science

Television lines

Television lines is a science 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 Television lines rather than just read about it. In short: Television lines (TVL) is a specification of an analog camera or monitor's horizontal image resolution. The TVL is one of the most important resolution measures in a video system.

Key takeaways

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

Reference excerpt

Television lines (TVL) is a specification of an analog camera or monitor's horizontal image resolution. The TVL is one of the most important resolution measures in a video system. The TVL can be measured with the standard EIA 1956 resolution chart.

Definition TVL is defined as the maximum number of alternating light and dark vertical lines that can be resolved per picture height. A resolution of 400 TVL means that 200 distinct dark vertical lines and 200 distinct white vertical lines can be counted over a horizontal span equal to the height of the picture. For example, on 4 by 3 inches (10.2 cm × 7.6 cm) monitor with 400 TVL, 200 vertical dark lines can be counted over 3 inches (7.6 cm) width on monitor (Note that the 3 inches (7.6 cm) of monitor height is used rather than the 4 inches (10 cm) of whole monitor width). TVL is an inherent quality of a camera or monitor, influenced by the visual bandwidth of the transmission system used. It should not be confused with the number of horizontal scanning lines of such systems, which e.g. 625 lines for the PAL system, 525 lines for the NTSC system. The following table shows the horizontal resolutions of some analog video systems:

Limitations

Since analog transmission of video is scan line-based, the same number of horizontal lines is always transmitted. However, several factors impede the ability to display fine detail within a line:

The camera or other source of material. The storage and processing of the picture. The transmission of the TV signal e.g. broadcast by radio or by cable. The reception and reproduction of the picture on a TV set.

See also Kell factor, which limits the vertical resolution in analog television, and both horizontal and vertical resolution in digital television, to a fraction of the number of scan lines or pixels

References

Illustrations

Worked examples

Example 1 — a first encounter with Television lines

Start with the simplest possible case. Write down what Television lines claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Television lines 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 Television lines 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 Television lines

In research: Television lines appears in science 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 Television lines 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: Television lines is common in secondary-school and first-year university syllabi. It links to neighbouring topics Television technology, so understanding it makes those chapters shorter.
In everyday life: Look for Television lines 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 Television lines in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Television lines 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 Television lines out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Television lines in simple terms?

Television lines (TVL) is a specification of an analog camera or monitor's horizontal image resolution. The TVL is one of the most important resolution measures in a video system.

Why does Television lines matter?

Because it connects several science 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 Television lines?

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 Television lines.