APRS

[KB0OXT]

I am a member of the Missouri Wing Civil Air Patrol, my call sign is KB0OXT name is Jerry. We made an attempt to track our aircraft on a SAR (serch and rescue) with the help of APRS. I just wanted to pass on some of the problems we ran into. The APRS systems were supplyed by KC0CZI and some of his ham friends.

The APRS packages consisted of a ht. 2meter rig, battery, and APRS board home brewed and a inexspencive GPS.

The type of planes we were using on this SAR mission was Cesna 172's, so with a pilot and an observer the room was limited where we could put the APRS package where the GPS could get a good lock.

One thing we learned was that it is a must to get your GPS lock while the aircraft is still on the ground, once the plane was wheels up, the cheaper GPS units just couldn't obtain a lock.

Also some type of outside antenna system for the GPS would be much more desirable. TX was not a problem the units TX every 2 min. So we had 50% of what we wanted, we will try again with better GPS systems.
Jerry KB0OXT

[n1agv]

I run APRS from my plane (PA28) all the time without any problems. Because of the nature of GPS, its harder for the unit to initialize if it is moving. I start the GPS on the ground (garmin 12XL), and most of the time just let it lie on the rear seat. Never needed an external antenna for it, or the main unit I use to navigate( Garmin Pilot series). I have an antenna for the 2 meter radio attached to the belly of the plane, just a 19" wire soldered into a BNC connector that goes to a bnc socket under the seat... Peter

[WA9SVD]

There have been external antennas described in QST and CQ magazine in the last few years.
Also be aware that some of the inexpensive or older GPS units are not able to operate accurately over 100 MPH; not a problem with your Cessna, but it could be an issue with other planes. (This was done to prevent the inexpensive units from being used for aircraft navigation!http://www.qrz.com/iB_html/non-cgi/emoticons/wink.gif

[k9po]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (wa9svd @ Mar. 11 2003,02:17)</td></tr><tr><td id="QUOTE">inexpensive or older GPS units are not able to operate accurately over 100 MPH; not a problem with your Cessna, but it could be an issue with other planes. #[/QUOTE]<span id='postcolor'>
Why is this not a problem with a Cessna 172S? The cruise speed is 120 knots (132mph) Va is 109 knots (120mph) and I have gotten ground speeds of over 180mph.

Ground speed is really what we are more concerned with when it comes to the 100mph problem with older units but since most planes can easily have a ground speed of over a 100mph this is a problem for most airplanes.

Scott

[k2gw]

In addition to the previous suggestions about max speed on older Garmins and first obtaining "lock" (downloading ephemeris data) while stationary, an external GPS antenna is pretty much of a must, especially with a high wing Cessna. #You might have some luck if the GPS antenna were placed far forward under the windscreen, but even there, you will being denying yourself data from some of the satellites behind you. #

High wing Cessnas give great views of the ground (essential for SAR) but your GPS unit wants a good view of the sky to hear those very weak signals.

Best of luck in your efforts!

73

Gary Wilson, K2GW
Lt Colonel, CAP (Ret)
Former NJW-CAP/DOE

[WA9SVD]

OK, I stand corrected. I haven't kept up with Cessna Aircraft (or any others) in a LONG time. Perhaps I was thinking of the older 150 models from the late 60's. Thanks for that information. 73.

[k3msb]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (k2gw @ Mar. 11 2003,09:48)</td></tr><tr><td id="QUOTE">You might have some luck if the GPS antenna were placed far forward under the windscreen, but even there, you will being denying yourself data from some of the satellites behind you. #[/QUOTE]<span id='postcolor'>
Gary --

I mounted my GPS antenna as far forward under the windscreen as I could, using velcro, on my high wing Cessna 170A. # Worked fine.

Your are cetrainly correct though, that an external GPS antenna would allow you to pick up signals from the entire GPS constellation above the horizon. #However, you do not need all the visible satellites for navigation.

73 Mark K3ZX

[KD7LDH]

Here is AZ wing we run APRS in all Aircraft and Alot (and growing) amount of Vehicles (we also have digipeaters on all the major coverage area mountains and on all the aircraft with APRS)..... Works Great esp if your IC or Air Ops....

We also run SSTV here - I've been palying around with that a bit, we have a training program here in AZ wing.....




APRS by far is one of the better tools invented to help CAP operations and the ICS (system)









-KD7LDH




P.S. - Are you using Mission Management Utilities (MMU) to handle your APRS (Grid Assist as MMU calls it)....

[K7LCS]

IF I DIDNT HAVE MY GPS IN THE CESSNA T-210, I WOULD GET LOST. IT WORKS PERFECT.

