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LAUNCHXL-CC1310: Using different LNA & PA amplifier for test with LAUNCHXL-CC1310

Dimitar Belev
Prodigy 30 points
Part Number: LAUNCHXL-CC1310
Other Parts Discussed in Thread: CC1310, CC1190,

Dear support team,

We are developing new project for outdoor vehicle telemetry system in tracks. We are using CC1310 at 868MHz for Europe and 915MHz for US. For this project we need external amplifier for both transmission (PA) and reception (LNA). We bought several pcs LAUNCHXL-CC1310 and LAUNCHXL-CC1390 (CC1310 + CC1190 PA/LNA). The performance of LAUNCHXL-CC1390 is OK for our need. Unfortunately we cannot deliver CC1190 for production any time soon, and we were forced to use another manufacturer for the amplifier (we use SKY66420).

For the comparison, we combined LAUNCHXL-CC1310 and SKY66420 demo boards, but have receive issues. Is it possible to describe the connections and setup we use (at the end the amplifier is not TI part), in order to advice us if we use wrong adjustments.

Our problem is:

When in receive mode, the setup, including the LNA works much worse, than the setup with only CC1310 and passive antenna, some additional information:

- In short distance from the transmitter, the LNA setup provides ~10dBm better RSSI, than the standalone CC1310 test board

- After specific distance (~120m from the transmitter), the LNA setup starts much more CRC errors and packet loss, than the CC1310 standalone board (it barely receives 1% of the packets), but the OK received packets again shows better RSSI, than the standalone board. In standalone mode, the typical performance on the same distance is ~60% loss, which is much better.

We double checked the external LNA configuration (proper pin levels for receive mode), the CC1310 board is working perfect when in standalone mode)

We checked the external LNA RX parameters, it should provide 16dB LNA gain and typical added noise of 1.5dB.

We tested with receiving with LAUNCHXL-CC1390 and it works brilliant (~25% losses, which is totally perfect for our case)

Do you think the LNA gain is too much for CC1310 input, or we should have setup error in connection on the boards in general

If needed, we can provide the exact connection approach, and setup details in order to solve this.

Thanks in advance

Kind Regards

Dimitar

  • 0
    Genius 5610 points

    My guess is that you need to adjust AGCREF due to the increased gain in the RF frontend, see https://www.ti.com/lit/pdf/swra682 for more details.

  • 0 in reply to TheGhostOf
    Prodigy 30 points

    Thanks for the suggestion. We tested the possibility to change the AGCREF from SmartRF studio and it can be adjusted via "override editor" panel in the application. Then we checked the default value of this setting. It seems, that the default AGCREF value is different, for each speed setting. Four our setting of 500kbps, it is 0x24 (LS bytes in the 0x6088 address).

    - In the receiver we tried to change the value, without moving the position of the transmitter and receiver, and we received the packets with different measured RSSI, this means, that the override procedure has some effect.

    - Then we did the range tests with different override setting, using 2 digits steps in both directions: 0x24, 0x26, 0x28.... and also 0x22, 0x20, 0x1E..... We did not found any big difference in the behavior with changed value.

    We double checked the SKY transmit/receive jumper settings, the used connections and did not find anything wrong in the setup.

    Any suggestion what the 0x24 value means, is it in dBm, does it bigger value increase the threshold, or decrease it.

    Any suggestions for competitive tests we can do to find the problem will help us a lot.

    Regards

    Dimitar

  • 0 in reply to Dimitar Belev
    Genius 5610 points

    Are you able to run a conducted PER vs level (measure sensivitivity vs input level)?