Team Prometheus help wanted with NBTV link

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Team Prometheus help wanted with NBTV link

Postby Monroe Lee King Jr. » Tue Feb 18, 2014 12:16 am

Hello all new to this forum and NBTV we have a team that is trying to launch a small autonomous UAV Spaceplane into space and return it safely.

The problem we are having with live video feed at ranges up to and beyond 150 miles. Using 900 Mhz video transmitter's we where able to get 70 miles range but this is about the limit with transportable and relatively easy to set up tracking antennas.

We have a 3 band tracking antenna with 15db helicals for 433, 900 and 2.4 Ghz. We have an optical tracker that also has a 1.2 Ghz helical and these 2 trackers are tied together.

I discovered that NASA used NBTV during the Apollo missions and starting thinking about the possibility for us to get the range we need using NBTV.

The only real need we have is the ability to see the horizon with enough detail to manually fly the the plane in case of autopilot failure.

10 fps is plenty and 12.5 would be great. We use qudrafiller antennas on the spacecraft one facing forward and one facing aft.

I also understand it may be possible to include telemetry in the video frame and this would be an advantage for redundant telemetry.

If your interested in suggesting any ideas or helping with this project please reply or contact me personally monroe@teamprometheus.org

Thanks for taking the time to consider our project.

Monroe L King Jr - Team Prometheus
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Postby Steve Anderson » Tue Feb 18, 2014 1:49 am

Definitely an interesting project! However, let's review that stats from the Apollo 8 missions onwards. They transmitted sorta NBTV from lunar distances at 10fps, 320 lines in a bandwidth of 500kHz on 10W, and monochrome for most part.. They had three huge tracking dishes, only two being available at any one time...I think they were in the region of 25m or so in diameter...I'll do a search through my files...might take a little while!

Now for the same antenna arrangement at only 150 miles you'll need a lot less TX power and/or you can reduce your signal capture area.

Lets face it many have satellite TV that comes from a geostationary bird at around 40,000 km on a dish less than one metre in diameter (sorry, I'm predominately metric even though English). So it can be done. Tracking is going to be your issue...as well as the bird's antenna orientation...

Keep us (me) up to date...

Steve A.

If you need more data on Apollo mission TV, I have it...
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Postby Monroe Lee King Jr. » Tue Feb 18, 2014 2:27 am

Tracking is not a problem we actually have that down using GPS and optical tracking.

The dishes used for Apollo where 30m minimum I know that much.

We can fly a Raspberry Pi to convert the signal if necessary for transmission that's not a problem.

My main issue right now is sorting out whether there is already software out there we can use to do this. I saw a friend on #highaltitude irc channel using a Raspberry Pi but he's not telling how.

It has to be in real time with as little lag as possible of course. Some lag is doable but not more than say 250ms optimal from the software.

We use the helicals to take advantage of circular polarization to reduce signal fade and multipathing and it works very well with the QFH on the spacecraft because of size limitations on the transmitter side.

Any help or advice appreciated. Will will give credit where credit is due for advice or assistance.

Monroe
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Postby Monroe Lee King Jr. » Tue Feb 18, 2014 2:36 am

I'm trying to add a photo here of a test flight so you can get an idea of what we are doing.
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Postby Monroe Lee King Jr. » Tue Feb 18, 2014 2:40 am

More Photo's. I hope this is not too many attachments if so please delete them if you wish.

Monroe
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Postby Steve Anderson » Tue Feb 18, 2014 2:42 am

It's obvious you're had a large degree of success, where now is your bottleneck?

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Postby Monroe Lee King Jr. » Tue Feb 18, 2014 2:48 am

Range is now the limiting factor. I think with lower Freq. 433 Mhz and the right amount of power we can get there, ATV is not very good it seems for this application I believe the bandwith is too high and our gain is too low. So if trade one for the other I believe we can be successful.

Monroe
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Postby DrZarkov » Tue Feb 18, 2014 3:22 am

Maybe what you are looking for is Digital NBTV? http://www.qsl.net/zl1bpu/NBTV/Digital.htm
Best possible picture with lowest bandwidth.
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Postby Monroe Lee King Jr. » Tue Feb 18, 2014 3:45 am

I have seen this site and I'm trying to make heads or tails of what this guy's software is doing. From what I see he's recording and then processing the data from there it could be rebroadcast. Unless I'm reading it wrong? Also the digital looks like 9 seconds for a single frame again if I'm not reading it wrong and that is too slow for sure.

