Frequency Xlating FFT Filter: Difference between revisions

From GNU Radio
Jump to navigation Jump to search
(Created page with "Category:Block Docs This is a hier block, consisting of a FFT Filter block and a Rotator block. It performs a frequency translation on the signal, as well as down...")
 
No edit summary
 
Line 1: Line 1:
[[Category:Block Docs]]
[[Category:Block Docs]]
This is a hier block, consisting of a [[FFT Filter]] block and a [[Rotator]] block.  It performs a frequency translation on the signal, as well as downsamples the signal by running a decimating FIR filter on it.  It can be used as a channelizer, to pull out a narrowband portion of a wideband signal, without that narrowband portion having to be centered in frequency. 
This is a hier block, consisting of a [[FFT Filter]] block and a [[Rotator]] block.  It performs the same function as the [[Frequency Xlating FIR Filter]], except using an [[FFT Filter]]. See [[Frequency Xlating FIR Filter]] for more information.
 
[[File:freq-xlating-filter.png|250px]]
 
(note- taken from http://blog.sdr.hu/grblocks/xlating-fir.html)
 
See [http://blog.sdr.hu/grblocks/xlating-fir.html this page] or [http://www.andrej-mohar.com/frequency-xlating-fir-filter-and-channeling-basics-in-gnuradio this page] for more details.


== Parameters ==
== Parameters ==

Latest revision as of 03:52, 15 July 2019

This is a hier block, consisting of a FFT Filter block and a Rotator block. It performs the same function as the Frequency Xlating FIR Filter, except using an FFT Filter. See Frequency Xlating FIR Filter for more information.

Parameters

Decimation
The integer ratio between the input and the output signal’s sampling rate.
Taps
The vector of the complex or real taps of the FIR filter. You can generate these taps within the parameter box using firdes, for example:
Real taps:
 firdes.low_pass(1,samp_rate,samp_rate/(2*decimation), transition_bw)
Complex taps:
 firdes.complex_band_pass(1, samp_rate, -samp_rate/(2*decimation), samp_rate/(2*decimation), transition_bw)
Note: transition_bw is the transition bandwidth of the filter in Hz. The lower it is, the more taps the function will generate, and the more CPU time it will take to apply this filter. This parameter will determine the CPU usage and thus the execution speed of the block.
Center Frequency
The frequency translation offset frequency.
Sample Rate
The sample rate of the input signal.
Sample Delay
Sets the sample delay of the filter block, see FFT Filter for more info.
Num Threads
Sets the number of threads used by the filter block, see FFT Filter for more info.

Source Files

Python Hier Block