> > Nicolas, the 21365 has on-board sample-rate converters. Check out the
> > manual!
> >
> > Regards,
> > AndoR
>
>
> Hi Andor
>
> Thanks for the tip.
>
> Which manual are you referring to?
The manual for the ADSP-21364.
You can use its on-board sample-rate converters to convert the 48kHz IO
stream to 8kHz for processing in the DSP, ie. you have 48kHz input ->
downsample to 8kHz with the SRCs of the 21364 -> process -> upsample
the 8kHz stream to 48kHz with the SRCs of the 21364 -> output the 48kHz
stream.
Reply by Nicholas●January 13, 20062006-01-13
Hi Jerry
> Do you filter adequately after interpolating the zeros?
Yes, in my previous post I wrote that I use the filtfilt-command in matlab.
> It may be simpler, and will certainly preserve bandwidth better, if you
> redesign the algorithm.
Yes, but that will take time ....too much time....
Appreciate the advice. Thanks.
//Nico
Reply by Jerry Avins●January 13, 20062006-01-13
Nicholas wrote:
...
> Interpolating with zeros gives horrible results.
Do you filter adequately after interpolating the zeros? Before
downsampling and again after upsampling, you must low-pass to remove
energy above 4 KHz. The actual cutoff must be below that. It may be
simpler, and will certainly preserve bandwidth better, if you redesign
the algorithm.
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Al Clark●January 12, 20062006-01-12
"Nicholas" <nicholas@nospam.please> wrote in
news:43c6ce62$0$78284$157c6196@dreader1.cybercity.dk:
>> Nicolas, the 21365 has on-board sample-rate converters. Check out the
>> manual!
>>
>> Regards,
>> AndoR
>
>
> Hi Andor
>
> Thanks for the tip.
>
> Which manual are you referring to?
>
> I am checking out the "talkthru"-example that came along with the
> board. Is it possible to change some registers or something such that
> it samples at 8kHz?
>
> Cheers,
> Nico
>
>
>
No,
You could scale the AD183x by changing the MCLK, but I don't remember
what's involved. I think you might just need to replace a clock
oscillator. The anti-imaging filters will not be optimum and you may see
some high frequency clock noise (The AD183x is a sigma delta converter)
As I believe Andor mentioned earlier, the ADSP-21364 has very good sample
rate converters built in. This is the easiest approach.
You could also use one of our dspstak systems. We have boards that
include the EZ-Kit debugger (and therefore work like an EZ-Kit). Many of
our I/O boards support 8k sampling
--
Al Clark
Danville Signal Processing, Inc.
--------------------------------------------------------------------
Purveyors of Fine DSP Hardware and other Cool Stuff
Available at http://www.danvillesignal.com
Reply by Nicholas●January 12, 20062006-01-12
> Nicolas, the 21365 has on-board sample-rate converters. Check out the
> manual!
>
> Regards,
> AndoR
Hi Andor
Thanks for the tip.
Which manual are you referring to?
I am checking out the "talkthru"-example that came along with the board. Is
it possible to change some registers or something such that it samples at
8kHz?
Cheers,
Nico
Reply by Nicholas●January 12, 20062006-01-12
I did the following in matlab:
resampled_signal=filtfilt(bbb,aaa,u)
where
[bbb,aaa]=butter(7,0.22)
and 'u' is the upsampled signal (zeros between samples).
It seems that it works fine...
Any problems in this approach??
Reply by Andor●January 12, 20062006-01-12
Nicholas wrote:
> >
> > The ADDS-21364-EZLITE is populated with an AD1835 codec. This one is
> > primarily targeted at high quality audio apps (as well as the DSP, too).
> > Reading from its datasheet, it seems like it can only be configured for
> > 48, 96 or 192 kHz sampling rate.
>
> Hi Jaime
>
> Appreciate the fast reply.
>
> I also read the datasheet for the AD1835A so I guess it's not possible with
> a 8kHz sample rate.
>
> However, I could just downsample the incoming signal to 8kHz, do what ever
> signal processing I have to do, and then resample the result up to 48kHz,
> right?
>
> The reason that I want to do this is because my algorithm is targeted
> (designed) for 8kHz signals.
>
> Is there a simple way to resample such that the resampled signal x(n) sounds
> just a nice as the 8kHz processed signal?
>
> Interpolating with zeros gives horrible results.
Nicolas, the 21365 has on-board sample-rate converters. Check out the
manual!
Regards,
AndoR
Reply by Nicholas●January 12, 20062006-01-12
>
> The ADDS-21364-EZLITE is populated with an AD1835 codec. This one is
> primarily targeted at high quality audio apps (as well as the DSP, too).
> Reading from its datasheet, it seems like it can only be configured for
> 48, 96 or 192 kHz sampling rate.
Hi Jaime
Appreciate the fast reply.
I also read the datasheet for the AD1835A so I guess it's not possible with
a 8kHz sample rate.
However, I could just downsample the incoming signal to 8kHz, do what ever
signal processing I have to do, and then resample the result up to 48kHz,
right?
The reason that I want to do this is because my algorithm is targeted
(designed) for 8kHz signals.
Is there a simple way to resample such that the resampled signal x(n) sounds
just a nice as the 8kHz processed signal?
Interpolating with zeros gives horrible results.
Reply by Jaime Andres Aranguren Cardona●January 12, 20062006-01-12
"Nicholas" <nicholas@nospam.please> wrote in message
news:43c638b7$0$67258$157c6196@dreader2.cybercity.dk...
> Hello,
>
> I am running the "talkthru"-example on ADSP21364 EZ-KIT.
>
> The sampling rate is 48kHz.
>
> Is it possible to reconfigure the sampling rate to 8kHz?
>
> Thanks.
Hello Nicholas:
The ADDS-21364-EZLITE is populated with an AD1835 codec. This one is
primarily targeted at high quality audio apps (as well as the DSP, too).
Reading from its datasheet, it seems like it can only be configured for 48,
96 or 192 kHz sampling rate.
Regards,
--
Jaime Andres Aranguren Cardona
jaac@sanjaac.com
SanJaaC Electronics
Soluciones en DSP
www.sanjaac.com
Reply by Nicholas●January 12, 20062006-01-12
Hello,
I am running the "talkthru"-example on ADSP21364 EZ-KIT.
The sampling rate is 48kHz.
Is it possible to reconfigure the sampling rate to 8kHz?
Thanks.