comm.SDRRxPluto

Receive data from Analog Devices ADALM-PLUTO radio

Description

The comm.SDRRxPluto System object™ is a signal source that receives data from an Analog Devices® ADALM-PLUTO radio. This connection enables you to simulate and develop various software-defined radio applications.

The following diagram shows the interaction between MATLAB®, the comm.SDRRxPluto System object, and the radio hardware.

After connecting a PlutoSDR device to a USB port on the host computer, to receive data from the radio hardware:

  1. Create the comm.SDRRxPluto object and set its properties.

  2. Call the object as if it were a function.

To learn more about how System objects work, see What Are System Objects? (MATLAB).

Channel Output

The ADALM-PLUTO radio has a single channel for receiving data and sending it to the comm.SDRRxPluto System object. The SDR System object outputs a column vector signal of fixed length.

The first call to the comm.SDRRxPluto System object might contain transient values, which can result in packets containing undefined data.

Creation

Description

rxPluto = sdrrx('Pluto') creates a PlutoSDR receiver System object with default properties that you can use to receive data from the PlutoSDR device.

example

rxPluto = sdrrx('Pluto',Name,Value) creates a PlutoSDR receiver object with the specified property Name set to the specified Value. You can specify additional name-value pair arguments in any order as (Name1,Value1,...,NameN,ValueN). Unspecified properties take default values.

Example: rx = sdrrx('Pluto','CenterFrequency',3.5e9,'BasebandSampleRate',2.0e6);

Properties

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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 (MATLAB).

Radio identification number, specified as one of the following character vectors:

  • (recommended) A device-independent index, with the prefix usb:, such as 'usb:0', 'usb:1', 'usb:2', …, indicating the first, second, third, ..., attached ADALM-PLUTO radio, respectively

  • An IP address, with the prefix ip:, such as 'ip:192.168.2.1'

  • A serial number, represented by a hexadecimal string with the prefix sn:, such as'sn:100000235523730700230031090216eaeb'

Note

When working with multiple radios, if devices are inserted or removed, the host computer assignment of USB addresses might change. Any time an SDR device is inserted or removed from a USB port, the host computer polls all USB ports and assigns or reassigns the radio addresses associated with connected devices.

When operating on Windows® keep these considerations in mind.

  • When running multiple radios on the same host in separate MATLAB sessions, for each MATLAB session the first radio is assigned usb:0, and the ID number increments by one for subsequent radios.

  • Radios that are being used by one MATLAB are not seen by other MATLAB sessions. Use findPlutoRadio and check the reported serial number to identify the radios seen in a particular MATLAB session.

To ensure that all assigned radio identities remain static, do not connect or disconnect radios after SDR objects have been created. The best practice is to connect radios and create SDR objects in this order:

  1. Clear all SDR objects.

  2. Connect all radios.

  3. Check to confirm that the connected radios are recognized by running this command:

    findPlutoRadio

  4. Create SDR objects.

To interface with the radio hardware, the RadioID property of the radio object must match the radio ID of the radio hardware. Update the RadioID property, if necessary.

When running multiple radios on the same host, the host assigns each radio a different radio ID. When identifying the radio by USB ID, the first radio is assigned usb:0, and the ID number increments by one for subsequent radios. For example, to assign IDs to two radios connected on the same host computer, at the MATLAB command prompt, enter:

rx = sdrrx('Pluto','RadioID','usb:0'); 
tx = sdrtx('Pluto','RadioID','usb:1');

RF center frequency setting in Hz, specified as a scalar from 70.0e6 to 6.0e9.

Note

Analog Devices qualifies the PLUTO radio over a tuning range of 325 MHz to 3.8 GHz. This support package enables you to use the PLUTO radio outside the qualified tuning range by configuring the radio to operate using the AD9364 firmware. To extend the frequency range, at the MATLAB command prompt, enter configurePlutoRadio('AD9364').

Tunable: Yes

Data Types: double

This property is read-only.

The channel mapping is always set to 1.

Gain source, specified as one of the following:

  • 'AGC Slow Attack' — For signals with slowly changing power levels

  • 'AGC Fast Attack' — For signals with rapidly changing power levels

  • 'Manual' — For setting the gain manually with the Gain property

Radio receiver gain in dB, specified as a scalar from -4 to 71.

