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Before broadcast stations became a Wall Street game of monopoly pieces to be bought and sold, most radio and TV stations were locally owned or comprised a small group of stations. Even the local Rev. Whomever could get a license to broadcast. But today, you have to have big bucks to afford the frequency and license auctions, comparative hearings, etc., making existing stations even more expensive. Therefore, the cost of becoming a “diverse” voice is too high for many.

As public policy, the FCC should be looking out for the ravages of the eventual melting of ownership into a few hands, just as it fostered the growth of new networks and media so we can watch more than the political bias of CBS, ABC, NBC and PBS.
Henry Ruhwiedel
Crown Point, IN

No more hum bars

Paul McGoldrick:

I have just read your “No more hum bars” article on the Broadcast Engineering Web site. While I completely sympathize with your world compatibility viewpoint (and particularly that Hollywood is still using the antiquated 24fps!), the reason I was given for Europe not changing to 60fps was production lighting. Yes, TV monitors have better power supplies these days, but with studios using tens, if not hundreds, of kilowatts for lighting, mains power is the only reasonable source for that, and avoiding a 10-cycle flicker on the camera outputs would be difficult.
Peter Vince
Senior engineer
BBC Television

Paul McGoldrick responds:

I heard the same story about hum bars at Wood Norton during my “C” course 40 years ago. It was totally disproven when we went, by necessity, to crystal lock on the SPGs at TC in the late '60s. With the SPGs unlocked from the mains, there was absolutely, and still is, no slow hum bar on the camera outputs that should have been there if there was any kind of “beating” effect.

It was a myth to promote 625/50 PAL against those who were proposing we go with NTSC (at 625/59.94). Even at that time, we knew that the receiver phase benefits of PAL were going to be short-lived with improvements in signal handling and UHF transmitters with IF modulation. But those who pushed NTSC, and demonstrated incredible picture quality at Studio H in Lime Grove, found their careers grinding to a rapid halt. It was a pretty nasty time in the corporation's engineering history.

CBC PPM scale

Michael Robin:

In the July issue of Broadcast Engineering, I am confused regarding the Figure 2 upper scale details. You state that the meters are all showing a corresponding steady-state signal level, but the difference shown in the CBC PPM and the CBC VU do not match (assuming that the VU is calibrated to +4dBu). The Sony digital Betacam meter is showing a -20dBfs scale, which should equal +4PPM and 0 on the CBC PPM and VU meters. Could you expand please?
Gary Gornik

Michael Robin responds:

The CBC PPM concept was developed when the standard alignment level (SOL) in the TV studios was +8dBm. For historical reasons, the radio studios were using a +4dBm SOL. So in my drawing, the +8 on the CBC PPM scale (+8dBu) corresponds to 0VU (+8dBm) on the CBC VU scale.

The CBC, in an effort to popularize the PPM concept, was circulating to its major production centers a 3RU panel where a CBC VU meter and a CBC PPM were mounted side by side and fed with the same audio signal to allow operators to familiarize themselves with the new concept. The Sony digital Betacam scale, as designed, implemented and delivered to the CBC, had -20dBFS corresponding to +8dBu and 0dBFS corresponding to +28dBu. Welcome to the audio level monitoring controversy!

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