comm.SDRuReceiver
Receive data from USRP device
Add-On Required: This feature requires the Wireless Testbench™ Support Package for NI™ USRP™ Radios add-on.
Description
The comm.SDRuReceiver
System object™ receives data from a USRP™ radio, enabling simulation and development for software-defined radio
applications; for USRP
200-series radios, see the Communications Toolbox™ documentation.
Use this object to communicate with a USRP radio on the same Ethernet subnetwork or a via a USB connection. You can write a MATLAB® application that uses the System object, or you can generate code for the System object without connecting to a USRP radio.
This object receives signal and control data from a USRP radio using the universal hardware driver (UHD™) from Ettus Research™. The System object receives data from a USRP radio and outputs a column vector or matrix signal with fixed number of rows.
To receive data from a USRP radio device:
Create the
comm.SDRuReceiver
object and set its properties.Call the object as if it were a function.
To learn more about how System objects work, see What Are System Objects?.
Note
Starting in R2024a, the MathWorks® products and support packages you require to use this System object depend on your radio device.
Radio Device | Required MathWorks Products | Support Package Installation |
---|---|---|
USRP2™ USRP N200, N210 USRP B200, B210 | Communications Toolbox Support Package for USRP Radio | Install Communications Toolbox Support Package for USRP Radio |
USRP N300, N310, N320, N321 USRP X300, X310 | Wireless Testbench™ Wireless Testbench Support Package for NI™ USRP Radios | Install Support Package for NI USRP Radios |
For details on how to use this System object with a radio device supported by Communications Toolbox Support Package for USRP Radio, see comm.SDRuReceiver
.
Creation
Syntax
Description
creates an SDRu receiver System object for a USRP radio with the specified model number at the default IP address,
192.168.10.2.rx
= comm.SDRuReceiver(Platform
=radioDevice)
creates an SDRu receiver System object for a USRP radio with the specified model number at the specified IP address.rx
= comm.SDRuReceiver(Platform
=radioDevice,IPAddress
=radioIPAddress)
sets Properties
using one or more name-value in addition to any input argument combination from previous
syntaxes. For example, rx
= comm.SDRuReceiver(___,Name
= Value
)CenterFrequency
= 5e6
specifies the center frequency as 5 MHz.
Properties
Unless otherwise indicated, properties are nontunable, which means you cannot change their
values after calling the object. Objects lock when you call them, and the
release
function unlocks them.
If a property is tunable, you can change its value at any time.
For more information on changing property values, see System Design in MATLAB Using System Objects.
Connection PropertiesPlatform
— Model number of radio
"N300"
| "N310"
| "N320/N321"
| "X300"
| "X310"
Model number of the radio, specified as one of these values.
"N300"
— A connected USRP N300 radio."N310"
— A connected USRP N310 radio."N320/N321"
— A connected USRP N320 or USRP N321 radio."X300"
— A connected USRP X300 radio."X310"
— A connected USRP X310 radio.
Data Types: char
| string
IPAddress
— IP address of USRP device
"192.168.10.2"
(default) | character vector | string scalar
IP address of the USRP radio, specified as a character vector or string scalar containing dotted-quad values. When you specify more than one IP address, you must separate each address using commas or spaces.
This value must match the physical IP address of the radio device assigned when you set up your radio using the Radio Setup wizard. If you configure the radio device with an IP address other than the default, update this property accordingly.
To find the logical network location of all connected USRP radios, use the findsdru
function.
Example: "192.168.10.2, 192.168.10.5"
or "192.168.10.2
192.168.10.5"
specifies IP addresses for two radio devices.
Data Types: char
| string
IsTwinRXDaughterboard
— Option to enable TwinRX daughterboard
false
or
0
(default) | true
or 1
Option to enable the TwinRX daughterboard, specified as a
numeric or logical 0
(false
)
or 1
(true
). To enable the
TwinRX daughterboard on an X-series radio, set IsTwinRXDaughterboard
to 1
(true
).
When you enable the TwinRX daughterboard, you can use the
EnableTwinRXPhaseSynchronization
property to enable
phase synchronization between channels of the TwinRX
daughterboard.
Dependencies
To enable this property, set the Platform
property to "X300" or "X310"
.
Data Types: logical
EnableTwinRXPhaseSynchronization
— Option to enable phase synchronization
false
or
0
(default) | true
or 1
Option to enable phase synchronization between channels of the
TwinRX daughterboard, specified as a numeric or logical
0
(false
) or
1
(true
). When you set this
property to 1
(true
), the
TwinRX daughterboard provides phase synchronization between all the
channels. In this case, the value of the CenterFrequency
property must be the same for all the
channels.
