philip@axis.fr (Philip Peake) (06/20/89)
> I would like some adivce/references about compatibility/incompatibility > between the NTSC and PAL color TV systems. I have several questions like: > Are b/w receivers built for the NTSC and PAL markets compatible? B/w > signals recorded on VHS tapes? Are there any add-on products that let you > see VHS tapes recorded with NTSC signals on PAL systems? > Are VHS VCR's compatible, or do they have special components directed > toward the interpretation of NTSC or PAL signals? I can't say too much about NTSC/PAL, but my experience of PAL/SECAM indicates that although the basic VHS system is the same, the encoding of the info on the tape is not compatible between the two. The main difference between PAL and SECAM is how the colour info is coded (the sub-carrier frequencies are different, and the means of indicating the current phase of the colour info is different) - the line frequencey is the same though (not true for NTSC). On moving from England to France, I tried using my english (PAL) vcr to play SCAM tapes, and lent some of my PAL tapes to people with SECAM vcrs. The result was the same in both directions - good B&W picture and sound, but absolutley no colour. I would be interested if anyone could explain why the difference in coding between the two systems - I would have just put the colour info directly onto the tape ona parallel track - this would give compatability between the two systems. As it is, I bought a new vcr PAL/SECAM model, which solves the problem - maybe this is why the coding is different - to make bigger profits from selling dual standard machines, where one would do ? Philip
myers@hpfcdj.HP.COM (Bob Myers) (06/21/89)
>I would like some adivce/references about compatibility/incompatibility >between the NTSC and PAL color TV systems. I have several questions like: >Are b/w receivers built for the NTSC and PAL markets compatible? Well, if not, it's obviously not because of the color encoding! :-) However, both the PAL and SECAM systems use different timing than the NTSC standard; we're using a 525 lines/frame, 60 Hz interlaced system (15,734 Hz horizontal), and PAL (and, I believe, SECAM) is a 625 lines/frame, 50 Hz system. The question is whether or not the TV in question would sync up (or could be adjusted to sync up) to the "other" standard. > B/w signals recorded on VHS tapes? Same timing concerns as before. >Are there any add-on products that let you see VHS tapes recorded with > NTSC signals on PAL systems? Yes, but they're expensive. Not only are you changing the color encoding, but you must also change the signal timing - this requires frame stores and other expen$ive goodies. >Are VHS VCR's compatible, or do they have special components directed >toward the interpretation of NTSC or PAL signals? PAL and NTSC VCRs are incompatible. Some manufacturers have produced models, though, that can be switched back and forth between the two systems. However, the tapes produced in, say, NTSC mode are still incompatible with PAL. Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not Ft. Collins, Colorado | those of my employer or any other myers%hpfcla@hplabs.hp.com | sentient life-form on this planet.
welch@cg-atla.UUCP (John Welch) (06/22/89)
Just off the top of my head, the main difference between SECAM and PAL
is the way in which color information is processed on each line.
Roughly, SECAM stands for Systeme Electronique Couleur Avec Memoire.
Or, Sequential Color with Memory, not a direct translation, but it
gives a good description of what happens in a SECAM system.
In a SECAM system, the red and blue color difference signals are
transmitted on alternate lines. This requires a one scan line memory to
decode for green.
In PAL, or Phase Alternation ,or alternating, Line, one of the subcarrier phasesderived from the color burst is inverted in phase from one line to the
next. This is done to minimize errors in hue which may occur during
color transmission.
These systems are both 625 line 50 Hz, which is why Black and White
signals would work. The only difference in the two is how they encode
color.
Remember, NTSC = Never The Same Color :-)
This info was culled from the Raster Graphics Handbook put out by
Conrac.
--
John Welch | "Why should YOU care what other
Agfa Compugraphic Division | people think?"