[w7atc]

I'll add in one suggestion. as some noted it's benificial to locate the antenna as far forward... there is another possible location, that works pretty good on most high wing cessna's. Most of the GPS antenna I've delt with have some sort of suction cup for mounting on a window. the best window in a high wing cessna is the very rear window. in most it's at a flater angle than the windscreen isn't near as much electrical noise and just generally tends to work better... in my experience. Some of the antennas may need a little adjustment of the suction cup mount to attatch at that angle but I've only seen one not work (it did eventually work but it lost it's "look")

of course this does depend on where you need the gps mounted or laying and the length of your antenna lead.

73
kd7evs

[wb3ijz]

I'm also a pilot, and a member of Civil Air Patrol Missouri Wing.

I've been running APRS in my plane for a couple of years, at least on trips. #I typically use a yoke-mounted Garmin III Pilot GPS, a TinyTrak II encoder in the side pocket by my leg, and a 2m HT laying in the front corner of the windscreen. #Things generally work well. #GPS lock is rarely a problem for this unit. #I once turned it on in an airliner (100's of knots, 100's of miles from where it was last on), and it locked quickly.

APRS would be ideal for CAP missions, and would work quite well, especially if the plane is also a relay for position reports of ground units.

Capt Marlin Sipe, MO Wing CAP
WB3IJZ

[N3CRT]

maybe you could look into getting a external mounted used GPS antenna from say garmin aviation. Talk to your local avionics shop and see what they can do for you.
This will probably need a 337 major alteration form but they might be able to work with the local FAA office to get an approval, being that this is for CAP work... you may have some luck. I have seen many GPS antenna wires run into sidewall pockets for such use on a yokemount.
just an idea

[n9kpn]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (K7LCS @ Mar. 12 2003,08:21)</td></tr><tr><td id="QUOTE">IF I DIDNT HAVE MY GPS IN THE CESSNA T-210, I WOULD GET LOST. IT WORKS PERFECT.[/QUOTE]<span id='postcolor'>
Pilotage? Dead reconing? #IFR (I Follow Roads?)

:*)

[WA9SVD]

Just a couple of comments:

1. Some early GPS units (upto and including the Garmin GPS II I own; I'm not versed in other manufacturers) would not give readings if the speed was over (either 100 MPH or 100 Knots; I'm not exactly sure which.)

2. Use of a GPS aboard a commercail Airliner may be in violation of FAA or the airline's rules, as it's considered a potential interference source that can compromise the aircraft's navigation systems, and I'd make sure it was all right with the flight crew before I tried to use one on a commercial aircraft.

3. I do not know if some sort of FAA documentation/approval etc. would be needed if an external GPS antenna was installed for APRS only operation, as that should have nothing to do with the aircraft's avionics. My understanding (which may be in error) is that FAA certification would only be required if the external antenna was attached to a GPS unit that was part of the aircraft's navigation system. (In which case, I'd think the unit would already be attached to an external GPS antenna as part of the avionics package.) I don't think an external APRS unit is regulated by FAA regulations. (Please, educate me if I'm in error.)

[N3HGB]

If you are drilling holes and mounting things, the FAA wants to approve it. They don't care if you are using APRS or HBO.
73

[w7atc]

yup.. have to agree the only place that is "easy" to mount an antenna is on the wing strut. but this is usually for searching out ground signals (my experience, tracking animals with radio collars). even just using pipe clamps around the strut to mount small a yagi, you have to have an ok from an a&p. to mount a gps you'd have to do it somewhere on top of the aircraft. most notably on the upper side of the tail behind the rear window. that takes a bit more doing.

[N3CRT]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (wa9svd @ Mar. 12 2003,23:39)</td></tr><tr><td id="QUOTE">3. #I do not know if some sort of FAA documentation/approval etc. would be needed if an external GPS antenna was installed for APRS only operation, as that should have nothing to do with the aircraft's avionics. #My understanding (which may be in error) is that FAA certification would only be required if the external antenna was attached to a GPS unit that was part of the aircraft's navigation system. #(In which case, I'd think the unit would already be attached to an external GPS antenna as part of the avionics package.) #I don't think an external APRS unit is regulated by FAA regulations. #(Please, educate me if I'm in error.)[/QUOTE]<span id='postcolor'>
Yes if you drill into the airplane u need an aprooval 337 form but extra antennas for handheld emergency comms are used all the time and approved. IT is for emergency use, im sure u should have little problem.

Charles
Certificated Mechanic

[KD5LJH]

The only question i have about APRS, is where do I download it? The old links i used to have dont work anymore when I downloaded it a couple years ago. Also, what is the latest version? What files do i need?

[N8SG]

I'm kind of new to APRS, especially in a CAP context. Can someone please clarify something. We're using CAP frequencies on compliant radios, right?

I have a Garmin eTrex Legend GPS [w/no external ant http://www.qrz.com/iB_html/non-cgi/emoticons/mad.gif]and the Vertex Standard 2m ht. What kind of TNC/encoder would be suitable for such an APRS setup? (We do have a pigtail installed for a 2m antenna mounted on the belly)

I'd love to get some pointers on this

Thanks and 73,
Larry St. George N8SG
2LT CAP
Lansing, MI Scott M Burgess Comp Sq.