Note
The local oscillator (LO) source on channel 1 is the master source that drives the other LOs of the TwinRx daughterboard channels.
To share LOs between two TwinRx daughterboards, attach the four MMCX RA male cables on one daughterboard to the MMCX RA male cables on the other daughterboard by crossing the cables between the two daughterboards. Make these cable connections.
J1 to J2
J2 to J1
J3 to J4
J4 to J3
This figure shows the connections between the TwinRx daughterboards.
Dependencies
To enable this property, set the Platform
property to "X300" or "X310"
and IsTwinRXDaughterboard
property to
1
(true
).
Data Types: logical
ChannelMapping
— Channel mapping for radio or bundled radios
1
(default) | positive scalar | row vector of positive values
Channel mapping for the radio or bundled radios, specified as a positive scalar or a row vector of positive values. This table shows the valid values for each radio platform.
Platform Property Value |
ChannelMapping Property Value |
---|---|
|
|
|
|
|
|
|
|
| When the
When the
|
When the IPAddress
property contains multiple IP
addresses, the channels defined by ChannelMapping
are ordered first
by the order in which the IP addresses appear in the list and then by the channel order
within the same radio.
For example, if the Platform
is
"X300"
and IPAddress
is
"192.168.20.2, 192.168.10.3"
, then the
ChannelMapping
must be [1 2 3 4]
. Channels 1
and 2 of the bundled radio refer to channels 1 and 2 of the radio with IP address
192.168.20.2, respectively. Channels 3 and 4 of the bundled radio refer to channels 1
and 2 of the radio with IP address 192.168.10.3, respectively.
Data Types: double
CenterFrequency
— Center frequency
2.45e9
| nonnegative scalar | row vector of nonnegative values
Center frequency in Hz, specified as a nonnegative scalar or a row vector of nonnegative values. The valid range of values for this property depends on the RF daughter card of the USRP device.
When you set the IsTwinRXDaughterboard
property to
0
(false
), specify the
value according to these conditions.
For a single-input single-output (SISO) configuration, specify the value for the center frequency as a nonnegative scalar.
For multiple-input multiple output (MIMO) configurations that use the same center frequency, specify the center frequency as a nonnegative scalar. The center frequency is set by scalar expansion.
For multiple-input multiple output (MIMO) configurations that use different center frequencies, specify the values in a row vector (for example,
[70e6 100e6]
). The object applies the ith element of the vector to the ith channel that you specify in theChannelMapping
property.Note
For a MIMO scenario, the center frequency for a N300 radio must be a scalar. You cannot specify the frequencies as a vector.
The channels corresponding to the same RF daughterboard of an N310 radio must have the same center frequency.
When you set the IsTwinRXDaughterboard
property to 1
(true
), specify the center frequency according
to these conditions.
To tune all channels to the same frequency, specify the center frequency as a scalar and the
EnableTwinRXPhaseSynchronization
property as1
(true
).To tune the channels to different frequencies, specify the center frequency as a row vector. Each value in the row vector specifies the frequency of the corresponding channel. Set the
EnableTwinRXPhaseSynchronization
property to0
(false
).
Note
When you set IsTwinRXDaughterboard
and EnableTwinRXPhaseSynchronization
to
1
(true
), the LO source on
channel 1 is the master source that
drives the other LOs of the TwinRX daughterboard channels. In this
case, the CenterFrequency
property value must be the same for
all channels of the TwinRX daughterboard.
For more information, see EnableTwinRXPhaseSynchronization
.
Tunable: Yes
Data Types: double
LocalOscillatorOffset
— Local oscillator (LO) offset frequency
0
(default) | scalar | row vector
LO offset frequency in Hz, specified as a scalar or row vector. The valid range of this property depends on the RF daughterboard of the USRP device.
The LO offset does not affect the received center frequency. However, the LO offset does affect the intermediate center frequency in the USRP radio, as this diagram shows.
In this diagram:
f RF is the received RF frequency.
f center is the center frequency that you set in the System object.
f LO offset is the LO offset frequency.
Ideally, fRF - fcenter = 0.
To move the center frequency away from interference or harmonics generated by the USRP radio, use this property.
To change the LO offset, specify the value according to these conditions.
For a SISO configuration, specify the LO offset as a scalar.
For MIMO configurations, the LO offset must be zero. This restriction is due to a UHD limitation. In this case, you can specify the LO offset as 0.
