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Silver Dream ! <email@domain.com>: Mar 16 07:55PM +0100 Hi group! I am looking for documentation that would clearly say what colour is expected at which phase difference between the reference phase (colour burst) and the actual signal subcarrier phase in given time. Sure, I can connect generator to a vectorscope and measure it, but I am looking for the official source/documentation that engineers who needed to build colour decoders back then had to use. Any clues?   -- SD!

Jeff Urban <jurb6006@gmail.com>: Mar 16 07:48PM -0700 From what I've read PAL is very similar to NTSC. It has a scheme with a comb filter that makes a phase (tint) control unnecessary, 50Hz frame rate rather than 60 and a higher horizontal rate resulting in more lines in the raster. (your spelling says you are across the pond)   The burst phase is considered -I, where I is 180º out that is blue or actually B-Y, which is blue without the Y component which is what the black and white signal is called here. For red there is Q for quadrature which is 90º out of phase with the I and therefore the two do not interfere with each other. our vector algebra will tell you that a mixed 90º signal with the original phase does not affect the amplitude. Thus you get two discrete signals from one carrier. In the US it is 3.579545MHz which inherently causes interlace, I imagine the PAL carrier, which I think is 4.43MHz accomplishes the same in PAL.   A vectorscope would give you the data. It is a bit easier to see when you have a phase control. You DO but it is not user adjustable because of the system making undesirable phase shifts cancel each other out.   These color levels and phases are selected due to several factors having to do with visual perception. They also match the contour - for lack of a better word - to the makeup of the Y signal. It is not 33%, 33%, 33%, it is actually mostly green. Thus the -Y for the green is the least precedent in comparison.   The I and Q do not exactly match red and blue for whatever reason. They are a hair off, so many manufacturers went with a different demodulation angle than 90º, usually wider like 105º or whatever.   In the US the I signal is transmitted with a wider bandwidth and there are rare receivers that can use that. It requires an extra delay line. Also with that the only choice is true I and Q so whatever matrixing that has to be done falls on the engineer. Very very few units had that. I do not know if anything similar to that exists in the PAL system.   The bottom line is that I is blue and Q is red. Green was derived from those usually here, not demodulated itself.   I have worked (in the states) on some sets that had PAL capability but it was mostly all in chips so further detail would have to come from a manufacturer training courses or the standards committee of the government.   So you may gloat that your analog color TV system was better than ours, however it is based on the same principles. Also your PAL, phase alternate by line system's one advantage depends on the comb filter, which I BELIEVE was invented or at least made practical by Sony for the color under home video recorder format.   But we had it first. And from what I heard the Russian system was the worst.   Now the French developed system called SECAM, I really have little to no idea how that works. However the US was first and the government insisted on compatibility with the kagillions of black and white sets out there in use. I think PAL also has that capability but I doubt it with SECAM.   Still, we invented the dot matrix color CRT without which all this would be impractical. All color TVs would be projection of some type and that means three CRTs. We did use that scheme quite a bit for projection TVs but it took much better technology to accomplish it. I was one of the few who really knew the convergence (registration) circuitry in those things and that was my job for some time.   Form what I recollect, which means was told, the first color broadcasts were in the CBS system which was not compatible. Separate carriers for each of the three primary colors. Used on the moon. Funny now that we are back to that. What do you think is on them HDMI cables or comes out of the switcher ? Three channels, one for each color.   Anyway, the compatible NTSC system owes something to FM stereo which uses a very similar approach but no Q carrier.   In parts of Europe they used to call the NTSC system Never The Same Color but that was more due to engineers taking liberties with the accuracy of the design. For one the wider angle >90º actually had the benefit of auto flesh tone. When the phase was a bit of the red and green wound up demodulated differently and the phase shift affected the picture less. And their attitude was "Who cares if a wall is aqua or blue ?". They actually concerned themselves much less with accuracy than with producing a picture pleasing to the eye. Sony was one major exception. Their attitude was to go for the accuracy and if the customer has to adjust the tint (phase) control so be it, but you KNOW if the wall is blue or aqua. It also got pleasing real quick like and other sets with all these liberties taken in the design started having their own "look". That was mostly brown and blue. When people saw the Sony after watching all this faux color they liked the fact that it seemed to have a better range of colors. It is like speakers in a way, if everything sounds the same it is not high fidelity. That is the US forya. In fact one manufacturer chose different phosphors for their CRTs to look better under the lights at a supermarket or big box store. Then you got it home and like, ewwww.   The BBC bought up the rights to a bunch of Star Trek TNGs. I wonder if they got the original series. The test of a TV color system ? Is Spock green and everyone else normal color ? I shit you not. they only put a little bit of green tint on him so many TVs displayed the same color. Sonys, certain RCAs, Zeniths, they were the main ones to give at least somewhat accurate color rendition.   We had an RCA, one of the good ones - a CTC25 chassis.   Enough. This is probably more information than you wanted. (I am an expert on the NTSC system) But you can prove it all with the vectorscope. All you need to do is to find a way to vary the phase of the subcarrier a bit to see what happens. It will come clear.

