What's this term mean?

denverpilot said:
What’s on board and what’s approved in the install manual by Artex?
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No GPS for sure. 2 KX 170Bs, 1 ADF, Old tech Transponder, mode C, and intercom.
 
Tom-D said:
How would a non-geek know that ? but to learn it the hard way.
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I’ve seen articles on it for years in the aviation magazines as to how the system works.

Don’t know how you convince someone to educate themselves before spending money. If you figure it out, let me know.

Have seen businesses spend millions on things that didn’t do what they thought they did. ELT seems a lot easier to figure out.
 
Tom-D said:
No GPS for sure. 2 KX 170Bs, 1 ADF, Old tech Transponder, mode C, and intercom.
Click to expand...

It’ll still work as an ELT. It’ll tell AFRCC the tail number (easier to know if the aircraft is missing off the ramp versus hours of ramp checks in an area), if he registered it properly, and it’ll still get searchers to within roughly 3km and give them a weak 121.5 beacon to home on.

Won’t be “fly right to the airplane” but with nothing in space monitoring 121.5 anymore and few on the ground monitoring it, and reports from airliners in the flight levels nearly worthless, at least they’d know he actually went down somewhere.

Ain’t nobody coming for a long long time on a 121.5 only beacon anymore.
 
Ok.

in·ter·face
ˈin(t)ərˌfās/
noun
  1. a point where two systems, subjects, organizations, etc., meet and interact.
    "the interface between accountancy and the law"

  2. COMPUTING
    a device or program enabling a user to communicate with a computer.
verb
  1. interact with (another system, person, organization, etc.).
    "his goal is to get people interfacing with each other"

  2. COMPUTING
    connect with (another computer or piece of equipment) by an interface.
 
Okay, it’s legally clear. However, it could (and probably should) be worded better, something like The ARTEX ELT 345 transmits on 406 MHz and 121.5 MHz frequencies while providing position accuracy thanks to the built-in GPS navigational interface (requires external GPS).

At this point, either return it or one star review it if you’re unhappy with the description.
 
It is fairly weasel wordy from Artex. That’s for sure. Typical marketing wank.
 
Tom-D said:
How would a non-geek know that ? but to learn it the hard way.
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This is a fairly basic GPS interface from the 1990's
Tom-D said:
But the next question is, what should we use to feed pin 9 that data to get a position to transmit.
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Being that it takes NMEA serial input, that connects to the NMEA serial output of the GPS. You'll have to look in the manual for the GPS.
See page 45 here: http://www.aircraftspruce.com/catalog/pdf/artex_elt345Manual.pdf

You may also find this useful- Cessna Service Bulletin for this unit: https://support.cessna.com/custsupt/contacts/pubs/ourpdf.pdf?as_id=25793
 
Tom-D said:
How would a non-geek know that ? but to learn it the hard way.
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By reading your own thread. To quote myself from your other thread:

arnoha said:
Am I reading it wrong? It says it has a GPS navigation interface, but I don't think I'm reading that it has GPS. The giveaway for me was the lack of a GPS antenna. But I might be wrong.

EDIT: This is in specs:

GPS:
Built-in GPS Navigational Interface (NMEA 0183 or RS 232)

So, that suggests to me that it takes GPS from another source, same as the ACK.
Click to expand...

I'll note that that ACK, which you correctly noted does not have a GPS built-in, has exactly the same verbiage in the specs as the ARTEK.
 
Tom-D said:
  1. 2) The information contained in the message includes:
    1. a) Beacon serial number, or

    2. b) Aircraft identification or registration number

    3. c) Country of registration and country code

    4. d) Position coordinates, if beacon is programmed to receive position data from the aircraft navigation system
      1. 5) The location accuracy of the 406 MHz transmitter is typically 3 km. If position information is extracted from the aircraft navigation system, the accuracy improves to approximately 100 meters (standard or national location protocol).

