CCU for the Panasonic F15 video camera

There is a WV-RC35 studio CCU or RCU (camera control unit, or remote control unit) for the F15 camera, it connects to the camera through the WV-AD37 back end. And there's another WV-CR12 control unit designed for security camera type of operation, which also includes remote control of the lens, and a pan/tilt head.

These are described as using a serial control method. This isn't a digital serial data signal, like computers use, it's a sequentially switched (time multiplexed) digitisation of the different analogue control voltages [1]. The output voltage from all the CCU controls (iris, pedestal, tally etc.) is sampled, one after another, digitised with a very small number of bits [2], and fed down a single control line to the camera head. And in the head, the converse is done. A single DAC provides an analogue voltage control line that's switched between various control inputs, and a different DC control voltage will be held at each input, proportional to each of the CCU's controls. Both the CCU and head switch between the different controls at the same moment in time, every few horizontal lines, with the sequence being reset during the vertical interval.

The genlock controls are the only ones handled differently. There's an analogue sub-carrier phasing circuit in the CCU that varies the fine sub-carrier phase of the video signal going to the camera's genlock input. And there's separate DC voltages that goes to the camera, to control the camera's course sub-carrier phasing, and horizontal phasing.

This appears to be an advance on a technique used in a much older Panasonic camera and CCU, that did sequentially switch analogue control voltages down a control line, with sample and hold circuitry in the camera end.
From playing with some CCU controls, and looking at the CCU circuitry, it seems like there's only thirty-two steps of quantisation when digitising the controls. Some controls only seem to have about 16 different levels.

14 pin RCU connector on the WV-RC35 CCU and WV-AD37 back-end

Power ground
+12 volt supply
Intercom talk (CCU direct to camera operator headset mike)
Intercom receive (CCU output direct to volume knob, then to camera operator headset earphones)
Audio ground
Video out
Video out ground
Line view video
Line view ground
Serial control data
Genlock video
Serial clock / tally in (*)
Horizontal phase control
Sub-carrier phase control (coarse phasing)

* This line is 75Ω loaded in the CCU output and camera back-end, and AC coupled through buffer amplifiers at each end. The tally isn't a DC voltage on this pin. The tally moniker seems to have stuck from a description of how the (different) 14-pin VTR connector uses the same signal line in the camera head, for the VTR tally. That tally only works when in the 14-pin VTR mode, the CCU tally is one of the serially encoded control voltages. If you want the viewfinder tally light to come on, when you don't have a CCU and WV-AD37 back-end, you need to modify the viewfinder.

Unfortunately the CCU is rather poor, compared to what you'd find with a broadcast camera CCU. The manual white balance controls only have a small range of adjustment. So you couldn't really use them for a completely manual white balance set-up. Unless the camera's already close to being white balanced, you'd have to auto-white balance, then use the manual controls to slightly tweak the results of the auto-white balance. But, you might have been wanting to manually set the white balance, because circumstances make it impossible for auto-white balance to work, at all. Similarly, the pedestal control has a very limited range of adjustment, though it should be adequate for the normal range that you might tweak the black level about (unlike some CCUs, that will let you set black level up to about half luminance, for some crazy reason). Though, the biggest nuisances are: You have no manual iris control, it only lets you sway the auto-iris settings more open or closed, and it has a very slow response. And all the rotary controls are almost flush with the panel, you need a screw driver, or you have awkwardly to press your thumb against the panel to rotate them.

NB: On the camera head, in the section between the camera and where the WV-AD37 back-end plugs into, below the 32-pin connector is a +/− “run” switch. It's obvious purpose is to do with the polarity of the record-pause start/stop signal. However, it also affects the CCU operation, and needs switching up to the + position for the CCU to work. Otherwise, most of the camera head and CCU controls are disabled.