In a message dated 4/11/01, Jeffrey Race writes: > What is the smallest 33.6 or 56k modem I can source > (to be embedded in a space-saving communication product)? > What about small, but not smallest, modems that are > inexpensive as well? (I am not yet certain about the > cost/size tradeoff so need multiple datapoints to > present to potential customers.) >
Hi Jeffrey: For several years Rockwell (then Conexant) produced a small module called a Socketmodem. I believe the footprint was the same as a 40-pin dip. This device may still be available from Conexant, but I think I read just today that Conexant was exiting the module business, so check carefully. Pin-compatible versions of the Socketmodem are manufactured by Multitech. I believe that Analog Devices also sells a pin compatible version that uses their DSP and codec. Xecom (http://www.xecom.com) used to make modem modules, and they may still do so. Lastly, there is a company called Radicom (www.radi.com) that advertises regularly in EDN. They claim to offer a large selection of modular modems. You should be aware that in general, modem modules are primarily a convenience solution where the buyer pays a fairly high price in exchange for not having to design their own modem. This can be a fine solution for low volume applications or for applications where the modem cost is not an issue. However, for high volume and/or cost sensitive applications, it is generally more cost effective to design your own modem using component parts. Another advantage to designing your own modem is that you can make it more robust than the typical modem module for things such as lightning immunity. Modem chips or chip sets are readily available from many vendors such as Conexant. The tricky part, though, is the design of a suitable phone line interface circuit (sometimes called a DAA). There are many subtle design issues to consider regarding modem performance, UL approval, CE marking, and use in multiple countries. If you decide to develop your own design, make sure that you get an experienced designer. Otherwise you might waste a lot of money on failed regulatory tests and field problems. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com
