multiple channel filter bank

I have a newbie question. I am about to embark on a project for which I am
designing a multiple channel filter bank. This device will have an input
signal from 20 to 10K Hz and and 8 outputs. The outputs will split the
signal into 8 frequency bands approx. 
20 to 100
100 to 200
200 to 300
300 to 400
400 to 500
500 to 600
600 to 700
700 to 10k

Since I have never tackled a DSP project I thought I would see how others
might tackle this. I am quite familiar to using PIC mucrocontrollers so am
leaning towards using there dsPICs. I am considering using a dsPIC for the
filters and a CS42518 2 in 8 out CODEC.
http://www.cirrus.com/en/products/cs42518-28.html . I want at least 16 bit
audio. Another possibility I was thinking was to use 2 ADAU1701 Analog
Devices processors as they have 4 built in DACs and their Sigma Studio
Software looks quite slick.
http://www.analog.com/en/audiovideo-products/audio-signal-processors/adau1701/products/product.html
My questions with respect to these two solutions: 
Can the Sigma Studio software handle 4 different filters with 4 outputs.
( I still have to determine my filter characteristics so this may be hard
to answer)
Also can the dsPIC do 8 filters simultaneously and speak with the CODEC in
real time.
Thanks, these may not be the best solution to the problem so I'm open to
better solutions. 
Jim

cinetron wrote:

> I have a newbie question. I am about to embark on a project for which I am
> designing a multiple channel filter bank. This device will have an input
> signal from 20 to 10K Hz and and 8 outputs. The outputs will split the
> signal into 8 frequency bands approx. 
> 20 to 100
> 100 to 200
> 200 to 300
> 300 to 400
> 400 to 500
> 500 to 600
> 600 to 700
> 700 to 10k
> 
> Since I have never tackled a DSP project I thought I would see how others
> might tackle this. I am quite familiar to using PIC mucrocontrollers so am
> leaning towards using there dsPICs. I am considering using a dsPIC for the
> filters and a CS42518 2 in 8 out CODEC.
> http://www.cirrus.com/en/products/cs42518-28.html . I want at least 16 bit
> audio. Another possibility I was thinking was to use 2 ADAU1701 Analog
> Devices processors as they have 4 built in DACs and their Sigma Studio
> Software looks quite slick.
> http://www.analog.com/en/audiovideo-products/audio-signal-processors/adau1701/products/product.html
> My questions with respect to these two solutions: 
> Can the Sigma Studio software handle 4 different filters with 4 outputs.
> ( I still have to determine my filter characteristics so this may be hard
> to answer)
> Also can the dsPIC do 8 filters simultaneously and speak with the CODEC in
> real time.
> Thanks, these may not be the best solution to the problem so I'm open to
> better solutions. 


1. For 8 channels of processing at audio sample rate, I would take a 
real DSP like Blackfin-531 or TMS55xx.

2. Codec interfacing to the DSP is no problem.

3. Each band is likely to require two cascaded biquads at least.

4. The processing should be implemented with ~31 bit precision.

5. Do you need to update the filter settings during the run time?

6. dsPICs and Sigma Studios isn't an answer.

