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Baseband Sample Rate in NI USRP Radios

Each Wireless Testbench™ reference application object enables you to set the baseband sample rate of the radio by using the SampleRate object property. The object automatically selects the master clock rate on the radio hardware based on the specified sample rate. If necessary, to achieve the specified sample rate, the radio uses a Farrow rate converter.

Supported Master Clock Rates

The analog-to-digital converter (ADC) and digital-to-analog converter (DAC) in USRP™ radios run at the full master clock rate, which is hardware-dependent. This table shows the master clocks rates available on supported NI™ USRP radios.

Radio DeviceMaster Clock Rate

USRP N310

  • 122.88 MHz

  • 125.00 MHz

  • 153.60 MHz

USRP N320

  • 200.00 MHz

  • 245.76 MHz

  • 250.00 MHz

USRP N321

  • 200.00 MHz

  • 245.76 MHz

  • 250.00 MHz

Set Baseband Sample Rate

The object automatically selects the master clock rate on the radio hardware based on the SampleRate property value. If necessary, to achieve the specified sample rate, the radio uses a Farrow rate converter along with integer interpolation for transmit signals or integer decimation for capture signals.

To bypass the Farrow filter, set the SampleRate property to a master clock rate value or to a value such that MCR/SampleRate is a supported decimation or interpolation factor, where MCR is the master clock rate that the object selects.

RadioSupported Decimation or Interpolation Factor

USRP N310

USRP N320

USRP N321

1

2

3

Even integer in the range from 4 to 256

Integer multiple of 4 in the range from 256 to 512

Integer multiple of 8 in the range from 512 to 1020

Farrow Rate Converter

If MCR/SampleRate is not a supported decimation or interpolation factor, the signal passes through the Farrow rate converter. Because of hardware limitations, the Farrow rate converter can only convert sample rates that are less than MCR/2.

See Also

Objects

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