SDRu Receiver
Receive data from USRP device
Add-On Required: This feature requires the Wireless Testbench™ Support Package for NI™ USRP™ Radios add-on.
Libraries:
Wireless Testbench Support Package for NI USRP Radios
Description
The SDRu Receiver block supports communication between Simulink® and a Universal Software Radio Peripheral (USRP™) device, enabling simulation and development for various software-defined radio applications. The SDRu Receiver block and the USRP board must be on the same Ethernet subnetwork.
The SDRu Receiver block receives signal and control data from a USRP board using the Universal Hardware Driver (UHD™) from Ettus Research™. The SDRu Receiver block is a Simulink source that receives data from a USRP board and outputs a column vector or matrix signal with a fixed number of rows. The first call to this block can contain transient values, in this case the resulting packets contain undefined data.
This block diagram illustrates how Simulink, the SDRu Transmitter and Receiver blocks, and the USRP hardware interface.
When this block is called, it is possible that the host has not yet received any data from the USRP hardware. The data length port, length, indicates when valid data is present. When the data length port contains a zero value, there is no data. To qualify the execution of part of the model, use the data length with an enabled subsystem.
If your computer is not connected to any USRP hardware, you can still use this block to develop a model that propagates sample time and data type information. To propagate this information, select Simulation > Update diagram.
For information about the USRP hardware products that interface with this block, see the Supported Radio Devices.
This icon shows all ports, including optional ones:
Note
Starting in R2024a, the MathWorks® products and support packages you require to use this Simulink block 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 Simulink block with a radio device supported by Communications Toolbox Support Package for USRP Radio, see SDRu Receiver.
Ports
Input
fc — Center frequency setting
positive scalar
Center frequency setting in Hz, specified as a positive scalar.
Example:
88.9e6
tunes the receiver to a
center frequency of 88.9 MHz.
Dependencies
To enable this port, set Source of
center frequency to
Input
Port
.
Data Types: double
LO offset — Local oscillator offset
scalar
Local oscillator (LO) offset in Hz, specified as a scalar.
Example:
10
sets the LO offset to 10
Hz.
Dependencies
To enable this port, set Source of
LO offset to Input
Port
.
Data Types: double
gain — Receiver gain setting
scalar | vector
Receiver gain setting in dB, specified as a scalar or vector. The valid range of this gain depends on the RF daughterboard of the USRP device.
Dependencies
To enable this port, set Source of
gain to Input
Port
.
Data Types: double
Output
data — Output data
vector of complex values
Output data received from the radio hardware, returned as a vector of complex values. The complex output data values range from -1 to 1.
Dependencies
To specify the base data type, use the Output data type parameter.
Data Types: int8
| int16
| single
| double
Complex Number Support: Yes
length — Length of received data
nonnegative integer
Length of the received data, returned as a nonnegative integer. This output port provides the number of samples received from the USRP radio.
Dependencies
To enable this port, select the Enable data length output port parameter.
overrun — Data discontinuity flag
0
| 1
Data discontinuity flag, returned:
0
— Data samples are not lost.1
— Data samples are lost
Use this port as a diagnostic tool to determine real-time operation of the SDRu Receiver block. If your model is not running in real time, you can adjust parameters that reduce the number of transported samples. To approach or achieve real-time performance, you can decrease the baseband sampling rate or increase the decimation factor.
Dependencies
To enable this port, select the Enable overrun output port parameter.
Data Types: Boolean
refLocked — Lock status of USRP radio to 10 MHz clock signal
0
| 1
Lock status of the USRP radio to the 10 MHz clock signal, returned as one of these Boolean values.
0
— The USRP radio is not locked to the 10 MHz clock signal of an external clock source or a global positioning system disciplined oscillator (GPSDO).1
— The USRP radio is locked to the 10 MHz clock signal of an external clock source or a GPSDO.
Dependencies
To enable this port, select the Enable ref_locked output port parameter.
Data Types: Boolean
gpsLocked — Lock status of GPSDO to GPS constellation
0
| 1
Lock status of the GPSDO to the GPS constellation, returned as one of these Boolean values.
0
— The GPSDO is not locked to the GPS constellation.1
— The GPSDO is locked to the GPS constellation.
Dependencies
To enable this port, select the Enable gps_locked output port parameter.
Data Types: Boolean
timeStamps — Time stamp of each received sample
column vector
Time stamp of each received sample, returned as a column vector. The length of timeStamps output equals the length of received data output data.
