A wideband signal need to be processed to extract several narrowband channels from it. There are two straightforward approaches to do so:
- For each narrowband channel shift frequency and filter it with FIR filter.
- Implement polyphase channelizer and select only those chunks that correspond with target narrowband channels.
Considering the following extreme situations:
- Need to select 1 narrowband (25 kHz) channel from a wideband channel (56 MHz)
- Need to select 2048 narrowband (25 kHz) channels from a wideband channel (56MHz)
It seems to be obvious that in the first case time-domain filtration is more efficient and polyphase channelizer is more efficient in the second case.
The question is what will be more be more efficient (require fewer FPGA resources) if only 12 (25 kHz) arbitrary placed channels need to be extracted from a 56 MHz wideband signal?