basebandTransmitter

Configure SDR as baseband transmitter

Since R2022a

Description

Use the basebandTransmitter object to configure the specified software-defined radio (SDR) as a baseband transmitter to transmit IQ waveforms to the air.

This diagram shows the conceptual overview of transmitting radio signals in Wireless Testbench™ using a radio that you configure with this object. The onboard data buffering ensures contiguous data transmit. The transmission controller enables you to specify continuous or single-shot transmissions.

Creation

Syntax

bbtx = basebandTransmitter(radio)

bbtx = basebandTransmitter(radio,Name=Value)

Description

bbtx = basebandTransmitter(radio) creates a baseband transmitter object for the specified radio radio.

Note

The object requires exclusive access to radio hardware resources. Before creating this object, clear any existing Wireless Testbench object associated with the specified radio from the workspace.

bbtx = basebandTransmitter(radio,Name=Value) sets properties using one or more name-value arguments. For example, CenterFrequency=2.2e9 sets the center frequency to 2.2 GHz.

Input Arguments

radio — Radio setup configuration

string scalar

Radio setup configuration, specified as a string scalar. To create a radio setup configuration, set up your radio and save your radio setup configuration using the Radio Setup wizard. To list all saved radio setup configurations, call the radioConfigurations function. For more information, see Connect and Set Up NI USRP Radios.

Example: "MyRadio" indicates that you saved a radio setup configuration under the name MyRadio in the Radio Setup wizard.

Properties

CenterFrequency — Radio center frequency in Hz

2.4e9 (default) | positive numeric scalar | numeric array

Radio center frequency in Hz, specified as one of these options.

• Positive numeric scalar — The object applies this value by scalar expansion to each antenna in the Antennas property.

• Numeric array — The object applies the ith array element value to the ith antenna in the Antennas property.

The valid center frequency range depends on the radio device.

Radio Device	Center Frequency
USRP™ N310	1 MHz to 6 GHz
USRP N320	1 MHz to 6 GHz
USRP N321	1 MHz to 6 GHz
USRP X310	10 MHz to 6 GHz
USRP X410	1 MHz to 8 GHz

Note

When setting this property for multiple antennas on the USRP N310 radio, consider these hardware characteristics.

• The antenna ports on the RF0 and RF1 radio channels use the same center frequency. Therefore, set identical center frequency values for the antennas specified as "RF0:TX/RX" and "RF1:TX/RX".

• The antenna ports on the RF2 and RF3 radio channels use the same center frequency. Therefore, set identical center frequency values for the antennas specified as "RF2:TX/RX" and "RF3:TX/RX".

Data Types: double

Antennas — Transmit radio antennas

string scalar | string array

Transmit radio antennas, specified as one of these options.

• String scalar — Specify use of single antenna.

• String array — Specify use of multiple antennas.

Use this table to identify a supported radio antenna port on the radio device and the corresponding string constant that you can specify for this property. The default value depends on the radio.

Radio Device	Supported Antenna Port	String Scalar
USRP N310	RF0 channel: TX/RX port	"RF0:TX/RX" (default)
	RF1 channel: TX/RX port	"RF1:TX/RX"
	RF2 channel: TX/RX port	"RF2:TX/RX"
	RF3 channel: TX/RX port	"RF3:TX/RX"
USRP N320	RF0 channel: TX/RX port	"RF0:TX/RX" (default)
	RF1 channel: TX/RX port	"RF1:TX/RX"
USRP N321	RF0 channel: TX/RX port	"RF0:TX/RX" (default)
	RF1 channel: TX/RX port	"RF1:TX/RX"
USRP X310	RFA channel: TX/RX port	"RFA:TX/RX" (default)
	RFB channel: TX/RX port	"RFB:TX/RX"
USRP X410	DB0 RF0 channel: TX/RX 0 port	"DB0:RF0:TX/RX0" (default)
	DB0 RF1 channel: TX/RX 0 port	"DB0:RF1:TX/RX0"
	DB1 RF0 channel: TX/RX 0 port	"DB1:RF0:TX/RX0"
	DB1 RF1 channel: TX/RX 0 port	"DB1:RF1:TX/RX0"

Note

When you update this property, the execution time of the next object function call increases by a few seconds.

Data Types: string

RadioGain — Transmit radio gain in dB

10 (default) | positive numeric scalar | numeric array

Transmit radio gain in dB, specified as one of these options.

• Positive numeric scalar — The object applies this value by scalar expansion to each antenna that you specify in the Antennas property.

• Numeric array — The object applies the ith array element value to the ith antenna in the Antennas property.

The valid gain range depends on the radio device.

Radio Device	Transmit Radio Gain
USRP N310	0 dB to 65 dB
USRP N320	0 dB to 60 dB
USRP N321	0 dB to 60 dB
USRP X310	0 dB to 31.5 dB
USRP X410	0 dB to 60 dB

Data Types: double

SampleRate — Baseband sample rate in Hz

highest device sample rate (default) | positive numeric scalar

Baseband sample rate in Hz, specified as a positive numeric scalar. For more information on how the radio achieves the specified sample rate, see Baseband Sample Rate in NI USRP Radios.

The sample rate depends on the radio device.

Radio Device	Sample Rate
USRP N310	120,945 Hz to 76.8 MHz 122.88 MHz 125.00 MHz 153.60 MHz (default)
USRP N320	196,851 Hz to 125 MHz 200.00 MHz 245.76 MHz 250.00 MHz (default)
USRP N321	196,851 Hz to 125 MHz 200.00 MHz 245.76 MHz 250.00 MHz (default)
USRP X310	181,418 Hz to 100 MHz 184.32 MHz 200.00 MHz (default)
USRP X410	241,890 Hz to 125 MHz 245.76 MHz 250.00 MHz (default)

Note

To update this property, you must stop any ongoing transmission by calling the stopTransmission function on the object. When you update this property, the execution time of the next object function call increases by a few seconds.

Data Types: double

Object Functions

transmit	Transmit waveform using baseband transmitter or transceiver
stopTransmission	Stop transmission from baseband transmitter or transceiver

Examples

Configure Baseband Transmitter and Transmit Waveform

Create a baseband transmitter object, specifying a radio setup configuration previously saved in the Radio Setup wizard.

bbtx = basebandTransmitter("MyRadio")

bbtx = 
  basebandTransmitter with properties:

          RadioGain: 10
    CenterFrequency: 2.4000e+09
         SampleRate: 250000000
           Antennas: "RF0:TX/RX"

Set the baseband sample rate and center frequency.

bbtx.SampleRate = 122.88e6;
bbtx.CenterFrequency = 2.2e9;

Generate random transmit waveform.

txWaveform = complex(randn(1000,1),randn(1000,1));

Transmit the generated waveform continuously with the radio associated with the baseband transmitter object using the default antenna.

transmit(bbtx,txWaveform,"continuous");

Stop the continuous transmission after 5 seconds.

pause(5);
stopTransmission(bbtx);

Tips

You cannot use save and load to store and reload Wireless Testbench objects. Instead, you can re-create the object with these steps:

1. Write code to create a basebandTransmitter object with a saved radio setup configuration radio and set the properties.

2. Save the code to a script.

3. Run the script in a new MATLAB^® session with the same saved radio setup configuration.

Version History

Introduced in R2022a