CNN-rtlsdr

Deep learning signal classification using rtl-sdr dongle.

Current pre-trained model is able to classify 4 kinds of signals: WFM, TV Secam carrier, DMR signal and "Others".

TEST WITH PRETRAINED MODEL

Unpack software archive into some folder, e.g. C:\rtlsdr

Go to https://www.anaconda.com/download/ and choose Python 3.6 version, 64-Bit Graphical Installer or download directly: https://repo.continuum.io/archive/Anaconda3-5.0.1-Windows-x86_64.exe

If you do not have modern NVIDIA graphics card, to install CPU version, just remove the following line in requirements.txt:

tensorflow-gpu==1.4.0

Run anaconda prompt, change dir to C:\rtlsdr, then run:

conda install pip
pip install -r requirements.txt

Only for CUDA version of Tensorflow, if you have installed CPU version, skip these steps:

• Download and install CUDA 8 Toolkit: https://developer.nvidia.com/cuda-80-ga2-download-archive
• Download CUDNN for Toolkit 8. https://developer.nvidia.com/cudnn
• Extract file [bin\cudnn64_6.dll] from zip into C:\Windows folder.

Last step is to copy 2 files from x64!!! osmocom rtl-sdr drivers: https://osmocom.org/attachments/download/2242/RelWithDebInfo.zip

Copy these [rtl-sdr-release/x64/]: rtlsdr.dll & libusb-1.0.dll into C:\Windows folder.

Reboot your system.

Now open your anaconda prompt again, change folder to C:\rtlsdr and run:

python predict_scan.py

to scan entire band and predict signal types , or the full version scan:

python predict_scan.py --start 85000000 --stop 108000000 --step 50000 --gain 20 --ppm 56 --threshold 0.9955

Watch CNN-rtlsdr in action on YouTube:

Some help also available:

python predict_scan.py --help

LINUX INSTALLATION

Linux installation issues discussed here: randaller#1

TRAIN YOUR OWN DATA

To train your own model, edit the settings in file [prepare_data.py] to set own frequencies of local stations and ppm error.

sdr.err_ppm = 56     # change it to yours

collect_samples(104000000, "wfm")
collect_samples(942200000, "gsm")

Then to obtain some samples run:

python prepare_data.py

Delete unnecessary folders under [/testing_data] and [/training_data] as they are responsible for classificator. E.g., if you want to train only WFM and OTHER classes, delete everything, except of:

• /training_data/wfm/
• /training_data/other/
• /testing_data/wfm/
• /testing_data/other/

Cleanup previous model checkpoint before starting a new train (otherwise it will continue training old model).

cleanup.cmd

Finally, we may now run training (of course, we are still inside anaconda prompt):

python train.py

Best decision is to stop the training [ctrl+c], when validation loss becomes 0.1 - 0.01 or below. Lowest values shows better performance. Really, you may terminate training even after a few (20-30) epochs with values about 0.4 - 0.3 and evaluate the model.

Also, it is better to obtain different samples of signals at different frequencies, gain levels. Edit [prepare_data.py] and run it again. Then train the classifier again to see the difference. Feel free to sample your own signal classes to train a bigger model.

SOME TECH FOR GEEKS

First version of this project was built using adaptation of image classification network, as the RF signal is representating also in 2D . I fed network with raw IQ samples, formed in a square as image, and even this gave me the model, doing it's job! This CNN graph was:

Conv2D (32*3*3) -> Conv2D (32*3*3) -> Conv2D (64*3*3) -> Dense (128) -> Dense (output)

Inspired of success, I began to try different preprocessing methods before feeding the network with complex. Neural networks generally has no idea, which input they serves, so I have tried to form into image shape the following:

FFT data

iq_samples = np.fft.fft(iq_samples)

AM demodulation data

iq_samples = np.sqrt(np.real(iq_samples) ** 2 + np.imag(iq_samples) ** 2)

FM demodulation data

iq_samples = np.unwrap(np.angle(iq_samples))
iq_samples = np.diff(iq_samples)

and all of those gave me some results. FFT version converged very fast, in a 3-5 epochs, while AM demod version showed worst performance. Finally, I've started googling to get more info and found the paper https://arxiv.org/pdf/1602.04105.pdf with all the CNN math great explanation. Then I have adapted network to match paper one, and graph now becomes:

Conv2D (64*1*3) -> Conv2D (16*2*3) -> Dense (128) -> Dense (output)

Feeding it with 1/4 sec raw IQ samples, sampled at 2.4 MSPS, and then decimated to a constant value of 48, left 12500 Hz bandwidth for classification.

KERAS VERSION

This is an optimized version of network, that reaches 99% accuracy while training.

python prepare_data.py
python train_keras.py