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LP-CC1352P7: How to measure that my custom design is transmitting effectively at 20dbm?

albgarc2014
Genius 3395 points
Part Number: LP-CC1352P7
Other Parts Discussed in Thread: CC2531, CC1352P7, CC1352P

Hi Ti!

What is the best way to measure that my custom design is transmitting effectively at 20dbm?

Best Regards!

  • +1
    Guru 735495 points

    I would suggest to use spectrum analyzer to do conductive test to measure TX power.

  • +1
    TI__Guru**** 207547 points

    Hi albgarc,

    You can also use Smart RF Studio 7 to alter TX power settings being transmitted by one device and compare the RSSI of a receiving device (keeping the distance fixed).  YK's suggestion is the most conclusive.

    Regards,
    Ryan

  • 0
    Genius 3395 points

    Part Number: LP-CC1352P7

    Hi TI!!!

    If I measure the transmitted RF signal with a spectrum analyser or with a receiver I read the rssid, I am measuring the power received by the receiving antenna and not the power of the transmitter.

    Maybe if I assume the launchpad to be the standard 20dbm transmitter (with the correct configuration) I do the measurements for the LP and repeat the measurements (at the same distance) for my pcb and I can get an approximation.

    In this case assuming a linear relationship between the 20dbm of the standard (LP) and the received power at the receiver is correct?

    Is the approach correct or can I do better?

    Thank you very much!

  • +1 in reply to albgarc2014
    Guru 735495 points

    If you are doing radiation test, it’s recommended to put transmitter’s antenna as close as possible to receiver’s antenna.

  • 0 in reply to YiKai Chen
    Genius 3395 points

    I have the zigbee device (CC1352P7) under test in a radio-free environment with no other RF signals and a CC2531 as sniffer. When the device under test sends the beacon I can see in the sniffer the lqi and the rssid. If the device under test is not connected to any other device/network whose RRSID and QLI do I see in the packets shown by the sniffer? 

  • +1 in reply to albgarc2014
    TI__Guru**** 207547 points

    I don't fully understand your question, please clarify if possible.  Beacon Requests do not contain MAC address information so the sniffer will not be capable of knowing from what device the request originated. The sniffer will display the MAC address starting from the Association Request.  You should use Smart RF Studio 7 if evaluating packets outside of n established network.

    Regards,
    Ryan

  • 0 in reply to Ryan Brown1
    Genius 3395 points

    Hi Ryan, thank you very much!

    Please forget my previous question about RSSI and LQI in the sniffer. I was confused and I understand it now. The sniffer shows me frame information that is captured by the sniffer itself. So in the frame information the rssi and lqi is the one received by the sniffer coming from my device under test. 

  • 0 in reply to albgarc2014
    Genius 3395 points

    Hi Ryan, Yikai

    I have tested with LPCC1352P-2, LPCC13527P-4 and sniffer.

    LPCC1352P-2 set to 20 dbm.
    LPCC1352P7-4 configured at 20 dbm. In order to set 20 dbm I followed the instructions:
    e2e.ti.com/.../cc1352p7-error-in-sysconfig-when-switching-to-20dbm-rf-design

    Both LP's are together at the same distance from the sniffer (4m),
    With LPCC1352P-2 I always have LQI = 105
    With LPCC1352P7-4 I always have LQI = 78

    Why does LPCC1352P7-4 have less transmit power? Both LP's (LPCC1352P-2 and LPCC13527P-4) are at 20dbm and the same distance from the sniffer.

    Do I have to do anything else to LPCC13527P-4 reach the power of LPCC1352P?

  • +1 in reply to albgarc2014
    TI__Guru**** 207547 points

    Although the CC1352P7 device is capable of transmitting +20 dBm in the same capacity as the CC1352P, the LP-CC1352P7-4 hardware itself is designed to support +10 dBm whereas the LAUNCHXL-CC1352P-2 is intended for +20 dBm.  This is clearly shown in the Design File schematic along with the necessary passive component changes to support +20 dBm.  As it stands, the incorrect matching circuit is likely resulting in unexpected attenuation of the output signal.  You could part-swap the CC1352P7 onto a LAUNCHXL-CC1352P-2 or change the passive components as explained in the schematic.  As always, I recommend that you first verify results with Smart RF Studio 7 as the instructions from the previous E2E thread are written for BLE5 projects.

    Regards,
    Ryan 

  • +1 in reply to Ryan Brown1
    Genius 3395 points

    Hi Ryan!!

    Our design has the CC1352P7 with the passive impedance-matching network of the LPCC1352P2.

    With this: e2e.ti.com/.../cc1352p7-error-in-sysconfig-when-switching-to-20dbm-rf-design our design has the same RRI and LQI that LPCC1352P2. Then we have the 20dBm!!!

    Thank you very much!

    Best regards