        My take on this is, it improves with a GPS input, but will give the last position prior to the activation.
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COSPAS satellite system "triangulates" your position from the ELT signal. Sort of like reverse GPS. The ELT can "improve" the COSPAS location accuracy, if it receives a serial navigation input from a GPS. I believe the ground shown should be grounded to ELT case ground with pin 7. Avoid ground studs or general area where power circuits are grounded.
 
wilkersk said:
COSPAS satellite system "triangulates" your position from the ELT signal. Sort of like reverse GPS. The ELT can "improve" the COSPAS location accuracy, if it receives a serial navigation input from a GPS. I believe the ground shown should be grounded to ELT case ground with pin 7. Avoid ground studs or general area where power circuits are grounded.
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Not really “improve”, completely different technologies.

One is based upon timing of acquisition of signal and loss of signal as the satellite passes overhead and Doppler shift of the received signal.

The GPS equipped beacons simply transmit their last known position which is decided immediately on first reception.

Without an NMEA location fed into it or a built in GPS, the ELT will simply transmit a data packet without a location. A ground computer that knows the current orbits of the satellites and thus, their “line of sight” coverage can take the signal acquisition and loss times and figure out where the signal is located mathematically over time and multiple passes, using that “no location” packet. As well as hear the Doppler shift in received frequency as they pass the transmitter.

Anyone can receive and decode ELT or EPIRB data bursts, and all the SARSAT satellites are, are transponders... they hear the 406 transmission and retransmit it back to the ground...

Here’s a guy listening to the downlink frequency with very little equipment. He’s not decoding the data bursts but you can hear them at 3:09.


Another guy wrote or has a copy of an ELT/EPIRB decoder on an android phone which is doing the demodulation from PSK audio and displaying what the raw and decoded data looks like here...


Here’s a pretty good chart of the two technologies that shows the initial uncertainty distances for a non-GPS equipped 406 ELT and the the old 121.5 ELT. Note the 121.5 ELTs even when they were being listened for by the satellites, were an initial area of 500 square miles. Not exactly useful until more satellite passes were processed and added to the previous ones.

http://www.sarsat.noaa.gov/406vs121.pdf

Additionally 121.5 has a LOT of noise and other interference including being used for stupid stuff like illegal taxicab radios in many third world countries. A satellite listening to a wide swath of the planet and retransmitting what it hears back down to analysis centers is constantly sending that crap down along with weaker ELT signals.

It even happens in the 406 example above, you can hear UHF two way radio users with five tone selective calling business band radios being transponded back down to the earth right after the EPIRB data packet in his recording. A listening center can simply decode the PSK data burst and ignore all the other crap being sent down via the satellite transponder.

Some satellites themselves now also do on board decoding of the PSK data and they store it until in view of their own ground stations which is what truly gives the polar orbit birds their near-global coverage.

When they’re over the poles they’re out of range of their ground stations but can relay down the data copied in their telemetry stream which is also shown in the reception video.

Notably the GOES geostationary weather satellites also listen for 406 beacons and can “see” a huge portion of the earth at once. They augment the low earth orbit satellites which can hear weaker ELTs because they’re so much closer, and because they move in relation to the ELT transmitter can be used for Doppler location finding, whereas the geostationary satellites can not.

Many people call the system COSPAS/SARSAT for the long term cooperation with the Russians in earlier decades, but there was a significant period of time after 2005 where all of the COSPAS satellites had either degraded and failed, or were decommissioned, parked, or re-entered and only the US had any satellites up.

SARSAT is a “tag along” package on other satellites, usually NOAA weather satellites. More bang for the launch bucks that way. There were some new SARSAT packages tagging along on some recent or upcoming launches, but I don’t know the status of them. The NOAA website is quite out of date. The US has typically not placed SAR packages on the GPS cluster, while Europe and Russia have done so on Galileo and GLONASS satellites, meaning a LOT more coverage from medium orbits than we provide.

Around 2005 there were very few remaining US assets that could copy SAR beacons, and all of the Russian satellites had dropped out completely, as I recall. But the addition of SAR packages on the “competing” position system satellites has filled in our weak showing there as of 2016. Russia and Europe are flying significantly more SARSAT packages than the US is right now.