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

On Oct 7, 11:13&#4294967295;am, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> cinetron wrote:
> > I have a newbie question. I am about to embark on a project for which I am
> > designing a multiple channel filter bank. This device will have an input
> > signal from 20 to 10K Hz and and 8 outputs. The outputs will split the
> > signal into 8 frequency bands approx.
> > 20 to 100
> > 100 to 200
> > 200 to 300
> > 300 to 400
> > 400 to 500
> > 500 to 600
> > 600 to 700
> > 700 to 10k
>
> > Since I have never tackled a DSP project I thought I would see how others
> > might tackle this. I am quite familiar to using PIC mucrocontrollers so am
> > leaning towards using there dsPICs. I am considering using a dsPIC for the
> > filters and a CS42518 2 in 8 out CODEC.
> >http://www.cirrus.com/en/products/cs42518-28.html. I want at least 16 bit
> > audio. Another possibility I was thinking was to use 2 ADAU1701 Analog
> > Devices processors as they have 4 built in DACs and their Sigma Studio
> > Software looks quite slick.
> >http://www.analog.com/en/audiovideo-products/audio-signal-processors/...
> > My questions with respect to these two solutions:
> > Can the Sigma Studio software handle 4 different filters with 4 outputs.
> > ( I still have to determine my filter characteristics so this may be hard
> > to answer)
> > Also can the dsPIC do 8 filters simultaneously and speak with the CODEC in
> > real time.
> > Thanks, these may not be the best solution to the problem so I'm open to
> > better solutions.
>
> 1. For 8 channels of processing at audio sample rate, I would take a
> real DSP like Blackfin-531 or TMS55xx.
>
> 2. Codec interfacing to the DSP is no problem.
>
> 3. Each band is likely to require two cascaded biquads at least.
>
> 4. The processing should be implemented with ~31 bit precision.
>
> 5. Do you need to update the filter settings during the run time?
>
> 6. dsPICs and Sigma Studios isn't an answer.
>
> Vladimir Vassilevsky
> DSP and Mixed Signal Design Consultanthttp://www.abvolt.com

Vlad's spot-on here.

I'm working on a little project with a dsPIC and a Wolfson WM8731
codec. One application I'm experimenting with is a 20-chl filterbank
with the codec sampling around 40kHz and the processor near it's
maximum 40MHz. For simple 2nd-order biquads this works, but just
barely. The dsPIC's native 16-bit resolution is really a limitation.
The filter coefficients are too heavily quantized to accurately
implement the desired passband shapes, and the IIRs are limit-cycling
like crazy - nowhere near the kind of SNR that you need for good
audio.

Unless your application can survive on low SNR and only rough
approximations of the filter shape I'd suggest you need a DSP with at
least 24-bits if not more, and more cycles/sample to throw at it as
well.

Eric

>
>
>cinetron wrote:
>
>> I have a newbie question. I am about to embark on a project for which I
am
>> designing a multiple channel filter bank. This device will have an
input
>> signal from 20 to 10K Hz and and 8 outputs. The outputs will split the
>> signal into 8 frequency bands approx. 
>> 20 to 100
>> 100 to 200
>> 200 to 300
>> 300 to 400
>> 400 to 500
>> 500 to 600
>> 600 to 700
>> 700 to 10k
>> 
>> Since I have never tackled a DSP project I thought I would see how
others
>> might tackle this. I am quite familiar to using PIC mucrocontrollers so
am
>> leaning towards using there dsPICs. I am considering using a dsPIC for
the
>> filters and a CS42518 2 in 8 out CODEC.
>> http://www.cirrus.com/en/products/cs42518-28.html . I want at least 16
bit
>> audio. Another possibility I was thinking was to use 2 ADAU1701 Analog
>> Devices processors as they have 4 built in DACs and their Sigma Studio
>> Software looks quite slick.
>>
http://www.analog.com/en/audiovideo-products/audio-signal-processors/adau1701/products/product.html
>> My questions with respect to these two solutions: 
>> Can the Sigma Studio software handle 4 different filters with 4
outputs.
>> ( I still have to determine my filter characteristics so this may be
hard
>> to answer)
>> Also can the dsPIC do 8 filters simultaneously and speak with the CODEC
in
>> real time.
>> Thanks, these may not be the best solution to the problem so I'm open
to
>> better solutions. 
>
>
>1. For 8 channels of processing at audio sample rate, I would take a 
>real DSP like Blackfin-531 or TMS55xx.
>
>2. Codec interfacing to the DSP is no problem.
>
>3. Each band is likely to require two cascaded biquads at least.
>
>4. The processing should be implemented with ~31 bit precision.
>
>5. Do you need to update the filter settings during the run time?
>
>6. dsPICs and Sigma Studios isn't an answer.
>
>Vladimir Vassilevsky
>DSP and Mixed Signal Design Consultant
>http://www.abvolt.com
>
Thanks Vladimir for the suggestion.
Presently I don't have to update the filters at run time but eventually it
would be nice to have that flexibility. I was thinking the processing
overhead of 8 channels wouldn't be huge doing an FIR based filter for
example since the input value doesn't change for each channel. All 8
channels are processing the same input just spitting out different results
based on different coefficients. I'm also considering 2 of these chips from
quickfilter to do the filter work. 
http://www.quickfiltertech.com/html/content_page.php?content_id=7&
Jim