Note

The acceptable minimum and maximum gain setting depends on the center frequency. An incompatible gain and center frequency combination returns an error.

Tunable: Yes

Dependencies

To enable this property, set GainSource to 'Manual'.

Data Types: double

Baseband sampling rate in Hz, specified as a scalar from 65105 to 61.44e6 samples per second.

Note

The actual computed value and your specified setting can have a small mismatch. To confirm that the actual computed value is close enough to your specified setting, call the info object function on the radio object.

Data Types: double

Output signal data type, specified as one of the following:

  • int16 — 16-bit signed integers

  • double — Double-precision floating point

  • single — Single-precision floating point

Number of samples per frame, specified as an even positive integer from 2 to 16,777,216. Using values less than 3660 can yield poor performance.

Option for burst mode, specified as false or true. When set to true, this property produces a set of contiguous samples without overflow. This setting can help simulate models that cannot run in real time. When you enable burst mode, specify the amount of contiguous data using the property. For more information on how to use this property, see Burst Mode.

Data Types: logical

Number of frames in a contiguous burst, specified as a strictly positive integer.

Dependencies

To enable this property, set EnableBurstMode to true.

Data Types: double

Advanced Properties

Option to show advanced properties, specified as false or true.

Use custom filter, specified as one of these values.

  • false — The filter chain uses the default filter design.

  • true — The filter chain uses a custom filter design. To design a custom filter, call the designCustomFilter function.

Note

When applying a custom filter to a comm.SDRRxPluto System object, the UseCustomFilter property is automatically set to true. To switch between the default and your custom filter, set UseCustomFilter property to false or true, respectively.

For more information, see Baseband Sampling Rate and Filter Chains.

Data Types: logical

Quadrature correction, specified as true or false. When this property is true, the object applies in-phase and quadrature (IQ) imbalance compensation. For more information, see Quadrature Tracking.

Dependencies

To view this property, set ShowAdvancedProperties to true.

RF direct current (DC) correction, specified as true or false. When the property is true, the object applies an RF DC blocking filter. For more information, see DC Offset Tracking.

Dependencies

To view this property, set ShowAdvancedProperties to true.

Baseband DC correction, specified as true or false. When the property is true, the object applies a baseband DC blocking filter. For more information, see DC Offset Tracking.

Dependencies

To view this property, set ShowAdvancedProperties to true.

Frequency correction value in ppm, specified as a scalar from -200 to 200. This property value corrects frequency shifts in data due to local oscillator frequency offset or clock rate inaccuracy.

Note

  • When the FrequencyCorrection setting is 0, the factory-calibrated setting of the radio will be used.

  • The FrequencyCorrection property changes the actual radio setting for BasebandSampleRate and CenterFrequency.

Tunable: Yes

Dependencies

To view this property, set ShowAdvancedProperties to true.

Data Types: double

Built-in self-test loopback mode, specified as one of these options:

  • 'Disabled' — Disable BIST loopback.

  • 'Digital Tx -> Digital Rx' — Enable digital signals to loop back within the AD936x device. The signals bypass the RF stage.

  • 'RF Rx -> RF Tx' — Enable incoming receiver RF signals to loop back to the RF transmitter port. The signals bypass the FPGA.

Dependencies

To enable this property, set ShowAdvancedProperties to true.

Data Types: char | string

BIST signal injection mode, specified as one of these options:

  • 'Disabled' — Disable BIST signal injection.

  • 'Tone Inject Tx' — Enable BIST signal injection to transmit path.

  • 'Tone Inject Rx' — Enable BIST signal injection to receive path.

When you enable BIST signal injection, you can set the source of BIST signal generation with the BISTSignalGen property.

Dependencies

To enable this property, set ShowAdvancedProperties to true.

Data Types: char | string

Source of BIST signal generation, specified as one of these options:

  • 'PRBS' — Use the pseudo random binary sequence (PRBS) generator of the board.

  • 'Tone' — Use the tone generator of the board. To set the tone frequency and tone level, use the BISTToneFreq and BISTToneLevel properties, respectively.

Dependencies

To enable this property, set BISTToneInject to 'Tone Inject Tx' or 'Tone Inject Rx'.

