engineering

Pre-sunrise and post-sunset authorization

Pre-sunrise and post-sunset authorization is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Pre-sunrise and post-sunset authorization rather than just read about it. In short: In USA AM broadcasting, presunrise authorization (PSRA) and postsunset authorization (PSSA) are permission from the Federal Communications Commission to broadcast in AM on mediumwave using a power level higher than what would normally be permitted prior to sunrise/after sunset, or in the latter case, provide Class D stations with service into the evening where they would otherwise be required to sign off. Sunrise an…

Key takeaways

Pre-sunrise and post-sunset authorization belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Pre-sunrise and post-sunset authorization to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Pre-sunrise and post-sunset authorization from memory before moving on to harder problems.

Reference excerpt

In USA AM broadcasting, presunrise authorization (PSRA) and postsunset authorization (PSSA) are permission from the Federal Communications Commission to broadcast in AM on mediumwave using a power level higher than what would normally be permitted prior to sunrise/after sunset, or in the latter case, provide Class D stations with service into the evening where they would otherwise be required to sign off. Sunrise and sunset times are provided on the licensee's basic instrument of authorization. The power level for both PSRA and PSSA service cannot exceed 500 watts. Power calculations are based on co-channel stations.

PSRA At 6:00am local time, stations may power up using the station's daytime antenna (if applicable).

Daylight saving Provided the locale participates in daylight saving time, special provisions must be made since the PSRA time is based on local time. The exact wording of the rule states:

Between the first Sunday in April and the end of the month of April, Class D stations will be permitted to conduct pre-sunrise operation beginning at 6 a.m. local time with a maximum power of 500 watts (not to exceed the station's regular daytime or critical hours power)... For example, if the instrument of authorization states sunrise as being at 5:30am local standard time in April, the station does not require PSRA operation since sunrise time is prior to the 6:00am rule. When the clocks advance, this becomes 6:30am local time. PSRA will permit the station to power up at 5:00am standard time, since that would be 6:00am advanced time and local time would reflect the advanced time. As of 2007 (when the new US daylight saving times went into effect), the FCC instructed licensees to use the April advanced times when DST goes into effect in March.

PSSA At sunset, Class D stations must sign off if they do not possess a nighttime license. PSSA operation allows the station to remain on the air an additional two hours at reduced power level determined by several factors:

International boundaries Class A Clear-channel stations Whether the station is on a Regional channel

Daylight saving There are no specific provisions related to daylight saving time within PSSA operation.

Exceptions PSSA operation must cease at local sunset time for the closest co-channel Class A located west of the Class D station. Class D stations west of a co-channel Class A do not qualify.

History The first presunrise authorizations came from a proposed rulemaking in 1967 (Operation by Standard Broadcast Stations, 8 FCC 2d 698 (1967)). There were major concerns of skywave interference to clear channel stations, so only a handful of stations were permitted to apply. On February 25, 1981, the FCC determined that there were no detrimental effects to clear-channel stations in remote areas, therefore, they permitted even more stations to apply for authorization. [1]

Current authorization Applications for PSRA and PSSA operation are no longer required. The licensee must merely notify the FCC.

External links 47 CFR 73.99 (Official) FCC Radio and Television Rules 47 CFR Part 73 (Official) FCC Rules and Regulations (unofficial)

Worked examples

Example 1 — a first encounter with Pre-sunrise and post-sunset authorization

Start with the simplest possible case. Write down what Pre-sunrise and post-sunset authorization claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Pre-sunrise and post-sunset authorization before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Pre-sunrise and post-sunset authorization ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Pre-sunrise and post-sunset authorization

In research: Pre-sunrise and post-sunset authorization appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Pre-sunrise and post-sunset authorization in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Pre-sunrise and post-sunset authorization is common in secondary-school and first-year university syllabi. It links to neighbouring topics Broadcast engineering, so understanding it makes those chapters shorter.
In everyday life: Look for Pre-sunrise and post-sunset authorization outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Pre-sunrise and post-sunset authorization in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Pre-sunrise and post-sunset authorization means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Pre-sunrise and post-sunset authorization out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Pre-sunrise and post-sunset authorization in simple terms?

Why does Pre-sunrise and post-sunset authorization matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Pre-sunrise and post-sunset authorization?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Pre-sunrise and post-sunset authorization.