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Comment Re:ADS-B? Why reinvent the wheel? (Score 1) 61

That's the point...there are more drones involved than what are being discussed here that would be affected by such a blanket requirement.

There are, but they aren't the topic of this discussion. And those "other drones" are very much larger, and capable of much larger payloads. They are not going to have an issue with a few ounces for an ADS-B OUT transmitter or the power drain from it.

Again, there are more than DJI drones involved here, including home-builts without any restrictions whatsoever except the builder's ability & budget.

I'm sorry, but there is still the 400 foot flight limit imposed by class of UAS and operator privileges. You claim no restrictions, which is patently absurd.

That 7 watts is transmitter output power, not consumed power. Even with a very efficient final power amplifier, it's going to need at least 10-11 watts or more, and that's for *just* the final transmitter output stage, not including signal generation and driver stages for the final amplifier stage. That's a serious amount of power drain for a small drone and will seriously reduce flight endurance and performance.

I guess you are ignoring all of the electrical budget discussion already posted. In my budget, I assumed just 50% efficiency, and that means 14 watts, not just 10-11W, and still managed to show that it would be an unmeasurable effect on a typical (DJI Phantom 3 Pro) UAS. I ignored the control electronics because those would be a trivial amount of the power requirement. Your cellphone has more processing power than what it necessary for an ADS-B OUT, and it will run for a very long time on a very small battery.

Please stop waving your hands and stomping your feet about a "7 watt radio" and actually look at the system.

At lower altitudes ground clutter has even more of an effect as the signal 'horizon' is that much nearer for the aircraft as well as the UAV.

You are worried about ground clutter when the UAS will be us where the 200 knot speed limit doesn't apply. That's not "at lower altitudes". Please look up 14CFR91.117 and learn. I am off by 50 knots -- the limit is 250 knots below 10,000 AGL. Ten thousand feet. But still, there is a 200 knot limit below 2500 feet (two thousand five hundred) within 4 nm of an airport and under any Class B airspace.

To find a jet going at "jet speeds" you need to be up 10,000 AGL -- which a DJI isn't going to be. Ever.

And they won't be below 500' unless they are departing or landing at an airport nearby, so they MUST be going less than 200 knots there. If your UAS is up where you can find a jet, it won't be in ground clutter anymore, it will be free and clear of the ground.

A 7 watt transmitter will draw effectively the same amount of power regardless of physical size.

That's right. It will draw an average of less than 50mA if it is the size of an elephant or the more realistic size of a pack of cigarettes. I have 5W radios that contain GPS and will transmit their position via APRS that fit in my pocket. Very small. Very light. I have an 8 W radio sitting on my desk here, and it's not very much bigger than a 5W radio. Most of the size of those radios is user interface -- speaker, dials, etc. Remove the speaker, make the "dial" on/off, and you can reduce the size of the radio even smaller.

Why do you think that a radio that weighs just a few ounces and consumes, over the course of a 20 minute flight, about 20mAH, will be an issue for any UAS that would be regulated by any proposed rule?

As to your link, I thought you said that a full 7-watt ADS-B-out transmitter was "easily accommodated"? Which is it?

You didn't look at the link, did you? You just want to blow smoke. The ADS-B OUT radio I linked to would be trivial to reduce in size and install almost anywhere.

Or we could, you know, *not* go apeshit-authoritarian trying to track & trace toy quadrotors

If you actually read what I've written (I know, this is /. and that's not required) you might notice I've been talking about the technical limits and how the smoke you have been blowing is based on pure ignorance. I haven't argued that it should be done, only that your excuses why it cannot be done are empty and wrong.

Go get 'em, Tiger!

I suppose if you can't argue the technical things, go for insult and emotion.

Comment Re:ADS-B? Why reinvent the wheel? (Score 1) 61

Again, if you're in a quarry or in the fields, you won't have an open network to connect to.

You seem to be stuck thinking that broadcasting the UAS location using the control channel requires an "open network" to connect to. Sorry, that's just not a requirement. I've flown these things, and they fly just fine without an "open", or closed even, network. If they're flying, they have a location to transmit back to the controller, and that's what the Aero-thingy is picking up. No network is needed.

Comment Re:The market will do its job. (Score 1) 61

DJI drones are used by the military and other government departments for surveying etc. A few million is a drop in the ocean

I know what they are used for. Non-military operations. They aren't strapping hand grenades on them and taking out gun emplacements, for example.

That "few million" you claim is a "drop in the ocean" would be a large part of the USGS budget, or any other government agency, and it is unlikely any agency would try to get it past the funding sources given the existence of COTS solutions already available.