On Oct 7, 6:30&#4294967295;pm, "cinetron" <cinetron@n_o_s_p_a_m.passport.ca>
wrote:
> >cinetron wrote:
>
> >> I have a newbie question. I am about to embark on a project for which I
> am
> >> designing a multiple channel filter bank. This device will have an
> input
> >> signal from 20 to 10K Hz and and 8 outputs. The outputs will split the
> >> signal into 8 frequency bands approx.
> >> 20 to 100
> >> 100 to 200
> >> 200 to 300
> >> 300 to 400
> >> 400 to 500
> >> 500 to 600
> >> 600 to 700
> >> 700 to 10k
>
> >> Since I have never tackled a DSP project I thought I would see how
> others
> >> might tackle this. I am quite familiar to using PIC mucrocontrollers so
> am
> >> leaning towards using there dsPICs. I am considering using a dsPIC for
> the
> >> filters and a CS42518 2 in 8 out CODEC.
> >>http://www.cirrus.com/en/products/cs42518-28.html. I want at least 16
> bit
> >> audio. Another possibility I was thinking was to use 2 ADAU1701 Analog
> >> Devices processors as they have 4 built in DACs and their Sigma Studio
> >> Software looks quite slick.
>
> http://www.analog.com/en/audiovideo-products/audio-signal-processors/...
>
> >> My questions with respect to these two solutions:
> >> Can the Sigma Studio software handle 4 different filters with 4
> outputs.
> >> ( I still have to determine my filter characteristics so this may be
> hard
> >> to answer)
> >> Also can the dsPIC do 8 filters simultaneously and speak with the CODEC
> in
> >> real time.
> >> Thanks, these may not be the best solution to the problem so I'm open
> to
> >> better solutions.
>
> >1. For 8 channels of processing at audio sample rate, I would take a
> >real DSP like Blackfin-531 or TMS55xx.
>
> >2. Codec interfacing to the DSP is no problem.
>
> >3. Each band is likely to require two cascaded biquads at least.
>
> >4. The processing should be implemented with ~31 bit precision.
>
> >5. Do you need to update the filter settings during the run time?
>
> >6. dsPICs and Sigma Studios isn't an answer.
>
> >Vladimir Vassilevsky
> >DSP and Mixed Signal Design Consultant
> >http://www.abvolt.com
>
> Thanks Vladimir for the suggestion.
> Presently I don't have to update the filters at run time but eventually it
> would be nice to have that flexibility. I was thinking the processing
> overhead of 8 channels wouldn't be huge doing an FIR based filter for
> example since the input value doesn't change for each channel. All 8
> channels are processing the same input just spitting out different results
> based on different coefficients. I'm also considering 2 of these chips from
> quickfilter to do the filter work.http://www.quickfiltertech.com/html/content_page.php?content_id=7&
> Jim

Curious, how does a common filter input value save anything when the
filters are all different?

John

>>
>>1. For 8 channels of processing at audio sample rate, I would take a 
>>real DSP like Blackfin-531 or TMS55xx.
>>
>>2. Codec interfacing to the DSP is no problem.
>>
>>3. Each band is likely to require two cascaded biquads at least.
>>
>>4. The processing should be implemented with ~31 bit precision.
>>
>>5. Do you need to update the filter settings during the run time?
>>
>>6. dsPICs and Sigma Studios isn't an answer.
>>
>>Vladimir Vassilevsky
>>DSP and Mixed Signal Design Consultant
>>http://www.abvolt.com
>>
>Thanks Vladimir for the suggestion.
>Presently I don't have to update the filters at run time but eventually
it
>would be nice to have that flexibility. I was thinking the processing
>overhead of 8 channels wouldn't be huge doing an FIR based filter for
>example since the input value doesn't change for each channel. All 8
>channels are processing the same input just spitting out different
results
>based on different coefficients. I'm also considering 2 of these chips
from
>quickfilter to do the filter work. 
>http://www.quickfiltertech.com/html/content_page.php?content_id=7&
>Jim

