duration), but just report 1 RSSI.

        If we have 3 ANTs, can you help to explain the reported RSSI value is for which one ANT? I need to understand the RSSI report mechanism, very thank you.

  • 0 in reply to Valery Wu
    TI__Guru** 101450 points

    Hi Valery,

    1- Are you using the same TX Power while advertising and while connected?

    2- You cannot get an RSSI value for each IQ sample. The RSSI reported is calculated considering all the antennas used during the CTE sampling.

    To get a better understanding, I suggest you to review the rtls_master example, starting with the function RTLSCtrl_estimateAngle().

    I hope this will help,

    Regards,

  • 0 in reply to Clément
    Expert 1100 points

    Hi Clément,

    1.Yes, we use the sam TX power, and RF cable always connected. scan and measurement are in the same session.

    2.Looks like the RSSI be reported from firmware, and 1 CTE frame just report 1 RSSI value. i just hope to know if it is a average value in this CTE frame.

  • 0 in reply to Valery Wu
    TI__Guru** 101450 points

    Hi,

    Do you have the BOOSTXL-AOA connected on both devices?

    Do you get the same results if you exchange the devices (i.e. flash the rtls_master code on the current passive device, and the rtls_passive on the current master device)?

    Kind regards,

  • 0 in reply to Clément
    Expert 1100 points

    Hi Clément,

    1. I only have 1 type RF cable but connector size is not match with BOOSTXL-AOA, so i just can do wireless test on BOOSTXL-AOA, but wireless signal is not stable

    2. Yes, result is same

  • 0 in reply to Valery Wu
    TI__Guru** 101450 points

    Hi,

    I think the differences observed are related to the same causes than the ones we are chasing in this thread:https://e2e.ti.com/support/wireless-connectivity/bluetooth/f/538/p/902433/3357670#3357670

    Best regards,