The 75% bars are the only ones used in production and transmission as far as I can tell. At least here in what-used-to-be-PAL-land this now is 98% archaeology since the production chain since 20 years is SDI (or encoded with compression to transmit over IP, to be decoded back to SDI later) and transmission is DVB-T / DVB-T2.
These days transmission is tested using Wireshark (https://www.wireshark.org/) for protocols like SMPTE ST2110. Yes, our instrument (https://www.telestream.net/video/prism.htm) has bars, but the most work is done using the timing and packet stream analysis tools.
"All broadcast engineers are closet time-nuts"
(Another forum member to me, in privmsg)
The 75% bars are the only ones used in production and transmission as far as I can tell.
By production do you mean making video intended to be transmitted? Or do you mean calibrating studio monitors?
At least here in what-used-to-be-PAL-land this now is 98% archaeology since the production chain since 20 years is SDI (or encoded with compression to transmit over IP, to be decoded back to SDI later) and transmission is DVB-T / DVB-T2.
I don't know much about European technology, as I live in the US, and my question was about NTSC (even the spec about 120IRE being full moduluation, is an NTSC standard, so I don't think info about the PAL system will help me much here).
These days transmission is tested using Wireshark (https://www.wireshark.org/) for protocols like SMPTE ST2110. Yes, our instrument (https://www.telestream.net/video/prism.htm) has bars, but the most work is done using the timing and packet stream analysis tools.
"All broadcast engineers are closet time-nuts"
(Another forum member to me, in privmsg)
Wireshark really? I thought that was a network protocol analyzer for internet and LAN type networks (like 802.11 wireless, and Ethernet wired networks). I didn't know it could analyzer protocols that weren't designed specifically for computer networking.
Also I'm surprised you even need bars in digital video. Digital video makes sure that the output is a bit-for-bit accurate reproduction of the input, so no possibility to have wrong phase of the chroma carrier or other issues that would make the color wrong output in analog video. Digital video means that all colors are precisely accurate.
The color bar test signal had a number of uses but these were primarily in the studio equipment, not at the transmitter.
The widest and perhaps most known use was as a standard reference level that was placed at the head of every video tape recording. About one minute of bars and audio tone was the first thing on virtually every reel of video tape. The color bar signal provided:
1. A luminance or black and white level reference.
2. A color sub carrier level reference.
3. A sync level reference.
4. A means of adjusting parameters like phase and amplitude errors that were luminance level dependent (aka: differential gain and phase) in video tape recorders.
These things were checked and adjusted prior to playing every video tape. This was a constant routing for the engineer working in the tape room during broadcast hours.
But there were many other uses for this signal. It was the primary signal used to perform maintenance set ups on the encoders which produced the composit video in cameras and other items of equipment. It was also a quick way of checking and adjusting the performance of video amplifiers which were everywhere. And it was used extensively in maintenance adjustments and troubleshooting of video tape recorders. In the TV studio it was the most used test signal.
It is not useless in a digital facility, but is not used as often as other test signals that can tell more about the digital signals and their transmission.
The 75% bars are the only ones used in production and transmission as far as I can tell. At least here in what-used-to-be-PAL-land this now is 98% archaeology since the production chain since 20 years is SDI (or encoded with compression to transmit over IP, to be decoded back to SDI later) and transmission is DVB-T / DVB-T2.
These days transmission is tested using Wireshark (https://www.wireshark.org/) for protocols like SMPTE ST2110. Yes, our instrument (https://www.telestream.net/video/prism.htm) has bars, but the most work is done using the timing and packet stream analysis tools.
"All broadcast engineers are closet time-nuts"
(Another forum member to me, in privmsg)