The term high definition once described a series of television systems originating from August 1936; however, these systems were only high definition when compared to earlier systems that were based on mechanical systems with as few as 30 lines of resolution. The ongoing competition between companies and nations to create true "HDTV" spanned the entire 20th century, as each new system became more HD than the last.In the beginning of the 21st century, this race has continued with 4k, 5k and current 8K systems. 

The British high-definition TV service started trials in August 1936 and a regular service on 2 November 1936 using both the (mechanical) Baird 240 line sequential scan (later to be inaccurately rechristened 'progressive') and the (electronic) Marconi-EMI 405 line interlaced systems. The Baird system was discontinued in February 1937. In 1938 France followed with their own 441-line system, variants of which were also used by a number of other countries. The US NTSC 525-line system joined in 1941. In 1949 France introduced an even higher-resolution standard at 819 lines, a system that should have been high definition even by today's standards, but was monochrome only and the technical limitations of the time prevented it from achieving the definition of which it should have been capable. All of these systems used interlacing and a 4:3 aspect ratio except the 240-line system which was progressive (actually described at the time by the technically correct term "sequential") and the 405-line system which started as 5:4 and later changed to 4:3. The 405-line system adopted the (at that time) revolutionary idea of interlaced scanning to overcome the flicker problem of the 240-line with its 25 Hz frame rate. The 240-line system could have doubled its frame rate but this would have meant that the transmitted signal would have doubled in bandwidth, an unacceptable option as the video baseband bandwidth was required to be not more than 3 MHz. QUESTIONS:

Q1:
1. What can video baseband bandwidth not exceed?
2. What is it unacceptable for video baseband bandwidth to exceed?
3. Video baseband bandwidth is required to not exceed what?
Q2:
1. Who had the first trials of high-definition TV service?
2. Whose trials for high-def TV service were the first ones?
3. Who was the first to do trials of high-def television service?
Q3:
1. When did the Brits begin their trials of high-definition TV?
2. When were the first trials of high-definition television?
3. When did trials for high-definition TV first start in Great Britain?
Q4:
1. When did regular service for high-definitions TVs begin?
2. When was the first service of high-definition television?
3. When did regular service get put into place for high-def televisions?
Q5:
1. What was high definition originally a reference to?
2. What was the first definition of high definition TV?
3. In the beginning, what did high definition describe?
Q6:
1. How many lines of resolution did the first high-definition TVs have?
2. How many lines of resolution were there on the first high-definition TVs?
3. Give the exact number of lines on the first models of high-definition televisions.
Q7:
1. Why did companies and nations create true HDTV?
2. What was the animus for countries and companies to create real HDTV?
3. What pushed corporations and countries to invent actual HDTV?
Q8:
1. How long did the competition to create real HDTV last?
2. For how long did the race to make real HDTV last?
3. How long was there a worldwide race to create true HDTV?
Q9:
1. What is the resolution of the most current HDTV systems?
2. What resolution do the most current HDTVs have?
3. What is the resolution of the newest HDTV?
Q10:
1. What is an older system in the race to create true HDTV?
2. What resolution came before 8K in trying to make real HDTV?
3. In the race to make real HDTV, what system preceded the 8K one?
Q11:
1. Was the Baird 240 line sequential scan electrical or mechanical?
2. Would you classify the Baird 240 line sequential scan as electrical or mechanic?
3. Did the Baird 240 line sequential scan use a mechanical or electric system?
Q12:
1. What was the inaccurate description of the Baird 240 line sequential scan?
2. What was the Baird 240 line sequential scan wrongly known as?
3. What incorrect term was used to describe the Baird 240 line sequential scan?
Q13:
1. What was the electronic system?
2. What system was electronic instead of mechanic?
3. What was the electronic, not mechanic, system?
Q14:
1. How many lines did the Marconi-EMI 405 have?
2. How many lines were there on the Marconi-EMI 405?
3. What was the number of lines on the Marconi-EMI 405?
Q15:
1. Was the Marconi-EMI 405 interlaced?
2. Could the Marconi-EMI 405 be described as interlaced?
3. Is it accurate to say the Marconi-EMI 405 was interlaced?
Q16:
1. When did the Brits kill of the Baird system?
2. When did Great Britain stop using the Baird system?
3. When was the Baird system discarded by the Brits?
Q17:
1. Which nation had their own system in 1938?
2. In 1938, what was the country with their own system?
3. Which nation had invented their own line system by the year 1938?
Q18:
1. How many lines did the French system have in 1949?
2. In 1949, how many lines were there in the French system?
3. What was the number of lines used by the French system by 1949?
Q19:
1. Was the French system in color?
2. Did the French system have color?
3. Was the French system a color Tv one?
Q20:
1. What was the aspect ratio of the French system?
2. What aspect ratio did the French system use?
3. Give the aspect ratio of France's system.
