Baseband Sample Rate in NI USRP Radios

Each NI™ USRP™ radio supports a set of master clock rates (MCRs) and decimation or interpolation factors.

The following Wireless Testbench™ objects enable you to set the baseband sample rate of the radio by using the SampleRate object property. These objects automatically select the MCR on the radio hardware based on the specified sample rate.

• basebandReceiver

• basebandTransmitter

• basebandTransceiver

• energyDetector

• preambleDetector

If necessary, to achieve the specified sample rate, the radio uses a Farrow rate converter. For details, see Farrow Rate Converter. To bypass the Farrow filter when using these objects, set the SampleRate property to an MCR value, or a supported decimation or interpolation factor of an MCR value.

The usrp System object™ also selects the MCR and decimation or interpolation factor on the radio hardware based on the specified baseband sample rate, but it does not use a Farrow rate converter. You must set the SampleRate property to an MCR value, or a supported decimation or interpolation factor of an MCR value.

Supported Master Clock Rates

The analog-to-digital converter (ADC) and digital-to-analog converter (DAC) in USRP radios run at the full MCR, which is hardware-dependent. This table shows the master clocks rates available on supported NI USRP radios. For more information about radio support, see Supported Radio Devices.

Radio Device	MCR
USRP E320 (since R2025a)	Using one transmit channel, one receive channel, or both: 40.00 MHz 50.00 MHz 61.44 MHz Using two transmit or receive channels: 20.00 MHz 25.00 MHz 30.72 MHz
USRP N300 USRP N310	122.88 MHz 125.00 MHz 153.60 MHz
USRP N320 USRP N321	200.00 MHz 245.76 MHz 250.00 MHz
USRP X300 USRP X310	184.32 MHz 200.00 MHz
USRP X410	245.76 MHz 250.00 MHz 491.52 MHz (since R2025a) 500 MHz (since R2025a)

Set Baseband Sample Rate

NI USRP radios can transmit and receive waveforms at a sample rate of MCR divided by a supported decimation or interpolation factor, where MCR is the master clock rate.

Radio	Supported Decimation or Interpolation Factor
USRP E320 (since R2025a)	1
	2
	3
	Even integer in the range from 4 to 256
	Multiple of 4 in the range from 256 to 512
	Multiple of 8 in the range from 512 to 1008
USRP N300 USRP N310 USRP N320 USRP N321 USRP X410	1
	2
	3
	Even integer in the range from 4 to 256
	Multiple of 4 in the range from 256 to 512
	Multiple of 8 in the range from 512 to 1016
USRP X300 USRP X310	Integer in the range from 1 to 128
	Even integer in the range from 128 to 256
	Multiple of 4 in the range from 256 to 512
	Multiple of 8 in the range from 512 to 1016

Note

If you have a USRP X410 radio, the application can derive a sample rate using interpolation or decimation from an MCR value up to 250 MHz. Without using the Farrow rate converter, the radio can generate the following sample rates:

• 245.76 MHz divided by a supported decimation or interpolation factor

• 250 MHz divided by a supported decimation or interpolation factor

• 491.52 MHz (since R2025a)

• 500 MHz (since R2025a)

Farrow Rate Converter

For the following Wireless Testbench objects, if MCR/SampleRate is not a supported decimation or interpolation factor, the signal passes through the Farrow rate converter.

• basebandReceiver

• basebandTransmitter

• basebandTransceiver

• energyDetector

• preambleDetector

Note

• Because of hardware limitations, the Farrow rate converter can only convert sample rates that are less than MCR/2.

• If you have a USRP X410 radio, the Farrow rate converter can only convert sample rates using an MCR value up to 250 MHz. This means that the radio can generate sample rates from 241,890 Hz to 125 MHz using the Farrow rate converter.

Resampling Transmit Waveform

When you call the transmit function with an object that uses a Farrow rate converter to achieve the sample rate specified by the SampleRate property, the object resamples the transmit waveform. The resulting waveform has an increased number of data samples.