Electronics > RF, Microwave, Ham Radio

RF module hunting

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tggzzz:

--- Quote from: hendorog on February 15, 2016, 02:51:45 am ---
--- Quote from: tggzzz on February 15, 2016, 01:52:27 am ---
--- Quote from: hendorog on February 14, 2016, 11:59:41 pm ---
--- Quote ---
--- Quote ---He might do that by tethering after making changes, and/or by having a 'master' RC receiver which can switch out the autopilot for example.

--- End quote ---

The only way your comment could have been relevant and helpful would be if it was a 5 mile tether. In that light, how should we interpret your comment?


--- End quote ---
There were two parts to my comment:

He could use a short tether (say 2 metres) to avoid fly-aways so that he could test the autopilot in flight instead of on the bench - e.g. for tuning the PID loops.
For longer flight tests he could use a master RC receiver to take over from the autopilot if it went haywire.

Perhaps over a period of time that information could be used to build confidence that that autopilot was working and therefore can be used safely?

Disclaimer: I am not an expert in autopilot development and the UK ANO.

--- End quote ---

Nor, it would seem in threat definition, system validation, system development nor system verification.

Start by considering the effects of windspeed, turbulence and windshear near obstacles (ask parascenders and hang glider pilots), the Fresnel zone and other multipath effects (simple physics), GPS non-availability (which happens; there are usually NOTAMS about it), ISM band interference (guaranteed to happen), to name a few off the top of my head.

Next consider how you won't be able to test those with a few tethered flights - except to demonstrate that you haven't got necessary reliability.

If you really want to get into autopilots, I would suggest starting with RC cars or boats. There's less chance of knackering other people with those.


--- End quote ---

Are these things you have experience in?

--- End quote ---

Yes. All of them, bar one: I haven't used RC aircraft/boats. Some as a professional engineer, some as a leisure activity, some both.

Being sufficiently humble to know what I don't know, I've kept my eyes open over the years, and asked people that do know about RC flying. I try to avoid being an example of the Dunning-Kruger effect, usually succeeding.

What's your experience in these things?

hendorog:

--- Quote from: tggzzz on February 15, 2016, 09:47:05 am ---
--- Quote from: hendorog on February 15, 2016, 02:51:45 am ---
--- Quote from: tggzzz on February 15, 2016, 01:52:27 am ---
--- Quote from: hendorog on February 14, 2016, 11:59:41 pm ---
--- Quote ---
--- Quote ---He might do that by tethering after making changes, and/or by having a 'master' RC receiver which can switch out the autopilot for example.

--- End quote ---

The only way your comment could have been relevant and helpful would be if it was a 5 mile tether. In that light, how should we interpret your comment?


--- End quote ---
There were two parts to my comment:

He could use a short tether (say 2 metres) to avoid fly-aways so that he could test the autopilot in flight instead of on the bench - e.g. for tuning the PID loops.
For longer flight tests he could use a master RC receiver to take over from the autopilot if it went haywire.

Perhaps over a period of time that information could be used to build confidence that that autopilot was working and therefore can be used safely?

Disclaimer: I am not an expert in autopilot development and the UK ANO.

--- End quote ---

Nor, it would seem in threat definition, system validation, system development nor system verification.

Start by considering the effects of windspeed, turbulence and windshear near obstacles (ask parascenders and hang glider pilots), the Fresnel zone and other multipath effects (simple physics), GPS non-availability (which happens; there are usually NOTAMS about it), ISM band interference (guaranteed to happen), to name a few off the top of my head.

Next consider how you won't be able to test those with a few tethered flights - except to demonstrate that you haven't got necessary reliability.

If you really want to get into autopilots, I would suggest starting with RC cars or boats. There's less chance of knackering other people with those.


--- End quote ---

Are these things you have experience in?

--- End quote ---

Yes. All of them, bar one: I haven't used RC aircraft/boats. Some as a professional engineer, some as a leisure activity, some both.

Being sufficiently humble to know what I don't know, I've kept my eyes open over the years, and asked people that do know about RC flying. I try to avoid being an example of the Dunning-Kruger effect, usually succeeding.

What's your experience in these things?

--- End quote ---

None of the development items (electronics hobbyist),  some exposure to the aviation items (student pilot in the past and RC), and most of the RF items (RC/FPV/HAM). I'm certainly no expert and don't profess to be one.

The reason I asked that question was that it sounded like you had developed professional UAV's and were therefore approaching the problem from that direction.
My experience is with hobby level equipment which is not verified/validated. Therefore my expectation is that a DIY autopilot would not require that level of rigour either.




tggzzz:

--- Quote from: hendorog on February 15, 2016, 12:32:39 pm ---The reason I asked that question was that it sounded like you had developed professional UAV's and were therefore approaching the problem from that direction.

--- End quote ---

Definitely not, but I certainly would try to have a professional approach with anything of mine that could kill/injure/affect other people. And UAVs, whether or not they have an autopilot, certainly fall into that category.

The key point is to thoroughly define how things might fail. Amateurs starting in a field usually consider how things might work; the better amateurs go on to develop an appreciation of failure modes. The OP leads me to believe they are an amateur starting in this field and the RF field.

Today's news report, merely the latest of many: http://www.bbc.co.uk/news/business-35577124


--- Quote ---My experience is with hobby level equipment which is not verified/validated. Therefore my expectation is that a DIY autopilot would not require that level of rigour either.

--- End quote ---

The laws make no distinctions between professional and amateur control systems, for the obvious sound reasons.

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