The main purpose is to make the community gravitate away from proprietary to open source.

The funding for USGS, USACE, etc, is not there to "make a community gravitate", it is to get a job done. "A few million dollars" is a very large expenditure, and it is just not going to happen.

Comment Re: It was harmful... (Score 1) 299

No... I responded to this... which isn't even an AC post, so I'm not sure how you thought I was responding to myself.

Because the broken /. message display system (maybe the "classic" version, I don't know) when not showing a message that is below the mod cutoff indents the messages incorrectly to make it look like the reply was to something else. For example, I see two comments in a row from you, one that appears to be a reply to yourself.

And the broken /. display system doesn't clearly identify which is "parent" when the "read parent" link is selected. I've gotten entire threads displayed by doing that, and I have to still guess which is the parent being replied to.

That's why is it is good to quote some context from the parent so everyone knows.

Comment Re: It was harmful... (Score 1) 299

I am saying that there needs to be proof that it *COULD* have been a weapon.... could plausibly be caused by some weapon that is known to factually exist.

You want proof of something that nobody it going to tell YOU about because it is probably classified. I've already presented a reasonable hypothesis of how such a weapon could operate even if I cannot prove that it exists. By demanding proof that the weapon exists you demand something you know cannot be provided to you, and so you will never accept anything by "natural causes", no matter how unlikely it is that a "natural cause" would impact only US and Canadian diplomats and nobody else.

Comment Re: It was harmful... (Score 1) 299

Except of course for the fact that the tech you referred to couldn't cause this because if it could then they would know how the attack was done

Knowing one way of doing it is not proof that it was done that way. No, until they find the actual source they won't know how it was done, but they can guess. That's sure a lot more productive than repeated denials that it was being done based on ignorance of technology.

I bet that the people who are looking into this have theories, but they aren't giving you a daily briefing because you don't have a need to know. Nor do I. The difference between you and me appears to be that I can think of ways that current technology can be used to cause harm to people and you can't.

until we can show some real world working weapon that could have actually done this in those exact circumstances.

Yes, nobody can point to a secret weapon, so it doesn't exist. Nobody could point you to the A-bomb until we dropped a couple of them, and even then there was nothing left to point at. Apparently A-bombs are "natural phenomenon" because I can't point at the ones that wiped out Hiroshima or Nagasaki as proof of how it was done. Since I don't have access to any of them, I can't even point at an existing atomic weapon as a potential cause.

Comment Re:It was harmful... (Score 1) 299

Right.... show me the weapon, or even come up with some kind of explanation for what kind of weapon it actually might have been, and I might be inclined to believe you.

Megahertz-capable high-power ultrasonic transducers are commonly used in underwater applications. If you want to create a dangerous super-audible signal it is trivial. And phasing can deal with directionality. This is all a quite trivial extension of existing technology.

If you doubt that you can focus ultrasonic signals, think about what is now a nearly ubiquitous application of that. If you can't think of one, ask any pregnant woman to "see the pictures". If you can't imagine ultrasound being able to cause damage, ask any tree-hugger, I mean, whale-hugger, about US naval sonar -- another example of focused sound.

The mindset that there must have been some kind of intelligence behind it is entirely unsubstantiated superstition until you can at least *hypothesize* how it might actually happened.

Ok. Just did that. And since the damage was being done to US and Canadian citizens and not to a large number of Cubans, that makes a "natural process" very doubtful. Is there some genetic difference between US/Canadians and Cubans that would account for a difference in damage to someone's hearing?

Occam's razor.

Comment Re:ADS-B? Why reinvent the wheel? (Score 1) 61

There are more than DJI drones involved if ADS-B is required,

The models of drones that are being discussed here ALL fly at much lower altitudes than the flight levels, and at the altitudes they DO fly at, jets are limited to 200 knots.

and there's little to prevent a UAV operator from sending the UAV as high as it can go, possibly placing it in general airspace.

You mean nothing but the 400 foot limit, which I believe DJI, for one, tries to enforce.

Even at 200 knots with a reduced-power ADS-B drone transmitter

Who says it will be "reduced power"? It's well within technical capability to meet the 7 watt minimum.

There is also signal blockage from ground clutter

Not if you are up high enough that the 200 knot speed limit no longer applies.

Ummm, what? What difference does it make to the antenna if the 7 watt ADSB signal comes from a UAV or a manned aircraft?

That statement is in relation to a low-powered ADS-B transmitter for small UAVs unable to reasonably accommodate a standard ADS-B-out package.

A 7 watt package is easily accommodated.

The engineering has already been done, and the only rule-making the FAA needs to do is to mandate it for UAV above a certain minimum weight.