Wilmington Ma 01824 |
{ulowell|decvax|cgeuro}!cg-atla!welch | Richard FeynmanISW@cup.portal.com (Isaac S Wingfield) (06/23/89)
As I remember, PAL stands for Phase Alternate Line, and does just that. The 3.58 MHz color subcarrier flips phase by 180 deg after each line, and to recover the signal properly, the receiver needs to have a 1-line (63 uSec) delay line which is kicked in on alternate lines to straighten things out. The (supposed) justification for this is to average out phase errors incurred during the distribution of the signal. I believe PAL sets have no "tint" control (everything's perfect; you don't need it). Interesting sidenote: despite all the "improvements" brought about by PAL or secam, the best commercially broadcast stuff around used to be (maybe still is) in Japan, where they use the old, kludgy NTSC system invented here. They just pay attention to the adjustments and keep it tweaked up real good. (NTSC = "never twice same color") Isaac isw@cup.portal.com
ingoldsb@ctycal.COM (Terry Ingoldsby) (06/24/89)
In article <566@axis.fr>, philip@axis.fr (Philip Peake) writes: > > I would like some adivce/references about compatibility/incompatibility > > between the NTSC and PAL color TV systems. I have several questions like: ....> > The main difference between PAL and SECAM is how the colour info is coded > (the sub-carrier frequencies are different, and the means of indicating > the current phase of the colour info is different) - the line frequencey > is the same though (not true for NTSC). > ....> > I would be interested if anyone could explain why the difference in > coding between the two systems - I would have just put the colour info > directly onto the tape ona parallel track - this would give compatability > between the two systems. > First of all, unless I'm very mistaken ordinary VCR's do not separate the chrominance and luminance info when they store it on the tape. It is all stored together. Somebody please correct me if I'm wrong about this (no flames, just corrections please :^). As for putting the chroma on a parallel track, do you mean a parallel helical track or a linear track? If the former, then you are going to complicate the head design considerably, if the latter then 1) You will have a hard time getting enough bandwidth out of a linear track to store chroma info 2) It will be a *devil* of a job keeping chroma and luminance synchronized to the necessary accuracy. (You don't notice if the audio is 5 msec off, but you would sure notice if the chroma was 5 msec out) -- Terry Ingoldsby ctycal!ingoldsb@calgary.UUCP Land Information Systems or The City of Calgary ...{alberta,ubc-cs,utai}!calgary!ctycal!ingoldsb
kencr@haddock.ima.isc.com (Kenny Crudup) (06/26/89)
In article <367@ctycal.UUCP> ingoldsb@ctycal.COM (Terry Ingoldsby) says: >First of all, unless I'm very mistaken ordinary VCR's do not separate the >chrominance and luminance info when they store it on the tape. It is all >stored together. Somebody please correct me if I'm wrong about this. > Terry Ingoldsby ctycal!ingoldsb@calgary.UUCP The chroma is seperated and 'mixed-down' (for want of a better term this early a.m.) to a lower frequency (680k?) so that head speed changes don't screw the color up too bad. -- Kenneth R. Crudup, Contractor, Interactive Systems, Cambridge MA StarTrekV 3'rd favorite line: "Oh yeah?! Beam THIS up, pal!!" - D. Letterman E-Mail, (which tends not to be delivered :-( ) Phone (617) 661 7474 x238 {encore, harvard, spdcc, think}!ima!haddock!kencr kencr@haddock.ima.isc.com
lars@salt.acc.com (Lars J Poulsen) (06/27/89)
In article <7263@cg-atla.UUCP> welch@cg-atla.UUCP (John Welch) writes: > SECAM stands for Systeme Electronique Couleur Avec Memoire. > PAL ... Phase Alternation ,or alternating Line > NTSC = Never The Same Color :-) >This info was culled from the Raster Graphics Handbook put out by >Conrac. Back around 1965 or so, when Europe was all aflame with political wars about selecting TV color systems, I heard: NTSC = Never Twice Same Color SECAM = Supreme Effort Contre Americains PAL = Phase Alternating Line PAL was technically much superior to both alternatives (much like beta was technically superior to VHS), but France would not budge (pigheaded Gaullist nationalism). Later, France licensed their system to the East bloc; DDR wanted a system that would deprive their citizens of color when watching western TV. Since then, NTSC has adopted color standards at the top of the frame that allow dynamic compensation for phase shift in the transmission channel, so the practical difference has diminished (somewhat like VHS-HQ). / Lars Poulsen <lars@salt.acc.com> (800) 222-7308 or (805) 963-9431 ext 358 ACC Customer Service Affiliation stated for identification only My employer probably would not agree if he knew what I said !!