Data Types: char | string

BIST tone frequency, specified as 'Fs/32', 'Fs/16', 'Fs*3/32', or 'Fs/8'.

Dependencies

To enable this property, set BISTSignalGen to 'Tone'.

Data Types: char | string

BIST tone level in dB, specified as '0', '-6', '-12', or '-18' .

Dependencies

To enable this property, set BISTSignalGen to 'Tone'.

Data Types: char | string

Usage

Description

rxdata = rxPluto() receives signal and control data from a PlutoSDR device, as represented by a comm.SDRRxPluto System object. The rxPluto object outputs a column vector of complex values.

example

[rxdata,datavalid,overflow] = rxPluto() outputs an indication of lost samples, overflow.

Output Arguments

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Received data, returned as a vector of complex values. The value range depends on the data type of the output.

  • int16 — Output data consists of 16-bit signed integer values in the range [–2048, 2047]. The AD936X RF chip has a 12-bit ADC. The 12-bit data from the ADC is stored in the lower 12 bits of the output value and sign-extended to 16 bits.

  • double — Output data consists of double-precision floating point values scaled to the range of [–1, 1].

  • single — Output data consists of single-precision floating point values scaled to the range of [–1, 1].

Note

The AD936X RF chip has a 12-bit ADC. Double-precision and single-precision floating point representations of received data values are directly created from the sign-extended int16 value received from the board. These representations occupy only the range [–0.0625, 0.0625].

To specify the data type of the received data, use the OutputDataType property.

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

Data valid indicator, returned as a logical.

  • A 0 indicates that received sample is not valid.

  • A 1 indicates that received sample is valid.

Lost samples indicator, returned as a logical.

  • A 0 indicates that no samples were lost.

  • A 1 indicates that samples were lost.

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)

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captureCapture RF signal data using SDR device
infoObtain radio information
designCustomFilterDesign custom filter for Analog Devices AD936x RF chip
stepRun System object algorithm
releaseRelease resources and allow changes to System object property values and input characteristics
resetReset internal states of System object

Examples

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Configure an ADALM-PLUTO radio with the RadioID property set to 0. Set the radio to receive at 2.5 GHz with a baseband rate of 1 MHz. Save the data using a log.

Create a ADALM-PLUTO radio receiver System object to use for data reception and dsp.SignalSink System objects to log the received data when the data does not overflow and when the data is valid.

rxPluto = sdrrx('Pluto',...
           'RadioID','usb:0',...
           'CenterFrequency',2.5e9,...
           'BasebandSampleRate',1e6); 
rxLogNoOverflow = dsp.SignalSink;
rxLogDataValid = dsp.SignalSink;

Inside a for loop, receive data using the rxPluto object. Log the data when there is no overflow and when the data is valid. Display messages when received samples are dropped or when the received data is not valid.

for counter = 1:20
    [data,datavalid,overflow] = rxPluto();
% Check for overflow of received samples.
    if (overflow) % dropped samples
        disp('samples dropped');
    else
        rxLogNoOverflow(data);
    end
% Check for overflow and validity of received data.
    if ~(overflow) % no dropped samples
        if ~(datavalid) % received desired data
             rxLogDataValid(data);
        end
    else
        disp('no valid data received');
    end
end
## Establishing connection to hardware. This process can take several seconds.

When transmitting and receiving using one ADALM-PLUTO radio, individual transmitter and receiver objects use the same underlying radio hardware setting for frequency correction. Create separate ADALM-PLUTO radio System objects with default settings for the transmitter and receiver.

rx = sdrrx('Pluto');
tx = sdrtx('Pluto');
rx.ShowAdvancedProperties = true;
tx.ShowAdvancedProperties = true;

rxFreqCorr = rx.FrequencyCorrection
rxFreqCorr = 0
txFreqCorr = tx.FrequencyCorrection
txFreqCorr = 0

The default frequency correction value is 0 ppm. Here the underlying radio hardware setting for frequency correction when receiving and transmitting is 0.

data0 = rx();
## Establishing connection to hardware. This process can take several seconds.
tx(data0);
## Establishing connection to hardware. This process can take several seconds.