An interesting feature that has never been implemented is also flying on the Galileo satellites. The so-called “return link” system which was planned but never implemented which should allow a return message from the rescue center to the beacon directly. The current plan is that on properly outfitted beacons a light will illuminate indicating the signal was received by the rescue center.

No examples of ELTs, EPIRBs, or PLBs with reception capabilities have been demonstrated yet, AFAIK.
 
Tom-D said:
How would a non-geek know that?
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The lack of a GPS antenna.

Also from the other thread:
flyingbrit said:
Does your customer, like me, want GPS in the ELT but does not have a source in the aircraft? If so the ELT406GPS at about twice the price looks like the best deal.
Click to expand...
 
Tom-D said:
How would a non-geek know that ? but to learn it the hard way.
Click to expand...
Tom-D said:
But the next question is, what should we use to feed pin 9 that data to get a position to transmit.
Click to expand...

Tom-D said:
No GPS for sure. 2 KX 170Bs, 1 ADF, Old tech Transponder, mode C, and intercom.
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If there is no GPS, you've nothing to feed that pin 9.

I'd suggest, at this point, that this should be "outsourced" to someone with a better understanding of the system.

After is is all working, don't forget to register that ELT:
https://beaconregistration.noaa.gov/RGDB/index
https://beaconregistration.noaa.gov/RGDB/resources/forms/elt.pdf
 
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Capt. Geoffrey Thorpe said:
This has the NMEA output and might work (will work unless the ELT demands a WASS signal). Set it on the glare shield and you can even find your way to airports with it.
https://www.ebay.com/itm/Garmin-GPS-76-Marine-Navigator/372386976763?hash=item56b3fe53fb:g:AmgAAOSwcmBbYIML&_sacat=0&_nkw=gsmap76&_from=R40&rt=nc&_trksid=m570.l1313

'Approved' or not. Who cares. Unplug it when you go for an annual.
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His plane, no passengers, I'd agree- no one else would be affected if the sytem failed. Assuming he is working on someone else's plane he has a duty to do the job in accordance with the certification of the plane- if it is an experimental, he might be able to do that if the customer agrees. If something like a Cessna (as mentioned in another thread), he should do it in accordance with within the accepted practices (14 CFR 23?). If he doesn't understand the systems involved, he should get some outside help so it is completed properly.
 
Cap'n Jack said:
I'd suggest, at this point, that this should be "outsourced" to someone with a better understanding of the system.
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My ability to install has nothing to do with this discussion, but statements like that are what we expect from you.
 
Cap'n Jack said:
His plane, no passengers, I'd agree- no one else would be affected if the sytem failed. Assuming he is working on someone else's plane he has a duty to do the job in accordance with the certification of the plane- if it is an experimental, he might be able to do that if the customer agrees. If something like a Cessna (as mentioned in another thread), he should do it in accordance with within the accepted practices (14 CFR 23?). If he doesn't understand the systems involved, he should get some outside help so it is completed properly.
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As of now we have a ELT that meets FAR 91.207, installed properly, working properly. that's all the customer wanted.
Pin #9 is wired into the harness, for future use if needed as suggested.
 
Tom-D said:
My ability to install has nothing to do with this discussion, but statements like that are what we expect from you.
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Huh? Statements like what? No one was attempting to insult you. The discussion certainly seemed like the GPS was going to be connected, perhaps eventually. I'm sure you'd want that done properly.

JOOC, what sort of line did you connect to pin 9 for future use (post 24)? I won't pretend to understand what is suitable for aircraft, but it will carry digital data, when used, and may be different from just a simple wire.

Check post #27 in this thread if you want to see some real sarcasm.
 
Capt. Geoffrey Thorpe said:
The "unapproved" GPS connected to the ELT rolls over and dies. Who, exactly, is going to be effected? Worst case, he has what he has now.

This apparently has WASS. Install with duct tape. https://www.amazon.com/dp/B00N32HKIW/ref=nav_timeline_asin?_encoding=UTF8&psc=1
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Who's going to be affected? Please read @denverpilot 's posts, #55 & #4 above. It can take a lot longer to home in on a 121.5 signal. Depending on the injuries, that time may be important.