al@cs.strath.ac.uk (Alan Lorimer) (06/27/89)
In article <367@ctycal.UUCP> ingoldsb@ctycal.COM (Terry Ingoldsby) writes: >In article <566@axis.fr>, philip@axis.fr (Philip Peake) writes: >....> >First of all, unless I'm very mistaken ordinary VCR's do not separate the >chrominance and luminance info when they store it on the tape. It is all >stored together. Somebody please correct me if I'm wrong about this Er..... Sorry, you are wrong. One of these days I'm going to post a complete and concise description of television, colour systems (PAL SECAM NTSC) and various types of video recording techniques, so everyone will know once and for all! (You maight mail me if anyone's interested) VHS is a colour under system. The reason for this is that the luminance signal is band limited to around 3.5MHz. This unfortunately chops off the colour sub-carrier from most vision systems. Hence it is necessary to separate the colour signal and modulate it seperately onto the tape. The luminance signal is FM modulated and occupies a frequency band in the range 5-12MHz. The colour signal is modulated seperately onto a carrier at some freqency below the luminance signal. Hence, the colour is under the luminance signal. >(no flames, just corrections please :^). As for putting the chroma on a >parallel track, do you mean a parallel helical track or a linear track? >If the former, then you are going to complicate the head design considerably, >if the latter then > 1) You will have a hard time getting enough bandwidth out of a linear track > to store chroma info Quite right, that's why it is recorded by the helical scanning head. > 2) It will be a *devil* of a job keeping chroma and luminance synchronized > to the necessary accuracy. (You don't notice if the audio is 5 msec > off, but you would sure notice if the chroma was 5 msec out) No problem, since the luminance and chrominance are recorded by the same head on the same track, but at different frequencies synchronisation is not an issue. To answer another point made by another poster, the colour under signal is recorded as it is coded in the orginal signal be it PAL or NTSC (don't really know for sure about SECAM, since there will be lots of FM sidebands to try to fit in the same space, but it's probably not two much hassle to convert it to PAL and the back to SECAM - no I'm not joking, there are lots of reasons for doing this!) This means that you can't interchange tapes between standards, but there are a lot of multi-standard TV sets out there which won't mind. As an VHS tapes can be exchanged between PAL systems having different sub-carrier freqnencies, since the colour under frequency will be the same in all cases. Playing back a tape in Germany say, which was recorded in the UK will work in colour since the native video recorder will play back the colour at its native subcarrier frequency. PAL and SECAM tapes can also be interchanged without any hassle, but you won't get any colour. PAL and NTSC tapes cannot be interchanged as a rule, because the field rate of the vision signal is different. Some VCR servos may be willing to adapt, and you may get a picture (the TV set probably won't care much since the line frequency is nearly the same), but the comments on colour standard still apply. Note that if you do get a picture, the sound will probably be at the wrong speed, since your VCR will try to adapt to the field rate of the pulses on the control track. Have I answered any questions, or just provoked them ? Alan. ____________________________________________________________________________ Alan G. Lorimer, Strathclyde University, 26 Richmond Street, Glasgow G1 1XH. UUCP: ...!uunet!mcvax!ukc!strath-cs!al DARPA: al%cs.strath.ac.uk@ucl-cs JANET: al@uk.ac.strath.cs
henry@utzoo.uucp (Henry Spencer) (06/28/89)
In article <19790@cup.portal.com> ISW@cup.portal.com (Isaac S Wingfield) writes: >Interesting sidenote: despite all the "improvements" brought about >by PAL or secam, the best commercially broadcast stuff around >used to be (maybe still is) in Japan, where they use the old, kludgy >NTSC system invented here. They just pay attention to the adjustments >and keep it tweaked up real good. Reminds me of Ed Tufte's plenary speech at CHI+GI 87, where he showed a railroad time-vs-location chart and commented (roughly): "This is what they use to run the Shinkansen [the Japanese 120+ MPH trains]. In the control room in Tokyo there's an electronic version of this. If a red light comes on, that means a train is one minute behind schedule, and somebody is in big trouble. [dramatic pause] Amtrak thinks everything is fine if the train gets to the end of the line within five minutes of schedule, regardless of what happens at intermediate stations." -- NASA is to spaceflight as the | Henry Spencer at U of Toronto Zoology US government is to freedom. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