Tunable: Yes
Data Types: double
Gain
— Overall gain for USRP radio receiver data path
8
(default) | scalar | row vector
Overall gain in dB for the USRP radio receiver data path, including analog and digital components, specified as a scalar or row vector. The valid range of this property depends on the RF daughterboard of the USRP device.
Specify the gain according to these conditions.
For a SISO configuration, specify the gain as a scalar.
For MIMO configurations that use the same gain value, specify the gain as a scalar. The gain is set by scalar expansion.
For MIMO configurations that use different gains, specify the values in a row vector (for example,
[32 30]
). The object applies the ith element of the vector to the ith channel that you specify in theChannelMapping
property.
Tunable: Yes
Data Types: double
PPSSource
— PPS signal source
"Internal"
(default) | "External"
| "GPSDO"
Pulse per second (PPS) signal source, specified one of these values.
"Internal"
— Use the internal PPS signal of the USRP radio."External"
— Use the PPS signal from an external signal generator."GPSDO"
— Use the PPS signal from a global positioning system disciplined oscillator (GPSDO).
To synchronize the time for all the channels of the bundled radios, you can:
Provide a common external PPS signal to all of the bundled radios and set this property to
"External"
.Use the PPS signal from each GPSDO that is available on the USRP radio by setting this property to
"GPSDO"
.
To get the lock
status of the GPSDO to the GPS constellation, set this property to
"GPSDO"
and use the gpsLockedStatus
function.
Data Types: char
| string
EnforceGPSTimeSync
— Option to enforce GPS time synchronization
false
or 0
(default) | true
or 1
Option to enforce GPS time synchronization, specified as one of these values.
1
(true
) — Synchronize the USRP radio time to the valid global positioning system (GPS) time if the GPSDO is locked to the GPS constellation at the beginning of the transmit or receive operation.0
(false
) — Set the USRP radio time to the GPSDO time if the GPSDO is not locked to the GPS constellation at the beginning of the transmit or receive operation.
Each time you call the System object, it checks the lock status of the GPSDO. When the GPSDO is locked to the GPS constellation, the System object sets the USRP radio time to the valid GPS time.
Dependencies
To enable this property, set the PPSSource
property to
"GPSDO"
.
Data Types: logical
ClockSource
— Clock source
"Internal"
(default) | "External"
| "GPSDO"
Clock source, specified as one of these values.
"Internal"
— Use the internal clock signal of the USRP radio."External"
— Use the 10 MHz clock signal from an external clock generator."GPSDO"
— Use the 10 MHz clock signal from a GPSDO.
The external clock port has the label REF IN.
To synchronize the frequency for all the channels of the bundled radios, you can:
Provide a common external 10 MHz clock signal to all of the bundled radios and set this property to
"External"
.Provide a 10 MHz clock signal from each GPSDO to the corresponding radio and set this property to
"GPSDO"
.
To synchronize the frequency for all channels, set this property to "GPSDO"
and then verify that the outputs of the referenceLockedStatus
and gpsLockedStatus
functions both return an output of
1
.
Data Types: char
| string
MasterClockRate
— Master clock rate
positive scalar
Master clock rate in Hz, specified as a positive scalar. The master clock rate is the analog to digital (A/D) and digital to analog (D/A) clock rate. The valid range of values for this property depends on the connected radio platform.
Platform Property Value | MasterClockRate Property
Value (in Hz) |
---|---|
|
|
|
|
|
|
Data Types: double
DecimationFactor
— Decimation factor for SDRu receiver
512
(default) | integer in the range [1,1024]
Decimation factor for the SDRu receiver, specified as an integer in the range
[1,1024]
with restrictions that depend on the radio you use.
DecimationFactor Property Value | USRP N3xx Series Radio | USRP X3xx Series Radio |
---|---|---|
| Valid | Not valid with TwinRX daughterboard |
| Valid | Valid |
| Valid | Valid |
Odd integer from 4 to 128 | Not valid | Valid |
Even integer in the range
| Valid | Valid |
Integer multiple of 4 in the range
[256,512] | Valid | Valid |
Integer multiple of 8 in the range
| Valid | Valid |
The radio uses the decimation factor when it downconverts the intermediate frequency (IF) signal to a complex baseband signal.
Data Types: double
EnableTimeTrigger
— Option to enable timed transmission and reception
0
or false
(default) | 1
or true
Option to enable timed transmission and reception, specified as a numeric or logical
value of 1
(true
) or 0
(false
). When you set this property to 1
(true
), you can:
Transmit or receive after the time specified in the
TriggerTime
property.Transmit or receive at the specified GPS time in the
TriggerTime
property if you set thePPSSource
property to"GPSDO"
.Simultaneously transmit and receive after the time specified in the
TriggerTime
property.