Monroe
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Postby Harry Dalek » Tue Feb 18, 2014 2:28 pm

I used to be right into DX satellite tv analog how i miss you !
But being in Australia which is even for satellite tv at the time a hell of a job for a hobbyist to receive a usa satellite as you were just getting some spill over of the signal which was meant for the west coast of the usa .
Dropping the bandwidth of the receiver here in Australia it was possible .
For 625 line you can get down to 1 mhz but you loose the colour signal around there .
It should work the other way around on the transmitting side i suppose .
,would sure give you more range ...but if your playing with digital i never tried playing with the bandwidth on my digital receiver.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Steve Anderson » Tue Feb 18, 2014 6:19 pm

Indeed, Harry raises an interesting point there...do you need colour or is monochrome OK?

If as I understand it correctly it's for final re-entry navigation, please clarify.

Now, are you sure that 30-odd lines is enough? Does the equipment need flight/space approval? What is your power budget for this link? (Which includes camera, any processing and transmission). ...as well as the finances...also mass limits. Optical field of view and depth of field?

Environment? Temperature excursions? Launch g-forces and vibration? I assume a vacuum. Re-entry g-forces and thermal dynamics. Overall longevity? Re-use on a later vehicle?

Sorry to bombard you with so many questions...

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Postby Harry Dalek » Tue Feb 18, 2014 7:21 pm

I have to say this is a fascinating project !

A space plane wow...looking at the pictures its a rocket plane and glider and or parachute back ?

I am a sucker for the balloons people send up i think they record their missions via a usb or sd card camera idea bit easier than what you are doing .

I don't know if any one has tried but could you get your rocket plane up via a balloon and use it as a launch pad to get higher but looks pretty high as it is .

I bet all that you are doing would be illegal down here i am sure the fun police would come down on any budding amateur space hobbyist in Australia.

OH i am not sure about NASA used NBTV i know they used SSTV ?

Yes Steve its very interesting what hes up to ! i like the idea of NBTV in near out space having such a narrow bandwidth and that craft must travel some distance would it be better to use Short wave instead of VHF UHF SHF ? and such.
Not sure at the hight craft is .....would it be received wonder if any short wave ever makes it to outer space ? if it does make it to the hight of the rocket plane the link would be easier even the old 10 meter band CB best of both worlds...i did experiment with sstv on that band not that any one using it knew what the hell i was doing ...even trying SSTV might be an idea if you want colour and perhaps live B/w NBTV.
Last edited by Harry Dalek on Tue Feb 18, 2014 8:20 pm, edited 3 times in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Postby Steve Anderson » Tue Feb 18, 2014 7:35 pm

Forgot to ask...what bandwidth are you looking to use? 'Conventional' NBTV uses about 10kHz but if you want a bit better resolution that goes up by the square of the number of lines used (for the same aspect ratio).

Certainly a few 'dummy lines' could be inserted during retrace time for telemetry data akin to Teletext/Ceffax. Data rate would be a determining factor.

Steve A.

When I say 10kHz I mean baseband signal, an AM transmission would therefore be 20kHz wide...an FM transmission somewhat wider depending on the modulation index.
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Postby Steve Anderson » Tue Feb 18, 2014 8:09 pm

Gents, here's a link to the site...

http://teamprometheus.org/

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Postby Monroe Lee King Jr. » Wed Feb 19, 2014 12:00 am

The site is under construction (again) the facebook page is much older https://www.facebook.com/pages/Team-Pro ... 223?ref=hl

This is a project I've been working on for 7 years now. The goal is to carry the plane to an altitude of 100,000ft and launch it from there on a smallish 2 stage rocket the plane it's self also has a booster.

The plane/rocket is guided by cold gas thrusters during the boost phase and to reentry. It is a sub-orbital flight.

It is legal and we have a buddy Robert Brand in Australia. That has flown some balloons over there. There is an IRC channel any you can keep up with the balloon action on #ukhighaltitude irc. They use APRS for tracking and it is a lot of fun.

The altitude of the mission is about 100 miles therefore the slant range is not insignificant.

The team is international as well.

I have worked with the FAA, DOD, FCC, BATF, DOT as well as State and Local authorities.

The project is quite complex so and entire explanation is not possible in a post :)

If you visit the facebook page you must scroll all the way back to see the scope of the project it is very interesting indeed.

I am asking for your help at these final critical stages because I believe NBTV is the solution we need!

I have a balloon large enough to carry the rocket to altitude and I have a rocket powerful enough to reach space.

We are working on the design of the plane now and test dropping it from 100,000 ft in April we have made ground launch test and we have dropped other aircraft from that altitude and we now have the proper guidance system for a return to launch system.

I can now answer specific questions.

Monroe
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