cram@sunpix.UUCP (Marc W. Howard) (07/07/89)
In article <852@anise.acc.com>, lars@salt.acc.com (Lars J Poulsen) writes: > In article <7263@cg-atla.UUCP> welch@cg-atla.UUCP (John Welch) writes: > > SECAM stands for Systeme Electronique Couleur Avec Memoire. > > PAL ... Phase Alternation ,or alternating Line > > NTSC = Never The Same Color :-) > >This info was culled from the Raster Graphics Handbook put out by > >Conrac. > > Back around 1965 or so, when Europe was all aflame with political wars > about selecting TV color systems, I heard: > > NTSC = Never Twice Same Color > SECAM = Supreme Effort Contre Americains > PAL = Phase Alternating Line > Pardon moi! Everyone knows that SECAM stands for: System Engineered Contrary to American Methods (I heard a good one for PAL many years ago but forgot it) P.S. I remember reading in a book about the era that Moscow was almost set to choose NTSC (again, no problems with receiving captialist pig broadcast from western European dogs). RCA moved a full demonstration setup there. Unfortunately for them, the State and/or Defense departments decided that the VTR head technology that Ampex had developed to too "sensitive" for export to Russia. The French had no qualms about that and the rest is history. Marc W. Howard Sun Microsystems Visualization Products Res. Tri. Park, NC cram@sunpix
Ploni.Almoni@mailcom.FIDONET.ORG (Ploni Almoni) (07/09/89)
I thought that everyone knew that:
SECAM = System Electronique Contre (les) Americains
and that:
PAL = Pray And Learn !
Adeiu et/und Guten Tag !!
-=Ploni=-
--
Via apple!mailcom, Fido 1:204/444Ploni.Almoni@f444.n204.z1.FIDONET.ORG (Ploni Almoni) (07/09/89)
I thought that everyone knew that:
SECAM = System Electronique Contre (les) Americains
and that:
PAL = Pray And Learn !
Adeiu et/und Guten Tag !!
-=Ploni=-
--
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Help Line Questions: help@bmug.fidonet.orgPloni.Almoni@f444.n204.z1.FIDONET.ORG (Ploni Almoni) (07/09/89)
Allo M'sieu' Marc --
The WHOLE WORLD knows that:
SECAM = System Electronique Contre (les) Americains
while:
PAL = Pray And Learn !!
In the mid-60s I was a consultant to a foreign government (EBU member)
and was very involved in the politics of how standards were chosen. It
had very little to do with the technology, and very much to do with how
Kennedy was viewed in the Soviet Union. The RCA story, however, has the
odor of truth to it.
Adieu et/und Guten Tag !! (The next round we may all be saying
"Sayonara")
-=Ploni=-
--
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Help Line Questions: help@bmug.fidonet.orgPloni.Almoni@mailcom.FIDONET.ORG (Ploni Almoni) (07/09/89)
Allo M'sieu' Marc --
The WHOLE WORLD knows that:
SECAM = System Electronique Contre (les) Americains
while:
PAL = Pray And Learn !!
In the mid-60s I was a consultant to a foreign government (EBU member)
and was very involved in the politics of how standards were chosen. It
had very little to do with the technology, and very much to do with how
Kennedy was viewed in the Soviet Union. The RCA story, however, has the
odor of truth to it.
Adieu et/und Guten Tag !! (The next round we may all be saying
"Sayonara")
-=Ploni=-
--
Via apple!mailcom, Fido 1:204/444pjd@hpuxa.ircc.ohio-state.edu (07/22/89)
I would like some adivce/references about compatibility/incompatibility between the NTSC and PAL color TV systems. I have several questions like: Are b/w receivers built for the NTSC and PAL markets compatible? B/w signals recorded on VHS tapes? Are there any add-on products that let you see VHS tapes recorded with NTSC signals on PAL systems? Are VHS VCR's compatible, or do they have special components directed toward the interpretation of NTSC or PAL signals? I'm not sure whether this is the right newsgroup for this issue, so recommendations in that direction are also welcome. Thanks. Peter J. Dotzauer