hello, i am trying to do 12 to 1 downsampling and 1 to 12 upsampling with polyphase fir filter, I wanted to know how to design the inner filter. suppose passband frquency is 0.5, stopband freq is 0.75. input sample rate is 24 ,inband ripple is 0.1 and outband attenuation is 80db.and it is 12 path filter with filter length is equal to 348 .each path is followed by 29 taps.how to design the inner filter such that it meets the specification of the synthesis filter.. --------------------------------------- Posted through http://www.DSPRelated.com

# Resampling Polyphase Fir Filter

Started by ●October 23, 2015

Reply by ●October 23, 20152015-10-23

On 23.10.15 14:13, angeleye wrote:> hello, > i am trying to do 12 to 1 downsampling and 1 to 12 upsampling with > polyphase fir filter, I wanted to know how to design the inner filter. > suppose passband frquency is 0.5, stopband freq is 0.75. input sample rate > is 24 ,inband ripple is 0.1 and outband attenuation is 80db.and it is 12 > path filter with filter length is equal to 348 .each path is followed by > 29 taps.how to design the inner filter such that it meets the > specification of the synthesis filter.. >Homework / study project? -- -TV

Reply by ●October 23, 20152015-10-23

>hello,>suppose passband frquency is 0.5, stopband freq is 0.75. input samplerate>is 24 ,inband ripple is 0.1 and outband attenuation is 80db.and it is 12 >path filter with filter length is equal to 348 .each path is followed by >29 taps.how to design the inner filter such that it meets the >specification of the synthesis filter.. >why suppose a harsh requirement? 0.1/24 & 0.75/24 upsampled by 12 means 0.1/(24*12) & 0.75/(24*12) = 0.0017 & 0.0026 ratio Too narrow and too sharp. Kaz --------------------------------------- Posted through http://www.DSPRelated.com

Reply by ●October 23, 20152015-10-23

>>hello, > >>suppose passband frquency is 0.5, stopband freq is 0.75. input sample >rate >>is 24 ,inband ripple is 0.1 and outband attenuation is 80db.and it is12>>path filter with filter length is equal to 348 .each path is followedby>>29 taps.how to design the inner filter such that it meets the >>specification of the synthesis filter.. >> > >why suppose a harsh requirement? 0.1/24 & 0.75/24 upsampled by 12 means >0.1/(24*12) & 0.75/(24*12) = 0.0017 & 0.0026 ratio > >Too narrow and too sharp. > >Kaz > >--------------------------------------- >Posted through http://www.DSPRelated.comhow to find the 2 sided bandwidth stopband frequency and the sampling rate AND weigth of the inner filter from the given analysis filter. for example, the input sample rate is 24 .if we do 12 to 1 downsampling and then upsampling of 1 to 12 .the output sample rate will become 24/12 = 2. but how do we find the transition band.i tried using sampling theorem. nyquist rate =2sided band + transition bandwidth. Asuming the 2 sided banwidth same as the analysis filter and nyquist rate equal to 2. Is it the right way to do it. --------------------------------------- Posted through http://www.DSPRelated.com

Reply by ●October 23, 20152015-10-23

>On 23.10.15 14:13, angeleye wrote: >> hello, >> i am trying to do 12 to 1 downsampling and 1 to 12 upsampling with >> polyphase fir filter, I wanted to know how to design the inner filter. >> suppose passband frquency is 0.5, stopband freq is 0.75. input sample >rate >> is 24 ,inband ripple is 0.1 and outband attenuation is 80db.and it is12>> path filter with filter length is equal to 348 .each path is followedby>> 29 taps.how to design the inner filter such that it meets the >> specification of the synthesis filter.. >> > > >Homework / study project? > >-- > >-TVstudy project --------------------------------------- Posted through http://www.DSPRelated.com

Reply by ●October 23, 20152015-10-23

>> >>--------------------------------------- >>Posted through http://www.DSPRelated.com > >how to find the 2 sided bandwidth stopband frequency and the sampling >rate AND weigth of the inner filter from the given analysis filter. >for example, the input sample rate is 24 .if we do 12 to 1 downsampling >and then upsampling of 1 to 12 .the output sample rate will become 24/122. but how do we find the transition band.i tried using sampling theorem.>nyquist rate =2sided band + transition bandwidth. Asuming the 2 sided >banwidth same as the analysis filter and nyquist rate equal to 2. Is it >the right way to do it. >--------------------------------------- >Posted through http://www.DSPRelated.comupsample by 12 then downsample by 12. Why? what do do in between? Kaz --------------------------------------- Posted through http://www.DSPRelated.com

Reply by ●October 23, 20152015-10-23

On 2015-10-23 13:13, angeleye wrote:> hello, > i am trying to do 12 to 1 downsampling and 1 to 12 upsampling with > polyphase fir filter, I wanted to know how to design the inner filter. > suppose passband frquency is 0.5, stopband freq is 0.75. input sample rate > is 24 ,inband ripple is 0.1 and outband attenuation is 80db.and it is 12 > path filter with filter length is equal to 348 .each path is followed by > 29 taps.how to design the inner filter such that it meets the > specification of the synthesis filter..Why polyphase for integer up/down sampling? Or I'm missing something? bye, -- piergiorgio

Reply by ●October 23, 20152015-10-23

>On 2015-10-23 13:13, angeleye wrote: >> hello, >> i am trying to do 12 to 1 downsampling and 1 to 12 upsampling with >> polyphase fir filter, I wanted to know how to design the inner filter. >> suppose passband frquency is 0.5, stopband freq is 0.75. input sample >rate >> is 24 ,inband ripple is 0.1 and outband attenuation is 80db.and it is12>> path filter with filter length is equal to 348 .each path is followedby>> 29 taps.how to design the inner filter such that it meets the >> specification of the synthesis filter.. > >Why polyphase for integer up/down sampling? > >Or I'm missing something? > >bye, > >-- > >piergiorgioDown Sample to Reduce Sample Rate in Proportion to Bandwidth Reduction and Up Sample to Preserve Input Sample Rate..it is followed by three filter... Analysis filter, inner filter and Synthesis Filter,. my question is how do we find the specification of the inner filter --------------------------------------- Posted through http://www.DSPRelated.com

Reply by ●October 23, 20152015-10-23

On 2015-10-23 21:24, angeleye wrote: [...]> Down Sample to Reduce Sample Rate in Proportion to Bandwidth ReductionYou wrote "12 to 1 downsampling". This does not need polyphase filter. The upsampling 1 to 12 does not need either. Other, I do not know... :-) bye, -- piergiorgio

Reply by ●October 23, 20152015-10-23

On 23.10.15 22:37, Piergiorgio Sartor wrote:> On 2015-10-23 21:24, angeleye wrote: > [...] >> Down Sample to Reduce Sample Rate in Proportion to Bandwidth Reduction > > You wrote "12 to 1 downsampling". > This does not need polyphase filter. > The upsampling 1 to 12 does not need either. > > Other, I do not know... :-) > > bye,It seems to me that his professor has some solution in his mind, and attempting to fish it out using a weirdly set up problem. -- -TV