Signal-to-Noise Ratio

By Lee Copeland

January 15, 2001 12:00 PM ET

Computerworld - Noise is the real enemy of data communications. Whenever electrons travel over a wire or radiate through space, they generate some electromagnetic noise. Therefore, whenever a data signal is sent across a transmission channel, such as a copper wire or a radio-frequency broadcast, background electromagnetic interference (EMI), or noise, accompanies that signal.

			S/N: It's Not Just for Electronics Although the term S/N originated in the field of electrical engineering as a specific, quantitative measure, the concept itself properly applies to any method of communication, electronic or otherwise. For example, smoke signals can be an effective means of long-distance communication for people who don't have electricity - as long as there isn't much surrounding environmental "noise," such as fog or rain. Or consider a large cocktail party, where dozens of people may be talking at once. If you want to communicate with someone else, you have to move close enough that your voice (the signal) can be heard above the din of everyone else's chatter (the noise). In other words, you have to achieve a sufficiently high S/N. Finally, look at the thousands of Internet newsgroups known collectively as the Usenet. One frequent comment I've heard from longtime Internet users (and indeed made myself on numerous occasions) - especially about many of the REC (recreational) or ALT (alternative, meaning totally unregulated) groups - is that "there isn't a high enough signal-to-noise ratio." In other words, too many people are posting messages with too little content; this is often the case when "flame wars" break out on a particular topic.

Signal-to-noise ratio (S/N) measures the amount of unwanted electromagnetic noise relative to a signal's strength. If the background noise on a data channel is higher than the signal, it can cause a reduction in data speed or a disruption in system circuit functioning.

That's why airlines require passengers to shut off all electronic devices, such as cell phones and laptops, before takeoff. This is a precaution to ensure that no electrical noise from these devices will disrupt the airplane's navigational, radio or fly-by-wire systems - admittedly a slight possibility.

Getting Wired

In the wired world, S/N issues are relatively easy to manage because of the closed nature of the environment. Take a typical corporate network, for example, where low-level noise from radios and other devices can cause interference. An Ethernet system running at 10 MHz would include a noise filter at the receiving end to eliminate unwanted signals above 10 MHz. Another method for increasing the S/N ratio is to amplify the transmission signal voltage.

Recommend Digg Twitter ShareThis

Email Print Send Feedback Reprints

Additional Resources

POLL RESULTS

Leading IT Pros Weigh In on Top IT Issues

Accelerate your knowledge of the IT world you inhabit by viewing the results of a series of polls taken by your IT peers. These polls of 100+ IT professionals each are available for full viewing. They cover key topics such as virtualization, processor performance, green IT, cloud computing and many others. Be a part of the buzz.

WHITE PAPER

For Best Results, Think Beyond the Box

Technology is complex. Keeping it running productively shouldn't be. To that end, you want to minimize the number of solutions needed in-house to simplify operations, maintenance, and support. Kodak offers a best-practices model. One company provides support for both scanner and software, for fast problem resolution without vendor finger-pointing. Download now!

WHITE PAPER

Accelerating the Path to Demand Intelligence with a Demand Signal Repository

Utilizing demand intelligence improves the precision of pricing, product assortments, channel/store placement, and promotion, which are all essential for sustainable revenue management performance. Learn more, download this free whitepaper today.

White Papers & Webcasts

2007 Gartner Magic Quadrant Report
Riverbed positioned in Leaders Quadrant of Gartner Magic Quadrant for WAN Optimization Controllers. Analyzing strengths vs. cautions, Gartner helps organizations looking to acquire...

5 Best Practice Tips for Managing BlackBerry, iPhone, & Windows Mobile Devices
(Source: Zenprise) Mobile devices continue to proliferate across the enterprise, driven largely by the increase in worker productivity, efficiency, and flexibility they provide....

Forrester Consulting - Optimizing Users and Applications in a Mobile World
Are your workers going increasingly mobile? Don't wait for their calls to slam Support when they experience poor application performance on the road....

Managing Laptops Outside the Office
(Source: Absolute Software) In this webinar, learn how you can reduce costs by tracking mobile computers no matter where they are located. Featuring...

IT Best Practices: To Support or Not Support Consumer Owned Smartphones
Companies have historically standardized on a single smartphone platform. Of late, IT is facing pressure to support the increasing influx of consumer owned...

What Are 'Free' Remote Support Tools Really Costing You?
(Source: LogMeIn) In this webinar from LogMeIn, discover how "next generation" remote support tools are optimized to provide advanced capabilities like scripting, system...

Lennox Goes Mobile and Increases Service Performance by 50%
This white paper explains how Lennox remedied major system malfunctions with Aeroprise Mobility for BMC Remedy Service Desk on smartphones....

IT Strategies for Remotely Supporting a Distributed Workforce
(Source: Citrix Online) Today's workforce is a distributed one - workers across industries are telecommuting, working out of satellite offices and connecting into...

Realizing Rapid ROI Through Mobility
Companies are reaping the benefits from mobile CRM, field service and sales force automation processes with the latest Research In Motion (RIM) offerings....

Usability Is Everything
Learn what sets Workday's HR and Payroll solutions apart from the competition....

All White Papers | All Webcasts