SECAM
SECAM, also written SÉCAM (French pronunciation: [sekam], Séquentiel de couleur à mémoire, French for color sequential with memory), is an analog color television system that was used in France, Russia and some other countries or territories of Europe and Africa.
Like PAL, a SECAM picture is also made up of 625 interlaced lines and is displayed at a rate of 25 frames per second (except SECAM-M).
NTSC was considered undesirable in Europe because of its tint problem, requiring an additional control, which SECAM (and PAL) solved.
Some have argued that the primary motivation for the development of SECAM in France was to protect French television equipment manufacturers.
The first proposed system was called SECAM I in 1961, followed by other studies to improve compatibility and image quality,[2] but it was too soon for a wide introduction.
[2][4] Soviet technicians were involved in a separate development of the standard, creating an incompatible variant called NIIR or SECAM IV,[2] which was not deployed.
A group of four suited men—a presenter (Georges Gorse, Minister of Information) and three contributors to the system's development—were shown standing in a studio.
Following a count from 10, at 2:15 pm the black-and-white image switched to color; the presenter then declared "Et voici la couleur !"
[10] This did not hinder mutual reception in black and white, because the underlying TV standards remained essentially the same in both parts of Germany.
Eventually, the government in East Berlin stopped paying attention to so-called "Republikflucht via Fernsehen", or "defection via television".
Later East German–produced TV sets, such as the RFT Chromat, even included a dual standard PAL/SECAM decoder as an option.
Another explanation for the Eastern European adoption of SECAM, led by the Soviet Union, is that the Russians had extremely long distribution lines between broadcasting stations and transmitters.
[11] Long co-axial cables or microwave links can cause amplitude and phase variations, which do not affect SECAM signals.
Other countries, notably the United Kingdom and Italy, briefly experimented with SECAM before opting for PAL.
With the fall of communism and following a period when multi-standard TV sets became a commodity in the early 2000s, many Eastern European countries decided to switch to the West German-developed PAL system.
The color space perceived by humans is three-dimensional because of the nature of their retinas, which include specific detectors for red, green and blue light.
) signals are usually chosen to be sent along luma but with comparably less resolution, to be able to save bandwidth while impacting the perceived image quality the least.
[13] Yet the same document indicates[14] that for existing (at the time of revision, 1998) SECAM sets, the following parameters (similar to the original 1953 color NTSC specification[15]) could be allowed: The assumed display gamma was also defined as 2.8.
In NTSC and PAL, each line carries color difference signals encoded using quadrature amplitude modulation (QAM).
This information is sent along the video signal at the start of every scan line in the form of a short burst of the color carrier itself, called a "colorburst".
FM modulation of the color information allows SECAM to be completely free of the dot crawl problem commonly encountered with the other analog standards.
Although the older analog camcorders (VHS, VHS-C) were produced in SECAM versions, none of the 8 mm or Hi-band models (S-VHS, S-VHS-C, and Hi-8) recorded it directly.
The result could be converted back to SECAM in some models; most people buying such expensive equipment would have a multistandard TV set and as such would not need a conversion.
Digital camcorders or DVD players (with the exception of some early models) do not accept or output a SECAM analog signal.
However, this is of dwindling importance: since 1980 most European domestic video equipment uses French-originated SCART connectors, allowing the transmission of RGB signals between devices.
On VHS tapes, the luminance signal is recorded FM-encoded (on VHS with reduced bandwidth, on S-VHS with full bandwidth) but the PAL or NTSC chrominance signal is too sensitive to small changes in frequency caused by inevitable small variations in tape speed to be recorded directly.
Instead, it is first shifted down to the lower frequency of 630 kHz, and the complex nature of the PAL or NTSC sub-carrier means that the down conversion must be done via heterodyning to ensure that information is not lost.
A true dual-standard PAL and SECAM video recorder therefore requires two color processing circuits, adding to complexity and expense.
The Swiss importers added a circuit with a specific IC for the French SECAM-L standard, making the tuner multi-standard and allowing the VCR to record SECAM broadcasts in MESECAM.
Video recorders like Panasonic NV-W1E (AG-W1-P for professional), AG-W3, NV-J700AM, Aiwa HV-MX100, HV-MX1U, Samsung SV-4000W and SV-7000W feature a digital standard conversion circuitry.
