What is a video signal

what is a video signal

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Video Signal. an electrical signal designed to produce an image. A video signal is formed by photoelectric converters (a superorthicon or vidicon in television or a photoelectric cell or photomultiplier in picture transmission) or by the detection of electromagnetic waves received by a radar set. Oct 17,  · A video signal is a signal produced by the video adapter that allows a display device, such as a computer monitor, to display a picture.

Signal What is a video signal Stack Exchange is a question and answer site for practitioners of the art and science of signal, image and video processing. It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. Viceo the radar literature, particularly in older references, the term "video signal", "downrange video", or just "video" is used to describe the radar signal at a certain point in the processing chain.

Also, I have come across the related term vdeo frequencies". In older radars with siggnal processing, I interpret the signnal signal" to mean the voltage as what is a video signal function of time at the fideo of an envelope detector after downconversion from the carrier frequency. In modern radars, particularly coherent pulse-Doppler systems, the term "video signal" seems to be equivalent to the general signal processing term "complex baseband signal" or "complex envelope", in that it contains an in-phase and quadrature component.

Although sometimes I see plots of the "video signal" where the magnitude of the baseband signal is plotted versus time, which seems roughly equivalent to the envelope-detected signal of an analog radar. I interpret the vdieo "video frequencies" to simply mean the signal has been downconverted to be centered at 0 Hz.

Are these interpretations of the term "video" correct, and is there any other nuance I should be aware of? You also see this on Spectrum Analyzers; "video bandwidth" for the same reason: the video is the output voltage from the power detector used to drive the vertical on a display when the horizontal is the sweepor isgnal the case of the polar displays used to drive the radius where the sweep drives the angle.

Since it is used for the display signal it is properly called the "video" signal. As I introduced, this is the same on a spectrum analyzer what does cellulose insulation look like we can adjust both "resolution bandwidth" and "video bandwidth": Resolution Bandwidth is the bandwidth of the effective bandpass filter prior to the power detector, while Video Bandwidth is the bandwidth of the signaal low pass filter after the power detector.

The first filter will reduce the total power incident on the detector when the input is spread as a spectral density, thus reducing the voltage out of the detector, while the second filter video filter will what is a video signal smooth average the measured noise.

So for the case what is a video signal radar, at least the original analog systems, the video output was a similar power detector used to drive one axis either magnitude or as was common siganl on a polar plot for a rotating system of the radar output display.

There's also a quick and dirty "practical" reason that one would use the term "video" and is especially true if working what is a video signal older analog radar systems.

People will tend to refer to the signal as ivdeo once the RF signal is processed by some analog or digital circuit therefore making it a "non-RF" signal. An example would be a legacy system that would siganl tuned vacuum tube RF pre-amplifiers to produce the "video". One would then consider the pre-amplifier the point of transition from RF to "video". The actual point of transition tends to be different to different people sibnal well, such as considering what clothes suit pear shapes "video" after envelope detection.

Keep in mind that this type of jargon is used a lot by technicians and others who are quickly trying to distinguish which signal they are talking about. It's definitely a legacy term.

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Improve this answer. Dan Boschen Dan Boschen It is mostly used by technicians testing or troubleshooting the system. Without detracting from your comment which appears to be another answer if that is what you intended you should post it therethe point of my response is that the origins of the sugnal "video signal" are from legacy systems. Envidia Envidia 1, 7 7 silver badges 16 16 bronze badges. Sign up or log in Sign up using Google.

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Video Signal

Analogue Video. Analogue video is commonly distributed as a composite signal, an almost universal connection between video cameras, VCR / DVD players and video monitors. When superimposed on a radio frequency carrier it forms the aerial signal transmitted to homes. It is also the most usual input connection found on a videoconference picture monitor. The fifth, and center, line is composite video (CVBS), formed by adding the Luma and Chroma components together with monaural audio, NTSC, PAL and SECAM are composite video signals. The CVBS signal is the lowest quality video on the chart and suffers from cross-color artifacts. In the radar literature, particularly in older references, the term "video signal", "downrange video", or just "video" is used to describe the radar signal at a certain point in the processing chain. Also, I have come across the related term "video frequencies".

Video started life as an analogue signal and remained so for over 50 years. However, digital television via satellite, cable and terrestrial transmission is now rapidly replacing analogue. Digital signals are less expensive to transmit because more information can be carried within a given bandwidth using digital multiplex and compression techniques.

Digital signals also hold a significant advantage when it comes to video recording, editing and reproduction: whereas an analogue recording degrades with each generation of copying, the digital equivalent can nearly maintain the original quality after numerous copies. On initial analysis, picture quality is also superior to analogue with no apparent interference, ghosting or other problems. On closer inspection, however, errors can be detected, especially on rapidly moving pictures e. When superimposed on a radio frequency carrier it forms the aerial signal transmitted to homes.

It is also the most usual input connection found on a videoconference picture monitor. This and other signal types are described below:. Analogue video signals degrade when material is recorded or distributed. To overcome this, digital signals are now used throughout broadcasting. Another important advantage of digital signals is that massive compression is possible. Skip to main content. You are here Home Library Network and technology service docs Vscene Technical details Videoconferencing standards Video displays, signals and formats The video signal explained.

The video signal explained. Contents Network and technology service docs.

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