Coerced IQ Rates

[krmills]

Hello all,

I'm working two USRP devices (2955 and 2920)and the IQ rates I set in each are being coerced. For instance, when I set the IQ rate to 10.23MHz, it is coerced to 10MHz.

Is there any way to get the ideal rate (10.23MHz) instead of the coerced rate (10MHz)?

Thank you for your help! 

[wiebe@CARYA]

Well, the signal is digital, so it's probably not possible to use just any frequency.

[cbutcher]

The help for the property does say it can be coerced, but the specification sheets look like they would allow a smaller than 230kHz step... What's the lowest value after 10MHz?

Are you using the property node to read the coerced value?

[krmills]

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@cbutcher wrote:

The help for the property does say it can be coerced, but the specification sheets look like they would allow a smaller than 230kHz step...

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I am using the property node to read the coerced value. Can you provide a link the specification sheets? The documents I saw did not mention a 230kHz step.

As for the lowest possible IQ rate, the USRP 2955 will coerce to 97.65625kHz for any value smaller than that. The next value lower than 10MHz that the device coerces to is 9.090909MHz.

[cbutcher]

Sorry - I didn't mean that I'd read there was any specific step size. I was just surprised that it was larger than 230kHz (since you can't seem to get 10.23 MHz).

As to the lowest value after 10MHz, I meant which is the next coerced value moving upwards (i.e. the lowest beyond 10MHz). Perhaps you can try doubling the target rate step (e.g. 10.46, 10.92, 11.84...) until it coerces to something other than 10MHz.

[wiebe@CARYA]

I'd expect there to be some base frequencies, some dividers and maybe multiplexers. So it probably won't be as simple as a step size.