I haven't got 10x10x20.
FYI I'm on 35Mhz and separate but I'm determined to get this to work.
Isn't 35MHz an air frequency in UK, thus illegal for ground use? That said, I am guessing that the Micron Falcon, at L 22mm, W 15mm, H 7mm, and £15.95 is too large, while the tiny MicroInvent series from
http://www.micronradiocontrol.co.uk/mi_radio.html are too dear at close to £60 (though one model has two ESC's built in, one of which would be dandy for the laser, methinks).
While we are at it - another potential solution. Use the Picaxe to read the pulsin and generate a serial output to a standalone, dedicated, serial servo controller like the tiny ones from
http://www.pololu.com/catalog/category/12 - which also come as kits that can be built even smaller, or even a preprogrammed, dedicated PIC (though, once you build it into a system, it will likely be larger than the micro SSC, which uses surface-mount components).
If you cannot fit one of the smaller radios, the Picaxe is going to be a challenge as well, mayhaps.
Another thought - have you considered making the turret ring and a brush or two the 4th connector while using your current 3-pole for the other 3? Personally, I think I would make it V+, as the servo only needs signal and ground for its commands (though it needs V+ to operate) - or putting a battery in the turret somewhere to operate the servos there, then all you need to communicate with the radio is G, S1 and S2.
All of that said, since you are wanting to do it with a pair of Picaxes, do be careful to realize the relationship of the word and byte variables - forgetting that B0 and B1 are parts of W0 has been known to screw people up (has me, at least). May be wrong, but I seem to recall Pulsin wants to store its result in a Word variable.
Also, if you do the routine that Hippy suggested (great implementation for Serial, by the way), you will want to use the Servo out instead of Pulsout, as it loses some of the RX's timing.
Also, there are 4 pole rotary connectors out there - and example being
http://www.wirelinetech.com/Rotary-Connectors.php or
http://www.mercotac.com/html/products.html
Methinks that with the relationship of the Servo Command to Serial communications, getting constant serial communications in every 20MS is going to wreak havoc on trying to get the final servo out signal timed right.
Also, haven't done the maths, but I wonder how long it takes to transmit/receive the serial commands you are using relative to the pulse train - the back of my brain is itching, trying to tell me something may be a "bad thing." Of course, it could be just needing to wash my hair.
I am thinking bitbanging your own pulses might be a better solution in this situation, if you do not want to go to a 4 ring connector. One possibility - the normal pulse is , say 75-225 for elevation (may be more like 100-200). If you want laser on, set the pulse +200. Then in the received Picaxe at mid elevation you will have two possibilities of pulse length - 150 or 350. If the pulsin > 225, elevation is pulsin-200, laser is on. If pulsin <225, elevation=pulsin, laser is off. Then you only need the connector you have - G, Pulscomstream, V+, and no serial communications issues.
Lots of possibilities.
Cheers,
Wreno
PS - OT, but for those who have followed my warship exploits - My son had to go to a meeting just as the battle was getting ready to commence Sunday, so I battled the Dunkerque for him. Keep in mind that I have never battled an armed ship - I drive freighters - my job is to be the rabbit/fox in the hunt.
Surprisingly, I did not embarrase myself. Though I was sunk (low on battery juice and stiff motors caused the ESC to shut down a time or two, and pump failed - mostly maintenance issues I plan to rectify - my responsibility), it was at the hands of a really good skipper with one of our best ships, the USS Missouri (he generally wins one of the top 3 spots in engineering, maneuvering, and gunnery at our nationals). And I got in first licks! He singlehandedly took on and sunk the Axis fleet that day, so I was in good company. I had 7-8 ea 1/4" holes above, 2 on, and 3 below the waterline. Yes, I was first to succumb, but tickled with my performance nonetheless. Accomplished my mission - to run interference for DKM Lutzow - for a while, anyway.