Related to the above project I'm wondering if anyone has any experience
with the AKM audio DSPs ie. http://akm.com/prodfolder-adc.asp?p=AK7742
There isn't a lot of info on their website but they look quite good for the
price. They have 2 input ADCs and 4 output DACs 24 bit CODEC, and 24 bit
floating point DSP .Digikey has them for $8.50 
Jim
>

cinetron wrote:
>>>1. For 8 channels of processing at audio sample rate, I would take a 
>>>real DSP like Blackfin-531 or TMS55xx.
>>>
>>>2. Codec interfacing to the DSP is no problem.
>>>
>>>3. Each band is likely to require two cascaded biquads at least.
>>>
>>>4. The processing should be implemented with ~31 bit precision.
>>>
>>>5. Do you need to update the filter settings during the run time?
>>>
>>>6. dsPICs and Sigma Studios isn't an answer.
>>>
>>>Vladimir Vassilevsky
>>>DSP and Mixed Signal Design Consultant
>>>http://www.abvolt.com
>>>
>>
>>Thanks Vladimir for the suggestion.
>>Presently I don't have to update the filters at run time but eventually
> 
> it
> 
>>would be nice to have that flexibility. I was thinking the processing
>>overhead of 8 channels wouldn't be huge doing an FIR based filter for
>>example since the input value doesn't change for each channel. All 8
>>channels are processing the same input just spitting out different
> 
> results
> 
>>based on different coefficients. I'm also considering 2 of these chips
> 
> from
> 
>>quickfilter to do the filter work. 
>>http://www.quickfiltertech.com/html/content_page.php?content_id=7&
>>Jim
> 
> 
> Related to the above project I'm wondering if anyone has any experience
> with the AKM audio DSPs ie. http://akm.com/prodfolder-adc.asp?p=AK7742
> There isn't a lot of info on their website but they look quite good for the
> price. They have 2 input ADCs and 4 output DACs 24 bit CODEC, and 24 bit
> floating point DSP .Digikey has them for $8.50 

Short answer: this is junk. Use a real DSP like BlackFin or TMS55xx.

Long answer: this is not DSP, but a DAP (Digital Audio Processor). There 
is a bunch of DAPs made by companies like TI, ST, AKM. With DAPs, you 
can only do a very limited set of a very limited things. DAPs are useful 
for tone control and equalization, only if they exactly fit the intended 
application (like car radio, for example). If you have to use more then 
one DAP, the DSP solution is going to be better for price.

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

cinetron wrote:
> I have a newbie question. I am about to embark on a project for which I am
> designing a multiple channel filter bank.
[snip]
> http://www.analog.com/en/audiovideo-products/audio-signal-processors/adau1701/products/product.html
> My questions with respect to these two solutions: 
> Can the Sigma Studio software handle 4 different filters with 4 outputs.

Just did a project with adau1442 and found it a powerful tool for audio processing, it can do 24 
inputs and 24 outputs and lots of filters.
Sigmastudio helped me a lot in creating my prototype.
http://www.analog.com/en/embedded-processing-dsp/sigmadsp/adau1442/processors/product.html
I know the adau1442 can do a lot more than what you need.

> ( I still have to determine my filter characteristics so this may be hard
> to answer)
> Also can the dsPIC do 8 filters simultaneously and speak with the CODEC in
> real time.

Never worked with dsPIC.

