DAA suggestions

Pointers to reference designs for v.90, FAX, etc. to get
an idea of what the line interface should look like?

On 12/08/16 01:51, Don Y wrote:
> Pointers to reference designs for v.90, FAX, etc. to get
> an idea of what the line interface should look like?

History books?  It is a good many years since I have seen a fax, and
even longer since I have dealt with modems.

More seriously, I'd look for some ready-made modem modules, and then
look at their application notes and reference designs for the line
interface.

On Thu, 11 Aug 2016 16:51:10 -0700, Don Y wrote:

> Pointers to reference designs for v.90, FAX, etc. to get an idea of what
> the line interface should look like?


I'm not sure whether you're after specifications or parts / design ideas, 
but give this a try for some example parts:

http://www.silabs.com/products/modems/Pages/default.aspx


Regards,
Allan

On Fri, 12 Aug 2016 11:18:50 +0000, Allan Herriman wrote:

> On Thu, 11 Aug 2016 16:51:10 -0700, Don Y wrote:
> 
>> Pointers to reference designs for v.90, FAX, etc. to get an idea of
>> what the line interface should look like?
> 
> 
> I'm not sure whether you're after specifications or parts / design
> ideas,
> but give this a try for some example parts:
> 
> http://www.silabs.com/products/modems/Pages/default.aspx


I just checked the price: ~$10 at Digikey for an Si3018.  Ouch.  I guess 
it does include isolation and replaces the entire line hybrid though.


I can remember having to do that with transformers "back in the day."

Allan

On 8/12/2016 4:18 AM, Allan Herriman wrote:
> On Thu, 11 Aug 2016 16:51:10 -0700, Don Y wrote:
>
>> Pointers to reference designs for v.90, FAX, etc. to get an idea of what
>> the line interface should look like?
>
> I'm not sure whether you're after specifications or parts / design ideas,
> but give this a try for some example parts:

I'm looking for background information to help sort out the
advantages/disadvantages of various approaches to the PSTN
interface.

E.g., the "old" transformer wet/dry approaches now seem to
be giving way to capacitive coupled designs.  But, I'm not
sure if that is advantageous from a performance point of
view or just a means of avoiding a "bulky" transformer
(as we now seem to like things tiny and sleek).

While my initial application is narrow bandwidth (voice),
I'd hate to naively settle on a design that later limits
other applications (cuz voice is far more forgiving of
"design slop")

On Thu, 11 Aug 2016 16:51:10 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>Pointers to reference designs for v.90, FAX, etc. to get
>an idea of what the line interface should look like?

TI has a bunch of app notes.
You'll find them in the softmodem (DSP) app notes.

Cheers

On 8/11/2016 7:51 PM, Don Y wrote:
> Pointers to reference designs for v.90, FAX, etc. to get
> an idea of what the line interface should look like?

Make sure the parts you select work 100% in your application before you 
commit to them.  Years ago I used a CP Clare pair of chips (or maybe it 
was three) for a DAA function.  The chip that did the signalling was not 
designed to come up in any particular state and couldn't retain it's 
programming while the line was on hook.  But the real gotcha was the 
chip with the analog interface has 0dB of PSRR.  Yes!  ZERO dB.  If I 
had 10 mV of noise on the power bus, I had 10 mV of noise on the line 
which could be heard.

Get an eval board and check out the devices thoroughly.

-- 

Rick C

On 8/12/2016 4:49 PM, Martin Riddle wrote:
> On Thu, 11 Aug 2016 16:51:10 -0700, Don Y
> <blockedofcourse@foo.invalid> wrote:
>
>> Pointers to reference designs for v.90, FAX, etc. to get
>> an idea of what the line interface should look like?
>
> TI has a bunch of app notes.
> You'll find them in the softmodem (DSP) app notes.

Yes, I've been rummaging through *old* 320 app notes.
More modern notes seem to just "give solutions" whereas
the older ones seem to give *explanations*.  (I want to
understand *why* particular design choices were made in
the pp note/reference design and not just embrace the
author's unwritten assumptions!)

On Sat, 13 Aug 2016 10:39:03 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>On 8/12/2016 4:49 PM, Martin Riddle wrote:
>> On Thu, 11 Aug 2016 16:51:10 -0700, Don Y
>> <blockedofcourse@foo.invalid> wrote:
>>
>>> Pointers to reference designs for v.90, FAX, etc. to get
>>> an idea of what the line interface should look like?
>>
>> TI has a bunch of app notes.
>> You'll find them in the softmodem (DSP) app notes.
>
>Yes, I've been rummaging through *old* 320 app notes.
>More modern notes seem to just "give solutions" whereas
>the older ones seem to give *explanations*.  (I want to
>understand *why* particular design choices were made in
>the pp note/reference design and not just embrace the
>author's unwritten assumptions!)

I was just looking through some old Radio Electonic mags, lost of
telco projects, might get some info there too.

Cheers