I'm sorry, but as someone with decades of experience in the avionics field, I don't believe that is true.

Decades of avionics experience hasn't taught you that electronics systems shrink in size over time. And experience in avionics apparently means no experience in Google. I posted a link to one portable ADS-B out system already, pretty small, pretty light, but only prevented from being used by FAA regulations. Mandating ADS-B OUT for UAV would include, you realize I hope, a rescinding of the prohibition on their use. That's the rule making that needs to be done.

Comment Re:Has anybody analyzed (Score 1) 299

That is the 'Killer Joke' from Monty Python. It is just random German gibberish.

Of course. If they had used the actual joke they would have caused the deaths of tens, if not hundreds, of Monty Python fans, and probably would have been sued. They had to replace it with a non-functional variant to protect us.

Comment Re:ADS-B? Why reinvent the wheel? (Score 1) 61

An ADS-B transponder is a chunky, heavy (and expensive) unit.

It's not a transponder, it is a transmitter. The information is broadcast at a regular interval, not polled for by the ground station. The 1090ES system does use the existing radar transponder hardware to transmit the signals ("extended squitter"), but the 978UAT uses separate hardware. Yeah, people call it the wrong thing. Big surprise.

The size of the hardware is dropping rapidly, just like the size of GPS receivers has dropped significantly since the creation of that system.

Rather, the issue is the massive amounts of power loss while the signal propagates over the air,

The ADS-B signals lose power at no different rate than any other signals at those frequencies, and that path loss is factored into the design service volume and power levels.

requiring not only big batteries but decent-sized heatsinks to draw heat away from the power amplifiers.

The average current draw is miniscule (50mA), and thus the heat sinks need be no larger than what you have in a cellphone. A 7AH SLA would power it for, umm, 140 hours continuous use.

thus creating a much larger market for portable ADS-B transponders. But I don't see it happening.

The market already exists, and solutions exist. While it appears that the FAA has prohibited the use of portable ADS-B OUT devices for a number of logistical reasons (different altitude source than radar transponder, incorrect registration info, etc.) this shows that the technology is there when the legislation is ready to cover it. This specific device looks like it has a lot of internal empty space to create a sleek box on the outside -- it can probably be reduced by half in size. If you can't find a place in your basket to strap the current solution, then I'd say your basket isn't airworthy enough to be flying. "Sardines" is not a safe way to carry passengers.

By 2020, there will have to be movement on the laws or there will be a huge number of aircraft that won't be flyable.

Comment Re:The market will do its job. (Score 1) 61

Seems like it would be in their interest to toss a few million into open source projects

That's a few million tax dollars they don't need to spend. DJI drones are not military. The government uses them for non-critical activities, and putting a few million dollars into building special ones just for them would be a complete waste of money.

Disclaimer: I work with (not at) a government agency that uses a lot of DJI drones, and none of them are "most needed" (critical) uses. They're cheap research tools.

Comment Re:ADS-B? Why reinvent the wheel? (Score 1) 61

That may sound like a lot, but at jet-aircraft speeds, 20 miles goes by in a few seconds.

Jet aircraft are limited to 200 knots in the altitudes that a UAV will be flying, at least the DJI model UAV.

The other limitation is with other aircraft's antennas & ADS-B receivers being designed around receiving signals from 7-watt and above transmitters.

Ummm, what? What difference does it make to the antenna if the 7 watt ADSB signal comes from a UAV or a manned aircraft?

Suffice it to say there's a significant amount of engineering and research, not to mention FAA rule-making/standards-defining, to be done before it's ready for hobby-drone prime-time.

The engineering has already been done, and the only rule-making the FAA needs to do is to mandate it for UAV above a certain minimum weight.

Comment Re:ADS-B? Why reinvent the wheel? (Score 1) 61

I did a power budget a few months ago during a discussion of ADSB-OUT on UAVs, but I can't find it quickly. It's not hard to redo. Because it is a PULSE signal, you cannot just say "7W is 500mA at 12V, assume 50% efficiency so that's 1A current draw". You have to take into account the duty cycle of the pulse, which is at most 450 microseconds out of 1 second, or 0.045%. Call it 0.05% for round numbers. The average current draw will then be 50mA.

The battery in my DJI is 4.5AH and lasts about 20 minutes in flight. That means the aircraft itself is drawing, on average, more than 12A from that battery. A 50mA draw will be undetectable, consuming only about 17mAH out of 4500mAH.

As for the fellow who doesn't want a "7W transmitter in his pocket", well, strap it to the side of your balloon and power it from some D cells. Or a small SLA, 7AH will be plenty for a day of use.

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