ApolloHoax.net

Apollo Discussions => The Reality of Apollo => Topic started by: Allan F on August 07, 2013, 10:12:41 PM

Title: LRV camera remote control
Post by: Allan F on August 07, 2013, 10:12:41 PM
Hi, I'm interested in the workings of the remote control system for the TV-camera on the LRV.

I'm up on the radio side of it, but what kind of mechanism did the actual pan, tilt, zoom, focus?

Was it step motors (one beep on the channel and the camera moved a certain number of degrees)?

What was the mechanical connections?

TIA
Title: Re: LRV camera remote control
Post by: Kiwi on August 09, 2013, 04:57:06 AM
Stand by until Dwight turns up -- he's the resident expert.  I had a quick look at his book "Live TV from the Moon" and there's heaps about the cameras, but couldn't see anything enlightening about the control mechanism.  Doesn't mean it isn't there though.

On page 202 Ed Fendell explains that his first job at each site was to do a pan in 3 degree increments with a pause at each so the backroom folk could take Polaroids and link them together to get a good view of the site, so that perhaps indicates the use of step motors.  Plus there's the fact that he made the movements with pushbuttons which must have locked down, because in the few movies I've seen, he doesn't hold them.  I've occasionally seen hoax-believers claim he must have used a joystick, which shows how much they know about Apollo.

Fendell's oral history interview might help:
http://www.hq.nasa.gov/pao/History/alsj/Fendell-OralHist.pdf

Have you Googled the subject?  There must be something out there in Cyberworld.
Title: Re: LRV camera remote control
Post by: Allan F on August 09, 2013, 09:19:00 AM
Yes, I tried google. And NASA's technical site. But the relevant document is not available online.

Title: Re: LRV camera remote control
Post by: Tanalia on August 09, 2013, 11:02:26 PM
Ground-Controlled Television Assembly: Final Report ( 8.6 Mb PDF ) (http://www.hq.nasa.gov/alsj/GCTA-Final-Report.pdf)

Doesn't have details on everything, but does have a bit about the elevation drive (Section III, Page 39).
Title: Re: LRV camera remote control
Post by: Allan F on August 10, 2013, 12:13:35 AM
Thank you - I'll read it later today.
Title: Re: LRV camera remote control
Post by: raven on August 10, 2013, 02:08:28 AM
This (http://www.hq.nasa.gov/alsj/GCTA-Manual.pdf) should hopefully provide some insight.
It's the manual after all.
Title: Re: LRV camera remote control
Post by: Donnie B. on August 11, 2013, 08:40:18 AM
It's stepper motors all the way down :)
Title: Re: LRV camera remote control
Post by: dwight on August 11, 2013, 10:11:32 AM
Hi everyone and sorry about the delay. The result of the Leverkusen Beer Festival - and I'm not a spring chicken anymore. A Friday drinkfest means I'm out of commission for 2 days. On Apollo 15 the clutch system on the camera motion controls had seized, rendering the tilt up/down feature useless. This system was completely redesigned for Apollo 16 and 17. On both those missions, with the exception of several brief times when the camera got stuck (to be freed again with help from the astronauts) the system work as promised. Another thing: the control panel in MOCR also had incremental controls allowing easier control of the camera for more complex operations. I'll have a look through all the documentation I have when I get home to see if there is more in depth discussion somewhere on the control mechanism.
Title: Re: LRV camera remote control
Post by: Allan F on August 13, 2013, 12:33:29 AM
@raven - thank you for the manual. Quite nerdy stuff, but I've managed to chew through the relevant part. Amazing how complicated something as "simple" as a left-right / up-down mechanism was made.

Title: Re: LRV camera remote control
Post by: smartcooky on August 13, 2013, 01:13:43 AM
@raven - thank you for the manual. Quite nerdy stuff, but I've managed to chew through the relevant part. Amazing how complicated something as "simple" as a left-right / up-down mechanism was made.

Given that one of the camera's tasks was to survey the moonscape in 3° increments, I don't consider the complication unnecessary.

