Browse Prior Art Database

Car Radio Scanner Differentiating Music From Speech

IP.com Disclosure Number: IPCOM000036644D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 3 page(s) / 49K

Publishing Venue

IBM

Related People

Chess, D: AUTHOR [+4]

Abstract

Disclosed is a radio station scanner which can differentiate broadcasts containing music or speech. This enables the user to conveniently scan for talk shows or music.

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Car Radio Scanner Differentiating Music From Speech

Disclosed is a radio station scanner which can differentiate broadcasts containing music or speech. This enables the user to conveniently scan for talk shows or music.

Music is differentiated from speech using an analog filter tuned to an 8 KHz cutoff. Generally speaking, broadcast frequencies above this cutoff contain music. Only strong stations are selected, so static will be eliminated or minimized.

To improve the accuracy of this approach, the scanner cycles through a broadcast repetitively. This is important in the case of the fricative sound "S" which contains the highest frequencies in speech and is a source of potential problems. However it has most of its energy concentrated below 5,500 Hz. To avoid false triggering on the "S" sound, the scanner cycles a few times a second over the broadcast so as to differentiate a 0.1 second "S" sound from continuous music (with continually high frequencies). Obviously, there will not be 100% accuracy, but the system will be accurate enough to warrant use of the device.

Note that this disclosed scanner does not perform digital sampling, which would incur extra expense and complexity over the straightforward analog approach. Possible applications include: 1) Given a list of stations, find one that is playing music. 2) When the broadcast no longer contains music, then search the list until the unit finds one that is playing music.

The music detection circuit consists of a high-pass filter and peak detector. The peak detector is the simplest way of ascertaining how much signal goes through the filter. The signal out of the filter is still AC, which is unsuitable input for a simple analog comparator.

To enhance human factors, an inexpensive bi-color LED is used on the front panel to indicate a scan-music or scan-talk mode for the device. Hewlett- Packard introduced a 3-leaded bicolor LED lamp in the industry-standard T-1 3/4 package. The new HLMP-4000 is designed for applications where space is limited and two colors of indication are needed.

The figure shows the controls for a radio scanner. A particular device can be manufactured to contain any or all of these controls. These controls are all incorporated into one control knob to simplify the front panel of the radio. The front panel of the radio contains the standard radi...