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CC2530: CC2530 6db minimum 500 kHz Bandwidth

Part Number: CC2530
Other Parts Discussed in Thread: CC2592

Looking to get some insight into configuring the cc2530 to fulfill the FCC 15.247 requirement ". The minimum 6 dB bandwidth of such systems is 500 kHz" . We are measuring a bandwidth of 156 kHz. From other forums (see reference), it appears this can be changed via a register setting? We are using a cc2530 with a cc2592 range extender. Any insight would be greatly appreciated. 

Thank you,

  • Hi,

    Can you share the screen shots of the measurements?

    The data chip rate of CC2530 is 2 MHz so 156kHz BW at 6dB down is suspect.

    regards,

  • Agreed. The 156 kHz bandwidth was a conducted captured when transmitting a packet ~30 bytes every 1 second. 

    With our own spectrum analyzer, under a constant carrier transmission mode, we were measuring the following:

  • Hi,

    The ANSI C63 recommends the settings for one of the methods of DTS bandwidth measurement as follows:

    RBW = 100kHz

    VBW >= 3 * RBW

    Detector = Peak

    Trace = Max hold

    Sweep = auto

    " Measure the maximum width of the emission that is constrained by the frequencies associated
    with the two outermost amplitude points (upper and lower frequencies) that are attenuated by
    6 dB relative to the maximum level measured in the fundamental emission."

    you can set the device (CC2530) to transmit a continuous modulated carrier.

    regards

  • We are consistently seeing a < 500kHz bandwidth even with continuous modulated carrier transmission. 



    Is there something within cc2530 configuration that would produce this issue? Are there registers that I am setting incorrectly?

  • Hi,

    Please see if your radio settings are consistent with the SmartRF studio settings for CC2530.

    Following is the 6dB BW plot of one of our CC2530 EM modules.

  • Hello,


    We have been using SmartRF Studio settings for the CC2530 with CC2592 range extender and we still see the same result under the continuous unmodulated tx. With the continuous modulated tx... i believe we are seeing better results. See below:


    NOTE: I have to adjust the following registers in order to get an output transmission from the RF studio:

    RFC_OBS_CTRL0 = 0x68

    RFC_OBS_CTRL1 = 0x6a

    OBSSEL2 = 0xfb

    OBSSEL3 = 0xfc

    I believe this is a result of the GPIO interface with the cc2592.

    Are there any other registers I should pay particular close attention to? All other registers appear to have same values.

    When I change transmission from unmodulated continuous to modulated continuous, we get the following result:

  • Thank you yes we were already using those register values in the app note provided.

    I was able to increase the bandwidth by adjusting the following registers:

    MDMCTRL0 = 0x85; MDMCTRL1 = 0x14; MDMTEST0 = 0xb1; MDMTEST1 = 0x08;

    From the image above, you can see the bandwidth is now ~2MHz. Is it possible to adjust the bandwidth closer to 500 kHz? Would the MDMCTRL/MDMTEST registers be the only place to adjust this? Or should I not be adjusting these register values.

    Thank you for your help,

  • Hi,

    I think this is the best you can do with the settings ( which are already optimal).

    You could try to set MDMCTRL0.TX_FILTER = 0x0 which will enable normal IEEE filtering but it will also degrade out-of-band emissions.

    regards