Fred Smith <fred@thejanitor.corp>: Mar 17 03:00AM > In parts of Europe they used to call the NTSC system Never The Same Color   NTSC: Never Twice Same Color   SECAM: System Essentially Contrary to AMericans   PAL: Perfect AT Last.

Jeff Urban <jurb6006@gmail.com>: Mar 17 12:20AM -0700 Fuck you ! LOL   No offense intended, this time...

Silver Dream ! <email@domain.com>: Mar 17 10:20AM +0100 On 2020-03-17 02:48:00 +0000, Jeff Urban said:   > From what I've read PAL is very similar to NTSC.   Colur encoding concept is the same.   > It has a scheme with a comb filter that makes a phase (tint) control > unnecessary,   It inverts phase every other line so that phase errors cancel each other out when summed.   > 50Hz frame rate rather than 60 and a higher horizontal rate resulting > in more lines in the raster. > (your spelling says you are across the pond)   :-)   > amplitude. Thus you get two discrete signals from one carrier. In the > US it is 3.579545MHz which inherently causes interlace, I imagine the > PAL carrier, which I think is 4.43MHz accomplishes the same in PAL.   Yes, the PM variant of QAM modulation is used in both. The differences are in frequencies and PAL error cancellation.   > manufacturer training courses or the standards committee of the > government.   > So you may gloat that your analog color TV system was better than ours,   It was better in terms of colour fidelity and resolution. It was worse in terms of flickering, due to lower refresh rate and some el cheapo decoders being employed too often.     > But we had it first. And from what I heard the Russian system was the worst. > Now the French developed system called SECAM, I really have little to > no idea how that works.   Instead of a variant of QAM modulation to encode U and V (I/Q) it sends the two in sequence, one per each line.   > However the US was first and the government insisted on compatibility > with the kagillions of black and white sets out there in use. I think > PAL also has that capability but I doubt it with SECAM.   All three have. The requirement was the same everywhere.   [...]   > expert on the NTSC system) But you can prove it all with the > vectorscope. All you need to do is to find a way to vary the phase of > the subcarrier a bit to see what happens. It will come clear.   Yeah, thanks - the thing is though: I can measure this with somewhat reasonable accuracy by sending pure R/G/B on to vectorscope and this will tell me how _does_ the generator encode the signal. What I am looking for though is the official/norm/standard specification telling how it _should_ encode it.   If chroma phase in reference to burst phase is the hue, what is the colour of 0 degrees, what angle should pure red, green, blue lie at in reference to the burst. You say "it's a hair off". Why so? Etc. Something like a real standard specification.   -- SD!

