BHB3@PSUVM.BITNET (08/04/89)
Does anybody know hwat the loewst cost device that would generate a 60Hz video sync signal would be. Preferably it would be best crystal locked. I have already tried the sync out from a commercial RCA video camera. It didn't work well enough. I was able to borrow a digital time base corrector and the sync sigal for it worked. The specific application is an Ardent Workstatio computer. The RS-170(NTSC) output from it requires that you put in a external sync signal.
cook@stout.ucar.edu (Forrest Cook) (08/05/89)
In article <89216.120136BHB3@PSUVM> BHB3@PSUVM.BITNET writes: >Does anybody know hwat the loewst cost device that would generate a 60Hz >video sync signal would be. ... >The specific application is an Ardent Workstation computer. >The RS-170(NTSC) output from it requires that you put in a external ???????????? >sync signal. RS-170 and NTSC are very different color signals, RS-170 uses separate R G and B lines and NTSC puts it all on the same signal. In 3 wire RS-170 setups, the sync signals (negative pulses) are often sent along the same line as the green video signal (positive waveform) during retrace. A fairly simple comparator circuit set to trigger on the Vsync level should work as a Vertical Sync Separator. It is best to look up some kind of RS-170 spec (preferably from Ardent in your case) to get the exact specs on the signal. ^ ^ Forrest Cook - Beware of programmers who carry screwdrivers - LB /|\ /|\ cook@stout.ucar.edu (The preceeding was all my OPINION) /|\ /|\ {husc6|rutgers|ames|gatech}!ncar!stout!cook /|\ /|\ {uunet|ucbvax|allegra|cbosgd}!nbires!ncar!stout!cook
leach@neptune.uucp (Tom Leach) (08/05/89)
In article <3881@ncar.ucar.edu> cook@stout.UCAR.EDU (Forrest Cook) writes: >In article <89216.120136BHB3@PSUVM> BHB3@PSUVM.BITNET writes: >... >>The specific application is an Ardent Workstation computer. >>The RS-170(NTSC) output from it requires that you put in a external > ???????????? > >RS-170 and NTSC are very different color signals, RS-170 uses separate >R G and B lines and NTSC puts it all on the same signal. Nope, I think that you got that switched around. RS-170A refers to an NTSC-encoded composite signal. You can use and encoder to take component RGB signals and convert them into a RS-170A signal, but the RS-170 is definately an NTSC signal. (Feb 89 iss of AV Video has a short piece on RS-170A and RGB in the Q&A column) Tom Leach Internet:leach@OCE.ORST.EDU UUCP:{tektronix, hp-pcd}!orstcs!leach ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Middle-of-the-road, man, it stanks. Let's run over Lionel Richie with a tank. >>>Disclaim: It's me, not OCE.<<< B. Catt, Deathtongue. (c 1986)
poynton@vector.Sun.COM (Charles A. Poynton) (08/05/89)
> Does anybody know what the lowest cost device that would generate a 60Hz > video sync signal would be. To cut a long story short, I suggest a VIDI/O BOX (TM) from Truevision, Inc. 800-858-8783, list $995. Certainly crystal stability will be required for your application (therefore you need 59.94 Hz field rate, not 60 Hz). Just horizontal and vertical 4 V 'sync' might work, it depends on the device being fed, but I suggest (and the VIDI/O BOX provides) 1 V "black burst" which includes colour burst and pedestal, and is in fact exactly a legal black video signal. All respectible (broadcast or industrial) video equipment will free-run and generate legal timing in the absence of reference video in, this may or may not be true of your workstation. I suspect that your workstation requires reference sync only so that an external sync generator can generate subcarrier locked to the sync. This is to allow you to externally encode a coherent NTSC colour signal, that is, a signal in which the colour subcarrier is phase-locked to the horizontal sync. The VIDI/O BOX includes an encoder. I suspect that your workstation outputs is colloquially called "RGB with RS-170-A timing" and not what you refer to as "RS-170(NTSC)"; the distinction is the subject of a following article. C. ----- Charles A. Poynton Sun Microsystems Inc. <poynton@sun.com> 2550 Garcia Avenue, MS 8-04 415-336-7846 Mountain View, CA 94043 "Japan has no laws against damage to its flag, but it has strict laws forbidding the burning of foreign flags lest this give offense to the country in question." -- The Economist, July 1, 1989, p. 19. -----
mmm@cup.portal.com (Mark Robert Thorson) (08/06/89)
I'm not really sure I understand your question, but if you want a source of a composite sync signal, you can use the National Semiconductor MM5320 TV camera sync generator chip (if they still make it). It outputs a composite sync signal. It can be sync'ed up to an external signal. Ferranti also makes a composite sync generator, but I don't recall if it can be sync'ed up to an external signal. I believe it can. The National chip is much cheaper, unless you count the cost of a -12V power supply. (Ferranti is 5V only.) I haven't heard of National re-casting the 5320 in n-MOS. It would be a sensible thing to do. I've worked with the p-MOS version. Here are some tips: 1) The outputs are TTL compatible, but they're not TTL. They pretty much swing between near +5 and near -12. This is important to know if you are designing a resistor summer to mix the sync with the video. 2) This chip really surges on the power consumption at certain points in its cycle. You need a good-size decoupling capacitor on the -12 supply right near the chip. I used 22 uF. 3) This chip runs hot. Take appropriate precautions. THe last time I bought chips, it was from Advanced Computer Products somewhere near LA. Half the chips didn't work. They ignored my requests for a refund. I do not recommend doing business with them.
