diff --git a/User-Preferences.md b/User-Preferences.md index 8bf8652..889c6fa 100644 --- a/User-Preferences.md +++ b/User-Preferences.md @@ -161,3 +161,16 @@ recordings, and MBE frame recordings are stored. ## Source ### Tuner Channelizer +SDR tuners capture a broad swath of the frequency spectrum containing multiple radio channels. sdrtrunk +employs a channelizer to extract each radio channel for decoding. sdrtrunk provides two channelizers to choose from. +![Image of the user preferences editor with the Source category and the Tuner Channelizer editor pane showing](images/user_preferences_tuner_channelizer.png "User Preferences Editor - Tuner Channelizer") + +* **Heterdyne** - the heterdyne channelizer applies a mixing frequency to mix the channel of interest +down to the zero frequency and then it uses a sequence of half-band decimation filters to incrementally +divide the sample rate and bandwidth in half. These half-band decimation filters are computationally +efficient. However, the filters do not provide a sharp cutoff at the channel band edges and this can sometimes +allow bleedover from strong adjacent channels. Use this channelizer if you are only decoding a few channels to +reduce the processing workload. +* **Polyphase** - the polyphase channelizer uses a single filter and an FFT to break the entire bandwidth of the SDR +into equal bandwidth channels. This channelizer is more efficient than the heterodyne channelizer when you are decoding +three or more channels at the same time. This is the default channelizer. diff --git a/images/user_preferences_tuner_channelizer.png b/images/user_preferences_tuner_channelizer.png new file mode 100644 index 0000000..4f67c72 Binary files /dev/null and b/images/user_preferences_tuner_channelizer.png differ