transmit

Transmit waveform using preamble detector

Since R2022a

Syntax

transmit(pd,waveform,"continuous")

transmit(___,Name=Value)

Description

transmit(pd,waveform,"continuous") continuously transmits the IQ waveform waveform to the air using the preamble detector pd. Use this function to send a test waveform to the air while trying to detect and capture a signal of interest using the same preamble detector. To stop the transmission, call stopTransmission(pd).

transmit(___,Name=Value) specifies optional name-value arguments for the transmission, in addition to the input arguments from the previous syntax.

Examples

Configure Preamble Detector and Capture Test Waveform

Configure a preamble detector to continuously send a test waveform with a known preamble sequence and capture data samples of the transmitted waveform.

Define a preamble sequence with good correlation properties. For example, generate and normalize a Zadoff-Chu sequence of length 137.

zcseq = zadoffChuSeq(38,137);
preamble = zcseq/norm(zcseq,2); 

Generate a test waveform.

prePadding = complex(zeros(999,1),zeros(999,1));                  
postPadding = complex(zeros(1000,1),zeros(1000,1));               
testWaveform = [prePadding;zcseq*0.75;postPadding]; 

Create and configure a preamble detector object, specifying a radio setup configuration previously saved in the Radio Setup wizard.

pd = preambleDetector("MyRadio")

pd = 
  preambleDetector with properties:

            CenterFrequency: 2.4000e+09
                  RadioGain: 10
                   Antennas: "RF0:RX2"
                 SampleRate: 153600000
            CaptureDataType: "int16"
       DroppedSamplesAction: "error"
                   Preamble: [16×1 double]
            ThresholdMethod: "adaptive"
             FixedThreshold: 0
    AdaptiveThresholdOffset: 0
      AdaptiveThresholdGain: 0
              TriggerOffset: 0

pd.SampleRate = 10.24e6;

Specify the preamble.

pd.Preamble = preamble; 

Send the test waveform continuously.

transmit(pd,testWaveform,"continuous", ...
    TransmitGain=30);

Capture 10 ms of data of the transmitted waveform.

[data,timestamp,droppedSamples,status] = capture(pd,milliseconds(10),milliseconds(50));

Stop test waveform transmission.

stopTransmission(pd);

Input Arguments

pd — Preamble detector

preambleDetector object

Preamble detector, specified as a preambleDetector object.

Note

The first object function call in which you specify this object as an input requires a few extra seconds to load the application onto the hardware.

waveform — IQ waveform to transmit

column vector of complex values

IQ waveform to transmit, specified as a column vector of complex values.

If you specify a waveform with a single or double data type, you must scale the transmit data sample values to the range [–1, 1).

The waveform length must be relative to the onboard radio memory buffer size.

Radio Device	Memory Buffer Size	Maximum Data Samples
USRP™ N310	2 GB	229
USRP N320	2 GB	229
USRP N321	2 GB	229
USRP X310	1 GB	228
USRP X410	4 GB	230

Note

• Transmit data samples and capture or plotted data samples are buffered in the onboard radio memory. Therefore, when specifying the transmit waveform, take also into account the data capture length or plotted data length that you specify when calling the capture or plotThreshold object functions, respectively, with the pd input.

• To avoid underflow during the transmission of a waveform of length less than 513 samples, the function reserves up to 1024 samples on the onboard radio memory.

• If the pd object uses a Farrow rate converter to achieve the sample rate that you specify by the pd.SampleRate property, the object resamples the transmit waveform. The resulting waveform has an increased number of data samples. For more information, see Baseband Sample Rate in NI USRP Radios.

Data Types: int16 | single | double
Complex Number Support: Yes

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: TransmitGain=50 applies a gain of 50 dB to the transmit waveform.

TransmitGain — Transmit gain in dB

10 (default) | positive numeric scalar

Transmit gain in dB, specified as a positive numeric scalar. 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

TransmitCenterFrequency — Transmit center frequency in Hz

pd.CenterFrequency (default) | positive numeric scalar

Transmit center frequency in Hz, specified as a positive numeric scalar. 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

Data Types: double

TransmitAntennas — Transmit radio antenna

"RF0:TX/RX" or "RFA:TX/RX" (default) | string constant

Transmit radio antenna, specified as a string constant. Use this table to identity a supported radio antenna port on the radio device and the corresponding string constant that you can specify for this input.

Radio Device	Supported Antenna Port	Valid 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"

Data Types: string

Version History

Introduced in R2022a