To get GPS time stamp of each received sample from a USRP radio, set the PPS Source parameter to
GPSDO
.To get time stamp of each received sample from bundled radios, set the PPS Source parameter to
GPSDO
orExternal
.
Dependencies
To enable this port, select the Enable timestamps output port parameter.
Parameters
When you set block parameter values, the SDRu Receiver block first checks that the values have the correct data types. Even if the values pass those checks, the values can still be out of range for the radio hardware. In that case, the radio hardware sets the actual value as close to the specified value as possible. When you next synchronize the block with the radio hardware by clicking Info, a dialog box open to display the actual values along with other radio information.
If a parameter is listed as tunable, then you can change its value during simulation.
Radio Connection
Platform — Radio to configure
(default) | N300
| N310
| N320/N321
| X300
| X310
Radio to configure, specified as one of USRP platforms listed.
IP address — IP address of radio hardware
192.168.10.2
(default) | dotted quad expression
IP address of the radio hardware, specified as a dotted quad expression.
This parameter must match the physical IP address of the radio hardware assigned when you set up your radio using the Radio Setup wizard. If you configure the radio hardware with an IP address other than the default, update IP address accordingly.
The IP address list displays IP addresses for USRP devices attached to the host computer. To specify another known dotted quad IP address, enter it directly into this field.
Refresh Device List — Refresh the list of connected devices
button
Refresh the list of all connected devices to update the IP address list. The updated list retains the value in focus before Refresh Device List is selected, even if the device with that setting was disconnected.
TwinRX Daughterboard — Option to enable TwinRX daughterboard
off
(default) | on
To enable the TwinRX daughterboard on an X-series radio, select this parameter.
When you select this parameter, you can use the Enable TwinRX Phase Synchronization parameter to provide phase synchronization between channels of the TwinRX daughterboard.
Dependencies
To enable this parameter, set
Platform to
'X300' or 'X310'
.
Info — Provides information about device
button
Provides information about the Platform associated with IP address. IP address applies for N-series and X-series devices. When you select the Info button, a new dialog box opens with information about the specified device.
Radio Properties
Enable TwinRX Phase Synchronization — Option to enable phase synchronization
off
(default) | on
When you select this parameter, the TwinRX daughterboard provides phase synchronization between all channels. In this case, the value of Center Frequency must be the same for all channels.
Note
The Local oscillator (LO) source present on channel 1 is the master source to drive 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 crisscrossing the cables between the two daughterboards. Make these cable connections, as also shown in the figure.
J1 to J2
J2 to J1
J3 to J4
J4 to J3
Dependencies
To enable this property, set
Platform to
'X300' or 'X310'
and
select TwinRX
Daughterboard.
Channel mapping — Channel output mapping for radio or bundled radios
1
(default) | integer | vector
Channel output mapping for radio or bundled radios, specified as a positive integer scalar or vector. This table shows valid values for various radio platforms.
Platform Value | Channel mapping Value |
---|---|
|
|
|
|
|
|
|
|
| When you clear the Enable TwinRX Phase Synchronization parameter, specify this parameter as one of these values.
When you select the Enable TwinRX
Phase Synchronization parameter, specify this
parameter as |
When a scalar, 1
or 2
is
specified, the device operates in SISO mode. When a vector is specified, the device
operates in MIMO mode. When IP address includes multiple IP
addresses, the channels defined by Channel mapping are sorted,
first by the order in which the IP addresses appear in the list and then by the channel
order within the same radio.
Example: When you set Platform
to X300
or N300
and IP
address
contains 192.168.20.2, 192.168.10.3
, then
Channel mapping
must be [1 2 3 4]
. Channel mapping
values
1
and 2
of the bundled radio refer to
channels 1 and 2 of the radio with IP address 192.168.20.2. Channel
mapping
values 3 and 4 of the bundled radio refer to channels 1 and 2
of the radio with IP address 192.168.10.3.
Data Types: double
Source of center frequency — Select source of center frequency
Dialog
(default) | Input port
Select source of center frequency, specified as:
Dialog
— Set the center frequency using the Center frequency (Hz) parameter.Input port
— Set the center frequency using the fc input port.
Center frequency (Hz) — RF center frequency
2.45e9
(default) | nonnegative finite scalar | vector of nonnegative finite scalars
RF center frequency in Hz, specified as a nonnegative finite scalar or vector of nonnegative finite scalars. The valid range of this parameter depends on the RF daughterboard of the USRP device.
