Update on the PPM


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The race to occupy space on the average American's belt is heating up. Along with the cell phone (or two), PDA, Blackberry and multipurpose knife, the Portable People Meter (PPM) will become a familiar site in the United States in the near future. Developed by Arbitron in 1992, the PPM has undergone trials in Europe and the United States. It is expected to see widespread deployment after 2006.

The PPM is a pager-sized monitor that automatically tracks listening.

It is hoped that the PPM will level the ratings playing field by having the unique ability to take into account virtually all forms of media, including those originating from Internet streaming, digital satellite, cable and background sources, as well as traditional over-the-air radio and TV broadcasting. The potential capabilities of this technology could also be expanded to gather information about consumer preferences with respect to where they shop, what billboards they are reading and even to what CDs or DVDs a respondent might be listening.

Another major advantage of the PPM is that it doesn't require the participant to write down any information in a diary or do anything that demands a person's time. The ability to passively measure a respondent's media use, no longer limited to over-the-air broadcasting, both in and out of the home, might paint an entirely different landscape of media use in the coming years.

The Technology behind the PPM, called Critical Band Encoding Technology or CBET, was developed by Lockheed Martin under contract to Arbitron. A CBET Encoder, inserted into the program chain, cleverly embeds specials codes in an audio stream. These codes are psycho-acoustically masked to make them undetectable to the human ear, but can be decoded with a pager-sized device that is fitted with a sensitive microphone.

The components

The encoder unit must be inserted into the program chain of the station. It can interface with analog and AES/EBU digital audio streams, as well as television-specific digital formats such as SDI and, soon, HDTV. Arbitron is also in the process of developing multichannel encoders intended for satellite or cable operations.

The deployment of the PPM into a typical household is somewhat hardware-intensive and consists of three devices: the PPM, the base station and the household hub.

The PPM is the pager-sized device that is intended to be carried by respondents throughout the day. It is described as measuring four cubic inches and weighing 2.6 ounces. The PPM is built around a custom digital signal processor that recognizes and decodes the assigned encoded signals originating from the station or other source. Those decoded codes, called event-codes, can be stored in the pager. The PPM also contains a motion detector, which is used to verify that a respondent is actually carrying the device with him throughout the day. A green light on the PPM remains lit while in motion as a reminder to the participant that he is fulfilling his obligation to Arbitron. The PPM can store a day's worth of data containing event and motion detector information.

A consumer’s PPM system has three elements: (left to right) The PPM base station, the PPM and the household hub.

The base station is reminiscent of early pager and cell phone base-charger units and, similar to those chargers, the base station provides a convenient means to charge the PPM's internal battery. The major difference, though, is that the base station has three other functions: to extract the codes from the PPM; to display the participants “points” accumulated as a result of the amount of time the PPM was active; and to send the data to the Household Hub.

The Household Hub collects the data from one or more base stations and subsequently delivers the data to Arbitron through standard telephone lines. The data transfer between the base station and the Household Hub takes place through the existing house ac wiring.

How it works

The fundamental concept is pretty simple; a station encodes its audio with an inaudible (to humans) code unique to the particular station. Participants are asked to carry the pager-sized PPM throughout the day. The PPM listens to what the participant is also hearing. If the source to which the participant and device are listening happens to be encoded with certain signals, the PPM records the unique code. When the participant is ready for bed, he drops the PPM into the base station where the codes can then be downloaded to Arbitron to compile the data into useable ratings information. As an incentive, participates are compensated based on the amount of points, or the amount of time, they carry the PPM.

The first test of the PPM occurred in Manchester, England in 1998 using a total of 50 participants in 25 households for a three-month period. The test was principally used to ascertain that all of the physical components of the system performed properly. In 1999 the testing was expanded in Manchester to include 300 participants in 140 households.

December 2001 marked the first U.S. deployment of the PPM in the Wilmington, DE, market, in which the test was expanded to include radio, TV and cable outlets. As many as 300 participants were included in this phase of testing. The second phase of this trial was expanded to the Philadelphia market in March of 2002 with 1,500 additional participants and is currently underway.

A final test of the PPM is planned for 2005/2006. It will take place in the Houston market and will be a final opportunity for broadcasters to evaluate and make comments on the system.

It's not hard to imagine applications for the PPM that go beyond a tool for broadcast ratings. Future versions of the PPM may include a GPS subsystem that will not only be able to determine listening habits, but can also record where the listener is located, i.e traveling in a vehicle, what time, which direction, how much time was spent in a car. Specific habits of participants at a grocery or other retail store could be recorded based on what departments or aisles that are frequented and how much time was spent in the store. Arbitron has also suggested applying the technology to car dealerships to analyze potential buyer interest in a particular vehicle.

In May of 2000, Neilsen signed an agreement with Arbitron to access the technology for its TV ratings service. As part of the agreement, Neilsen agreed to assist with a portion of the costs for development and deployment of the PPM. It is not clear if Neilsen will ultimately embrace the PPM as its system of choice, or if it will move forward with its own version of a portable measurement device that is currently being tested.


McNamara is president of Applied Wireless, Elkins Park, PA.




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