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Embedded Modems: Costs and Considerations

Wednesday, June 18, 2014

Embedded modems offers quick network access for applications with limited transmission requirements. Today, more and more applications such as set-top boxes, electronic point-of-sale (EPOS) terminals, digital video recorders, digital televisions, and remote monitoring systems distribute information by taking advantage of widely available modem connectivity.

A Quick History of Modems

Years ago modem standards were typically very slow. 300 bps or 1200bps held the reins for speed for many years. These were external modems connected to remote terminals to a dial up or timeshared network. When the PC explosion took place and before networking became a thing of the future, speeds of 9600; 14,400; 19,200; and 28,000 were used.  At these rates it would take many hours to download a mere 20MB file. Today most modems are designed to meet requirements at 56K and are either V.90 or V.92 classified by domestic and international standards. Applications vary but for the most part are not data intensive.

Cost Considerations when selecting an Embedded Modem

In today's changing technology environment, there are several factors to take into consideration when choosing an embedded modem such as global standards, speed, and the feature requirements of a customer’s application. Implementing a module is a compelling story for design engineers because there are no external components, which significantly reduces the time to market enabling an easier-to-use, lower-cost solution. Another important factor in designing with an embedded modem module is global compliance. Different countries specify different standards and speeds for various applications. For simplified designs and lower costs, modules are the answer.

The 4 Basic Parts of a Modem

The components of a modem have four basic parts:

  1. Controller
  2. DSP data pump
  3. Memory
  4. Direct access arrangement (DAA)

Some solutions integrate a modem controller and a DSP data pump, but use external memory and a discrete DAA requiring numerous components. A DAA serves as the hardware interface to the Public Switched Telephone System (PSTN). A standard RJ-11 jack connects the modem to the phone line. The interface allows the modem to detect signals on the line: dial tone, busy signal, etc.

By sharing the same globally compliant line-side device, a single embedded modem design can be used in all countries and for all mandated modem speeds. A single, globally compliant design reduces the time-to-market risks associated with specific country approvals and the risks associated with transmission emissions, immunity, and over all safety.

A modem connection needs to be cost effective, reliable, and easy to design. A fully featured, highly integrated module solution can dramatically reduce time to market and create solutions that will mesh with the application.

A typical application example is a vending machine. The system periodically dials up the main office and connects, sending data alerting the vending machine operator to inventory levels, temperature changes in the machine, mechanical wear and tear for MTTR (mean time to repair); all of this assists the delivery or service person with information before they arrive. 



Interested in adding an embedded modem to your design? Please call Symmetry at (310) 536-6190 or contact us online.

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Why partner with Symmetry Electronics? Symmetry's technical staff is specially trained by our suppliers to provide a comprehensive level of technical support. Our in-house Applications Engineers provide free design services to help customers early in the design cycle, providing solutions to save them time, money and frustration. Contact Symmetry for more information.

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