Weekly Tech Reminders: C4, C-Band & Vocabulary - Radio Magazine

Weekly Tech Reminders: C4, C-Band & Vocabulary

An excerpt from this week’s Monday Morning Coffee and Technical Notes
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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.

STATUS OF C4 PROPOSAL

As most engineers are aware the commission has launched a Notice of Inquiry looking toward the creation of a new “C4” class of FM broadcast station, with an effective radiated power limit of 12 kW. This will be made available only to class A stations in zone II currently operating with a maximum ERP of 6 kW.

The proceeding is only an inquiry and not a rulemaking. It won't result in actual new rules until a subsequent rulemaking proceeding is initiated and concluded.

C-BAND SATELLITE USAGE

The World Broadcasting Unions has added its support to the C-Band satellite usage problem. WBU explains that C-Band FSS downlink frequencies between 3,400-4,200 MHz, have been and are extensively used worldwide by WBU members for Fixed Satellite Services applications and will continue to be used for the near future, in particular above 3,600 MHz.

The organization also argues that potential allocation of C-Band FSS spectrum to mobile services would "create chaos to the economics of broadcasting by satellite, potentially interrupting services to audiences around the world."

The ABA Engineering Services continues to urge broadcasters to register their C-band receive dishes. This will give the FCC a better understanding concerning how much this spectrum is used and how it can cause program interruptions for thousands of radio and television stations.

WELCOME TO 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.

To help better understand dithering, use the hand over your computer monitor analogy. How it works is you start by holding your hand over your computer monitor. Notice that you can see your computer monitor perfectly, with the exception of the block where your hand is. Now, if you wave your hand rapidly back and forth from left to right across the screen (applying dither), it allows you to see the entire screen as opposed to blocks of the screen.

If you try and play a 24 bit audio file through one of these 16 bit playback devices, it will sound awful. In this regard, you should keep the consistency of bit-depth throughout your production process from beginning to end. If you are producing in 24bit and your playback is set to 16bit, then you should be using a dithering tool in your production chain. Most modern Digital Audio Workstations will do this automatically.

INCREASE YOUR WORD POWER: DOOHICKEY

The name for object you either can't remember or never knew in the first place. Other variations are whatchamacallit and thingamajig.

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