INTRODUCTION The ASG 100 Audio Signal Generator was developed by Tektronix to meet the audio testing requirements of commercial broadcasting. The ASG 100 reduces testing time by transmitting short, predefined audio test sequences that produce precise and easily reproduced results in its AUTO mode. It can also transmit source identification, a voice segment (either continually or as part of the AUTO test) and user defined tones. The user defined tones of LINE UP and MANUAL test signal operation provide the continuous signals needed for adjusting audio levels and manual checking of the left/right audio channels. AUTOMATIC AUDIO CHANNEL TESTING Test equipment for sound programming and the sound channels of television programming must be capable of quickly checking the audio signal path to make sure of the circuit's quality. Automatic equipment must be able to rapidly measure the test signal in ways that give repeatable and meaningful test results. To assist in the repeatablity area, standard test signal sequences have been defined. These sequences begin with the necessary components to start the measurement, identify the source of the test signals, and identify the stored automatic test that is to be done. Then the test signal portion of the sequence runs in predefined frequency, level, and timing patterns that permit automated testing of the signal path characteristics. Each of the test signals in the automatic test sequence are used to check on the different parameters that are important to signal quality. The tests have defined sequences for both monaural and stereo audio testing, and are based on Recommendation 0.33 of the CCITT Specification For Measuring Equipment, Volume IV, Series O Recommendations-1988. When used with a CCITT 0.33 compliant receiver, such as the Tektronix VM700A Option 40 or Option 41, the results of the AUTO testing sequence can be documented automatically without the need for human intervention (unless of course, an out—of—tolerance condition is found by the test). The Tektronix VM700A Option 40 and Option 41 receiving and measuring equipment uses the test signals sent by the companion ASG 100 audio signal generator to measure the following parameters as defined in Recommendation 0.33 for monophonic audio paths. Insertion Gain Frequency Response Distortion Signal-to-Noise Ratio Compandor Linearity Expanded Noise For stereophonic audio paths, additional measurements are done to assure the A/B (left/right) channel parameters of the signal paths are sufficiently matched for proper transmission of the program audio.