Even worse, I've personally observed GPS devices displaying a position up to 2 miles from its actual position and also displaying an incorrect track, probably due to a satellite's signal being reflected around inside the plane or automobile (I've seen it both places). This is a worse situation because the rescuers will be searching at some distance from the crash site. They'll either decide there is no crash, or need to use the techniques described by @denverpilot to find the actual site, requiring several more hours of time.

I think you are trying to use the term WAAS (wide area augmentation system, not WASS). The Amazon link you provided won't work for this situation- although it delivers a subset of the NMEA data strings, probably sufficient for the task, it still won't connect to the ELT in question. The GPSr in the link connects to a USB port- this is much different than what the ELT uses. The ELT expects something that looks like the old RS232 protocol, probably 4800 baud, 8,N,1. The old Garmin GPS III, GPS V, or GPS III Pilot GPSr's would work better because the provide the serial NMEA output and could be connected to an external antenna.
 
Cap'n Jack said:
No one was attempting to insult you.
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Making statements like isn't an insult to you ??
"" I'd suggest, at this point, that this should be "outsourced" to someone with a better understanding of the system. ""

Would be if I said it to you
 
Tom-D said:
Making statements like isn't an insult to you ??
"" I'd suggest, at this point, that this should be "outsourced" to someone with a better understanding of the system. ""

Would be if I said it to you
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Actually, no. If you said it to me, I may well be in too deep and not seeing the possible issues. I'd appreciate someone asking such questions.

If I were to build an airplane, I certainly would want an A&P to look at it during the build. I'd probably have to pay him or her to make it right too :rofl:. I recognize that while the individual steps might be "simple", there are certain parts that must be used in the correct places, in the correct fashion, to build a safe airplane. I'd consider such help to be "outsourcing". There's a lot of detail that must be correct.

In the past few years, I've run reactions with potentially explosive components. One utilized a peroxyacid which was shock/spark sensitive. The other was synthesis of an azide, where I was asked to demonstrate I wasn't going to make explosive hydrazoic acid as a byproduct. In both cases, I appreciated the back-stop. I like having all my body parts. :rofl:
 
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Tom-D said:
As of now we have a ELT that meets FAR 91.207, installed properly, working properly. that's all the customer wanted.
Pin #9 is wired into the harness, for future use if needed as suggested.
Click to expand...

That’s probably the way to go and an admonition to have the pilot educate themselves on the limitations of a 406 beacon without a GPS input. It’ll work, it just won’t work as well as it could.

Capt. Geoffrey Thorpe said:
The "unapproved" GPS connected to the ELT rolls over and dies. Who, exactly, is going to be effected? Worst case, he has what he has now.

This apparently has WASS. Install with duct tape. https://www.amazon.com/dp/B00N32HKIW/ref=nav_timeline_asin?_encoding=UTF8&psc=1
Click to expand...

I wouldn’t want to write in a logbook that I installed any cheapie GPS for life-safety purposes. Just me. Many probably do stuff like that. It’s a trade off, if it works it’s a better beacon than without.

Cap'n Jack said:
Even worse, I've personally observed GPS devices displaying a position up to 2 miles from its actual position and also displaying an incorrect track, probably due to a satellite's signal being reflected around inside the plane or automobile (I've seen it both places).
Click to expand...

Actually it’s because the GPS receiver can’t find a solution for whatever reason, satellite signal blocked by the vehicle, weak/poor antenna, old style non-sensitive receiver, whatever. What happens on cheap GPSs is the manufacturer has code in the software to guess at the location from last known location and speed and the non-aviation/non-professional spec GPS software will display that “coasting track” until it gets a valid fix.

How long it’s allowed to display the mathematical time/speed/distance guesswork is part of the professional specs on a certified GPS. On your smartphone or similar there’s often a spec thats much more willing to guess for long periods of time.

