with proper engineering precautions, towers can survive intense lightning attacks.
Adequate grounding means different things to different engineers.
Some transmitter manufacturers have already announced the availability of FM IBOC transmitting equipment, and offered actual equipment at the NAB show. FM IBOC requires considerably more equipment than the AM version, and it is more expensive.
The Commission is on the verge of approving the Ibiquity standard, but serious questions still exist as to the value of the system to broadcasters and whether a full-time AM system will ever work.
It would not be correct to say that IBOC was on everybody's lips at NAB, but there was considerable interest in it.
Ranging from spotless high-rise suites to dirt road shacks, the transmitter site represents a station's final, vital link to the listener.
To all but those who must maintain them, studio-to-transmitter links are a silent and sometimes forgotten step in the transmission chain.
Many engineers anxiously awaited the release of the National Radio Systems Committee's AM IBOC Report, in hopes that the report would reveal good news about AM IBOC.
In the U.S., the joint TIA//EIA-222 standard oversees the design of broadcast and antenna supporting towers.
Broadcasters who propose to locate their antennas on new towers near historic sites will face greater scrutiny to determine the environmental impact of their towers.
Directional antenna maintenance is primarily an ongoing process based on experience and adequate written records.
Solid-state, digital exciter
There are very few jobs in broadcasting where one can start at the top; but tower maintenance is the one where it is best to start at the top and work down.
For towers that require incandescent lighting, regular tower-light inspection and maintenance is a task that tower owners must undertake. The annoyances lie in changing a burned-out lamp, affording the cost of a tower climber, timing convenience of the failure.
Solid-state technology has taken over the major AM broadcast transmitter manufacturers, and up to 40kW of solid-state power is available in FM. When making the decision to buy a new transmitter, there are several factors to consider.
Part One described the events leading to the development of top loading of broadcast AM antennas. This part continues with details of the types of top loading and discusses the use of the FCC's Rules in planning a top-loaded antenna system.
In November 2000 the Commission created a new FM channel classification to join Classes A, B, B1, C, C1, C2 and C3. Use of the new class - Class C-0 (C-Zero) - permits upgrades of existing stations and new allocations based on the reduced spacing protections, which will apply when Class C stations are converted to Class C-0.
Part 1 of our Special Report.
Engineers charged with the job of designing a new AM transmitter facility nearly always try to plan for the tallest tower possible. This is not just an ego trip; it's because the taller the AM radiator, the higher the field strength developed in the listening area with a given power.
When Northwestern College Radio acquired WMAD, one of the first priorities was to replace the transmitter. Mark Croom reviews the AM-1A.
The article titled "Transmission: Implementing IBOC" in the October 2001 issue of BE Radio is very informative, but one concept in it may need further clarification.
We have all been taught that the load impedance must match the generator impedance in the case of non-DC voltages in order to obtain the most efficient transfer of power. In DC work it seems that loads with an improper resistance fail to work because the supply voltage is too low, or else burn out because their resistance is too low for the applied voltage, and simple Ohm's law applies.
Transmitting several frequencies from a single broadband antenna system requires the use of a combining system, or combiner, composed of RF filters and interconnecting transmission line. Generally, a combiner can be categorized as branched (star point) or balanced (constant-impedance). These types may use band-reject (notch) or band-pass filters.
It's a cool Monday morning; the first in October, in fact. After opening your office, and after downing the requisite two cups of coffee, you turn on your computer and open them: The dreaded capital budget spreadsheets.
In the early days of radio engineering, it was necessary to calculate every value used in determining coverage and antenna design manually. Slide rules were the norm, and many engineers carried one in a hip holster -- well, almost. My slide-rule case certainly had a belt slot in it.