Data Types: logical
TriggerTime
— Trigger time in seconds
5
(default) | nonnegative scalar
Trigger time in seconds, specified as a nonnegative scalar. Specify the trigger time
after which the radio starts transmitting or receiving data. The
TriggerTime
value must be greater than the current USRP radio time. Use the getRadioTime
function to get the current USRP radio time.
Note
After you call the getRadioTime
function, call the System
object before releasing it to ensure that the object is released properly.
When you set the PPSSource
property to
"GPSDO"
, specify the TriggerTime
property
as the exact GPS time in seconds at which you want the radio to start transmitting or
receiving data.
Note
For USRP N3xx series radios, you can expect a consistent delay between the specified trigger time and the start of transmission or reception.
Dependencies
To enable this property, set the EnableTriggerTime
property
to true
.
Data Types: double
TransportDataType
— Transport data type
"int16"
(default) | "int8"
Transport data type, specified as one of these values:
"int16"
— Use 16-bit transport to achieve higher precision."int8"
— Use 8-bit transport to achieve a transport data rate that is approximately two times faster than 16-bit transport. The quantization step is 256 times larger than 16-bit transport.
The default transport data type assigns the first 16 bits to the in-phase (I) component and the remaining16 bits to the quadrature (Q) component, resulting in 32 bits for each complex sample of transport data.
Data Types: char
| string
OutputDataType
— Data type of output signal
"Same as transport data
type"
(default) | "double"
| "single"
Data type of the output signal, specified as one of these values.
"Same as transport data type"
— Set the output data type to the same as the transport data type: eitherint8
orint16
.When the transport data type is
int8
, the output values are raw 8-bit I and Q samples from the board in the range [–128, 127].When the transport data type is
int16
, the output values are raw 16-bit I and Q samples from the board in the range [–32 768 32 767].
"single"
— Specify single-precision floating point values scaled to the range [–1, 1]."double"
— Specify double-precision floating point values scaled to the range [–1, 1].
Data Types: char
| string
Complex Number Support: Yes
SamplesPerFrame
— Number of samples per frame
362
(default) | positive integer
Number of samples per frame of the output signal, specified as a positive integer. A 16-bit I/Q sample requires 4 bytes. The default 362 samples per frame value is set to fit a frame of data within one Ethernet packet, which is 1500 bytes.
Note
You can now set the SamplesPerFrame
property to any
positive integer value. Before R2021b, the maximum value is
375000
.
Data Types: double
EnableBurstMode
— Option to enable burst mode
0
or
false
(default) | 1
or true
Option to enable burst mode, specified as a numeric or logical
value of 1
(true
) or
0
(false
). To produce a set
of contiguous frames without an overrun or underrun to the radio,
set this property to 1
(true
).
Enable burst mode to simulate models that cannot run in real
time.
When you enable burst mode, specify the number of frames in a burst by using the
NumFramesInBurst
property.
For an example, see Burst Mode Buffering With SDRu Receiver.
Data Types: logical
NumFramesInBurst
— Number of frames in a contiguous
burst
1
(default) | nonnegative integer
Number of frames in a contiguous burst, specified as a nonnegative integer.
Dependencies
To enable this property, set EnableBurstMode
to
1
(true
).
Data Types: double
Usage
Syntax
Description
receives data from a USRP radio associated with the data
= rx()comm.SDRuReceiver
System object, rx
.
[
also returns the timestamp of each received sample from a USRP
device.data
,dataLen
,overrun
,timeStamps
]
= rx()
Output Arguments
data
— Output signal
complex column vector | complex matrix
Output signal, returned as a column vector or matrix. For a single-channel radio, this output is a column vector. For a multichannel radio, this output is a matrix. Each column in this matrix corresponds to a complex data received on one channel.
Data Types: int16
| single
| double
Complex Number Support: Yes
dataLen
— Data length
nonnegative integer
Data length, returned as a nonnegative integer. The value of this output is the number of samples received from USRP radio.
Data Types: double
overrun
— Data discontinuity flag
0
| 1
Data discontinuity flag, returned as one of these values.
0
— The object does not detect an overrun.1
— The object detects an overrun. The output data does not represent contiguous data that is transmitted from the USRP radio to the host.
Although the value of this output does not represent the actual number of packets dropped, as this value increases, the farther your execution of the object is from achieving real-time performance. You can use this value as a diagnostic tool to determine real-time execution of the object.
For an example, see Burst Mode Buffering With SDRu Receiver.
