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, firstname.lastname@example.org.
Last week, the FCC rule concerning the "site locations where FM translators can rebroadcast AM radio stations" was finally published in the Federal Register.
The new rule, which took effect Wednesday (3/21) allows the rebroadcasting FM translator to be located anywhere within the AM station's daytime service contour or anywhere within a 25-mile radius of the transmitter, even if the contour extends farther than 25 miles from the transmitter.The old rule stated an AM station could place a rebroadcasting FM translator either within its daytime service contour or within a 25-mile radius of its transmitter, whichever distance was less.
SPECTRUM AUCTION REPACK
The Federal Budget bill, signed by President Trump this last week included $1 billion in additional funding for the broadcast spectrum incentive auction repack.
Of special interest is $50 million for radio stations' expenses. A good number of radio stations will be forced to construct auxiliary transmission sites due to the TV repack construction. There was also $150 million for low-power TV station and translator relocation expenses.
NAB SHOW NEWS
The National Association of Broadcasters annual convention is coming up April 7–12 at the Las Vegas Convention Center. It appears from all the reviews, that this year will focus on everything IP! Great advancements are being made by all vendors to create, transmit and receive everything via IP.
If you have never been to an NAB convention, this should be the year to go. Not only will you be able to view, first hand equipment and services from over 1700 vendors but also you can network with 100,000+ other broadcast professionals like yourself.
PRECISION TIME PROTOCOL
One of the newest terms you may have already begun seeing in most equipment is PTP or Precision Time Protocol. The Precision Time Protocol (PTP) is a protocol used to synchronize clocks throughout a computer network. On a local area network, it achieves clock accuracy in the sub-microsecond range, making it suitable for measurement and control systems.
It is a vital part of digital audio and video creation and transmission systems and also a major item in ATSC 3.0.
There is a most informative video presentation by Paul Briscoe covering PTP here.
Here is a little "refresh you memory" for you AM radio engineers.
What is the percentage of increase in the AM antenna current from no modulation to 100% modulation?
The answer is 22.5%
To determine what the antenna current would be for 100% modulation use the following formula. It would be the total current (with modulation), Ic would be current (with no modulation) and m would be the modulation index. The modulation index of 1 equals 100% modulation. Assume 5 amps for Ic .
It = Ic√1+(m2 /2)
It = 5 x √ 1.5
It = 5 x 1.225
It = 6.124 amps
6.124 - 5.00 = 1.124 (increase in current)
1.124/5.00 = .2248 or 22.5% (increase in current in percentage)