|Terrestrial Transmission Standards|
|Satellite Transmission Standards|
|Faroe Islands (DK)||B||PAL|
|Germany (prev East)||B/G||SECAM/PAL|
|Greece||B/G||PAL (was SECAM)|
|Hungary||B/G & D/K||PAL (was SECAM)||Nicam (Budapest only)|
|United Arab Emirates||B/G||PAL|
The first of these is what I loosely refer to as transcoding. This applies primarily to efforts to replay material from other TV systems using equipment designed with a single particular TV system in mind. Almost all of the solutions based on this technique are replay only and make no provision for the production of material in the foreign tv system.
The second approach is that of the true multi-standard equipment. These are pieces of video equipment that can work as fully operational pieces of equipment in any one of a number of TV systems. With a multi-standard video recorder, you expect an NTSC tape to be reproduced as a standard NTSC signal, and the same machine if fed with a PAL tape will reproduce it as a standard PAL signal. A multi-standard VCR can also be expected to make a perfectly normal NTSC recording of an NTSC input signal, and a perfectly normal PAL recording of a PAL input signal.
The third approach is that of standards conversion where the TV signal
is actually converted from being a standard signal in one TV system to
being a standard signal in another. This is the only way in which material
can be sent from one TV system to another with an absolute garentee of
working, and where operations such as recording and copying become possible
in the destination TV system.
In the early days of television when everything was locked to mains frequency, it was next to impossible to get a TV to accept a signal with even the smallest instability. With the advent of switch mode power supplies and VCRs, there came both the ability and the need to decouple the field timing reference from the mains frequency. The reason for this was that the nature of video recording creates relatively unstable tv signals on replay, and as a result the TV has to follow the fluctuations and variations of the signal in order to reproduce the picture. The down side is that the field timing reference signal now has to be generated by dividing down the ticks from a quartz crystal, something that requires an increased component count in the TV receiver.
As time went by TV manufacturers tried to reduce the number of components by producing a dedicated VLSI chipset which did all the work. The majority of designs for these were actually implemented as a single chipset for the world, which would support either 525/60 or 625/50 pictures. It so happens that TV sets based upon such a chipset can actually produce a very acceptable monochrome picture of the other TV system when feed with such a video signal. The chipset will automatically adjust the number of lines in the picture to match those of the incoming signal.
Since PAL and NTSC are not that different in the way they encode colour
signals, it's not actually that difficult to modify the signal to achieve
a reasonable colour reproduction at the same time. The net effect is that
you end up with a signal that has the frame rate/ scan line characteristics
of the original TV system, but the colour coding and subcarier characteristics
of the local TV system. This hybrid cannot be recorded but does provide
a very effective way of
painting over the cracks and allowing the
reproduction of material in the other TV system.
If for example, you had a multi-standard VCR which supported NTSC and PAL, you could record the playback signal of an NTSC camcorder and make a genuine NTSC copy, or record an off-air PAL broadcast and make a genuine PAL VHS recording. What you could not do is to perform any kind of conversion; the VCR changes it's TV system personality rather than making any change to the signal. Any signal that is NTSC 525/60 will remain that way, and any signal that is PAL 625/50 will remain PAL 625/50. In order to make effective use of a multi-standard VCR, you will need either a multi-standard TV to display on, or a TV of each TV system you want to watch (as a general rule).
Multi-standard VCRs are not amongst the easiest things to find since they are not a mass-market item. Although most of the major VCR manufacturers do make them, surprisingly few actually distribute them on a world wide basis. As a result, other than in export markets such as those of countries such as Singapore and Hong Kong, they can only be found at a few specialist dealers and then often only as grey imports. The best advice would normally be to look for adverts in the back of a local video magasine, for example Video in the USA or What Video in the UK and parts of Europe.
While machines in the transcoding category are only available in a few major colour systems, there will be a multi- standard VCR for every country in the world. This does not mean that all multi-standard VCRs support all the world's TV systems, although some do. There are a number of multi-standard machines that support only the various 625/50 systems such as PAL/SECAM/MESECAM in use in eastern Europe and the Middle East. There are others that support PAL and NTSC but not SECAM, or maybe only certain versions of SECAM (usually MESECAM). Further complexities are added when you consider the capabilities of the TV tuners and RF adaptors of these machines, many of these support less combinations than the VCR itself can handle as video signals. A common example of this is the French SECAM-L; many multi-standard VCRs can handle this only through the video inputs and outputs, not through the Tuner and RF adaptor. To make a recording of French TV with one of these, you would need to attach it to the video outputs of a French TV and select the TV's tuner to the channel you want to record - not a lot of use if you want to do a timer recording.
In addition to being cautious and making sure that the multi-standard machine supports the TV systems you need, you also need to check for more advanced features, particularly stereo sound systems. Although there are a few exceptions, most stereo (VHS HiFi) multi-standard video recorders can only actually receive stereo broadcasts using one of the techniques, be it NICAM, MTS or FM-FM. In countries using the other systems, you will only be able to receive the mono TV soundtrack with these machines.
Finally, multi-standard machines tend to be fairly basic. Most manufacturers
only offer about two models; typically one with only mono sound and one
with VHS HiFi sound. Fancy extras like flying erase heads, manual audio
record level controls, edit connections, and SuperVHS operation are not
available. Neither are multi-standard camcorders. Actually, the last one
- the camcorder, seems a bit of a surprise since it is camcorder footage
that most often leads people into the morass that is TV system incompatibility
in the first place. To be able to buy a camcorder that can record in PAL
if you know you're going to send it to relatives in a PAL country, and
NTSC if you're going to use it say in the USA would seem quite attractive
to many people.
Conversion between TV systems with same frame rate are usually reasonably effective, except of course that the resultant signal usually suffers from the deficencies of both the source and destination colour system.
Conversion between TV systems with differing frame rates is extremely difficult and there is no perfect solution. With a trained eye, it is possible to spot that any given piece of material has been standards converted within a matter of seconds. The units that perform these conversions are known as Digital Standards Converters. For many years digital standards converters were very expensive indeed and as a result were only used by TV stations and video facilities houses. This all changed in the 1990 with the launch by Panasonic of the NV-W1, a combination VHS deck/digital standards converter at around UK#1,600 (approx US$2300). Since then other manufacturers have also introduced domestic standards converters at even lower prices. Among the manufacturers with standards converters in their range are Panasonic, Aiwa, Sharp, and Samsung.
Professional standards converters also exist, many of which can achieve
significantly better results, but at a price. One of the best is the DEFT,
which costs a cool UK#65,000 (approx US$100,000)!
| ATVS | REPEATERS | DVMS | NET | PACKET RADIO | BROADCASTING |
| HARDWARE & SOFTWARE | DV-IN | DV-NLE | CD | VIDEO | MALI OGLASI |