In an iPhone it’s even weirder. “GPS” applications actually ask the operating system’s built in “Location Services” for location and can choose to receive it only when it’s reported by the OS to have a particular calculated accuracy level, etc, but the direct GPS data is somewhat “abstracted” from the application. You can turn on an info bar item in ForeFlight to see the accuracy level the OS is reporting to ForeFlight and watch it go up and down during a flight if you’re bored in cruise.) :) I assume Android is similar but haven’t looked into it.

The Apple API for location services has a lot of options an application can set to force only certain accurate data. The phones use AGPS which is a generic location finder based on where the cell phone towers are to feed to their actual GPS receiver as an initial position to avoid GPS cold start. They also can use the motion sensors to tell if you’re turning the car around in a parking lot, etc.

(“Coast track” what controllers call it when their computer guesses at an aircraft’s location when they lose radar/transponder returns temporarily from an aircraft, the aircraft’s track displays a symbol that it’s computer-created and in “coast”. So I use that phrase because it’s common to aviation. The GPS engineers use a completely different terminology based upon accuracy levels. Often when an aircraft goes below radar coverage and/or crashes, the controllers see the computer generated “coast” moving along the predicted flight path for a while. When radar data is pulled to find a downed aircraft, the coast track is disregarded and the last known position is the true last known position.)

Anyway... back to the post reply...

Using an old GPS IIII or similar I still wouldn’t do, they’re just too old and too non-sensitive and also have batteries to deal with or remove since they’re designed as handheld devices, and while they can take vehicle power, back when I had one mounted on the dashboard of a Jeep using its own antenna on the back of it, it would often get into a state where it was doing a cold start or warm start trying to find satellites and took forever to come all the way up with a position solution. Could easily drive for five minutes before it knew where it was.

I guess something old like that would be better than nothing but without an external antenna many of those older GPS receivers would be deaf as a post and probably not great at holding a position solution. That was my experience with the old stuff, anyway. The modern receivers have incredible filtering and amplification and can lock up multiple satellites standing inside the basement of a house, which considering the signal strength of the received signals from low earth orbit, is an incredible RF engineering success for the GPS receiver makers. And of course they almost all can use the additional WAAS correction signal to be significantly more accurate than their older non-WAAS counterparts.

That tech advanced RAPIDLY in just a few years a little over a decade ago and the receivers in use today are light years ahead of the original consumer devices.

One of those ancient (in tech time) receivers hooked to an ELT wouldn’t be my first choice. If I was going for non-certified cheap ghetto GPS to feed an ELT, I’d be looking for something made for a car (good power supply built for lots of nasty transients) and no battery in it. Just made to turn on and off with application of 12V. And I have a 12V airplane... 28V airplane you have a different problem to deal with finding a cheap GPS receiver. And definitely not mounted with duct tape and bailing wire. :) Something made for car audio systems that is in a metal (RF noise shielded) case that could be bolted down.
 
denverpilot said:
That’s probably the way to go and an admonition to have the pilot educate themselves on the limitations of a 406 beacon without a GPS input. It’ll work, it just won’t work as well as it could.



I wouldn’t want to write in a logbook that I installed any cheapie GPS for life-safety purposes. Just me. Many probably do stuff like that. It’s a trade off, if it works it’s a better beacon than without.
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Agreed!



denverpilot said:
Actually it’s because the GPS receiver can’t find a solution for whatever reason, satellite signal blocked by the vehicle, weak/poor antenna, old style non-sensitive receiver, whatever. What happens on cheap GPSs is the manufacturer has code in the software to guess at the location from last known location and speed and the non-aviation/non-professional spec GPS software will display that “coasting track” until it gets a valid fix.

How long it’s allowed to display the mathematical time/speed/distance guesswork is part of the professional specs on a certified GPS. On your smartphone or similar there’s often a spec thats much more willing to guess for long periods of time.
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Actually, I've seen the difference between "coasting" and reflected signals. As long as the unit could solve the equations, it would display a position. It would still display sufficient satellites to get a fix. That's also why I wouldn't consider a portable GPSr for IFR, especially without an external antenna. I wasn't using a "smart phone", but rather a real GPSr.

denverpilot said:
Using an old GPS IIII or similar I still wouldn’t do, they’re just too old and too non-sensitive and also have batteries to deal with or remove since they’re designed as handheld devices, and while they can take vehicle power, back when I had one mounted on the dashboard of a Jeep using its own antenna on the back of it, it would often get into a state where it was doing a cold start or warm start trying to find satellites and took forever to come all the way up with a position solution. Could easily drive for five minutes before it knew where it was.

