# Why are 625 lines used in TV transmission?

## Why are 625 lines used in TV transmission?

“Suppose there are x lines in 1 field. Then for two field its 2x. For 1 field there are 292.5 scanning lines, so for 2 fields there are 2x=292.5*2=585 & 40 other lines ( because of merging effect and all). So 585+40=625.”

### What is the significance of choosing the number of lines as 625 and not 623 or 627?

Thus for interlaced scanning the total number of lines in any TV system must be odd. What is the significance of choosing the number of lines as 625 and not 623 or 627 and the frame reception rate as 25 and not 24 as in motion pictures? In motion illusion the minimum refresh rate is 24 frames / sec.

Which scanning method is used in TV receiver with 625 lines?

This method of scanning is known as interlaced scanning. In the 625 line TV system, for successful interlaced scanning, the 625 lines of each frame or picture are divided into sets of 312.5 lines and each set is scanned alternatively to cover the entire picture area.

When did TV change to 625 lines?

In November 1969 BBC1 and ITV also started broadcasting in 625-line PAL colour on UHF.

## What is the maximum color TV bandwidth?

Therefore, maximum bandwidth necessary for color signal transmission is around 3 MHz (± 1.5 MHz).

### How many lines does a TV have?

Actual values in use in television broadcasting in various regions are 405 lines, 525 lines, 625 lines, and 819 lines per frame. These values have been chosen to suit the frequency band of the channel actually assigned in the respective geographic regions.

Why do we use odd number of lines for scanning?

Concept: In television pictures, an effective rate of 50 vertical scans per second is utilized to reduce flicker. This is accomplished by increasing the downward rate of travel of the scanning electron beam so that every alternate line gets scanned instead of every successive line.

What is the role of Scanning in TV system?

Why is scanning necessary in television system? Scanning is the important process carried out in a television system in order to obtain continuous frames and provides motion of picture. As a result sufficient number of complete picture of frames per second is obtained to give the illusion of continuous motion.

## What happened RCA Victor?

During this period, RCA was closely identified with the leadership of David Sarnoff. He was general manager at the company’s founding, became president in 1930, and remained active, as chairman of the board, until the end of 1969….RCA.

Industry media industry
Founder Guglielmo Marconi
Defunct 1986

### What is the bandwidth of TV signal?

A typical TV signal requires 4 MHz of bandwidth. With adding sound, something called a vestigial sideband and a little buffer space, a TV signal requires 6 MHz of bandwidth for transmission.

How many lines per second does 625 line TV use?

625-line TV This is the European standard (except France which uses 819 lines) and the one to which the U.K. TV service is to be changed. In this standard there are still 25 complete frames per second but each frame contains 625 lines. France will also use 625 lines for any new service.

Why are there 625 lines [ PAL ] in t.v.scanning or odd lines?

n.b. Adjusting for different mains frequencies gives 50/60 x 625 = 520 (near enough 525) This refers to the 625 50Hz PAL system ( a similar argument also applies to 525 60 Hz NSTC) There is a limited frequency space for each transmission. Depending on the type of PAL signal the channel bandwidth is between 6 to 8 MHz.

## Why is b.b.c.changing to 625 line TV?

ⒶThe B.B.C. is being pressed to open its second TV service and extend it to National coverage as quickly as possible. By Government decree the new service must be on 625 not 405 lines. By the same token the Government represented by the P.M.G. wish to change over the existing B.B.C. 1 and I.T.V. services to 625 lines as quickly as possible.

### What’s the difference between 625 and 50 Hz in PAL?

The frequency 50 Hz is the optional refresh frequency of the monitor to be able to create an illusion of motion, while 625 lines means the vertical lines or resolution that the PAL system supports. The original colour carrier is required by the colour decoder to recreate the colour difference signals.