jimc@iscuva.ISCS.COM (Jim Cathey) (08/07/89)
In article <3881@ncar.ucar.edu> cook@stout.UCAR.EDU (Forrest Cook) writes: >RS-170 and NTSC are very different color signals, RS-170 uses separate >R G and B lines and NTSC puts it all on the same signal. RS-170 is monochrome. Isn't the 3-wire RGB RS-170-like video spec RS-343? I can't remember anymore. +----------------+ ! II CCCCCC ! Jim Cathey ! II SSSSCC ! ISC-Bunker Ramo ! II CC ! TAF-C8; Spokane, WA 99220 ! IISSSS CC ! UUCP: uunet!iscuva!jimc (jimc@iscuva.iscs.com) ! II CCCCCC ! (509) 927-5757 +----------------+ "With excitement like this, who is needing enemas?"
rpw3@amdcad.AMD.COM (Rob Warnock) (08/08/89)
In article <21056@cup.portal.com> mmm@cup.portal.com writes: +--------------- | I'm not really sure I understand your question, but if you want a source | of a composite sync signal, you can use the National Semiconductor MM5320 TV | camera sync generator chip (if they still make it). It outputs a | composite sync signal. It can be sync'ed up to an external signal. +--------------- Ah, yezzz... used it once in a project I was doing... Jameco (a local/mail_order distributor) still carries it; cost is about $12 each. But it's listed as a "closeout item, will not be reordered". (But it's been listed that way for over a year now...) +--------------- | ... The National chip is much cheaper, | unless you count the cost of a -12V power supply. | ...some tips: | 1) The outputs are TTL compatible, but they're not TTL. They pretty much | swing between near +5 and near -12. This is important to know if you are | designing a resistor summer to mix the sync with the video. +--------------- Or if you want to feed something other than TTL, like CMOS. The current that's sourced from the -12 supply can blow CMOS inputs (or even blow the whole chip by causing the CMOS to go into "latch-up"), so use a "real" TTL or LS-TTL chip as a buffer first. The National chip's outputs are actually *designed* to use the input undershoot diodes of the following TTL input as a clamp on the output voltage. (Ugh!) +--------------- | 2) This chip really surges on the power consumption at certain points in | its cycle. You need a good-size decoupling capacitor on the -12 supply | right near the chip. I used 22 uF. | 3) This chip runs hot. Take appropriate precautions. +--------------- Ottherwise, it works o.k., I guess... But for just those reasons, plus the uncertainty about future availability, I gave up using it and built a PROM/counter-based circuit instead. A naive version would use 455 x 525 locations (clocked at Color-Burst x 2), but you can do what the National chip does and clock at (CB * 4) / 7 = 2.045454286 Mhz which gives 130 clocks per H line, or 130 x 525 = 68250 locations in the PROM. [Note that "CB*4" is supplied on the bus of most IBM PC clones.] Since most EPROMs are 8 bits wide, you can use some of the extra bits that you wouldn't need for outputs to do some run-length compression, which lets you pack the pattern into a 4Kx8 EPROM (2732 or equiv). [A slightly simpler counter circuit uses more ROM but still gets it into a single 2764 EPROM, at about the same price. You also get an extra usable output, which I use for a "test pattern".] Using a 29C64 EPROM and 74HCTxxx counters, the power drain is pretty low. The total parts cost is *less* than the National chip, though the board area is greater. Besides, you get to completely choose the outputs. The outputs I needed were NTSC composite sync, NTSC composite blanking, start_of_line (similar to H_sync, but keyed at the edge of blanking), start_of_field (similar to V_sync, but keys on at line 22), and "test_pattern". (The other three bits go back to the first counter section and control how many clocks to repeat each output pattern.) If you feed the composite sync, blanking, and test pattern outputs to a simple resistive adder, you get an analog output monochrome composite-video test pattern. Using a bigger PROM, you could use an address bit to select between several patterns stored in the ROM, for example, between NTSC and PAL. More details if anybody really needs them... Rob Warnock Systems Architecture Consultant UUCP: {amdcad,fortune,sun}!redwood!rpw3 DDD: (415)572-2607 USPS: 627 26th Ave, San Mateo, CA 94403
brown@astroatc.UUCP (Vidiot) (08/09/89)
In article <26659@amdcad.AMD.COM> rpw3@amdcad.UUCP (Rob Warnock) writes:
<
<Otherwise, it [MM5320] works o.k., I guess...
