Weekly Tech Reminders: Dither, and Equipment Performance Measurements

An excerpt from this week’s Monday Morning Coffee and Technical Notes August 28, 2017

The following is from the Alabama Broadcasters Association’s weekly e-newsletter, Monday Morning Coffee and Technical Notes. Thanks to ABA’s Larry Wilkins. To subscribe to the newsletter, email lwilkins@al-ba.com.

Weekly Acronym: Dither

Dither is low volume noise, introduced into digital audio when converting from a higher bit-resolution to a lower bit-resolution. The process of reducing bit-resolution causes quantization errors, also known as truncation distortion, which if not prevented, can sound very unpleasant. Introducing this subtle noise to an audio file prior to reducing the bit-depth eliminates the truncation distortion. You are in effect trading the distortion for noise.

Weekly FCC rule review:  Equipment Performance Measurements

Station engineers are reminded that Equipment Performance Measurements are still required by all broadcast stations.

Measurements for spurious and harmonic emissions must be made to show compliance with the transmission system requirements of 73.44 for AM stations, 73.317 for FM stations and 73.687 for TV stations.

Basically these measurements must be made “upon initial installation of a new or replacement main transmitter or any modification of the transmission system”.  AM stations are reminded that NRSC measurements are required each year with not more than 14 months between measurements.  Results of any Equipment Performance Measurements are required to be maintained for a period of two years.  Complete details are found in section  73.1590 of the FCC rules.

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