Update the frequency correction setting to 50 ppm for the receiver object. This does not update the frequency correction setting for the transmitter object, but here the master clock rate of the underlying radio hardware is adjusted based on the setting of 50 ppm for the frequency correction when receiving or transmitting. The last update of the radio hardware frequency correction setting is made by the receiver object. Even though the transmitter object indicates a frequency correction value of 0, the radio transmitter uses the updated value set with rx.FrequencyCorrection when the transmitter object is executed.

rx.FrequencyCorrection = 50;
data1 = rx();
tx(data0);

rxFreqCorr = rx.FrequencyCorrection
rxFreqCorr = 50
txFreqCorr = tx.FrequencyCorrection
txFreqCorr = 0

Similarly, update the frequency correction setting to 100 ppm for the transmitter object. This does not update the frequency correction setting for the receiver object, but here master clock rate of the underlying radio hardware is adjusted based on the setting of 100 pmm for the frequency correction when receiving or transmitting. The last update of the radio hardware frequency correction setting is made by the transmitter object. Even though the receiver object indicates a frequency correction value of 50, radio receiver uses the updated value set with tx.FrequencyCorrection when the receiver object is executed.

tx.FrequencyCorrection = 100;
tx(data0);
data2 = rx();

rxFreqCorr = rx.FrequencyCorrection
rxFreqCorr = 50
txFreqCorr = tx.FrequencyCorrection
txFreqCorr = 100

Use the info object function to get information from the connected ADALM-PLUTO radio. The actual values used in the radio are shown by info and can be vary slightly from the values specified in the object.

rx = sdrrx('Pluto');
info(rx)
## Establishing connection to hardware. This process can take several seconds.
ans = struct with fields:
                     Status: 'Full information'
            CenterFrequency: 2.4000e+09
         BasebandSampleRate: 999999
                  SerialNum: '104473222a870010050020009db5d52277'
            GainControlMode: 'AGC Slow Attack'
       RadioFirmwareVersion: "0.30"
    ExpectedFirmwareVersion: "0.30"
            HardwareVersion: "B0"

Use the capture function and an ADALM-PLUTO radio to record RF signals for post-capture processing in MATLAB®. Save an FM broadcast signal to a file as baseband samples. Read the file containing the recorded signal and demodulate the baseband samples.

Configure SDR Hardware

To configure your ADALM-PLUTO radio for host-radio communication, see Guided Host-Radio Hardware Setup.

Attach an antenna suitable for the 88-108 MHz band to the first RX channel. The FM radio band is outside the default tuning range for the ADALM-PLUTO radio. The configurePlutoRadio function enables you to extend the frequency range and use your ADALM-PLUTO radio outside the qualified tuning range. The extended frequency range includes the full FM radio band.

configurePlutoRadio('AD9364');
## Establishing connection to hardware. This process can take several seconds.

Configure Receiver System Object

Create an SDR receiver System object with the specified properties. The specified center frequency corresponds to a local FM station.

deviceName = 'Pluto';
samplerate = 528e3;
fmStationFrequency = 88.9e6; % Adjust to select an FM station nearby
rx = sdrrx(deviceName,'BasebandSampleRate',samplerate, ...
    'CenterFrequency',fmStationFrequency,'OutputDataType','double');

Initiate Data Capture to File

Call the capture function, specifying the receiver object, capture duration, and file name. After capturing the FM signal, unlock the receiver object using the release function.

capture(rx,5,'Seconds','Filename','FMRecording.bb');
## Establishing connection to hardware. This process can take several seconds.
release(rx);

Demodulate FM Recording

Create a comm.BasebandFileReader System object to read the captured signal and extract frames of data from the file. Set baseband file reader to take 4400 samples per frame when reading the saved baseband signal.

bbr = comm.BasebandFileReader('FMRecording.bb');
bbr.SamplesPerFrame = 4400;

Use the BasebandSampleRate field of the baseband file reader object to set the SampleRate property of the demodulator. Find the BasebandSampleRate field in the MetaData structure. Create a comm.FMBroadcastDemodulator System object. Demodulate and play back each frame of the FM data. Use a while loop to read all frames of the captured data.

fmbDemod = comm.FMBroadcastDemodulator('AudioSampleRate',48e3, ...
    'SampleRate',bbr.Metadata.BasebandSampleRate,'PlaySound',true);
while ~isDone(bbr)
    fmbDemod(bbr());
end

Introduced in R2017a