Can anyone suggest a single chip 2400 baud modem solution pl

D

David Eather

Guest
Can anyone suggest a single chip 2400 baud modem solution please?

(sorry to repeat myself)
 
On 17/05/2010 10:27 PM, David Eather wrote:
Can anyone suggest a single chip 2400 baud modem solution please?

(sorry to repeat myself)
I should also add in small quantity, PDIP, SOIC or TQFP preferable
 
David Eather wrote:
On 17/05/2010 10:27 PM, David Eather wrote:
Can anyone suggest a single chip 2400 baud modem solution please?

(sorry to repeat myself)

I should also add in small quantity, PDIP, SOIC or TQFP preferable
These days? Either a really old chip that's still in production, or a
fairly new microprocessor with an ADC and some appropriate code.

Have you looked at the usual suspects? National Semi, ON, Fairchild?
At one point there were a number of these chips to be had, all (IIRC)
either 24- or 40-pin PDIP parts. But I suspect the market for them has
become a victim of advancing technology: this is something that you
could easily do in one corner of an ASIC that's also capable of 38.4k,
56k, and auto-negotiated speeds. So I don't know if anyone still makes
them outside the context of one-chip Hayes compatible telephone modems.

If all you want to do is just a cruddy V.22bis 2400 baud modem, and you
don't want to haunt back-ally gray-market used semiconductor brokers,
consider that this is an easy task to accomplish with either a
ridiculously small DSP chip or fairly accomplished microprocessor.
There's a lot of details to get the procedural signaling correct, but
the actual signal processing would be a snap for the right guy*. In
fact, if you can't find a new modem to do this for you, this is probably
the reason.

I did a quick search to remind myself just what the standard was, and
found at least one vendor that'll sell you modem software -- although by
the time you've gotten your system twisted around to match their
assumptions, you may have wasted more time than it'd take to roll your
own, and spent licensing money to boot.

* Like me. Since you have given me this outstanding opportunity for a
shameless plug I'll take it: contact me if you want to roll your own,
but don't feel up to writing the signal processing code.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
 
On 18/05/2010 2:25 AM, Tim Wescott wrote:
David Eather wrote:
On 17/05/2010 10:27 PM, David Eather wrote:
Can anyone suggest a single chip 2400 baud modem solution please?

(sorry to repeat myself)

I should also add in small quantity, PDIP, SOIC or TQFP preferable

These days? Either a really old chip that's still in production,
What can I say? I'm a man of the 20th century - it's just a pity were in
the 21st.

I was hoping the sales pitch / blurbs about smart vending machines etc
had translated into easy to access parts.

or a
fairly new microprocessor with an ADC and some appropriate code.

Have you looked at the usual suspects? National Semi, ON, Fairchild? At
one point there were a number of these chips to be had, all (IIRC)
either 24- or 40-pin PDIP parts.
Yep, tried them. No real luck. I came to the same conclusion of
microprocessor and code. Microchip's dsPIC30 series have a soft modem
library with a free sub library or 5$ per copy for evaluation of the
higher performance library (up to 14400).


But I suspect the market for them has
become a victim of advancing technology: this is something that you
could easily do in one corner of an ASIC that's also capable of 38.4k,
56k, and auto-negotiated speeds. So I don't know if anyone still makes
them outside the context of one-chip Hayes compatible telephone modems.
After more searching and re-examining the project assumptions I found
these guys

www.radi.com

who seem to be happy to sell small quantities and samples (under 50$ for
the 1/2" 14400 and 33600 modems). So I have a grin from ear to ear. I
don't really need the speed but over time project bloat might make it
useful.

If all you want to do is just a cruddy V.22bis 2400 baud modem, and you
don't want to haunt back-ally gray-market used semiconductor brokers,
ummm..... no.

consider that this is an easy task to accomplish with either a
ridiculously small DSP chip or fairly accomplished microprocessor.
There's a lot of details to get the procedural signaling correct, but
the actual signal processing would be a snap for the right guy*. In
fact, if you can't find a new modem to do this for you, this is probably
the reason.
I had come down to thinking my options were just that, or to go and buy
dial-up modems (big, lots of cables, extra power-supply requirements,
looks horrible etc)

I did a quick search to remind myself just what the standard was, and
found at least one vendor that'll sell you modem software -- although by
the time you've gotten your system twisted around to match their
assumptions, you may have wasted more time than it'd take to roll your
own, and spent licensing money to boot.
I have some experience with PIC's but was also coming to that conclusion.
* Like me. Since you have given me this outstanding opportunity for a
shameless plug I'll take it: contact me if you want to roll your own,
but don't feel up to writing the signal processing code.
Shameless plug welcomed. Thanks for your answers, experience and
considerations.
>
 
On May 17, 5:30 am, David Eather <eat...@tpg.com.au> wrote:

Can anyone suggest a single chip 2400 baud modem solution please?

I should also add in small quantity, PDIP, SOIC or TQFP preferable
Pull open a set-top box and see what it uses. A Samsung STB
I have handy has Si2400 and Si3015 on the telephone port.
 
On 20/05/2010 4:51 AM, whit3rd wrote:
On May 17, 5:30 am, David Eather<eat...@tpg.com.au> wrote:

Can anyone suggest a single chip 2400 baud modem solution please?

I should also add in small quantity, PDIP, SOIC or TQFP preferable

Pull open a set-top box and see what it uses. A Samsung STB
I have handy has Si2400 and Si3015 on the telephone port.
The Si3015 is no longer available - but it did lead to some great Si
chips sets to do the job - thanks
 
"David Eather" <eather@tpg.com.au> wrote in message
news:eek:cOdneWgH5-p6GnWnZ2dnUVZ_u8AAAAA@giganews.com...
On 20/05/2010 4:51 AM, whit3rd wrote:
On May 17, 5:30 am, David Eather<eat...@tpg.com.au> wrote:

Can anyone suggest a single chip 2400 baud modem solution please?

I should also add in small quantity, PDIP, SOIC or TQFP preferable

Pull open a set-top box and see what it uses. A Samsung STB
I have handy has Si2400 and Si3015 on the telephone port.

The Si3015 is no longer available - but it did lead to some great Si chips
sets to do the job - thanks
It seems to me that many alarm systems still incorporate a 2400 baud
modem chipset.




--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
On Thu, 20 May 2010 13:32:22 -0500, "Jon" <No@one.com> wrote:

"David Eather" <eather@tpg.com.au> wrote in message
news:eek:cOdneWgH5-p6GnWnZ2dnUVZ_u8AAAAA@giganews.com...
On 20/05/2010 4:51 AM, whit3rd wrote:
On May 17, 5:30 am, David Eather<eat...@tpg.com.au> wrote:

Can anyone suggest a single chip 2400 baud modem solution please?

I should also add in small quantity, PDIP, SOIC or TQFP preferable

Pull open a set-top box and see what it uses. A Samsung STB
I have handy has Si2400 and Si3015 on the telephone port.

The Si3015 is no longer available - but it did lead to some great Si chips
sets to do the job - thanks

It seems to me that many alarm systems still incorporate a 2400 baud
modem chipset.
Alarm systems, POS systems, ATMs... For small payloads 2400bps (FSK, etc.) is
faster than PCM modems, like V.92. It's far more reliable, too. These
things don't need to access the WWW. ;-)
 

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