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40m in door range at 315MHz with CC1101 possible?

Hans
Genius 12865 points


Hello,

I am looking for a RF solution which communicates at low speed (38.4k) in house over 40m range. FCC forces me to reduce power when going lower in frequency (-20dBm at 315MHz). My question is: how to design a communication system which meets FCC and 40m in door range? Does FCC only spec the TX power? I see also that FCC specs the RX bandwidth e.g. for 915MHz to 523kHz for 38.4kbaud in DN006. Why do I have to reduce my sensitivity at the receiver by increasing the bandwidth?

Thanks for your help,

Hans-Günter

  • 0
    TI__Mastermind 39860 points

    FCC does not spec any RX bandwidth. DN006, which you refer to, is applicable for systems targeting compliance with FCC section 15.247. This is not relevant for the appliaction you refer to (315 MHz operation, 38.4 kbps and  -20 dBm output power). Use the preferred settings for 38.4 kbps you get from SmartRF Studio (Rx BW = 101 kHz, frequency deviation = 20 kHz). The sensitivity will be approx -104 dBm. Note that the CC1101EM 433 MHz reference design is not optimized for 315 MHz operation. There is a note note in the reference design ZIP-file that explains what component changes are needed for optimum performance at 315 MHz.