Would like to buy DSP filter design

Hi,

My company needs an linear phase digital audio low pass filter, but we don't
have DSP skills. We hope to find a student who would like to supply the
circuit diagram and code for a simple circuit using readily available
components.

The cut-off would need to be 15kHz.

We will pay a one off fee, or buy the (pre-programmed) devices on an
on-going basis.

Please e-mail me using:

mail_me [at] freenet [dot] co [dot] uk.

Many thanks.

Al
---

"Alex Collins" <me@privacy.net> wrote in message
news:31os34F36r3rdU1@individual.net...
> Hi,
>
> My company needs an linear phase digital audio low pass filter, but we
don't
> have DSP skills. We hope to find a student who would like to supply the
> circuit diagram and code for a simple circuit using readily available
> components.

Alex,
You will probably need to specify more details for someone to take up the
offer (not me).
You mention 'circuit diagram' and 'code' - does that mean you are looking
for a solution that is implemented in hardware (say an FPGA) and the code is
vhdl? Or...do you already have a DSP processor in your system and you just
need code (say in C or appropriate assembly) for your filter?
I suspect, by circuit you could also be referring to the fact that you don't
have any hardware (or software) to do what you want. In that case, this
contract would involve designing the hardware (say a DSP chip and associated
peripherals) and the software...but you'll need to provide information on
what the rest of the system is and how to interface to it.

> The cut-off would need to be 15kHz.

The cut-off freq has no meaning in digital filters unless you can also
provide the sampling frequency of your input signal that needs to be
filtered.


Cheers
Bhaskar


> We will pay a one off fee, or buy the (pre-programmed) devices on an
> on-going basis.
>
> Please e-mail me using:
>
> mail_me [at] freenet [dot] co [dot] uk.
>
> Many thanks.
>
> Al
> ---
>
>
>
>

"Bhaskar Thiagarajan" <bhaskart@my-deja.com> wrote in message
news:31osipF3cc8d8U1@individual.net...
>
> Alex,
> You will probably need to specify more details for someone to take up the
> offer (not me).
>

[...snip]

> Cheers
> Bhaskar
>

Hi Bhaskar

There is a company who used to sell an OEM component 'module' (about the
size of a matchbox) that could be used in analog circuits. It effectively
replaced an L/C lowpass filter block component. Unfortunately, they are no
longer available. The module simply had pins for circuit board mounting
(audio in, audio out, 3V in, GND, etc), and contained the necessary
components to implement an audio lowpass filter with a sharp cut-off at
15kHz, with linear phase.

This was ideal for audio companies like us who had no DSP skills, but who
wished to replace traditional audio L/C filter circuitry with a
self-contained digital module.

I'm hoping someone can design/supply something similar.

Perhaps it doesn't even need designing - perhaps there's something out there
that will do this already? Perhaps it doesn't even need to be DSP - there
could, I suppose, be some other form of linear phase FFT solution? Presume
that I know nothing!

Sorry to have been so vague, but I'm hoping that anyone who is interested
will contact me so that I can then send more info.

Alex
----

"Alex Collins" <me@privacy.net> wrote in message
news:31p1kiF3f940lU1@individual.net...
>
> "Bhaskar Thiagarajan" <bhaskart@my-deja.com> wrote in message
> news:31osipF3cc8d8U1@individual.net...
> >
> > Alex,
> > You will probably need to specify more details for someone to take up
the
> > offer (not me).
> >
>
> [...snip]
>
> > Cheers
> > Bhaskar
> >
>
> Hi Bhaskar
>
> There is a company who used to sell an OEM component 'module' (about the
> size of a matchbox) that could be used in analog circuits. It effectively
> replaced an L/C lowpass filter block component. Unfortunately, they are no
> longer available. The module simply had pins for circuit board mounting
> (audio in, audio out, 3V in, GND, etc), and contained the necessary
> components to implement an audio lowpass filter with a sharp cut-off at
> 15kHz, with linear phase.
>
> This was ideal for audio companies like us who had no DSP skills, but who
> wished to replace traditional audio L/C filter circuitry with a
> self-contained digital module.
>
> I'm hoping someone can design/supply something similar.
>
> Perhaps it doesn't even need designing - perhaps there's something out
there
> that will do this already? Perhaps it doesn't even need to be DSP - there
> could, I suppose, be some other form of linear phase FFT solution? Presume
> that I know nothing!
>
> Sorry to have been so vague, but I'm hoping that anyone who is interested
> will contact me so that I can then send more info.