The main difficulty would surely be feedback for any remote control system that wasn't in some way analogous to a stepper motor. For a system using something like a Control Synchro, a 5 second long feedback loop (Moon - Earth - Moon) is unworkable. With a stepper motor you know that N steps = 1 degree, so you send 3N steps to the motor and the camera turns through 3° - no feedback required.
Title: Re: LRV camera remote control
Post by: raven on August 13, 2013, 01:37:46 AM
@raven - thank you for the manual. Quite nerdy stuff, but I've managed to chew through the relevant part. Amazing how complicated something as "simple" as a left-right / up-down mechanism was made.
You are welcome. :)  I admit it's mostly over my head, but it seemed the logical place to find what you were looking for, at least one would hope.
Title: Re: LRV camera remote control
Post by: ka9q on August 13, 2013, 02:49:32 AM
I agree, a stepper motor is the way to go for a system like that. Today of course it would be more automated; you'd enter a specific position and the electronics in the camera would slew to that position (by emitting the appropriate number of pulses to the stepper motors) after compensating for the orientation and tilt of the vehicle. It would be easy to build up panoramas automatically.

Title: Re: LRV camera remote control
Post by: dwight on August 13, 2013, 04:40:52 AM
I located a cool report by Ed Fendell in which he discusses the aspects of panning, tilting, and zooming. I have uploaded it to dropbox:

https://dl.dropboxusercontent.com/u/4960558/j_mission_tv_req.pdf

Then there is a concise SMPTE article which goes more into the design characteristics of the GCTA:

https://dl.dropboxusercontent.com/u/4960558/dec72smpte.pdf

This report by Sam Russell also explains the GCTA, go to PDF page 265 (page 278 of the orginal report):

https://dl.dropboxusercontent.com/u/4960558/19730005102_1973005102.pdf
Title: Re: LRV camera remote control
Post by: Allan F on August 13, 2013, 09:15:16 AM
I've saved the two first - the third displays an error message.
Title: Re: LRV camera remote control
Post by: dwight on August 13, 2013, 07:52:08 PM
Yeah. Sorry its a big file and still uploading.
Title: Re: LRV camera remote control
Post by: dwight on August 14, 2013, 11:28:17 AM
ok file upload is finished. Should be OK now.
Title: Re: LRV camera remote control
Post by: Allan F on August 16, 2013, 01:54:24 AM
That's some big file 400+ pages. I'll read some of it, looks like fun.

I wonder, how would such a system be set up today? Obviously, with modern cameras, the weight and power consumption would go down, sothey could be made much smarter. Perhaps two cameras with "intelligent" tracking skills, one for each astronaut? HD, of course. And with automatic antenna tracking to keep contact with Earth. Local recording capability, so even if contact was lost, footage could be uploaded automatically when contact was renewed.

Also, lots of the hardware could be made from lightweight plastic - or carbon fiber perhaps? Modern composites have much more strength for the same weight. How do they work in vacuum? And temperature fluctuations?
Title: Re: LRV camera remote control
Post by: ka9q on August 16, 2013, 07:25:37 PM
Speaking to the communication side of things, it would now be easy to support at least one realtime HDTV channel back to earth. I'd have to look at what it would take to do more than one, but it might not be necessary. Additional, lower priority HDTV channels could be recorded locally on the moon and sent down when the astronauts are asleep.

Apollo TV was static for very long periods of time, so unless you're observing the astronauts there's little need for video; high resolution still photography would make much more sense. That would take much less bandwidth than HDTV, even for high resolutions.

Video compression already takes advantage of frame-to-frame correlations, sending only the difference between frames, but this method could be taken much further in a lunar exploration setting to suppress the sending of small differences that are pure noise. Only picture areas expected to change would normally send any difference information at all.

A remote controlled camera should give the ground operator a choice over resolution and frame rate (including still). It should have a built-in panorama collection feature, sending down a series of overlapping high resolution stills for each stop of a rover. And there should be a feature to keep track of the position of the astronauts relative to the camera so the operator can quickly view them at any time. Or maybe there could be one TV camera dedicated to each astronaut, sending low resolution video that can be changed to high resolution as needed.
Title: Re: LRV camera remote control
Post by: Noldi400 on September 08, 2013, 03:47:29 PM
Speaking to the communication side of things, it would now be easy to support at least one realtime HDTV channel back to earth. I'd have to look at what it would take to do more than one, but it might not be necessary. Additional, lower priority HDTV channels could be recorded locally on the moon and sent down when the astronauts are asleep.

Apollo TV was static for very long periods of time, so unless you're observing the astronauts there's little need for video; high resolution still photography would make much more sense. That would take much less bandwidth than HDTV, even for high resolutions.

Video compression already takes advantage of frame-to-frame correlations, sending only the difference between frames, but this method could be taken much further in a lunar exploration setting to suppress the sending of small differences that are pure noise. Only picture areas expected to change would normally send any difference information at all.