On Oct 7, 6:16&#4294967295;pm, John <sampson...@gmail.com> wrote:
> On Oct 7, 6:30&#4294967295;pm, "cinetron" <cinetron@n_o_s_p_a_m.passport.ca>
> wrote:
>
>
>
> > >cinetron wrote:
>
> > >> I have a newbie question. I am about to embark on a project for which I
> > am
> > >> designing a multiple channel filter bank. This device will have an
> > input
> > >> signal from 20 to 10K Hz and and 8 outputs. The outputs will split the
> > >> signal into 8 frequency bands approx.
> > >> 20 to 100
> > >> 100 to 200
> > >> 200 to 300
> > >> 300 to 400
> > >> 400 to 500
> > >> 500 to 600
> > >> 600 to 700
> > >> 700 to 10k
>
> > >> Since I have never tackled a DSP project I thought I would see how
> > others
> > >> might tackle this. I am quite familiar to using PIC mucrocontrollers so
> > am
> > >> leaning towards using there dsPICs. I am considering using a dsPIC for
> > the
> > >> filters and a CS42518 2 in 8 out CODEC.
> > >>http://www.cirrus.com/en/products/cs42518-28.html. I want at least 16
> > bit
> > >> audio. Another possibility I was thinking was to use 2 ADAU1701 Analog
> > >> Devices processors as they have 4 built in DACs and their Sigma Studio
> > >> Software looks quite slick.
>
> >http://www.analog.com/en/audiovideo-products/audio-signal-processors/...
>
> > >> My questions with respect to these two solutions:
> > >> Can the Sigma Studio software handle 4 different filters with 4
> > outputs.
> > >> ( I still have to determine my filter characteristics so this may be
> > hard
> > >> to answer)
> > >> Also can the dsPIC do 8 filters simultaneously and speak with the CODEC
> > in
> > >> real time.
> > >> Thanks, these may not be the best solution to the problem so I'm open
> > to
> > >> better solutions.
>
> > >1. For 8 channels of processing at audio sample rate, I would take a
> > >real DSP like Blackfin-531 or TMS55xx.
>
> > >2. Codec interfacing to the DSP is no problem.
>
> > >3. Each band is likely to require two cascaded biquads at least.
>
> > >4. The processing should be implemented with ~31 bit precision.
>
> > >5. Do you need to update the filter settings during the run time?
>
> > >6. dsPICs and Sigma Studios isn't an answer.
>
> > >Vladimir Vassilevsky
> > >DSP and Mixed Signal Design Consultant
> > >http://www.abvolt.com
>
> > Thanks Vladimir for the suggestion.
> > Presently I don't have to update the filters at run time but eventually it
> > would be nice to have that flexibility. I was thinking the processing
> > overhead of 8 channels wouldn't be huge doing an FIR based filter for
> > example since the input value doesn't change for each channel. All 8
> > channels are processing the same input just spitting out different results
> > based on different coefficients. I'm also considering 2 of these chips from
> > quickfilter to do the filter work.http://www.quickfiltertech.com/html/content_page.php?content_id=7&
> > Jim
>
> Curious, how does a common filter input value save anything when the
> filters are all different?
>
> John

if it's a bunch of FIR filters in direct form you can use the same x(n-
m) pipeline for all of them. Not much of a savings though since you
still have to do all the multiplies separately for each output SOP.

Eric

>cinetron wrote:
>> I have a newbie question. I am about to embark on a project for which I
am
>> designing a multiple channel filter bank.
>[snip]
>>
http://www.analog.com/en/audiovideo-products/audio-signal-processors/adau1701/products/product.html
>> My questions with respect to these two solutions: 
>> Can the Sigma Studio software handle 4 different filters with 4
outputs.
>
>Just did a project with adau1442 and found it a powerful tool for audio
processing, it can do 24 
>inputs and 24 outputs and lots of filters.
>Sigmastudio helped me a lot in creating my prototype.
>http://www.analog.com/en/embedded-processing-dsp/sigmadsp/adau1442/processors/product.html
>I know the adau1442 can do a lot more than what you need.

I see they have a development board EVAL-ADAU1442EBZ . A bit pricey at
$699.00 . Curious if you used the development board for your prototype or
if you know of any other evaluation boards for this processor.
Thanks,
Jim