Genlocking means locking the synchronisation pulse generators (SPG) in two more pieces of video equipment to work in phase as each other. For all intents and purposes, you're making two clocks run at exactly the same time as each other, by linking them electronically.
In the analogue world, synchronisation is required so you can mix and switch between cameras without any break up of the picture. There's simply no other option than for the equipment to all run in step with each other when you want to mix between them. You can switch between non-synchronous sources, but you'll see the picture roll or flick at every transition.
In the digitised video world, that's less of an issue. Many digital mixers will resynchronise input signals to suit themselves, however there are a couple of problems with working between non-synchronous sources that are eliminated when you do genlock the cameras together:
Mixers often can't instantly switch between non-synchronous cameras, they have to correct the sudden change in sync from the last camera to the next one, and may freeze the video momentarily, noticeably flick the image vertically, or delay the switchover. The first two are annoying to anyone watching, the last one is very annoying to the director (who can, no-longer, make camera cuts exactly when they want them).
Since the cameras are taking images at different times from each other, you get variable image delays between the different cameras. One camera could be almost a whole fifth of a second behind the other. That can be noticeable for fast action work, and ruins the use of multi-camera video split-screen images for slow motion timing measurements of sporting events.
Genlocking all the equipment, even when you think you won't need to, eliminates those problems. For digital mixers, you probably won't have to phase up the equipment, it'll usually be enough that the equipment all have the same vertical sync timing. And you could only check horizontal and sub-carrier phasing at the inputs to the mixer, you couldn't check the signal phasing through the mixer. Simply connecting black burst to everything, and doing nothing to the phasing controls, is usually all you'd need to do. It gets rid of the glitches that many small budget/no budget producers will have seen when they've used Panasonic MX-12, MX-20, MX-30, MX-50 video mixers in schools, churches, and whatnot.
In the olden days, that usually meant connecting a plethora of synchronisation signals (vertical sync, horizontal sync, blanking, sub-carrier, etc.) from a master SPG to all the equipment. But usually, these days, it means feeding black-burst to everything. Black burst is essentially the same video signal as produced by a camera with the lens cap on; black video with colour burst. More recently, a new thing called “tri-level sync” is the new reference signal, but only for equipment designed for it (such as digital and high definition video), not for the old standard definition analogue equipment (whether composite, Y/C, or component). For the F15 cameras, you want to use black burst, but you can only connect it to cameras that have one of the WV-AD36 or WV-AD37 genlock adaptor back ends, or a back end that you made yourself, the camera head doesn't have all the circuitry needed for genlocking in itself.
Using the video from a live picture or colour bars to lock equipment together is usually not a good idea. Not all equipment can handle a signal where the average picture levels keeps on changing, and you can get the genlock input video bleeding through into the output signal of the equipment. At least with black burst, there's nothing to see if that happens.
If you don't have a dedicated SPG, or a mixer that produces sync and burst signals, then you can usually use a lens-capped camera to produce black (even a completely worn out tube camera that's not useful for taking pictures any more). And even a lens-less camera head, just cover up the exposed image sensor. Though you have to be aware that some cameras, or other video equipment, produce non-standard video signals, so not everything will be suitable as a black-burst source.
Some instructions will tell you to do a split screen between a set of reference colour bars, and the camera's, and adjusting the horizontal phase so the bars line up against each other. This is a bad idea, since not all bars have the same widths or starting positions (though they should). It's the syncs that need aligning. This should be done with a waveform monitor, scope, or cross pulse (delayed sync) video monitor.
They'll also, often, say to line up the colour sub-carrier with a split screen, in the same manner, adjusting the phase until the colours look the same. That's also a bad idea. It's hard to do that correctly by eye, and you're relying on the monitor not having alignment errors (many do). You really should be using a vectorscope, and adjusting the phase until the vectors rotate into the right positions on the scope.
It probably can be done, if you feel up to some electronics engineering.
There's probably one or two other DC voltages that need setting up to place the camera into external sync mode. The back generates a regulated 1.8 volt DC supply that goes back into the head, amongst other things it's used as a reference level for various controls.
The genlock backs feed the camera head with composite sync to the Xth pin down on the left of the 32-pin connector at the back of the camera head, and a burst signal to the Xth pin down on the right of the 32-pin connector. However, the burst is all above zero volts, it's not above and below as you'd see when you look at the normal chrominance signal of the colour burst. It's possible that you could simply feed in the separated luminance and chrominance of a black burst signal from a S-Video connector, but I've not tested this. And you may need to add a DC bias to the burst signal, as it's used as a mode switch for some of the signals on the 32-pin connector.
Phasing control is separate. A DC voltage between about 2 and 6 volts is fed to the Xth pin on the right to control the horizontal phasing. The coarse sub-carrier phasing is controlled by switching a DC voltage between x or y volts on the Xth pin for 90° changes, and on the Xth pin for 180° changes. The genlock back had controls for adjusting the fine sub-carrier phasing internally, which weren't disabled by connecting a CCU (which had similar circuitry for adjusting the phasing, at the CCU end). You could probably do some fine adjustment using the colour phase control in the left hatch of the camera, although it produces strange distortions at the edges of the controls range, and needs to be tweaked using an insulated tool. You'd have to manage medium-fine sub-carrier adjustments by playing with the length of the wiring to and from the camera (depending on the cabling, that's around 20° for every 10 feet of cable), or build your own phase adjustment circuit.
Television stations have been using cable delay lines, for phasing adjustments, for many years. Especially when feeding one source to several different destinations, to avoid having to continually adjust the phasing between all of them. Though that sort of approach is really only practical for fixed installations. For variable set-ups, you'd want to do phase adjustments by adjusting the response of an electronic circuit.
Yes, it can. Although the NTSC back uses frequency filters set for 3.6 MHz and the PAL one uses filters set for 4.4 MHz, enough of the sub-carrier gets through for it to work. And the phase timing controls cover enough range for them to work, too. It's the camera head circuity that's concerned with generating the video from the camera (PAL or NTSC video encoding), the back end is just a sync separater, colour bandpass filtering, and delay circuitry, with a few controls, for the genlock signal to the camera. The video out connector is directly wired to the camera head output circuitry.
If you felt inclined, you could remove the three ceramic filters from the board, and swap them over for ones of the right frequency. But I haven't seen the need, even when running over 50 metre long cables with a bit of high frequency loss.
I don't know if the opposite is true, of using a PAL genlock back be used on a NTSC camera, but it probably will work just as well.
Yes it does, but you'll need an appropriate cable. We swapped the special 10-pin connector for a more common CCJ connector, which allowed us to add a few more useful signals (tally and line view) with common camera cables. But the original connector carries camera video, genlock, audio out, and power. (See the pinouts page.)