Order Calibration Frequency by maximum signal power

pyradiotracking

Detect signals of wildlife tracking systems with RTL SDR devices.

Usage

$ python3 -m radiotracking -h
usage: radiotracking [-h] [-v] [--config CONFIG] [--station STATION] [--schedule [SCHEDULE [SCHEDULE ...]]] [-d [DEVICE [DEVICE ...]]]
                     [-c [CALIBRATION [CALIBRATION ...]]] [-f CENTER_FREQ] [-s SAMPLE_RATE] [-b SDR_CALLBACK_LENGTH] [-g GAIN]
                     [--sdr-max-restart SDR_MAX_RESTART] [--sdr-timeout-s SDR_TIMEOUT_S] [-n FFT_NPERSEG] [-w FFT_WINDOW] [-t SIGNAL_THRESHOLD_DBW]
                     [-r SNR_THRESHOLD_DB] [-l SIGNAL_MIN_DURATION_MS] [-u SIGNAL_MAX_DURATION_MS] [--matching-timeout-s MATCHING_TIMEOUT_S]
                     [-mt MATCHING_TIME_DIFF_S] [-mb MATCHING_BANDWIDTH_HZ] [-md MATCHING_DURATION_DIFF_MS] [--sig-stdout] [--match-stdout]
                     [--path PATH] [--csv] [--export-config] [--mqtt] [--mqtt-host MQTT_HOST] [--mqtt-port MQTT_PORT] [--dashboard]
                     [--dashboard-host DASHBOARD_HOST] [--dashboard-port DASHBOARD_PORT] [--dashboard-signals DASHBOARD_SIGNALS]

Detect signals of wildlife tracking systems with RTL SDR devices

optional arguments:
  -h, --help            show this help message and exit
  -v, --verbose         increase output verbosity (default: 0)
  --config CONFIG       configuration file (default: etc/radiotracking.ini)
  --station STATION     name of the station (default: test)
  --schedule [SCHEDULE [SCHEDULE ...]]
                        specify a schedule of operation, e.g. 18:00-18:59:59 (default: [])

rtl-sdr:
  -d [DEVICE [DEVICE ...]], --device [DEVICE [DEVICE ...]]
                        device indexes or names (default: ['0'])
  -c [CALIBRATION [CALIBRATION ...]], --calibration [CALIBRATION [CALIBRATION ...]]
                        device calibration gain (dB) (default: [])
  -f CENTER_FREQ, --center-freq CENTER_FREQ
                        center frequency to tune to (Hz) (default: 150150000)
  -s SAMPLE_RATE, --sample-rate SAMPLE_RATE
                        sample rate (Hz) (default: 300000)
  -b SDR_CALLBACK_LENGTH, --sdr-callback-length SDR_CALLBACK_LENGTH
                        number of samples to read per batch (default: None)
  -g GAIN, --gain GAIN  gain, supported levels 0.0 - 49.6 (default: 49.6)
  --sdr-max-restart SDR_MAX_RESTART
                        maximal restart count per SDR device (default: 3)
  --sdr-timeout-s SDR_TIMEOUT_S
                        Time after which an SDR device is considered unrepsonsive (s) (default: 2)

analysis:
  -n FFT_NPERSEG, --fft-nperseg FFT_NPERSEG
                        fft number of samples (default: 256)
  -w FFT_WINDOW, --fft-window FFT_WINDOW
                        fft window function (default: 'hamming')
  -t SIGNAL_THRESHOLD_DBW, --signal-threshold-dbw SIGNAL_THRESHOLD_DBW
                        lower limit for signal intensity (dBW) (default: -90.0)
  -r SNR_THRESHOLD_DB, --snr-threshold-db SNR_THRESHOLD_DB
                        lower limit for signal-to-noise ratio (dB) (default: 5.0)
  -l SIGNAL_MIN_DURATION_MS, --signal-min-duration-ms SIGNAL_MIN_DURATION_MS
                        lower limit for signal duration (ms) (default: 8)
  -u SIGNAL_MAX_DURATION_MS, --signal-max-duration-ms SIGNAL_MAX_DURATION_MS
                        upper limit for signal duration (ms) (default: 40)

