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<br />, .'" <br /> <br />.' <br /> <br />",.' <br /> <br />Carrier to low frequency distortions ("Hum") <br /> <br />2% or less <br /> <br />System frequence response, peak to valley, across <br />the designed bandwidth < n/IO + 3 dB <br /> <br />where: <br /> <br />n - total number of ampli- <br />fiers in cascade <br /> <br />Audio frequency response, 50 Hz. to 15 KHz. shall not vary more <br />then 6 dB from the highest point to the lowest point. This test <br />will only be required when the City determines that an audio <br />problem may exist on a specified channel. <br /> <br />Method of Testing <br /> <br />The following methods are to be used to test the performance <br />standards for Video transmissions as outlined above. <br /> <br />System bandwidth <br /> <br />Downstream (Headend to Test Point) <br />Upstream (Test Point to Headend) <br /> <br />270 - 438 MHz <br />50 - l70 MHz <br /> <br />1. <br /> <br />Carrier-to-Noise <br /> <br />A suitable system analyzer is to be connected to a <br />bridger port via lOO foot calibrated test jumper. <br />System carrier-to-noise is recorded. System will be <br />tested in both directions. Measurements are to be made <br />in accordance with test equipment manufacturer's <br />standard procedure. <br /> <br />2. <br /> <br />Third Order Beats <br /> <br />A suitable system analyzer with a band pass filter tuned <br />to the channel being tested, is to be connected to a <br />bridger port via 100 foot calibrated test jumper. <br />System Third Order Beats ratio, expressed in dB, of the <br />peak level of the RF signal to the peak of the average <br />level of the cluster of distortion components centered <br />around the carrier tested is recorded. System will be <br />tested in both directions. Measurements are to be made <br />in accordance with test equipment manufacturer's standard <br />procedure. <br /> <br />3. <br /> <br />Hum Modulation <br /> <br />A suitable frequency selective voltmeter is connected to <br />bridger port via lOO foot calibrated test jumper. <br />System hum modulation is recorded. System tested in <br />downstream direction only. Measurements are to be made <br />in accordance with test equipment manufacturer's <br />standard procedure. <br /> <br />-2- <br />