# Overlapping channels in polyphase channelizer **URL:** \ **Category:** GNU Radio\ **Created:** [June 19, 2015, 3:15am UTC](https://www.ruby-forum.com/t/overlapping-channels-in-polyphase-channelizer/242367 "2015-06-19T03:15:34Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\ **Post date:** [June 19, 2015, 3:15am UTC](https://www.ruby-forum.com/t/overlapping-channels-in-polyphase-channelizer/242367/1 "2015-06-19T03:15:34Z")
Is it possible to have overlapping channels in a polyphase channelizer? say you have 10MHz of bandwidth, and you want to break it up into 10 channels, each 2MHz wide with the center frequencies being 1MHz apart. would you just set the taps to have the right bw and lowpass filter width (in this case it would be 1MHz to create a 2MHz channel), then set the number of outputs on the channelizer block in grc to be 10? thanks, -b ---
**Author:** ![ben\_Gee](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/85f322/32.png) [@ben\_Gee](https://www.ruby-forum.com/u/ben_Gee)\ **Post date:** [June 19, 2015, 6:58am UTC](https://www.ruby-forum.com/t/overlapping-channels-in-polyphase-channelizer/242367/2 "2015-06-19T06:58:11Z")
On Jun 18, 2015, at 6:14 PM, ben Gee \ wrote: Is it possible to have overlapping channels in a polyphase channelizer? say you have 10MHz of bandwidth, and you want to break it up into 10 channels, each 2MHz wide with the center frequencies being 1MHz apart. Hi Ben, perhaps this paper would be helpful. [http://static1.1.sqspcdn.com/static/f/679473/24573007/1395369129837/rondeau\_gr\_filtering.pdf?token=96KRK5gwTcSMhOfiIaaoFKDjZJk%3D](http://static1.1.sqspcdn.com/static/f/679473/24573007/1395369129837/rondeau_gr_filtering.pdf?token=96KRK5gwTcSMhOfiIaaoFKDjZJk%3D)[http://static1.1.sqspcdn.com/static/f/679473/24573007/1395369129837/rondeau\_gr\_filtering.pdf?token=96KRK5gwTcSMhOfiIaaoFKDjZJk=](http://static1.1.sqspcdn.com/static/f/679473/24573007/1395369129837/rondeau_gr_filtering.pdf?token=96KRK5gwTcSMhOfiIaaoFKDjZJk=) It describes a way to rig the filter in order to split a signal into channels using the polyphase channelizer so that no information is lost at the channel boundaries. You could use this technique to split your signal into 1 MHz segments and then join the 1 MHz segments together into the overlapping 2 MHz channels. Another thing that might work is to use two channelizer blocks, each generating five channels. ---
**Author:** ![ben\_Gee](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/85f322/32.png) [@ben\_Gee](https://www.ruby-forum.com/u/ben_Gee)\ **Post date:** [June 19, 2015, 9:08am UTC](https://www.ruby-forum.com/t/overlapping-channels-in-polyphase-channelizer/242367/3 "2015-06-19T09:08:25Z")
Hi Ben, yes, that should work; as you’ve guessed, the polyphase channelizer doesn’t really “care” what your filter looks like. That includes the band edges, too, so your last channel will overlap with your first. Best regards, Marcus ---
**Author:** ![ben\_Gee](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/85f322/32.png) [@ben\_Gee](https://www.ruby-forum.com/u/ben_Gee)\ **Post date:** [June 19, 2015, 3:18pm UTC](https://www.ruby-forum.com/t/overlapping-channels-in-polyphase-channelizer/242367/4 "2015-06-19T15:18:13Z")
On Fri, Jun 19, 2015 at 3:07 AM, Marcus Müller [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > On 06/19/2015 03:14 AM, ben Gee wrote: > thanks, > -b Also, look for the paper by harris and Rice, “Digital Receivers and Transmitters Using Polyphase Filter Banks for Wireless Communications.” There some good stuff in there about adjusting the bandwidth versus the sampling rate. Tom