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LAUNCHXL-CC1352P: Long-range communication using SubGHz based on CC1352P1

Marvn Arcangel
Genius 12605 points
Part Number: LAUNCHXL-CC1352P
Other Parts Discussed in Thread: CC2650, CC1352P

Hi Experts,

The customer was trying to use this platform to establish a long-range SubGHz (915MHz) communication network using an external antenna. However, after switching the default antenna to an external SMA antenna and make a LOS test, the maximum range was just around 200 meters. Since according to the document that SubGHz can reach several kilometers of communication range. 

Did I advise the customer to try a different place to do the test to check if they can get a different result and to check on the background noise by setting the launchpad in cont RX and looking at the RSSI without any known TX sources on. In addition, I also advise the customer to ensure that the launchpad is placed at least 1 meter above the ground and not close to anything that could interfere with the signal.

They did several tests accordingly, and the result is as follows:

1. I conducted the LOS experiment on grassland that has a small hill (6 meters high) on one side. I put the SubGHz transmitter on the hill about 2 meters above the hilltop, and held the SubGHz receiver on the other side of the grassland about 2 meters above the ground, and the distance between tx-rx is about 200 meters.
2. I tested the ground noise around the 915MHz band on the grassland, and the RSSI is approximately -96 dBm.
3. I took another LOS test on a plain road, and the ground noise is about -100 dBm. The tx-rx distance is also below 200 meters.
Additional questions from the customer after the experiment:
1. I put the spectrum analyzer near the CC2650-P1 antenna when it was broadcasting packets at 915MHz frequency, and found the RSSI was just about -37dBm. Yet when configuring the CC2650 platform, I set the tx power as 20dBm. Does this mean I missed something on setting the board? (For example, if the RF circuit requires external power supply?)
2. If I add an external RF amplifier on the CC2650 board, will it help on boosting the communication range?
I also verified that the 47pf capacitor is moved from C482 to C483 and that the antenna that they are using matches the impedance of the board.
Antenna 1:
Description: Dual-Band HT/Scanner Antenna (BNC)
Gain: 2.15dBi (430 MHz) Max Power: 50W (Watts) Impedance: 50 Ohm Length: 30 cm Weight: 40g Connector: BNC 1/4 wave length (144 MHz), 1/2 wave length (430 MHz) and finally Made in Japan.

Antenna 2:
Description: CHHLIUT GSM 3Ghz 4G LTE 18dBi High Gain
Frequency range 698-960 MHz, 1710-2170 MHz, 2500-2700 MHz, Gain: 18dBi, Impedance: 50 Ohm, Omni-Directional, SMA Screw-On, Swivel( 90°135° 180°), fine copper dipole, 19 inches.
Can you please help further?
Regards,
Marvin
  • 0
    TI__Guru**** 317180 points
    Marvn Arcangel said:
    CC2650-P1

    This is not a product. I assume that we are talking about LAUNCHPAD-CC1352P-1 (The CC1352P launchpad exist in 3 different versions, the -1 version has a 20 dBm PA optimized for 915 MHz. 

    - Do you have the link for the two antennas used? Does antenna 1 cover 915 MHz? Which antenna is used for which test? 

    - Which datarate was used? 

    - Was SmartRF Studio used or a CCS example? 

    The 20 dBm PA and the switch should be set correctly in SmartRF Studio/ CCS examples. But more details have to be provided to verify. Are they able to do conducted measurements to ensure that they get the expected output  power? Ideally they should start with this since if they don't get the expected output power conduced they will get poor radiated results. 

  • +1 in reply to TER
    TI__Genius 12605 points

    Hi Ter, 

    The customer has figured out the cause of the problem. They tested all of the antenna they are using and found out that they are broken. Upon replacing, the communication range under a LOS condition reaches ~600 meters. I will now mark this thread as closed.

    Thanks for the response.

    Regards,

    Marvin