Capture Over-the-Air Signals
You can use the Communications Toolbox™ Support Package for USRP™ Embedded Series Radio together with a supported SDR device to capture over-the-air signals to the MATLAB® workspace.
Capture RF Data to Baseband File Using E3xx Radio Hardware
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
If your radio hardware is already configured for host-radio communication, skip this section. To configure your radio hardware for host-radio communication, follow the steps in the Guided Host-Radio Hardware Setup. Attach an antenna suitable for the 88–108 MHz band to the first RX channel.
Configure Receiver System Object
Create a receiver System object with the specified properties. The specified center frequency corresponds to a local FM station.
stationCenterFrequency = 95e6; deviceName = 'E3xx'; rx = sdrrx(deviceName,'BasebandSampleRate',528e3,... 'CenterFrequency',stationCenterFrequency,'OutputDataType','Double');
Initiate Data Capture to File
capture function, specifying the receiver object, a capture duration, and a file name. The function returns the captured data in a file named "FMRecording.bb". After capturing the FM signal, unlock the receiver object by using the
## Establishing connection to hardware. This process can take several seconds.
Demodulate FM Recording
comm.BasebandFileReader System object to read the captured signal and extract frames of data from the file. Set the baseband file reader to take 4400 samples per frame when reading the saved baseband signal.
bbr = comm.BasebandFileReader('FMRecording.bb'); bbr.SamplesPerFrame = 4400;
BasebandSampleRate field of the baseband file reader object to set the
SampleRate property of the demodulator. You can 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