HDTV Systems Information

HDTV Broadcast Systems Information
Ever since High Definition Television (HDTV) came into the consumer domain, I did not understand all the numbers that were attached to it. I figured the higher the number the better it must be, after all bigger must be better. After much research, reading and re-reading, manuals and HDTV specifications, I was able to break the code. With that said, HDTV is an extremely scientific subject dealing with compression ratios of a digital signal, which is effected by the recording and broadcasting compression rates.

There are basically three major parameters that identify HDTV systems.
1. Frame size, which is denoted in Pixels, is the number of horizontal pixels by the number of vertical pixels. This is where you will usually see the numbers, 1280 X 720 or 1920 X 1080. Normally the number of horizontal pixels are constant based on the vertical pixels, and are usually omitted. That is why you will usually see only the 720 or 1080 numbers regarding the frame size.
2. Scanning system, is identified by the letter p, which stands for progressive scanning, or the letter i, for interlaced scanning. Progressive scanning simultaneously displays all 1,080 lines of resolution at 60 frames per second. The interlaced scanning systems, the 1,080 lines of resolution are divided into pairs, the first 540 alternate lines are painted on a frame, and the second 540 lines are painted on a second frame, effectively reducing the bandwidth.
3. Frame rate is the number of video frames per second.
When you see the numbers, 1920 X 1080p25, it represents the horizontal pixels of 1920, the vertical pixels of 1080, the letter p for progressive scanning, and the 25 that represents the number of video frames per second or the frame rate. This same representation may be written as, 1080p25, and I have seen it written just 1080p.
The configuration of 1080i25 or 1080i50, identifies an interlaced scanning system with a frame size of 1920 X 1080 pixels, and the frame rate noted as 25 for the frame rate per second or the 50 for the number of fields (remember the interlaced system was divided into pairs, so 50 number for fields is a different way of saying 25 frames per second).
Last but not least, in order to view High Definition TV, it must be initially recorded in HD, broadcast in HD, and connected to a HDTV using HDMI or component video cables that support the HD digital signal. If you use your old cables to connect your HD box, cable, or satellite TV and they are the standard SDTV cables, you will not be watching HDTV.