Data Types: uint32
timeStamps
— Timestamp of each received sample
column vector
Timestamp of each received sample, returned as a column vector. The length of this output equals the length of received data.
To get the GPS timestamp of each received sample from a USRP radio, set the
PPSSource
property to'GPSDO'
.To get the timestamp of each received sample from bundled radios, set the
PPSSource
property to'GPSDO'
or'External'
.
Object Functions
To use an object function, specify the
System object as the first input argument. For
example, to release system resources of a System object named obj
, use
this syntax:
release(obj)
Specific to comm.SDRuReceiver
info | Current USRP radio settings |
gpsLockedStatus | Lock status of GPSDO to GPS constellation |
referenceLockedStatus | Lock status of USRP radio to 10 MHz clock signal |
capture | Capture RF data using SDRu receiver |
getRadioTime | Get current USRP radio time |
Examples
Configure SDRu Receiver and Capture Data
Create an SDRu receiver System object for your USRP radio. Set the master clock rate and center frequency.
rx = comm.SDRuReceiver(Platform='X310',IPAddress='192.168.10.2');
Set master clock rate and center frequency.
rx.MasterClockRate = 184.32e6; rx.CenterFrequency = 2.4e9;
Capture 5 seconds of data.
[data,~] = capture(rx,5,'Seconds');
Release the hardware.
release(rx);
Get Radio Information for Multichannel Radio
Create an SDRu receiver System object for a multichannel radio configuration.
radio = comm.SDRuReceiver(Platform ="X300",IPAddress ='192.168.60.2'); radio.ChannelMapping = [1 2]; radio.CenterFrequency = [1.2 1.3]*1e9; radio.Gain = [5 6];
Get the radio information by calling the info
function.
info(radio)
ans = struct with fields:
Mboard: 'X300'
RXSubdev: {'UBX RX' 'UBX RX'}
TXSubdev: {'UBX TX' 'UBX TX'}
MinimumCenterFrequency: [-70000000 -70000000]
MaximumCenterFrequency: [6.0800e+09 6.0800e+09]
MinimumGain: [0 0]
MaximumGain: [37.5000 37.5000]
GainStep: [0.5000 0.5000]
CenterFrequency: [1.2000e+09 1.3000e+09]
LocalOscillatorOffset: 0
Gain: [5 6]
MasterClockRate: 200000000
DecimationFactor: 512
BasebandSampleRate: 390625
Receive Data and Write to Baseband File
Create an SDRu receiver System object for a USRP N320 radio. Configure the System object to receive at 1 GHz with a decimation factor of 512 and a master clock rate of 200 MHz. Calculate the baseband sample rate from the master clock rate and decimation factor.
rx = comm.SDRuReceiver( ... Platform="N320/N321", ... IPAddress="192.168.20.2", ... CenterFrequency=1e9, ... MasterClockRate=200e6, ... DecimationFactor=512); sampleRate = rx.MasterClockRate/rx.DecimationFactor;
Create a baseband file writer System object to write the received baseband data to a file named n320_capture.bb
. Configure the System object with the same center frequency and sample rate as the SDRu receiver.
rxWriter = comm.BasebandFileWriter( ... 'n320_capture.bb', ... sampleRate,rx.CenterFrequency);
Write the valid baseband data to the file.
for counter = 1:2000 data = rx(); rxWriter(data); end
Display information about the received signal.
info(rxWriter)
ans = struct with fields:
Filename: 'C:\MATLAB\n320_capture.bb'
SamplesPerFrame: 362
NumChannels: 1
DataType: 'int16'
NumSamplesWritten: 724000
Release the System objects.
release(rx); release(rxWriter);
Burst Mode Buffering With SDRu Receiver
This example shows how to detect overruns when using an SDRu receiver System object and how to overcome overruns by using burst mode buffering.
Detect Lost Samples
Create an SDRu receiver System object for a USRP N210 radio. Configure the System object to receive at 2.5 GHz. To increase the likelihood that an overrun will be occur, set the maximum baseband sample rate by setting the highest supported master clock and a decimation factor of 1. Set the number of samples per frame to 37500. Set the output data type to double
.
rx = comm.SDRuReceiver(Platform="N320/N321", ... IPAddress="192.168.20.2", ... CenterFrequency=2.5e9, ... MasterClockRate=250e6, ... DecimationFactor=1, ... SamplesPerFrame=37500, ... OutputDataType="double");
Create a comm.DPSKDemodulator
System object for capturing data.
demodulator = comm.DPSKDemodulator(BitOutput=true);
Receive 1000 frames of data using the SDRu receiver System object rx
. Additionally output the data continuity flag overrun
. Increment a variable n
when an overrun is detected. This indicates that the data transmitted from the USRP radio to the host is not contiguous.
