Receive data from RTL-SDR device
Communications Toolbox Support Package for RTL-SDR Radio
The RTL-SDR Receiver block supports communication between Simulink® and the RTL-SDR device, enabling simulation and development for various software-defined radio (SDR) applications. The RTL-SDR Receiver block is a Simulink source that receives data from an RTL-SDR device and outputs a column vector signal of fixed length.
This diagram shows the conceptual overview of receiving radio signals in Simulink by using the Communications Toolbox™ Support Package for RTL-SDR Radio. Simulink interacts with the RTL-SDR Receiver block to receive signals from the radio.
When the host computer is not connected to the radio, you can still use the block to develop a model that propagates sample-time and data-type information. To propagate this information, you must update your model.
This icon shows all ports enabled, including optional ones.
fc — Center frequency
Center frequency in Hz, specified as a positive scalar.
gain — Receiver gain
Receiver gain in dB, specified as a scalar.
Data — Received data from RTL-SDR device
column vector of complex
int16 values | column vector of complex single-precision values | column vector of complex double-precision values
Received data from an RTL-SDR device, returned as one of these values.
Column vector of complex
int16values — The complex values are the raw 16 bit I and Q samples from the RTL-SDR device.
Column vector of complex single-precision values — The complex values are scaled to the range of [–1, 1].
Column vector of complex double-precision values — The complex values are scaled to the range of [–1, 1].
To specify the base type, use the Output data type parameter.
Complex Number Support: Yes
lost — Number of lost samples
Number of lost samples, returned as a nonnegative integer. When the
RTL-SDR device reports no lost samples, lost is
If your model runs in real time, lost is
0. You can use this output value as a diagnostic
tool to determine real-time execution of the block. For more information
on real-time operation, see Real-Time Operation.
To enable this port, select the Lost samples output port parameter.
late — Latency of received data in frames
Latency of the received data in frames, returned as a nonnegative
integer. When the received frames of data have no latency,
late is less than or equal to
Even when your model runs in real time, received signals can experience latency. You can use this output value as a diagnostic tool to determine real-time execution of the block. For more information on real-time operation, see Real-Time Operation.
To enable this port, select the Latency output port parameter.
Radio address — USB address of RTL-SDR device
0 (default) | nonnegative integer
Specify the USB address of the RTL-SDR device with which you want to communicate as a nonnegative integer. To update block parameters in the model that is associated with the device specified by Radio address, use the Info parameter to update.
USB Port Address Assignment
The assignment of USB port addresses can be counterintuitive. If an RTL-SDR device is plugged into the first USB port, it is at address 0. However, if an RTL-SDR device is plugged into any port after the first one, the address varies depending on whether a device is plugged into any of the previous ports. This figure shows how the USB port addresses are assigned when devices are added and then removed in first in, first out (FIFO) order.
This figure shows how the USB port addresses are assigned when devices are added and then removed from port 0. The radio address for the second RTL-SDR device changes based on whether the first port has an RTL-SDR device in it. To access a radio with the correct radio address, you must keep track of the plugged-in devices in order.
Info — Update block parameters
Click this parameter to update block parameters in the model that is
associated with the device specified by the Radio
address parameter. When you click
Info, a dialog box opens that displays information
and parameter settings associated with the device. Use this parameter to
check connectivity between the block and the radio and to synchronize radio
settings between them. If the block is not connected to the radio device,
click Info to return this message in the
Source of center frequency — Center frequency source
Dialog (default) |
Select the source of the center frequency.
Dialog— Set the center frequency by using the Center frequency (Hz) parameter.
Input port— Set the center frequency by using the fc input port.
Center frequency (Hz) — Center frequency
102.5e6 (default) | positive scalar
Specify the center frequency in Hz as a positive scalar. The valid range of this parameter depends on the tuner chip of the RTL-SDR device. For a list of tuner chips and their frequency ranges, see .
To enable this parameter, set the Source of center
frequency parameter to
Source of gain — Source of gain
Dialog (default) |
Input port |
Select the source of the gain.
Dialog— Set the gain by using the Tuner gain (dB) parameter.
Input port— Set the gain by using the gain input port.
AGC— The RTL-SDR device uses an internal automatic gain control (AGC) algorithm to optimize the receiver gain setting.
Tuner gain (dB) — Tuner gain in dB
0 (default) | scalar
Tuner gain in dB, specified as a scalar.
To enable this parameter, set the Source of gain
Sampling rate (Hz) — ADC sample rate
250e3 (default) | positive scalar
Specify the analog-to-digital converter (ADC) sample rate in Hz, specified as a positive scalar. The valid range of sample rates are [225, 300] kHz and [900, 3200] in kHz. If you set this parameter greater than 2560 kHz, you might observe dropped samples. For more information about the maximum reliable sample rate, see .
Frequency correction (ppm) — Frequency correction
0 (default) | integer from –1e4 to 1e4
Specify the frequency correction in ppm as an integer from –1e4 to 1e4. This parameter corrects the frequency shift in the received data due to local oscillator frequency offset or clock rate inaccuracy.
Lost samples output port — Option to enable lost samples output port
off (default) |
Select this parameter to enable the lost output port.
Latency output port — Option to enable latency output port
off (default) |
Select this parameter to enable the late output port.
Output data type — Data type of output signal
int16 (default) |
Select the data type of the output signal.
single— The complex values are scaled to the range of [–1, 1].
int16— The complex values are the raw 16 bit I and Q samples from the RTL-SDR device.
Samples per frame — Number of samples per frame
1024 (default) | positive integer
Specify the number of samples per frame as a positive integer.
Enable burst mode — Option to enable burst mode
off (default) |
To produce a set of contiguous frames without an overflow to the radio, select this parameter. Enabling burst mode can help you simulate models that cannot run in real time.
When you select this parameter, specify the desired amount of contiguous data by using the Number of frames in burst and Samples per frame parameters.
Number of frames in burst — Number of frames in burst
20 (default) | positive integer
Specify the number of frames in a burst as a positive integer.
To enable this parameter, select the Enable burst mode parameter.
The RTL-SDR Receiver block waits until it receives the number of samples per frame specified by Samples per frame before it returns processing control to the simulation.
 SDR (Software Defined Radio), https://osmocom.org/projects/sdr/wiki/rtl-sdr#Specifications