Spurious emissions and bandwidth
Which of the following constitutes a spurious emission?
An emission outside the signal’s necessary bandwidth that can be reduced or eliminated without affecting the information transmitted.
The definition hinges on the second half. Anything outside your necessary bandwidth that you could remove without losing information is spurious: harmonics, mixer products, splatter. The sidebands that carry your voice are not, because removing them would destroy the message.
Which of the following is an acceptable bandwidth for digital voice or slow-scan TV transmissions made on the HF amateur bands?
3 kHz.
HF is crowded, and the practical standard is the width of an SSB channel. A digital voice or SSTV mode that fits in 3 kHz belongs on HF; one that does not belongs above 30 MHz.
Locations that constrain you
Three places where the ordinary rules are not enough.
Within what distance must an amateur station protect an FCC monitoring facility from harmful interference?
1 mile.
What is the National Radio Quiet Zone?
An area surrounding the National Radio Astronomy Observatory.
The NRQZ covers roughly 13,000 square miles across West Virginia, Virginia, and a corner of Maryland — a rectangle about 110 by 120 miles, established by the FCC in 1958. It protects the Green Bank radio telescope, an instrument that detects signals many orders of magnitude weaker than anything a receiver of yours will ever hear, and also the Navy’s facility at Sugar Grove. Building a station inside it requires coordination.
The pool’s keyed answer names only the observatory, which is the answer to give — but the zone protects both installations, and that is why its boundary is a rectangle rather than a circle around the telescope.
Which of the following additional rules apply if you are erecting an amateur station antenna structure at a site at or near a public use airport?
You may have to notify the Federal Aviation Administration and register it with the FCC as required by Part 17 of the FCC rules
Your Part 107 background makes this one familiar from the other direction: the FAA cares about obstructions near airports, and a tall tower is an obstruction. Part 17 covers antenna structure registration, marking, and lighting.
The trigger is in §97.15(a), and it is two conditions, either of which is enough: a structure more than 60.96 metres (200 feet) above ground level, or one near or at a public use airport at any height. The pool asks about the airport case; the 200 foot rule catches towers nowhere near an airport at all.
What must the control operator of a repeater operating in the 70-centimeter band do if a radiolocation system experiences interference from that repeater?
Cease operation or make changes to the repeater that mitigate the interference
Seventy centimetres is a secondary allocation shared with government radiolocation. Secondary means exactly this: when you interfere with the primary user, you stop. There is no negotiation and no appeal, and it applies to a repeater the same as to any other station.
Broadcast interference
What limitations may the FCC place on an amateur station if its signal causes interference to domestic broadcast reception, assuming that the receivers involved are of good engineering design?
The amateur station must avoid transmitting during certain hours on frequencies that cause the interference.
The classic quiet hours remedy. Note the qualifier — receivers of good engineering design. If the neighbour’s receiver is poorly designed, that is a receiver problem and not yours; the FCC’s remedy applies when your signal genuinely interferes with equipment that should have handled it.
PRB-1
To what type of regulations does PRB-1 apply?
State and local zoning.
What does PRB-1 require of state and local regulations affecting amateur radio antenna size and structures?
Reasonable accommodations of amateur radio must be made
PRB-1 is a 1985 FCC Memorandum Opinion and Order, reported at 101 FCC 2d 952 (1985). You do not have to take a secondary source’s word for what it says, because it is codified in the rules themselves — §97.15(b):
State and local regulation of a station antenna structure must not preclude amateur service communications. Rather, it must reasonably accommodate such communications and must constitute the minimum practicable regulation to accomplish the state or local authority’s legitimate purpose.
Read the words carefully, because the pool does:
- It is reasonable accommodation, not a guarantee. A locality may still regulate height, setback, and appearance.
- It binds state and local government. It does not reach private deed restrictions or homeowner-association covenants — a distinction that decides most real disputes.
RACES
Which amateur stations may be operated under RACES rules?
Any FCC-licensed amateur station certified by the responsible civil defense organization for the area served
What frequencies are authorized to an amateur station operating under RACES rules?
All amateur service frequencies authorized to the control operator.
Two things people expect to be true, and are not: RACES is not a special class of station, and it does not come with special frequencies. It is an ordinary amateur station with a certification from the civil defence organisation, operating on the frequencies its control operator already holds.
Check yourself
- Your neighbour’s forty-year-old stereo picks up your SSB. Is the FCC likely to impose quiet hours?
- Your HOA forbids outdoor antennas. Does PRB-1 help?
- A 70 cm repeater you control interferes with a military radar. What are your options?
Answers
- Probably not — the remedy applies to receivers of good engineering design. Fundamental overload of poorly filtered equipment is a receiver problem.
- No. PRB-1 applies to state and local zoning, not to private covenants or HOA rules.
- Cease operation, or change the repeater to mitigate the interference. Amateur is secondary on 70 cm to government radiolocation, so there is no third option.