n=1; for frame = 1:1000 [data,~,overrun] = rx(); demodulator(data); if overrun == 1 n = n+1; end end
Report the number of frames where overruns were detected.
fprintf("Overruns detected in %d frames without burst mode buffering",n-1)
Overruns detected in 54 frames without burst mode buffering
Release the hardware resources.
release(rx)
Use Burst Mode Buffering
To overcome overruns, enable burst mode buffering on the SDRu receiver System object rx
. Set the number of frames in a burst to 20.
rx.EnableBurstMode = true; rx.NumFramesInBurst = 20;
Receive 1000 frames of data using burst mode buffering.
n=1; for frame = 1:1000 [data,~,overrun] = rx(); if overrun == 0 demodulator(data); else n=n+1; end end
Report the number of frames where overruns were detected.
fprintf("Overruns detected in %d frames with burst mode buffering",n-1)
Overruns detected in 0 frames with burst mode buffering
Release the hardware resources.
release(rx)
Get Timestamps of Received Signal Using SDRu Receiver System Object
Configure a B210 radio with the serial number 3136D5F. Set the PPS signal source to the PPS signal from a GPSDO and enable GPS time synchronization. Set the clock source to GPSDO. Set the master clock rate to 20MHz, decimation factor to 20, and number of received samples per frame to 10.
Create an SDRu receiver System object to receive data form the USRP™ device.
format long; rx = comm.SDRuReceiver(Platform = "B210", SerialNum='3136D5F', ... PPSSource = "GPSDO", EnforceGPSTimeSync = true, ... ClockSource= "GPSDO", ... MasterClockRate=20e6, DecimationFactor=200, ... SamplesPerFrame = 20000);
Check the GPS lock status.
GPSLockStatus = 0; while ~GPSLockStatus disp("Trying to lock to GPS constellation ..."); GPSLockStatus = gpsLockedStatus(rx); end
Trying to lock to GPS constellation ...
if GPSLockStatus disp("GPSDO is locked. Acquiring data from radio ..."); [data,~, ~,GPSTimestamps] = rx(); d = datetime(GPSTimestamps(1), 'convertfrom', 'posixtime', 'Format', 'MM/dd/yy HH:mm:ss.SSS','TimeZone','Asia/Calcutta'); end
GPSDO is locked. Acquiring data from radio ...
USRP time synchronized to GPS time
Release the System object. Display the GPS timestamp of the first received data sample.
release(rx);
fprintf('GPS timestamp of first sample: %s',d);
GPS timestamp of first sample: 07/27/23 16:33:38.078
Receive Phase Synchronized Signals Using TwinRX Daughterboard
Receive phase synchronized signals using the TwinRX daughterboard. Transmit the sinusoidal signals with a B210 radio and receive the signals on an X300 radio with two TwinRX daughterboards. This example requires two MATLAB sessions running on your host computer.
To run this example, you require:
300-Series USRP radio (X3xx) and Wireless Testbench Support Package for NI USRP Radios. For information on mapping an NI USRP device to an Ettus Research 300-series USRP device, see Supported Radio Devices (Wireless Testbench).
200-Series USRP radio (B2xx or N2xx) and Communications Toolbox Support Package for USRP Radio, required when using the radio as the transmitter. For information on mapping an NI™ USRP device to an Ettus Research 200-series USRP device, see Supported Hardware and Required Software.
In the first MATLAB session, run the transmitter_twinrx.m
script.
In the second MATLAB session, configure an X300 radio with an IP address of 192.168.20.2. Set the radio to receive at 2.45 GHz with a decimation factor of 200 and a master clock rate of 200 MHz. Enable the TwinRX daughterboard and the TwinRX phase synchronization capability to receive phase synchronized signals. Set the ChannelMapping
property to [1 2 3 4]. Connect the power splitter from an B210 transmitter to four receiver channels of the X300 radio for calibration.
rx = comm.SDRuReceiver(Platform = "X300", ... IPAddress = '192.168.50.2', ... OutputDataType = "double", ... IsTwinRXDaughterboard = true, ... EnableTwinRXPhaseSynchronization = true, ... ChannelMapping = [1 2 3 4], ... MasterClockRate = 200e6, ... DecimationFactor = 200, ... Gain = 45, ... CenterFrequency = 2.45e9, ... SamplesPerFrame = 4000);
Set the frame duration for the signal reception based on the samples per frame and sample rate. Create time scope and frequency scope System objects to display time-domain and frequency-domain signals, respectively. Display a message when reception starts.
