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Oona Räisänen edited this page Jun 28, 2024 · 13 revisions

CPU usage

These results were obtained by running a batch of test MPX recordings through redsea at a real-time speed on different platforms.

Computer CPU Redsea version % CPU
Raspberry Pi 700 MHz ARMv6 0.17.0 40–45 %
Raspberry Pi 3B ARMv7 1.0-SNAPSHOT 11 %
2013 Macbook Pro 2.8 GHz i7 0.17.0 0.6 %
2021 Macbook Pro M1 Pro 1.0-SNAPSHOT 1.1 %

Noise performance

We measured how redsea 1.0-SNAPSHOT does under noisy conditions on different platforms:

  • took a recording of a clean MPX and added varying amounts of white rand() noise to it.
  • calculated the power coming through the narrow-band RDS shaping filter (signal + noise) and compared it with another filter running 5 kHz higher (noise only).
  • calculated the signal-to-noise ratio estimate as SNR_dB = 10log10((P_signal_plus_noise - P_noise_only) / P_noise_only).

Here, the percentage of correct syndromes received (before error correction) is plotted against the subcarrier's SNR estimate.

Syndromes vs. snr

Platform-dependent differences can already be seen in downmixing results from liquid-dsp. This could be due to --fast-math that liquid-dsp enables by default on some platforms like armv7.

See Error detection and correction for more discussion and measurements.