Portable People Meter

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A Portable People Meter worn by Arbitron panel members to monitor media exposure

The Portable People Meter (PPM) is a system developed by Arbitron to measure how many people are listening (or at least exposed) to individual radio stations and television stations, including cable TV. The PPM is worn like a pager, and detects hidden audio tones within a station or network's audio stream, logging each time it finds such a signal. It has proved[citation needed] to be much more accurate than the old handwritten logs or wired meters, and is immune to forgetful test subjects.

There are several parts to the PPM system:

  • An encoder which inserts the tones (via psychoacoustic masking) into a station's or network's airchain.
  • A monitor which checks that the encoder is working properly.
  • The wearable Portable People Meter itself.
  • A base station for each PPM, where each person in the household places it overnight to recharge the battery and to transmit information to the hub.
  • A portable recharger for vacations and other trips away from the home base.
  • A hub (or collector) for each household that takes the collected information and has a modem to upload it overnight via telephone.

The system can also be used for other media, such as movies and music which are recorded with a digital encoding. Various venues and retail locations are also encoding their media in the Houston area.[citation needed]


The original concept for the PPM can be traced back to a brainstorming session at Arbitron in November 1988.[citation needed] At that time, concerns over the forthcoming move from analog video to high-definition digital television had engineers concerned that the technology currently in use would become obsolete overnight. Drawing upon his experience in testing labs, Dr. Gerald Cohen proposed embedding an identifying signal in the audio and later decoding it. The rationale was simple. Dr. Cohen argued that audio was less likely to undergo as drastic a change in content and technology as would video, hence any technology developed would not likely to become obsolete in a few years.

The concept was presented to the company at that time and was also written up in a short concept document. A preliminary investigation was undertaken, but the technology was never given serious consideration. The concept was written off and forgotten as Arbitron had bigger fish to fry in its competition with the Nielsen Company for television ratings. Arbitron lost that battle and went back to its core business – radio ratings.

Dr. Cohen’s idea lay dormant until 1992 when Drs. Richard Schlunt and Patrick Nunally approached Arbitron. Meeting with Ronald Kolessar, Director of Technology, Dr. Cohen and others, they presented a new variation of the idea – selectively embed a code into the frequency spectrum of the baseband audio stream and use digital signal processing in a small wearable device to recover the embedded code buried in what a person watches or listens to.[citation needed]

Convinced that that concept could be achieved, Mr. Kolessar obtained approval from Arbitron's management to undertake a fast-track effort to determine feasibility. Lacking the internal expertise to do so – additional outside help from Martin Marietta was sought. Facing cutbacks in the defense industry, Martin Marietta agreed to take on commercial business even to the point of signing away all rights to the technology they were to develop. Engineers at Martin Marietta decided that the best approach was to employ the principle of psychoacoustics to mask the embedded code signal, an approach described in U.S. Patent No. 5,450,490.

Now a full-fledged project having management support, development by engineers at Arbitron focused on improving the encoding and detection methodology and miniaturization into a hand-held device. Additional capabilities such as motion detection were added later on.

In 2008, EE Times as part of their Great Minds, Great Ideas Project profiled Mr. Kolessar as the "Inventor of the Portable People Meter".

Research reports[edit]

The PPM is attempting to provide new insights into how audiences respond to the various programming elements radio stations offer. Arbitron, as well as other firms that provide research and consulting services to radio stations, have begun publishing numerous studies based on analysis of PPM data.

The PPM is an electronic measurement system that delivers empirical, verifiable audience measurement data. These results are sometimes at odds with the results generated with the diary method in which listeners were asked to note each change of their radio dial. Some minority diarists may have used their diaries as a way to support and show loyalty for stations which targeted their communities.[citation needed] To delay the shift to electronic audience measurement,[citation needed] the creator of the PPM, Arbitron, is being challenged by the Spanish Radio Association (SRA) and a number of politicians as to its accuracy in measuring minority listening.

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