frameduration = (rx.SamplesPerFrame)/(200e6/200); time = 0; timeScope = timescope(TimeSpanSource = "Property",... TimeSpan = 4/30e3,SampleRate = 200e6/200); spectrumScope = spectrumAnalyzer('SampleRate',200e6/200); spectrumScope.ReducePlotRate = true; disp("Reception Started");
Reception Started
Inside a while-loop, receive the sine wave using the rx System object. Normalize the signal with respect to the amplitude for each receive channel. Compute the fast Fourier transform (FFT) of each normalized signal. Calculate the phase difference between channels 1 and 2, channels 1 and 3, and channels 1 and 4. Display the phase difference between channel 1 and each of the other channels of the TwinRX daughterboard.
counter = 0; while time < 10 && counter < 10 data = rx(); amp(1) = max(abs(data(:,1))); amp(2) = max(abs(data(:,2))); amp(3) = max(abs(data(:,3))); amp(4) = max(abs(data(:,4))); maxAmp = max(amp); if any(~amp) normalizedData = data; else normalizedData(:,1) = maxAmp/amp(1)*data(:,1); normalizedData(:,2) = maxAmp/amp(2)*data(:,2); normalizedData(:,3) = maxAmp/amp(3)*data(:,3); normalizedData(:,4) = maxAmp/amp(4)*data(:,4); end freqOfFirst = fft(normalizedData(:,1)); freqOfSecond = fft(normalizedData(:,2)); freqOfThird = fft(normalizedData(:,3)); freqOfFourth = fft(normalizedData(:,4)); angle1 = rad2deg(angle(max(freqOfFirst)/max(freqOfSecond))); angle2 = rad2deg(angle(max(freqOfFirst)/max(freqOfThird))); angle3 = rad2deg(angle(max(freqOfFirst)/max(freqOfFourth))); timeScope([real(normalizedData),imag(normalizedData)]); spectrumScope(normalizedData); time = time + frameduration; counter = counter +1; disp([' Phase difference between channel 1 and 2: ', num2str(angle1)]); disp([' Phase difference between channel 1 and 3: ', num2str(angle2)]); disp([' Phase difference between channel 1 and 4: ', num2str(angle3)]); disp(' '); end
Phase difference between channel 1 and 2: 100.1443
Phase difference between channel 1 and 3: -70.6504
Phase difference between channel 1 and 4: -165.1414
Phase difference between channel 1 and 2: 100.147
Phase difference between channel 1 and 3: -70.6436
Phase difference between channel 1 and 4: -165.1362
Phase difference between channel 1 and 2: 100.1514
Phase difference between channel 1 and 3: -70.6434
Phase difference between channel 1 and 4: -165.1411
Phase difference between channel 1 and 2: 100.1505
Phase difference between channel 1 and 3: -70.6371
Phase difference between channel 1 and 4: -165.1357
Phase difference between channel 1 and 2: 100.1553
Phase difference between channel 1 and 3: -70.636
Phase difference between channel 1 and 4: -165.1205
Phase difference between channel 1 and 2: 100.1513
Phase difference between channel 1 and 3: -70.6337
Phase difference between channel 1 and 4: -165.1287
Phase difference between channel 1 and 2: 100.1536
Phase difference between channel 1 and 3: -70.6466
Phase difference between channel 1 and 4: -165.1361
Phase difference between channel 1 and 2: 100.1451
Phase difference between channel 1 and 3: -70.64
Phase difference between channel 1 and 4: -165.1323
Phase difference between channel 1 and 2: 100.1567
Phase difference between channel 1 and 3: -70.6353
Phase difference between channel 1 and 4: -165.1197
Phase difference between channel 1 and 2: 100.152
Phase difference between channel 1 and 3: -70.6353
Phase difference between channel 1 and 4: -165.1248
release(timeScope);
release(spectrumScope);
release(rx);
disp("Reception ended");
Reception ended
Generate MEX Function from MATLAB Function Using SDRu Receiver System Object
This example shows how to generate a MEX file
called sdruReceiveMex
from the function
sdruReceiveData
. When you run this MEX file, the
code shows a performance improvement and no overruns for data frames
that contain 10000 samples.