No need to apologize. Your explanation (above) makes things a lot more clear
about your needs and expectations.
So your need is for a 'module' that would contain both hardware and
software. Your approximate form factor for this seems to be a 'match box'
size and you expect to swap out LC filter blocks with this module.
The design would involve both hardware and perhaps software that is self
contained in this module. You are allowing the designer a lot of freedom -
that's good. One other item that you need to specify is cost...how much
(approx) do you expect this module to cost (how much you are willing to pay
for the design cost can be a more private discussion I guess).

I'm just trying to help you get more responses here...

Cheers
Bhaskar


>
> Alex
> ----
>

"Bhaskar Thiagarajan" <bhaskart@my-deja.com> wrote in message 
news:31p7drF3b2rehU1@individual.net...
> "Alex Collins" <me@privacy.net> wrote in message
> news:31p1kiF3f940lU1@individual.net...
>>
>> "Bhaskar Thiagarajan" <bhaskart@my-deja.com> wrote in message
>> news:31osipF3cc8d8U1@individual.net...
>> >
>> > Alex,
>> > You will probably need to specify more details for someone to take up
> the
>> > offer (not me).
>> >
>>
>> [...snip]
>>
>> > Cheers
>> > Bhaskar
>> >
>>
>> Hi Bhaskar
>>
>> There is a company who used to sell an OEM component 'module' (about the
>> size of a matchbox) that could be used in analog circuits. It effectively
>> replaced an L/C lowpass filter block component. Unfortunately, they are 
>> no
>> longer available. The module simply had pins for circuit board mounting
>> (audio in, audio out, 3V in, GND, etc), and contained the necessary
>> components to implement an audio lowpass filter with a sharp cut-off at
>> 15kHz, with linear phase.
>>
>> This was ideal for audio companies like us who had no DSP skills, but who
>> wished to replace traditional audio L/C filter circuitry with a
>> self-contained digital module.
>>
>> I'm hoping someone can design/supply something similar.
>>
>> Perhaps it doesn't even need designing - perhaps there's something out
> there
>> that will do this already? Perhaps it doesn't even need to be DSP - there
>> could, I suppose, be some other form of linear phase FFT solution? 
>> Presume
>> that I know nothing!
>>
>> Sorry to have been so vague, but I'm hoping that anyone who is interested
>> will contact me so that I can then send more info.
>
> No need to apologize. Your explanation (above) makes things a lot more 
> clear
> about your needs and expectations.
> So your need is for a 'module' that would contain both hardware and
> software. Your approximate form factor for this seems to be a 'match box'
> size and you expect to swap out LC filter blocks with this module.
> The design would involve both hardware and perhaps software that is self
> contained in this module. You are allowing the designer a lot of freedom -
> that's good. One other item that you need to specify is cost...how much
> (approx) do you expect this module to cost (how much you are willing to 
> pay
> for the design cost can be a more private discussion I guess).

I've responded to him with a suggestion that he uses the Alesis DSP chip 
set, they are *very* cheap, and 24 bit. I have designed a small system based 
on it (2.5" by 2.2"), but haven't had any boards made. I could make it a lot 
smaller by putting components on both sides of the board, but that would 
push the price up. Component price is under $30, small quantity pricing, 
excluding the PCB.

Leon 

"Alex Collins" <me@privacy.net> wrote in
news:31p1kiF3f940lU1@individual.net: 

> 
> "Bhaskar Thiagarajan" <bhaskart@my-deja.com> wrote in message
> news:31osipF3cc8d8U1@individual.net...
>>
>> Alex,
>> You will probably need to specify more details for someone to take up
>> the offer (not me).
>>
> 
> [...snip]
> 
>> Cheers
>> Bhaskar
>>
> 
> Hi Bhaskar
> 
> There is a company who used to sell an OEM component 'module' (about
> the size of a matchbox) that could be used in analog circuits. It
> effectively replaced an L/C lowpass filter block component.
> Unfortunately, they are no longer available. The module simply had
> pins for circuit board mounting (audio in, audio out, 3V in, GND,
> etc), and contained the necessary components to implement an audio
> lowpass filter with a sharp cut-off at 15kHz, with linear phase.
> 
> This was ideal for audio companies like us who had no DSP skills, but
> who wished to replace traditional audio L/C filter circuitry with a
> self-contained digital module.
> 
> I'm hoping someone can design/supply something similar.
> 
> Perhaps it doesn't even need designing - perhaps there's something out
> there that will do this already? Perhaps it doesn't even need to be
> DSP - there could, I suppose, be some other form of linear phase FFT
> solution? Presume that I know nothing!
> 
> Sorry to have been so vague, but I'm hoping that anyone who is
> interested will contact me so that I can then send more info.
> 
> Alex
> ----
> 
> 

Alex,

I am sure we can help you. We manufacture a variety of DSP boards and 
modules. Our simplest module is our DSP-8300. This module has a stereo 
ADC & DAC that samples at 48k. We can build a very good 15k LP with this 
board. We can supply the board preprogrammed with the filter. All we will 
need is your requirements. We will write the code (It might take us an 
hour).