Yep, the part works just fine. I use it to drive the sync inputs on the
3/4" Umatic decks that I use for editing (through a TTL buffer). I also
have a sync separator part that I use to set off a one-shot to resync the
sync generator every frame. The one shot is used because the timing of the
signals available do not exactly match what the generator needs, but since
one of them is early enough, I put it through a one-shot.
The problem with the 3/4" Sony decks (older ones) is that when the input
video is used for sync, a very minor glitch will cause the recorder to
lose gen-lock. It is worse when editing and the source tape is used as the
sync source. So, by feeding external sync into both decks, there isn't a
sync separator problem in the 3/4" deck. I looked at the internals of the
3/4" and noticed that the composite video signal used as sync was about
1/5th of the size of external TTL sync. This extra level internally provided
enough to keep glitches from screwing things up.
I use the sync separator to take in video signals from the TV and provide
re-sync for the sync generator. This keeps minor glitches from screwing up
the 3/4" deck when recording off-the-air stuff. Also, the one-shot is such
that it finishes a short while before the next frame starts, keeping random
glitches between frames was causing random re-syncs. Of course, massive
changes in original sync timing will still cause glitches. If only I had
a frame-store unit :-)
--
harvard\ att!nicmad\
Vidiot ucbvax!uwvax..........!astroatc!brown
rutgers/ decvax!nicmad/
ARPA/INTERNET: brown%astroatc.UUCP@spool.cs.wisc.edustevel@tybalt.caltech.edu (Steve Ludtke) (08/10/89)
If you just need a simple sync signal, and you have some sort of video source, the LM1881 is an excellent choice. It's pretty new; it provides composite sync, vertical sync, burst/back porch, and odd/even frame output, all in a 8 pin package. It takes any NTSC (might deal with PAL too) video signal as an input, and requires only 3 external components and a +5 thru +12 volt power supply. I've tried it with a number of video sources for genlocks, video decipering, etc ... and it's worked quite well. Even better, they only cost $4-6 each. I've seen a number of different scemes for accomplishing the same thing as this single chip. It usually involved several IC's and numerous resistors and cap's, and was usually less reliable than this. In any case, it's made by national, and might be worth looking into. --------------------------------------------------------------------------- Steve Ludtke stevel@tybalt.caltech.edu ..!cit-vax!tybalt.caltech.edu!stevel stevel@citiago (Bitnet) OBS949 (Amer PPl lnk) 72335,1537 (Compuserve) XJM16487 (Genie)
king@dciem.dciem.dnd.ca (Stephen King) (08/12/89)
In article <11525@cit-vax.Caltech.Edu> stevel@tybalt.caltech.edu.UUCP (Steve Ludtke) writes: >If you just need a simple sync signal, and you have some sort of video source, >the LM1881 is an excellent choice. [...] >I've tried it with a number of video sources for genlocks, >video decipering, etc ... and it's worked quite well. Even better, they >only cost $4-6 each. [...] Another interesting component is (was) the Motorola MC1378 video overlay synchronizer. Put NTSC in and get everything out, including phase locked 10xSc clock (35.8 Mhz). External circuitry has to feed H sync back to the chip - we accomplished that with one PAL. The thing also had RGB and overlay enable inputs. Anyway, what we worked with was a pre-production sample (labelled XC1378), and I haven't heard whether or not these things ever made it to full production. Anyone got more info? -- Se non e` vero, e` ben trovato ...{utzoo|mnetor}!dciem!dretor!king king@dretor.dciem.dnd.ca
mmm@cup.portal.com (Mark Robert Thorson) (08/12/89)
If you do as Rob Warnock suggest (use a counter to drive a PROM to generate your sync signals) you may need a reference for the TV sync signal itself. I once got an excellent booklet on the timing of standard TV signals for free from the local Tektronix representative. I believe the book was called TELEVISION BROADCAST MEASUREMENTS. It is a book intended for the engineer at a TV station, and tells what measurements you need to take, and how to take them, in order to comply with FCC standards.