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Unmodulated Carrier / Continues Wave (with CC1101)

Parcour
Intellectual 365 points
Other Parts Discussed in Thread: CC2500

Hi All,

I want to send out an unmodulated carrier @ 868 MHz. I know that I have to set the registers to ASK-Modulation like mentioned here https://community.ti.com/forums/p/446/1193.aspx#1193. But how to send out the continues wave? Currently I send TX-Strobe (STX) like in this example:

while(true)
{
halRfStrobe(CC2500_STX);
}

Is this correct?

Thank you!

Fabian

 

 

 

  • 0
    Mastermind 8170 points

    Here is the Ti code I use:

    /* Moduation deviation set to zero */

     /*  Setting both sync word registers to
         * 0xAA = 0b10101010, i.e., the same as the preamble pattern. Not necessary,
         * but gives control of what the radio attempts to transmit.
     */


        SYNC1     = 0xAA;
        SYNC0     = 0xAA;

        /* Put radio in TX. */
        RFST      = RFST_STX;

        /* Wait for radio to enter TX. */
        while ((MARCSTATE & MARCSTATE_MARC_STATE) != MARC_STATE_TX);

        /* Radio is now in TX. Infinite loop. */
        while (1);

        return 0;
    }

    The labels are different but the Ti flow is

    Initialize registers
    Enter Tx
    Wait till Tx
    Loop forever

    Your code strobes Tx over and over

  • 0 in reply to H Stewart
    Intellectual 365 points

    Okay, thank you!

    But is it wrong to use the ASK modulation to get an unmodulated carrier?

    Regards,

    Fabian

  • 0 in reply to Parcour
    Mastermind 8170 points

    I would not think so.  I have used OOK with two PA values set equal and  did not see any transtion noise.

  • 0 in reply to H Stewart
    Intellectual 365 points

    ...two PA values set equal. Nice idea. I used only one PA value. So i think the signal goes on...off...on...or not? I measured approx. + 10,5 dBm. So I think it seems to be ok, isn't it?

  • 0 in reply to Parcour
    Mastermind 8170 points

    I had other reasons to have two that were then set equal.  I never explored using just one. It is a better approach if doable, less chance of transitions as it switches between two.