Create a function that configures
comm.SDRuReceiver
System object. Set the frame
duration for the radio to receive data based on samples per frame
and sample rate. Display a message when reception starts. Inside a
for
-loop, receive the data using the
rx
System object and return the
overrun
output argument.
function [receiveTime,overrunCount] = sdruReceiveData() duration = 10; masterClockRate = 35e6; decimationFactor = 1; samplesPerFrame = 10000; sampleRate = masterClockRate/decimationFactor; frameDuration = samplesPerFrame/sampleRate; iterations = duration/frameDuration; rx = comm.SDRuReceiver(Platform = "B210",SerialNum = "30F59A1", ... MasterClockRate = masterClockRate, ... DecimationFactor = decimationFactor, ... OutputDataType = "double"); count = 0; rx(); disp("Started Reception..."); tic for i = 1:iterations [data,~,overrun] = rx(); if overrun count = count + 1; end end receiveTime = toc; overrunCount = count; release(rx); end
Generate a MEX file with the name
sdruReceiveMex
from the function
sdruReceiveData
.
codegen sdruReceiveData -o sdruReceiveMex;
Run this MEX file to receive data using the generated MEX and observe the reception time and number of overruns.
[ReceiveTime,overrunCount] = sdruReceiveMex()
More About
Single- and Multiple-Channel Output
USRP X300, X310, N300, and N321 radios support two channels that you can use to transmit and receive data with System objects. You can use both channels or a single channel (either channel 1 or 2).
Send data with the
comm.SDRuTransmitter
System object. Thecomm.SDRuTransmitter
System object transmits a matrix signal, where each column is a channel of data of fixed length.Receive data with the
comm.SDRuReceiver
System object. Thecomm.SDRuReceiver
System object outputs a matrix signal, where each column is a channel of data of fixed length.Note
When two TwinRX daughterboards are connected to a USRP X300 or X310 radio, the radio supports up to four channels.
USRP N310 and radios support four channels that you can use to transmit and receive data with System objects.
The
comm.SDRuTransmitter
System object receives a matrix signal, where each column is a channel of data with a fixed length.The
comm.SDRuReceiver
System object outputs a matrix signal, where each column is a channel of data with a fixed length.
You can set the CenterFrequency
,
LocalOscillatorOffset
, and Gain
properties
independently for each channel. Alternatively, you can apply the same setting to all
channels. All other System object property values apply to all channels.
For more information, see and Multiple Channel Input and Output Operations.
Blocking Behavior
Starting in R2022a, the comm.SDRuReceiver
System
object waits until it receives the number of samples per frame specified
by the
SamplesPerFrame
property before it returns processing control to the simulation.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Usage notes and limitations:
capture
System object method is not supported for code generation.
getRadioTime
System object method is not supported for code generation.
For more information on codegen
support to the System objects, see
System Objects in MATLAB Code Generation (MATLAB Coder).
For more information on MATLAB Compiler™ support to the System objects, see Acceleration and Deployment.
Version History
Introduced in R2011bR2024a: Support for N3xx and X3xx series radio devices moved to Wireless Testbench
Support for NI USRP N3xx and X3xx series radio devices has moved from Communications Toolbox Support Package for USRP Radio to Wireless Testbench Support Package for NI USRP Radios.
R2023b: Enhanced support for time triggering in SDRu System objects
You can now specify trigger time to enable transmission and reception of data at a
specified time for a USRP radio. This property is available in the comm.SDRuTransmitter
and comm.SDRuReceiver
System objects.
R2022b: Reduced setup time for comm.SDRuReceiver
The time required to initialize the comm.SDRuReceiver
System Object™ is now about 17
seconds faster for N3xx radio and about 30 seconds faster for
X3xx radio compared to R2022a release.
Simulation performance results for
comm.SDRuReceiver
System Object:
Platform: X310
Frame time: 0.001 s
Release | Time Required to Set Center Frequency (s) | Time Required to Set Gain (s) | Time Required to Run System Object (s) | Total Time Required to Set Properties and Call System Object (s) |
R2022a | 14.281994 | 15.285889 | 14.613851 | ~44.2 |
R2022b | 0.01113 | 0.001219 | 14.03521 | ~14 |
The code execution was timed on a Windows® 10, Intel® Xeon® W-2133 CPU @ 3.60 GHz installed RAM 64.0 GB test system.
R2020a: X3xx series radios no longer support 120 MHz master clock rate
Beginning with Ettus Research UHD version 003.014.000.000, X3xx series radios do not support a master clock rate value of 120 MHz. Consequently, starting in R2020a, which supports UHD version 003.015.000.000, Communications Toolbox Support Package for USRP Radio does not support a master clock rate value of 120 MHz for X3xx series radios.
For the comm.SDRuTransmitter
and
comm.SDRuReceiver
System
objects, when you specify an X3xx series radio for the Platform
property,
you can no longer set the MasterClockRate
property to
120e6
.
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