Author Topic: LRV camera remote control  (Read 7688 times)

Offline dwight

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Re: LRV camera remote control
« Reply #15 on: August 14, 2013, 11:28:17 AM »
ok file upload is finished. Should be OK now.
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Offline Allan F

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Re: LRV camera remote control
« Reply #16 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?
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Offline ka9q

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Re: LRV camera remote control
« Reply #17 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.

Offline Noldi400

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Re: LRV camera remote control
« Reply #18 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.   ;)

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Offline cjameshuff

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Re: LRV camera remote control
« Reply #19 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.

Offline ka9q

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Re: LRV camera remote control
« Reply #20 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.



Offline cjameshuff

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Re: LRV camera remote control
« Reply #21 on: October 23, 2013, 06:31:28 PM »

Offline ka9q

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Re: LRV camera remote control
« Reply #22 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.

Offline Bob B.

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Re: LRV camera remote control
« Reply #23 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.