Desired sample rate to best sample rate for mini v2

General Discussion
1

I am getting this error. Is there a way to get the best sample rate for the mini v2 from a “requested” sample rate?
set_rx_samplerate:552 Set RX sample rate 274285.000000
SetFrequencyCGEN(1.09714 MHz) - cannot deliver requested frequency
set_rx_samplerate:556 error setting RX sample rate SetFrequencyCGEN(1.09714 MHz) - cannot deliver requested frequency

2

the requested 274285 Hz is a very low sampling rate, it is lower than what the clock generator can provide directly. To achieve this 274285 sample rate, you need to increase oversampling ratio to 8.

3

So the minimum sample rate is what the clock generator is set to?
configure:190 clock LMS_CLOCK_REF freq 40000000.000000
configure:190 clock LMS_CLOCK_SXR freq 1400000000.000000
configure:190 clock LMS_CLOCK_SXT freq 1400000000.000000
configure:190 clock LMS_CLOCK_CGEN freq 4388559.982181
configure:190 clock LMS_CLOCK_RXTSP freq 1097139.995545
configure:190 clock LMS_CLOCK_TXTSP freq 1097139.995545

Is there anyway to set the clock generator? Is there a specific range?

Thanks,
M

4

CGEN range is 5-640 MHz
Sample rate equation is: sampleRate = CGEN/(4 * oversampling)
So to get your 274285Hz sample rate, the oversampling has to be at least 8, to bring CGEN into supported range.
Calling LMS_SetSampleRate(device, 274285, 8); will give your requested rate.

5

I am porting the driver to an embedded system that doesn’t have alot of processing power. Since I don’t have alot of processing power, I need to keep the sample rate low to reduce the data throughput and load on the CPU. If I set the oversample to 8 that will generate significantly more data (8 * 274285 * 32 bits/sec ).

6

It’s the RF oversampling(decimation/interpolation), it is done inside the LMS7002M chip itself, so no processing power is needed from your host system, the digital sample rate will remain the same 274285Hz.