30 Oct 00, Dan Michaels writes to All:

 P> Negatives for integrating chip modems:

 P> -Finding a chip <= 64-pin smt
 P> -Writing "all" the s.w.
 P> -Designing complex multi-layer pcb
 P> -Designing complex analog-digital-filtering ckt
 P> -Integrating DAA
 P> -Getting FCC approval
 P> -Cost [chips ain't cheap in < 100,000 qty]
 P> -Cost [prohibitive when using available DAA modules]

Did you check Si2400 from Silicon Labs ?
http://www.silabs.com/products/isomodem.asp
They have nice 2-chip solution (SOIC16) with integrated DAA, 3.3/5V 60 mW,
up to 2400 bit, check also Microchip Appnote AN731 for Si2400 application.
They quote $8.50 for chipset in 25000 quantity, it means about $15...$25 in
small qty.

If V.23 or Bell202 (1200 bit) will be enough for your project, you can find
another solution - software modem on the Scenix chip.
http://www.scenix.com/virtual/download/v23Kit.html
V.23 demo kit available for $89 from Monterrey Tools
Probably one can manufacture similar modem on SMD components
for the same $15...$25 in qty 100. And you will have some processor resources
left for another task...

 P> Seems every route has its own personal set of problems.

For low-speed mid-volume and high-volume applications integrated modem seems
the most adequate solution.

 >> Negatives for external modems:

 >> -Size
 >> -Power supply
 >> -Two boxes
 >> -"clunkiness"
 >> -Room for end users to goof things up
 >> -Cost

External modem will be the best solution, when you need several experimental
devices.

 P> Negatives for internal modems:

 P> -Size
 P> -Power supply
 P> -Two pcbs wired together
 P> -"awkwardness"
 P> -Pain-ina-butt interfacing to PCI or ISA bus
 P> -Writing modem-specific s.w.
 P> -Cost [cheap - only advantage I can see]

Possible application for internal modems - cheap multiport router under Linux -
put 4 modems into old desktop with 486 processor, 8/16 meg and small hard drive
and run Linux on it - it can be the cheapest solution for 4-port dial-up
server. However, it is not so reliable, as Cisco router, but works OK for
beginners. I know many internet providers, who start from this solution... You
can also found this solutions working today in some not so advanced
countries...
I am not sure, that internal ISA or PCI modems can be used successfully in
embedded applications.

Best regards

Alexey

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