STEREO ANALYSIS AND ALIGNMENT WITHOUT TEST TONES
NEWS RELEASE
| FOR ADDITIONAL INFORMATION CALL: TEL: 800-235-6960 FAX: 714-979-3355 |
FOR IMMEDIATE RELEASE |
STEREO ANALYSIS AND ALIGNMENT WITHOUT TEST TONES
Santa Ana, California- FM Systems, INC has invented a new way to test the stereo performance of cable system head-end equipment using the existing program audio signal. The CSPM-1 Cable Stereo Performance Meter does not require test tones to measure stereo separation, therefore stereo performance tests can be made without interrupting service to subscribers.
The CSPM-1 measures stereo separation at the 4.5 MHz output of the stereo multiplex modulator, the 41.25 MHz I.F. loop of the TV modulator, and at the CH-3 output of a set-top down converter. This enables the stereo signal to be traced from its origin to the point of delivery to the subscriber. Thereby making it possible to pinpoint any equipment that impairs the stereo signal path.
The Cable Stereo Performance Meter can also measure the actual stereo content of program audio as well as measure the stereo separation capability of the entire cable system. A prime example of the usefulness of this feature becomes evident when the CSPM-1 is taken to the residence of a subscriber that has complained of “no stereo”. First the stereo content of the channel in question is tested. It is not unusual for the actual stereo content of a program to be as low as 3-5 dB separation. The subscriber may very likely categorize that as “no stereo”. At this point the man at the head-end can be asked to actuate a switch at the head-end, at which time the CSPM-1 will now indicate the stereo capability of the cable system, thereby showing the stereo separation that the cable company would deliver if the program originator were to send a better stereo signal.
Stereo multiplexers can be adjusted for best stereo performance, using the actual program being transmitted by varying the multiplex deviation control ( of the 4.5 MHZ audio carrier) to produce the highest stereo separation.
This is much more accurate than the standard ” Bessel Zero ” test because all modulating frequencies are tested, not just a single test tone.
The CSPM-1 is both , portable and battery operated, thus enabling tests in locations where 115 VAC power is not readily available. The digital display indicates stereo separation from 0 to 50 dB in one dB steps. The accuracy is +/-1 dB up to 40 dB and +/-2 dB between 41 and 50 dB. Polarity inversion is also indicated when there is a wiring error between the Videocipher and the stereo multiplex modulator.
The Stereo Performance Meter sells for $ 3,150.00 . Specification sheets and other information can be obtained by calling Frank McClatchie in California on 714-979-3355 , or out-of-state on the 800-235-6960 Wats line.