tabbypurr@gmail.com: Mar 17 04:38AM -0700 On Tuesday, 17 March 2020 02:48:03 UTC, Jeff Urban wrote:     > The BBC bought up the rights to a bunch of Star Trek TNGs. I wonder if they got the original series. The test of a TV color system ? Is Spock green and everyone else normal color ? I shit you not. they only put a little bit of green tint on him so many TVs displayed the same color. Sonys, certain RCAs, Zeniths, they were the main ones to give at least somewhat accurate color rendition.   > We had an RCA, one of the good ones - a CTC25 chassis.   > Enough. This is probably more information than you wanted. (I am an expert on the NTSC system) But you can prove it all with the vectorscope. All you need to do is to find a way to vary the phase of the subcarrier a bit to see what happens. It will come clear.     We got the UK PAL system 10 years later than the US, it was effectively the mark 2 version of NTSC.   Re B&W compatibility, it was, but PAL colour was totally not compatible with the B&W standard it replaced. The older standard (adopted in the 1930s) was 405 lines, positive modulation, VHF transmission and AM sound on a separate broadcast frequency. 625 line PAL was -ve video modulation, UHF carrier, embedded FM sound. For a while there were dual standard sets with a huge sliding switch that ran the length of the main PCB.   Re dot matrix tubes, there were previous non-projection systems that were never popular. There was the colour wheel, a 3 colour filter wheel than spun on front of a B&W CRT giving field sequential colour. And there was the spinning mirror type, effectively an upgraded nipkov-esque system. That approach is still used in laser printers.   The first colour TV was nipkov type in the 1920s. Not a widley rolled out standard though.   'Never The Same Colour twice' was what I always heard. PAL certainly wasn't perfect but it was a significant upgrade.   Re colour setup, most PAL TVs were much the same but some sets were quite off. I never found out whether that was due to decoder or differing phosphors. I remember a minority of sets giving a rather yellowy green in lieu of green - the overall result was a quite pleasant warmer picture but it wasn't accurate.   I designed an analogue NR system that was effective at addressing noise in dark picture areas, PAL's biggest shortcoming, but that was just before digital took over so went nowhere.   Delta tube sets typically didn't converge accurately. That marred resolution as well as giving miscoloured fringes. It did not look good. The Sony tube really solved that. Also its higher output enabled more tinting giving better contrast as well as brighter picture. And less curvature meant less geometric distortion. Plus the Sonys were generally significantly lower video noise sets. OTOH early Sony colour sets used a throwback tuning knob, no channel preselectors. Sonys were also the only PAL sets I know of to have a tint control.     NT

Stephen Wolstenholme <steve@easynn.com>: Mar 17 12:06PM >Re colour setup, most PAL TVs were much the same but some sets were quite off. I never found out whether that was due to decoder or differing phosphors. I remember a minority of sets giving a rather yellowy green in lieu of green - the overall result was a quite pleasant warmer picture but it wasn't accurate.   I worked on TV when PAL was introduced in the UK. I set up a NTSC set and a PAL set so they could be compared. PAL was clearly the better system.   Steve   -- http://www.npsnn.com

N_Cook <diverse@tcp.co.uk>: Mar 17 12:18PM On 17/03/2020 12:06, Stephen Wolstenholme wrote: > and a PAL set so they could be compared. PAL was clearly the better > system.   > Steve   Hence the term Never The Same Color   -- Monthly public talks on science topics, Hampshire , England <http://diverse.4mg.com/scicaf.htm>

Chuck <chuck23@deja.net>: Mar 17 11:01AM -0500 On Tue, 17 Mar 2020 12:06:42 +0000, Stephen Wolstenholme >and a PAL set so they could be compared. PAL was clearly the better >system.   >Steve   When I came to the UK from the states, the 50hz flickering annoyed me. Did natives notice the flicker?

N_Cook <diverse@tcp.co.uk>: Mar 17 11:57AM Consulting a couple of medics about this, they seem to be as much in the dark about this and just use what they are given.   With no hand-sanitizing gel available anywhere, use methylated spirits or isopropal alchohol, decanted into a small bottle , to reduce any fire hazard, when used in public places. My attempts at gelling meths just ended up with snot/slime.   Converting a one-way valve-type dust mask , with strong cords around the back of the head. Cover the outer surface with micro-fibre cloth that you can spray coronavirus-specific disinfectant to. To hold the cloth in place:10 mm /3/8 inch silicone sleeving, length of the periphery. Cut axially and staple the join, the bit of overlap giving just the stretch to hold in place and pull out the ruckles from curving the sleeving.   Converting over-the-specs type of basic plastic goggles to a closer fit. Again the same sleeving. With a slivver of wood or something pushed along inside the sleeving , punch a line of holes. Then lines of hotmelt glue along the goggles edges, squashing the sleeving onto the glue, some of it splurging thru the holes for holding the silicone in place.   Any other idea?   As I was never anything to do with medical electronics, are hospitals likely to have a store of non-working ventilators,for parts-doning, that a group of volunteer retired electronic repairers could volunteer to try to get going again?   Ignor ethe sig, cancelled for the duration, like all the other local scicafs, talks series, repair cafes and similar presumably     -- Monthly public talks on science topics, Hampshire , England <http://diverse.4mg.com/scicaf.htm>

