Generalised Power Law Detector

Default Settings

Default values for several species are available by clicking on the Set Defaults button.


Note though that these default values were designed to work with specific sample rates, FFT lengths and FFT overlaps and you should adjust the FFT (Spectrogram) Engine parameters accordingly, including a Decimator module if necessary to provide data at the right sample rate. Nominal values for these parameters are provided below.

Key is to have about the right time and frequency resolution. The time resolution is the FFT Hop divided by the sample rate and the frequency resolution is the sample rate divided by the FFT Length. This means that data with a sample rate of 2000 Hz, and FFT length of 2048 samples and an FFT hop of 128 samples will have time and frequency resolutions of 64ms and 0.98 Hz respectively. Exactly the same time and frequency resolutions could be achieved with data sampled at 1000Hz if you were to use an FFT length of 1024 samples and FFT hop of 64 samples.

Note that PAMGuard does support FFT lengths which are not an exact power of 2, however such values may mean that the FFT's are slow to computer which may impact on processing speed.

Species Sample Rate FFT Length FFT Hop
Blue Whale D 2000 Hz 2048 128
Fin Whale 20Hz 2000 Hz 2048 128
Fin Whale 40Hz 2000 Hz 2048 128
Humpback 2000 Hz 2048 128
Bryde's whale 6000 Hz 4096 512