matching:
  --matching-timeout-s MATCHING_TIMEOUT_S
                        timeout for adding signals to a match group (default: 2.0)
  -mt MATCHING_TIME_DIFF_S, --matching-time-diff-s MATCHING_TIME_DIFF_S
                        error margin for timestamp matching (s) (default: 0)
  -mb MATCHING_BANDWIDTH_HZ, --matching-bandwidth-hz MATCHING_BANDWIDTH_HZ
                        error margin for frequency (Hz) (default: 0)
  -md MATCHING_DURATION_DIFF_MS, --matching-duration-diff-ms MATCHING_DURATION_DIFF_MS
                        error margin for duration (ms) (default: None)

publish:
  --sig-stdout          enable stdout signal publishing (default: False)
  --match-stdout        enable stdout matched signals publishing (default: False)
  --path PATH           file output path (default: data)
  --csv                 enable csv data publishing (default: False)
  --export-config       export configuration (default: False)
  --mqtt                enable mqtt data publishing (default: False)
  --mqtt-host MQTT_HOST
                        hostname of mqtt broker (default: localhost)
  --mqtt-port MQTT_PORT
                        port of mqtt broker (default: 1883)

dashboard:
  --dashboard           enable web-dashboard (default: False)
  --dashboard-host DASHBOARD_HOST
                        hostname to bind the dashboard to (default: localhost)
  --dashboard-port DASHBOARD_PORT
                        port to bind the dashboard to (default: 8050)
  --dashboard-signals DASHBOARD_SIGNALS
                        number of signals to present (default: 100)

Troubleshooting

Failed to allocate zero-copy buffer

The size of zero-copy kernel buffers is limited.

Failed to allocate zero-copy buffer for transfer 5
Falling back to buffers in userspace
Failed to submit transfer 6
Please increase your allowed usbfs buffer size with the following command:
echo 0 > /sys/module/usbcore/parameters/usbfs_memory_mb

For larger buffers, as preferable for high sampling rates in terms of effificiency, the usbfs memory limit can be removed:

echo 0 | sudo tee /sys/module/usbcore/parameters/usbfs_memory_mb

Clock Drift, Resyncing

Each analyzer holds a time stamp internally to derive the time of a detected signal from. The clock is initialized on first async callback from the RTL-SDR library and then incremented according to the data retrieved from the SDR in the following callbacks. Whenever the calculated timestamp differs from the system clock by more than one block length this is detected:

SDR 0 total clock drift (1.1482 s) is larger than two blocks, signal detection is degraded. Resyncing...

Resyncing resets the internal clock to the current system clock, such that even though samples have been lost, the detected signals are using the correct timestamp.

Whenever resyncing is happening, there is a high likelihood, that signals detected in the previous blocks are also undergoing delay.

Resyncing can be prevented by using less ressource hungry settings, such as: higher signal / SNR thresholds, lower gain, lower sampling rate, larger callback length.

Caveats

The sample rate of RTL-SDR is limited to certain numbers in 225 kHz - 3.2 GHz, excluding 300 kHz - 900 kHz.

	# loop down until threshold is undershot
	start = ti
	start_min = 0 if self._spectrogram_last is None else -len(self._spectrogram_last[0])
	while start > start_min:
	if start < 0:
	power = self._spectrogram_last[fi, start]
	else:
	power = fft[start]

	if power < self.signal_threshold:
	break

	start -= 1

	# loop up until threshold is undershot
	end = ti
	while end < len(fft):
	if fft[end] < self.signal_threshold:
	ti_skip = end
	break

	end += 1

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pyradiotracking's Introduction

pyradiotracking

Usage

Troubleshooting

Failed to allocate zero-copy buffer

Clock Drift, Resyncing

Caveats

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