Details are on our web site. Send me an email if you are interested.

-- 
Al Clark
Danville Signal Processing, Inc.
--------------------------------------------------------------------
Purveyors of Fine DSP Hardware and other Cool Stuff
Available at http://www.danvillesignal.com

Holy cow!

"Leon Heller" <leon_heller@hotmail.com> wrote in message
news:41b77140$0$16577> I've responded to him with a suggestion that he uses
the Alesis DSP chip
> set, they are *very* cheap, and 24 bit. I have designed a small system
based
> on it (2.5" by 2.2"), but haven't had any boards made. I could make it a
lot
> smaller by putting components on both sides of the board, but that would
> push the price up. Component price is under $30, small quantity pricing,
> excluding the PCB.
>

Is this the same Leon Heller who used to do the Leicester Computer group
back in the late '70s? Nascoms etc?

Kind Regards, Howard (http://www.g6lvb.com,
http://www.g6lvb.com/when_i_was_a_young_chap.htm)

"Howard Long" <howard@howardlongxxx.com> wrote in message 
news:cp89d8$iio$1@sparta.btinternet.com...
> Holy cow!
>
> "Leon Heller" <leon_heller@hotmail.com> wrote in message
> news:41b77140$0$16577> I've responded to him with a suggestion that he 
> uses
> the Alesis DSP chip
>> set, they are *very* cheap, and 24 bit. I have designed a small system
> based
>> on it (2.5" by 2.2"), but haven't had any boards made. I could make it a
> lot
>> smaller by putting components on both sides of the board, but that would
>> push the price up. Component price is under $30, small quantity pricing,
>> excluding the PCB.
>>
>
> Is this the same Leon Heller who used to do the Leicester Computer group
> back in the late '70s? Nascoms etc?

That's right! I was one of the founders of the group, together with Dick 
Foden and Dr Peacock. I didn't have a 'Nasty Computer', mine was a TRS-80. I 
was working at Loughborough University at the time.

Leon 

You probably can try
http://www.ScienceOxygen.com/design208.html

It does not sell anything there. It is just
a collection of links about DSP. Probably you can
start from there to collect some information...

Alex Collins wrote:
> Hi,
>
> My company needs an linear phase digital audio low pass filter, but
we don't
> have DSP skills. We hope to find a student who would like to supply
the
> circuit diagram and code for a simple circuit using readily available
> components.
>
> The cut-off would need to be 15kHz.
>
> We will pay a one off fee, or buy the (pre-programmed) devices on an
> on-going basis.
>
> Please e-mail me using:
>
> mail_me [at] freenet [dot] co [dot] uk.
> 
> Many thanks.
> 
> Al
> ---

oookhc@hotmail.com wrote in news:1105305684.257157.233600
@c13g2000cwb.googlegroups.com:

> 
> You probably can try
> http://www.ScienceOxygen.com/design208.html
> 
> It does not sell anything there. It is just
> a collection of links about DSP. Probably you can
> start from there to collect some information...
> 
> Alex Collins wrote:
>> Hi,
>>
>> My company needs an linear phase digital audio low pass filter, but
> we don't
>> have DSP skills. We hope to find a student who would like to supply
> the
>> circuit diagram and code for a simple circuit using readily available
>> components.
>>
>> The cut-off would need to be 15kHz.
>>
>> We will pay a one off fee, or buy the (pre-programmed) devices on an
>> on-going basis.
>>
>> Please e-mail me using:
>>
>> mail_me [at] freenet [dot] co [dot] uk.
>> 
>> Many thanks.
>> 
>> Al
>> ---
> 

Alex,

I didn't see your original post, but we have a very easy solution. We 
have a credit card sized DSP card (DSP-8300) that we can program for your 
application. The card includes a DSP and an AC-97 codec sampling at 48k.
These cards are in stock and inexpensive. They were speciacally designed 
for this type of application.

Email (or call) us if you are interested. Details are on our web site.


-- 
Al Clark
Danville Signal Processing, Inc.
--------------------------------------------------------------------
Purveyors of Fine DSP Hardware and other Cool Stuff
Available at http://www.danvillesignal.com