For a single channel (SISO), specify the value for the center frequency as a scalar.
For multiple channels (MIMO) that use the same center frequency, specify the center frequency value as a scalar. The center frequency is set by scalar expansion.
For multiple channels (MIMO) that use different center frequencies, specify the values in a vector. The ith element of the vector is applied to the ith channel specified by Channel mapping.
Note
For MIMO scenario, the center frequency for N300 radio must be a scalar. You cannot specify the frequencies as a vector.
The channels corresponding to the same RF daughterboard of N310 must have same center frequency value.
When you select the TwinRX Daughterboard parameter:
To tune all channels to the same frequency, select the Enable TwinRX Phase Synchronization parameter and set the center frequency as a scalar or row vector of the same values.
To tune channels to different frequencies, clear the Enable TwinRX Phase Synchronization parameter and set the center frequency to a row vector. Each value in the row vector specifies the frequency of the corresponding channel.
Note
When you select the TwinRX Daughterboard and Enable TwinRX Phase Synchronization, the LO source present on channel 1 is the master source to drive other LOs of the TwinRX daughterboard channels. In this case, the Center frequency value must be the same for all channels of the TwinRX daughterboard.
For more information, see Enable TwinRX Phase Synchronization.
Dependencies
To enable this parameter, set the Source of center frequency
to Dialog
.
Data Types: double
Source of LO offset — Select source of LO offset
Dialog
(default) | Input port
Select source of LO offset, specified as:
Dialog
— Set the LO offset using the LO offset (Hz) parameter.Input port
— Set the LO offset using the LO offset input port.
LO offset (Hz) — Offset frequency for local oscillator
0
(default) | scalar | vector
Offset frequency for the local oscillator, specified as a scalar or vector. The valid range of this parameter depends on the RF daughterboard of the USRP device.
This figure shows that the local oscillator offset affects the intermediate center frequency in the USRP hardware. It does not affect the received center frequency.
fRF represents the received RF frequency.
fcenter represents the center frequency specified by the block.
fLO offset is the local oscillator offset frequency.
Ideally, fRF – fcenter = 0.
To move the center frequency away from interference or harmonics generated by the USRP hardware, use the LO offset.
For a single channel (SISO), specify the value for the LO offset as a scalar.
For multiple channels (MIMO), the LO offset must be zero. This restriction is due to a UHD limitation. You can specify the LO offset as a scalar or as a vector.
Dependencies
To enable this parameter, set Source
of LO offset to
Dialog
.
Source of gain — Select source of gain
Dialog
(default) | Input port
Select source of gain, specified as:
Dialog
— Specify the gain using the Gain (dB) parameter.Input port
— Specify the gain using the gain input port.
Gain (dB) — Receiver gain
32
(default) | scalar | vector
Receiver gain in dB, specified as a scalar or vector. The valid range of this gain depends on the RF daughterboard of the USRP device.
Set the value of gain based on the Channel Mapping configuration:
For a single channel (SISO), specify the gain as a scalar.
For multiple channels (MIMO) that use the same gain value, specify the gain as a scalar. The gain is set by scalar expansion.
For multiple channels (MIMO) that use different gains, specify the values in a row vector. The ith element of the vector is applied to the ith channel specified by Channel Mapping.
Dependencies
To enable this parameter, set Source
of gain to
Dialog
.
Data Types: double
PPS source — PPS signal source
Internal
(default) | External
| GPSDO
Pulse per second (PPS) signal source, specified as 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 GPSDO.
To synchronize the time for all channels of the bundled radios, you can:
Provide a common external PPS signal to all of the bundled radios and set this parameter to
External
.Use the PPS signal from the GPSDO that is available on the USRP radio by setting this parameter to
GPSDO
.
To synchronize the USRP time to the valid GPS time, set this parameter to
GPSDO
. You must also enable the Ensure sync GPS
time parameter if the GPSDO is not locked to the GPS constellation at the
start of the simulation.
Enable gps_locked output port — Option to enable lock status of GPSDO to GPS constellation
off
(default) | on
Select this parameter to enable the gpsLocked output port, which indicates the lock status of the GPSDO to the GPS constellation.
Dependencies
To enable this parameter, set the PPS source parameter to
GPDSO
.
Ensure sync GPS time — Option to ensure GPS time synchronization
off
(default) | on
Select this parameter to ensure that the USRP radio time is synchronized to the valid GPS time.
