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Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

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Re: Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

#91

Post by matmatmatmat »

NikolaeVarius wrote: post #82
matmatmatmat wrote: post #77

Earlier quoted context omitted.

`The override is missing the droneship or blowing itself up.` Disagree, that's not an override. That's a program written by a human programmer (who makes mistakes) that autonomously decides that something went wrong. I would argue there has "got" to be an override precisely because humans make mistakes all the time and so there's no reason to think that an autonomous failsafe should work in all possible situations. I…

>> I don't know much about rocketry There you go. You are welcome to try and disagree with decades of rocket launch practices. The range safety officer can blow up the rocket if the rocket veers off and is in danger of overshooting the safe area. Otherwise, you know the reason why we launch over water? Since it doesn't goddamn matter after it clears the tower and clears the danger zone. It either blows up over water,…

>> You are welcome to try and disagree with decades of rocket launch practices.

>> The range safety officer can blow up the rocket if the rocket veers off and is in danger of overshooting the safe area.

I'm confused. Am I not the one arguing for a remote abort command (which, so far as I know, has been standard practice for a while) and you, above, argue that rockets don't need one because humans are bad at modeling rocket aerodynamics?

Re: Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

#92

Post by schiffern »

soapboxrocket wrote: post #87
drmpeg wrote: post #71

Earlier quoted context omitted.

Video decoded here. https://twitter.com/r2x0t/status/1370030702633312259

I'm interested in the ITAR implications here of the video. When asked about seeing the inside of the fuel tank during the crew demo mission Shotwell said no because it was covered by ITAR. This video clearly shows inside a tank.

Shotwell's comments are surprising since SpaceX has publicly shown that same interior tank camera view many times on previous webcasts.

I wonder if something was different about the demo mission?

Re: Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

#93

Post by vardump »

mikepurvis wrote: post #75
vardump wrote: post #72

Earlier quoted context omitted.

It would not affect at all. Flipped bits / transmit errors have no avalanche effect, unless the bit was flipped in the encryption module.

What if you have gaps in your stream with uncertain length, though? Based on quick read about stream ciphers, it seems like the alignment of the key and data is pretty critical.

Might be some truth here. Although at this point automatically interpreting plain text data would fail as well. In both cases, you could add separating symbols in the raw data stream.

Also, timing should help here. Sure there can be gaps, but at a given data rate the receiving end should be able to compensate for it, as long as velocity doesn't have large unexpected changes (doppler). Even then it should be decodable afterwards.

There are a lot of ways you can compensate for any of these issues. That said, of course plain text is going to be the easiest option for a human to decode when everything else fails.

Re: Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

#94

Post by bigiain »

NikolaeVarius wrote: post #47
ClumsyPilot wrote: post #39

Earlier quoted context omitted.

People who code still make mistakes. There's got to be an override of some sort

The override is missing the droneship or blowing itself up. Why the hell does there "got" to be an override. Humans are generally not good at doing hypersonic/supersonic aerodynamic modeling in their heads, especially remotely

> The override is missing the droneship or blowing itself up.

What if "missing the drone ship" means "hitting Chicago"?

I'm somewhat surprised to hear that there may not be a functional remote abort mechanism.

Re: Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

#95

Post by bigiain »

function_seven wrote: post #83
Lev1a wrote: post #8

Earlier quoted context omitted.

I personally don't have the kind of time to visit all of /S.*ia/, I'll have to make to do with just /S\w+ia/. Shame, really...

Not sure what you have against Sia, Cypress. I, for one, will try to make it to /S\w*ia/.

South East Asia are ramping up the hospitality as we speak...

Re: Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

#96

Post by bigiain »

sandworm101 wrote: post #59
ceejayoz wrote: post #58

Earlier quoted context omitted.

The article would seem to indicate it helps, but certainly doesn't get you all the way there. > Modern stealth aircraft, such as the F-117 Nighthawk attack jet and B-2 Spirit bomber, are painted in matte black or dark grey and are flown at night to limit their visual signature. Can't really do that in space; you've got a day/night cycle ever 90 minutes or so.

Space is black. Even in daylight, the background behind an object in space is always black (except when passing in front of the sun). A black plane against a blue sky stands out. A black satellite against the black of space does not. Or a blue plane against a blue background. The F117 is black and only flew at night, at lower levels. The bottom of the B2 isn't actually black, more a dark grey with a bit of blue in it…

https://www.newshub.co.nz/home/new-zealand/2018/06/kiwi-astr...

The ISS is way bigger than a highly classified satellite, but I'd guess a lot of nation states have way better capability than some guy with a telescope in his back yard in New Zealand.

Re: Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

#98

Post by gbrown »

SEJeff wrote: post #89
gbrown wrote: post #84

Earlier quoted context omitted.

The launch termination system at least needs a receiver

The way the automated FTS works is essentially that the USAF blasts a "DO NOT BLOW UP" signal with a very high power transmitter to the FTS. If the FTS doesn't receive that signal, it triggers and then you have a RUD.

That sounds terrifying

Re: Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

#99

Post by gbrown »

bumby wrote: post #86
gbrown wrote: post #84

Earlier quoted context omitted.

The launch termination system at least needs a receiver

Isn’t this only the case if the intent is for a range officer to abort? I.e., if this system is fully autonomous and on-board, a receiver wouldn’t be necessary?

Yes

Re: Receiving SpaceX Falcon 9 Telemetry with a HackRF and 1.2m Satellite Dish

#100

Post by SEJeff »

gbrown wrote: post #98
SEJeff wrote: post #89

Earlier quoted context omitted.

The way the automated FTS works is essentially that the USAF blasts a "DO NOT BLOW UP" signal with a very high power transmitter to the FTS. If the FTS doesn't receive that signal, it triggers and then you have a RUD.

That sounds terrifying

I don’t disagree, but that is in fact how it works!
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