A remote controlled camera should give the ground operator a choice over resolution and frame rate (including still). It should have a built-in panorama collection feature, sending down a series of overlapping high resolution stills for each stop of a rover. And there should be a feature to keep track of the position of the astronauts relative to the camera so the operator can quickly view them at any time. Or maybe there could be one TV camera dedicated to each astronaut, sending low resolution video that can be changed to high resolution as needed.
Give it a year or so and I'll wager you could design that based on laser transmission back to the ground instead of RF.  Electronics, as usual, is not my rice bowl, but that would bump the available bandwidth by a nice fat coefficient, no?

BTW, I have no idea how you still keep up a dialogue with Hunchy.  For me, he's gotten so boring it's just not worth the effort, not to mention he seems to have run out of ideas and started repeating himself.  No criticism, you takes your fun where you finds it.   ;)

Hi everyone and sorry about the delay. The result of the Leverkusen Beer Festival - and I'm not a spring chicken anymore. A Friday drinkfest means I'm out of commission for 2 days.

As one greybeard to another, do you remember back when the formula was the inverse? i.e.,

2D2 + Nq = GTG

Two Days Drinking plus Quick Nap equals Good To Go.





Title: Re: LRV camera remote control
Post by: cjameshuff on September 08, 2013, 10:15:53 PM
Give it a year or so and I'll wager you could design that based on laser transmission back to the ground instead of RF.  Electronics, as usual, is not my rice bowl, but that would bump the available bandwidth by a nice fat coefficient, no?

Free space optical communications has been feasible for some time now. MESSENGER was able to use its laser altimeter to send and receive pulses over much longer distances (~25 million km) during an Earth flyby. The just-launched LADEE has a laser communications system that can send 622 Mbps from lunar orbit with a 0.5 W infrared laser, and receive at 20 Mbps.

The biggest problem with laser comms is the atmosphere. Bad weather can block a ground station much more easily. Optical-radio bridge satellites in LEO would solve that problem, but the planners of our space program seem allergic to the idea of establishing any sort of infrastructure to increase our capabilities in space.

Another problem with laser comms is the same thing that makes them useful...they're directional and require a stable platform and good knowledge of the location of the other end. You could fan the laser out or cover the spacecraft in LED emitters as an equivalent to a low-gain antenna, but the massive bandwidth improvements and power reductions that come from being able to make a narrow beam with a small transmitter wouldn't be there. There may still be other improvements...individual photons at optical wavelengths can be detected with rather high efficiencies...but I don't know if they'd be worthwhile.
Title: Re: LRV camera remote control
Post by: ka9q on September 09, 2013, 06:21:49 AM
That's right, the big advantage of optical comes from the ability of the transmitter to focus more of its total output power on the receiver. And that necessarily requires much tighter pointing control, which can be quite difficult at interplanetary distances.

The secondary factors that affect throughput are the power that can be generated, which depends on both the efficiency of the laser/transmitter and the available DC power, the background noise level, and the efficiency and noise level of the detector. I'm not keeping up with these technologies but I think the available lasers are still well behind microwave transmitters, and the background noise levels are much higher than in the radio spectrum although directionality can exclude much of it.

As an illustration of the difference in noise levels, it is considered an achievement in the ham radio world to make a receiving station that can detect "sun noise", the sun's own radio output vs the cosmic background and the internal noise of the receiver. Your figure of merit is how much stronger the noise is when your antenna is pointed at the sun than when it is pointed away. I think a typical figure is a few dB. You can imagine that such ratios at optical frequencies are a little bit greater.


Title: Re: LRV camera remote control
Post by: cjameshuff on October 23, 2013, 06:31:28 PM
The LLCD has now been demonstrated in action.

http://www.parabolicarc.com/2013/10/22/nasa-laser-system-sets-record-data-transmissions-moon/
Title: Re: LRV camera remote control
Post by: ka9q on October 23, 2013, 07:20:22 PM
Cool! The 20 Mb/s forward link (earth->moon) will also be important if we ever get a manned human base on the moon. It'll help keep the astronauts sane.

The open question is whether they'll be able to get the Discovery Channel and NASA TV without having it bundled in with Fox News.
Title: Re: LRV camera remote control
Post by: Bob B. on October 23, 2013, 08:48:03 PM
The open question is whether they'll be able to get the Discovery Channel and NASA TV without having it bundled in with Fox News.

Fox News is a must in my TV bundle.