When you select this parameter, the block checks the lock status of the GPSDO. When the GPSDO is locked to the GPS constellation, the block sets the USRP radio time to the valid GPS time.
Dependencies
To enable this parameter, set the PPS source parameter to
GPSDO
.
Clock source — 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.
For N3xx and X-series radios, the external clock port is labeled REF IN.
To synchronize the frequency for all channels of the bundled radios, you can:
Provide a common external 10 MHz clock signal to all of the bundled radios and set this parameter to
External
.Provide a 10 MHz clock signal from each GPSDO to the corresponding radio and set this parameter to
GPSDO
.
Enable ref_locked output port — Option to enable lock status of USRP radio to 10 MHz clock signal
off
(default) | on
Select this parameter to enable the refLocked output port, which indicates the lock status of the USPR radio to the 10 MHz clock signal.
Dependencies
To enable this parameter, set the Clock source parameter to
External
or GPDSO
.
Master clock rate (Hz) — Master clock rate
scalar
Master clock rate, specified as a scalar in Hz. The master clock rate is the A/D and D/A clock rate. The valid range of values for this property depends on the radio platform that is connected.
Platform Value | Possible Master clock rate (Hz) Value |
---|---|
|
Default value is
|
|
Default value is
|
|
Default value
|
Data Types: double
Decimation factor — Decimation factor for SDRu Receiver
512
(default) | integer
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.
Enable time trigger — Option to enable timed transmission and reception
off (default) | on
Option to enable timed transmission and reception. To enable the radio to transmit or receive data after a specified time, select Enable time trigger.
When you select Enable time trigger parameter, you can:
Transmit or receive after the time specified in the Trigger time parameter.
Transmit or receive at the specified GPS time in the Trigger time parameter if you set the PPSSource parameter to
GPSDO
.Simultaneously transmit and receive after the time specified in the Trigger time parameter.
Trigger time — Trigger time in seconds
5
(default) | nonnegative scalar
Trigger time in seconds, specified as a nonnegative scalar. Specify the trigger time after which you want the radio to transmit or receive data. The Trigger time value must be greater than the current USRP radio time.
When you set the PPS Source parameter to
GPSDO
, specify the Trigger time parameter
as the exact GPS time in seconds at which the radio transmits and receives data.
Note
For AD936x-based N3xx USRP radios, you can expect a consistent delay between the specified trigger time and the start of transmission or reception.
Dependencies
To enable this parameter, select the Enable trigger time parameter.
Data
Baseband sample rate (Hz) — Baseband sample rate of output signal
scalar
This parameter is read-only.
Baseband sample rate of output signal, in Hz, specified as a scalar.
This parameter displays the computed baseband sample rate derived from the Master clock rate (Hz) and Decimation factor parameter values. This computation uses the formula, Baseband sample rate = Master clock rate/Decimation factor. If you change the Decimation factor during simulation, then the block changes hardware data rate, but does not change the Simulink sample time.
To get more information on sample time, see What Is Sample Time? (Simulink).
Data Types: double
Transport data type — Transport data type
int16
(default) | int8
Transport data type, specified as:
int16
— Uses 16-bit transport. Achieves higher precision than 8-bit transport.int8
— Uses 8-bit transport. Uses a quantization step 256 times larger and achieves approximately two times faster transport data rate than 16-bit transport.
Specifying transport data rate data type as int16
, assigns 16 bits for the in-phase component and 16 bits for the quadrature component, resulting in 32 bits for each complex sample of transport data.
Output data type — Data type of output signal
Same as transport
data type
(default) | double
| single
Data type of the output signal, specified as
Same as transport data
type
,
double
, or
single
. The complex
output data values range from –1 to 1.
Samples per frame — Number of samples per frame of output signal
362
| positive integer
Number of samples per frame of the output signal that the object generates, specified as a positive integer scalar. This value optimally utilizes the underlying Ethernet packets, which have a size of 1500 8-bit bytes.
Enable data length output port — Option to enable data length output port
off (default) | on
To indicate the number of samples received from USRP radio, select this parameter.
Enable overrun output port — Option to enable overrun output port
off (default) | on
To measure the number of samples lost during reception, select this parameter.
If your model is not running in real time, you can adjust parameters that reduce the number of transported samples. To approach or achieve real-time performance, you can increase the decimation factor.