"pfjw@aol.com" <peterwieck33@gmail.com>: Mar 17 08:01AM -0700 a) It is not a matter of IF, but WHEN. b) 'Social Isolation' will slow, but not stop the spread of the virus. c) And the point of slowing it is to reduce the stress on the healthcare infrastructure. d) Which will allow for better care for those who are ill. e) But, again, not stop the spread.   As to hand sanitizer - alcohol concentration, whatever the fraction, must be at/over 60%. And it does not take much.   As to masks, they help ONLY those who are already infected from spreading the disease from coughing, that is airborne droplets. Consider the size of a virus (smaller than a micron) and then consider exactly how a mask will screen it out of the air you are breathing. Similarly, goggles.   Isolation suits are a different deal altogether, self-contained, and sealed. Short of that, never mind.   So, social isolation, common sense, clean hands, limit unnecessary travel, eat well.   Peter Wieck Melrose Park, PA

legg <legg@nospam.magma.ca>: Mar 16 02:01PM -0400 On Tue, 25 Feb 2020 14:56:26 -0800 (PST), Michael Terrell   > When I started working in a TV shop in the mid '60s, every bench had a switch to shut off all power. It had two intended uses. A way to kill a bench if someone was being shocked or something was arching, and to turn off everything when the bench wasn't being used. They were mounted on the ends of the benches, where there was nothing to block access. My shop has each light fixture on its own switch, so all the tools and test equipment are powered down when I leave and turn out the lights. All of these are switched by the main door, so they are easy to get to.   > This is similar to the General Electric switches we used back in the '60s. They can be padlocked if you don't want anyone to use the bench when you aren't there.   ><https://www.homedepot.com/p/Siemens-General-Duty-30-Amp-240-Volt-1-Pole-Fusible-Safety-Switch-with-Neutral-LF111N/205623361?mtc=Shopping-VF-F_D27E-G-D27E-27_8_CIRCUIT_PROTECT_DEVICES-Generic-NA-Feed-PLA-NA-NA-CIRCUIT_PROTECT_DEVICES&cm_mmc=Shopping-VF-F_D27E-G-D27E-27_8_CIRCUIT_PROTECT_DEVICES-Generic-NA-Feed-PLA-NA-NA-CIRCUIT_PROTECT_DEVICES-71700000033149223-58700003867184469-92700048703482864&gclid=Cj0KCQiAqNPyBRCjARIsAKA-WFzSjmPf4oH9mo9HqD0H-giB1l_uK4ZN43EVnuJb8xHeTP1UwiYu F7UaArVpEALw_wcB&gclsrc=aw.ds>   This bench HAS a power switch. Unfortunately, it has to be on, to run anything.   You can't shut it off as a prevention for a soldering station to spontaneously go up in smoke. You CAN turn it off, if there's something burning on the bench.   This is also hooked up to a dead man harness. . . . but then that's probably too late. Power labs are advisedly no-lone-operator environments.   Best to restrict line-powered tools to those with safety approvals.   RL

Michael Terrell <terrell.michael.a@gmail.com>: Mar 16 04:53PM -0700 On Monday, March 16, 2020 at 1:56:28 PM UTC-4, legg wrote: > no-lone-operator environments.   > Best to restrict line-powered tools to those with safety > approvals.     Or at least make sure they are properly fused. I bought one of those heat sealers for plastic bags last year. It didn't work, so I opened it up Both wires to the spring loaded power switch had cold solder joints and one had cracked off in shipping. I always look into the design of imported equipment to look for safety hazards. Just because a case has some safety stick on it doesn't mean that it was properly built in a foreign factory.   We had a new employee miswire the IEC power connector on a chassis. She had the AC line connected to the chassis, and the ground wire connected wrong as well. The tech who knew better plugged it in without looking at the wiring. When it didn't turn on, He leaned over to look into the chassis as he touched the chassis and a grounded piece of test equipment. H got a really nasty shock that he could have avoided. If it hadn't knocked him on his ass, it could have killed him.

Ralph Mowery <rmowery28146@earthlink.net>: Mar 16 12:48PM -0400 In article <t49v6flk2rsb7529d6pulfv8ai6at9taav@4ax.com>, etpm@whidbey.com says... > instantly. I would expect this with a single phase motor but not 3 > phase. > Eric   Have you tried measuring the current on each leg to see if they are ballanced ?   Along the same line, measure the voltage to see if all 3 legs are being fed with the same (with in a couple of volts) voltage.

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