I guess something old like that would be better than nothing but without an external antenna many of those older GPS receivers would be deaf as a post and probably not great at holding a position solution. That was my experience with the old stuff, anyway. The modern receivers have incredible filtering and amplification and can lock up multiple satellites standing inside the basement of a house, which considering the signal strength of the received signals from low earth orbit, is an incredible RF engineering success for the GPS receiver makers. And of course they almost all can use the additional WAAS correction signal to be significantly more accurate than their older non-WAAS counterparts.
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Agreed, but at least those older units could use an external antenna as well as external power, and provide an NMEA output. They would also take 28 V power too. It isn't something I'd advocate either. The Garmin V mentioned was a WAAS receiver. I'm surprised your unit could cold-start and display a position while driving. I still turn on my modern GPS systems periodically so they could download ephemeris data and start more quickly, especially since I travel a lot and they need to recalculate their location wherever I arrive. Aside from your comments below, modern units also have a lot more satellites to work with. New systems collude with GLONASS, and receive GALILEO signals, so they have many more satellites usable to get a fix. My DSLR camera receives those and QZSS, but it is hindered by its tiny patch antenna. I still have a Garmin V which makes a fine bike computer.

denverpilot said:
That tech advanced RAPIDLY in just a few years a little over a decade ago and the receivers in use today are light years ahead of the original consumer devices.

If I was going for non-certified cheap ghetto GPS to feed an ELT, I’d be looking for something made for a car (good power supply built for lots of nasty transients) and no battery in it. Just made to turn on and off with application of 12V. And I have a 12V airplane... 28V airplane you have a different problem to deal with finding a cheap GPS receiver. And definitely not mounted with duct tape and bailing wire. :) Something made for car audio systems that is in a metal (RF noise shielded) case that could be bolted down.
Click to expand...
And an external antenna.
 
Tom, if you reread the answers to your 7/26 thread asking for advice on ELT choice, some answers mentioned the necessity of an external GPS source to feed position information to certain ELT's. Those mentions forewarned about the situation you find yourself in, but perhaps weren't emphasized clearly.

Sometimes this stuff happens. I hope you get it resolved to everyone's satisfaction.
 
3393RP said:
Tom, if you reread the answers to your 7/26 thread asking for advice on ELT choice, some answers mentioned the necessity of an external GPS source to feed position information to certain ELT's. Those mentions forewarned about the situation you find yourself in, but perhaps weren't emphasized clearly.

Sometimes this stuff happens. I hope you get it resolved to everyone's satisfaction.
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Home work aside, the owner won't spend that much for a built in GPS unit.
We got what was acceptable to them. Maybe out of sheer luck. But we are legal, and good to go.
 
Tom-D said:
Making statements like isn't an insult to you ??
"" I'd suggest, at this point, that this should be "outsourced" to someone with a better understanding of the system. ""

Would be if I said it to you
Click to expand...

Tom, you said yourself that you don't understand the ELT system. You started this thread specifically because you didn't understand the system. Jack was just repeating, perhaps a little bluntly, exactly what you'd already said about yourself. Unless you'd intended to insult yourself, that's not an insult. I believe Jack was just suggesting that an ELT has really become the domain of avionics shops once the GPS was added.
 
arnoha said:
Tom, you said yourself that you don't understand the ELT system
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That doesn't mean I can't follow installation instructions.

What it does mean is, that I did not understand the advertisement in Aircraft Spruce & speciality's catalog.
 
I believe it accepts gps position in RS-232 serial format (from a garmin), RS-232 typically has a TX pin and RX for bi-directional. You probably want to connect the RS-232 data source TX pin to the ELT RX pin.
 
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