Enable timestamps output port — Option to enable timestamps output port
off (default) | on
To get time stamp of each received sample from USRP radio, select this parameter.
Enable burst mode — Option to enable burst mode
off (default) | on
Option to enable burst mode. To produce a set of contiguous frames without an overrun or underrun to the radio, select Enable burst mode. Enabling burst mode helps you simulate models that cannot run in real time.
When burst mode is enabled, specify the desired amount of contiguous data using the Number of frames in burst parameter.
Number of frames in burst — Number of frames in contiguous burst
100
(default) | nonnegative integer
Number of frames in a contiguous burst, specified as a nonnegative integer.
Dependencies
To enable this parameter, select Enable burst mode.
Data Types: double
More About
Single and Multiple Channel Output
X300 and X310 radios support two channels that you can use to transmit and receive data with SDRu blocks. You can use both channels or only a single channel (either channel 1 or 2).
The SDRu Transmitter block receives a matrix signal, where each column is a channel of data of fixed length.
The SDRu Receiver block outputs a matrix signal, where each column is a channel of data of fixed length.
Note
When two TwinRX daughterboards are connected to X300 or X310 radio, the radio supports up to four channel reception.
N300, N320, and N321 radios support two channels that you can use to transmit and receive data with SDRu blocks. You can use both channels or only a single channel (either channel 1 or 2).
The SDRu Transmitter block receives a matrix signal, where each column is a channel of data of fixed length.
The SDRu Receiver block outputs a matrix signal, where each column is a channel of data of fixed length.
N310 radio support four channels that you can use to transmit and receive data with SDRu blocks. You can use up to four channels.
The SDRu Transmitter block receives a matrix signal, where each column is a channel of data of fixed length.
The SDRu Receiver block outputs a matrix signal, where each column is a channel of data of fixed length.
You can set the Center frequency, LO offset, and Gain block parameters independently for each channel or apply the same setting to all channels. All other block parameter values apply to all channels.
For more information, see Multiple Channel Input and Output Operations.
Accelerate Performance of SDRu Blocks
Run your application with Accelerator or Rapid Accelerator instead of Normal mode. Note that some scopes does not plot data when run in Rapid Accelerator mode.
When you use accelerator or rapid accelerator mode, on the Model Configuration Parameters dialog box, navigate to Compiler optimization level tab, and then set the parameter value to Optimizations on (faster runs).
Performance analysis for SDRu Blocks
Starting in R2022a, the SDRu blocks show improved speed performance with fewer underruns and overruns. For example, you can observe a speedup (in megasamples per second (MS/s)) with fewer underruns or overruns at 10000 samples per frame when you simulate these models in Normal, Accelerator, or Rapid Accelerator mode.
Transmitter performance model
Receiver performance model
The table shows the speedup analysis of these models with no underruns or overruns for USB-based radios and Ethernet-based radios. This speedup analysis is carried out between R2021b and R2022a.
Transmitter / Receiver | Radio type | R2021b Normal Mode | R2022a Normal Mode | R2021b Rapid Accelerator Mode | R2022a Rapid Accelerator Mode |
---|---|---|---|---|---|
Receiver | X-series | 2 MS/s | 50 MS/s | 15.36 MS/s | 61.44 MS/s |
Transmitter | X-series | 10 MS/s | 30.72 MS/s | 10 MS/s | 40 MS/s |
The models were timed on a Windows® 10, Intel® Xeon® CPU E5-1650 v4 @ 3.60 GHz test system.
Blocking Behavior
Starting R2022a, the SDRu Receiver block waits until it receives the number of samples per frame specified by Samples per frame parameter before it returns processing control to the simulation.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
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 Blocks
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 SDRu Transmitter and SDRu Receiver Simulink blocks.
R2020a: decim input port has been removed
Starting in R2020a, the SDRu Receiver block removed the decim input port. You can not set the decimation factor value for this block by using an input port. Instead use the Decimation factor parameter.
R2020a: Sample time parameter has been removed
Starting in R2020a, the SDRu Receiver block removed the Sample time parameter. Use the read-only Baseband sample rate (Hz) parameter instead. This parameter displays the computed baseband sample rate derived from the Master clock rate (Hz) and Decimation factor parameters.
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 SDRu Transmitter and SDRu
Receiver blocks, when you select an X3xx series
radio for the Platform parameter, you can
no longer set the Master
clock rate (Hz) parameter to
120e6
.
See Also
Blocks
Objects
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