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CC1310: What is Long Range mode

Greg Rosser
Prodigy 40 points

Part Number: CC1310

I've been playing with SmartRF studio and testing the performance of the CC1310. SmartRF studio has an option for Long Range mode. I need details of what long range mode is!!!

I think its called fecMode in the formateConf register. FEC mode talks about Manchester encoding. 

Also the Symbol rate is divided by 16 to get the data rate, add on the Manchester encoding and the duration of the transmission can be calculated.

SmartRF studio also does not appear to allow packet data length to be changed in "long range mode"

More detail on the operation of Long range mode is required. I've dug around looking to reference to long range mode but could find nothing. 

Any apps notes, etc would be great.

Thanks,

Greg

  • 0
    TI__Genius 9705 points

    Hello Greg, 

    Long range mode on CC13xx consists of a convolutional encoder (rate 1/2) followed by DSSS with the length of the spreading sequence can be programmable. Thie data is 2GFSK modulated. Because of spreading gain, the sensitivity is lower when using this mode and hence it provider long range. FEC mode setting should be set as per SmartRF studio for this mode to work and the spreading length can be changed with override. 

    Hope this helps. 

    Regards,

  • 0 in reply to SVS
    Prodigy 40 points

    HI,

    Thanks for information. We are looking at sending 802.15.4 packets, using the best receiver sensitivity we can achieve, however we have another limitation of radio communications restrictions of only being allowed to transmit for 0.4 second. (we have to implement frequency hoping, and will probably us TI, TI RTOS implementation. But I still need to limit maximum transmission time to 0.4sec.
    How can I calculate the transmission time using long range mode. I have played with the sample in SmartRF studio and and measured the duration to be 1,6 seconds for the 625bps sample. I changed the data rate to symbol rate to 20ks and it appeared to change correctly. Changed packet size and all when south, numbers did not make sense.
    Can you recommend a configuration that allows us to send a 128 byte payload packet with the best receiver sensitivity and transmit in less than 0.4 seconds.
    I could figure this out, but the documentation n the radio operation is somewhat lacking.
    Greg
  • 0 in reply to Greg Rosser
    TI__Guru**** 317180 points
    A 128 byte payload requires a minimum datarate equal to 2.8 kbps given 4 byte preamble, 4 byte sync and 2 byte CRC.

    To manage this you have to adjust the DSSS spread factor in addition to increasing the symbol rate, see e2e.ti.com/.../1962428