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CC1312R7: Help needed using RF power amplifier

Andre Mastella
Intellectual 300 points
Part Number: CC1312R7
Other Parts Discussed in Thread: LAUNCHXL-CC1310

Hi,

I'm designing a new product for metering purposes using CC1312R7. Testing at the development kit I could get a communication range of about 100m to 130m.
I need more than it so I decided to use a power amplifier (RF PA). The one I choose until now is CMX90A004 from CML (1 Watt).

I do not have much knowledge about RF so I'm asking for some help.

The transmit signal must pass through RF PA but not the receiving signal. I need to place RF "switches" but have no idea how to make it.

So could you help me with some application examples or how to connect CC1312 - CMX and control TX and RX signals?

Thank you very much!

Best regards

André

  • 0
    Genius 5610 points

    100 m - 170 m range is low. Which datarate did you use and how did you do your test? 

     

  • 0 in reply to TheGhostOf
    Intellectual 300 points

    Hi, 

    I used 912MHz 5kbps Long Range Mode.(EasyLink_Phy_5kbpsSlLr) based on the rfWsnNode/rfWsnConcentrator example.

    The test was not made at optimal conditions I know.

    One board was above one table inside the house connected to my PC and I got out walking to the street with the other board. The only change I made on the example is to blink the led at the sensor board when an ACK packet was received, so I know when the transmission was ok.

    Using a SDR I could see that at this frequency there were no more signals only mine.

    (Sorry for my English. It´s not my mother language ;) )

    Thank you for your interest in my case.

    Regards

  • 0 in reply to Andre Mastella
    Genius 5610 points

    - I would recommend using https://www.ti.com/tool/RF-RANGE-ESTIMATOR to estimate the range you can get and see if this is what you need. 

    - Are you allowed to transmit with 1-2 W at your location with LRM?

    With limited RF knowledge I would avoid FEMs is possible since designing 1 W transmitters require access to a RF lab for verification. 

  • 0 in reply to TheGhostOf
    Intellectual 300 points

    Hi Ghost,

    I´m using 2 LAUNCHXL-CC1312 so in Excel I selected DN024 (CC_ANTENNA_DK2). Is it correct?
    Do I need to change the rfWsn radio configuration parameters other than phy_5kbps?

    I´ll do other tests this weekend.

    Thank you

  • 0 in reply to Andre Mastella
    TI__Intellectual 2960 points

    Hi Andre,

    This example is no longer supported. Can you please you the example rfPacketRx/rfPacketTx instead please?

    Best regards,

    Haiatullah

  • 0 in reply to Haiatullah Gholami
    Intellectual 300 points

    Hi Haiatullah, I´ll do it

    Thanks

  • 0 in reply to TheGhostOf
    Intellectual 300 points

    Hi Ghost, I´ve made some tests using 2 CC1312R7 Development kit (LaunchXL), using the board antenna.
    The tests were made using SmartRF Studio 7 (2.28.0) at the transmitter side.

    The RX board running rfPacketRX example toggles a led at every received packet.

    The transmit board is on a tripod (photo) outside my house.

    Both boards were placed with the USB connector facing down and the board antenna up (Vertical position)..

    First Test:
    SimpleLink Long Range, f = 912.8000, Symbol = 19.99, Dev = 5.0, Rxf = 34.1, TxPower = 14dBm, Preamble 4 bytes, Sync 32 bits, Sync Word = 0x930B51DE, packet length = 20

    Second test:
    Narrowband, f = 912.8000, SymbolR = 9.599, Dev = 2.406, RxFilter = 17.1, TxPower = 14dBm, Preamble 4 bytes, Sync = 32 bits, Sync Word = 0x930B52DE, packet length = 20

    The Rx board I placed at a  rod (?) and walked on the street.
    I could not post a photo in the reply as I wish.
    The street were I made the tests is at -30.052927814231968, -51.18364240234436 and I walked through -30.05224525522544, -51.185283914223 - about 200m. This place is were the led of the RX board stoped blinking.

    The 2 tests gave me almost the same range and it´s strange for me. I thought Narrowband would give me much more range but not. I noted when using narrowband that the signal seems to be more directional so I need to turn the board to get the signal as the distance grew.

    Based on the above report, do you think I´m doing something wrong?
    The range obtained is the same as LaunchXL-CC1310 using SLLR 5kbps

    Thank you in advance.
    Regards

    Andre

    PS: With the new SDK for CC1312, were can I get the RSSI in rfPacketRX example?

  • 0 in reply to Andre Mastella
    TI__Intellectual 2960 points

    Hi Andre,

    To find out how long range you can expect, use the https://www.ti.com/tool/RF-RANGE-ESTIMATOR to figure it out. If you want to get rssi, it is best to use rfPacketErrorRare example instead of rfPacketRX/TX. It reports both the number of packets received and RSSI,

    Best regards,

    Haiatullah

  • 0 in reply to Haiatullah Gholami
    Intellectual 300 points

    Hi Haiatullah,

    RF Range estimator gives a range expectation of 500m considering 2 times 7" brick walls even though I put both boards outside the house which is almost line of sight (Range expectation of 1000 m).

    Thank you

    Andre