[KD7LDH]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">I'm kind of new to APRS, especially in a CAP context. Can someone please clarify something. We're using CAP frequencies on compliant radios, right?

I have a Garmin eTrex Legend GPS [w/no external ant ]and the Vertex Standard 2m ht. What kind of TNC/encoder would be suitable for such an APRS setup? (We do have a pigtail installed for a 2m antenna mounted on the belly)

I'd love to get some pointers on this

Thanks and 73,
Larry St. George N8SG
2LT CAP
Lansing, MI Scott M Burgess Comp Sq.[/QUOTE]<span id='postcolor'>


Yes, USE A COMPLIANT RIG (consult your squadron Comm NCOIC / OIC for the URL of the NTC for the right list of rigs) (Oh yeah there is some temporary waiver right now for radios in aircraft but since I dont work on the aircraft I don't know much about it.... I just use NTIA Narrowband Compliant....)

I think the HT should cut the mustard.... I am about to use a Garmin GPs-12, Yaesu VX-300 and a Tiny Trak 2 for my setup....


Oh yeah, If your gonna use your HT for VHF FM Aircraft voice in the air plane DO NOT DO IT!!!!! (give it to the ground pounders :-) Argh we have had a few pilots do that and in the MB all we could here was Backround noise....



# # # # # # # # # # # # # # #- Vinay Gidwani, C/CMSGT, CAP
# # # # # # # # # # #

[kc9bbm]

Hey everyone, this is Jared, KC9BBM, also known as, in the CAP world, as cadet 2nd LT Harris. #I live in Wisconsin, and belong to the most respected, technologically advanced unit in the state. Racine Composite Squadron. It is known throughout the wing and region that, if you need a full comm center and/or a full incident command post, you call on racine, and they will be there damn quick with all our equipment, and all their highly trained personnel. #Anyways, I see everyone talking about APRS, and the use of it in CAP aircraft. Here is my opinion, and our wing's past experiences, and their final decision on it. #I don't think it is needed in aircraft, it is just another thing to distract the pilot/observers/scanners, and keep them from doing their job, LOOKING for the plane, not messing with an HT, antenna, or GPS. Not anymore than they already have to for navigation and air/ground comm. Plus, it takes a lot more training, for both the ground and air operation, because there aren't a whole large group like myself, and people in my unit that already know how to use APRS, and wouldn't need the training. We have many other areas and fields that could be of much more use than APRS. Not to bash everyone else's opinions, that is the last thing i am trying to do, believe me on that, its just that i see it as a waste of time, and money, and can cause many more problems than needed if/ when something goes wrong with the system, which is NOT needed at a real mission, because obviously, TIME MATTERS. Anyways, that is my opinion, and ultimately our wing's decision, not to bother with APRS, and we have a very good record for safety, and swiftness in finding our target, in practice and the real thing, so we see no reason to bogue that down with a new, not really needed method of tracking, which is very sketchy to begin with. I would really like to hear EVERYONE'S opinions back, and you can get a hold of me at jc111588@wi.net
I would really appreciate it if every CAP member throughout the US emailed me, just to let me be aware of who is in the ham world and also heavily involved with CAP. I will make a valiant effort to back to each and every one of you. GREATLY APPRECIATED http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif


Jared C Harris, c/2nd LT, WI wing, CAP
KC9BBM
1543 Kearney Ave
Racine, WI 53405
(262)412-1676

[KD7LDH]

Sir,

I must disagree about your comment about APRS on our aircraft.... I find it super important!

Here in AZ wing all our APRS is out of the way and is completly automated (infact most pilots don't even know they have APRS) - When the master switch is on the APRS tracker and Digipeater activate....

-I can see where your coming from - Just make it automatic and it is no longer a safety concern....

Oh yeah, APRS I found is great for reporting a find (location) because here in AZ wing all the newsrooms have scanners


-KD7LDH

[N1ZWL]

I am AJ Murray, N1ZWL, from Vermont Wing CAP. I have tried APRS and had great success. We may or may not have had an advantage, we were using Kenwood TH-D7s and the Garmin GPS Etrex series. The etrex series is not limited, i believe anyway. The cheapest model is the the Etrex, little yellow unit. I personally have the Etrex Legend, the blue one, i am able to download topo maps onto my GPS of anywhere in the US, alittle more expensive though. It tracked our aircraft with no problem and we didn't need an external antenna.
Best of luck to you, email me if you'd like at AJMJr910@aol.com
73
AJ, N1ZWL
C/ Major
Cadet commander
Burllington Composite Squadron
NER-VT-005

[KD7LDH]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (N1ZWL @ Mar. 17 2003,14:35)</td></tr><tr><td id="QUOTE">I am AJ Murray, N1ZWL, from Vermont Wing CAP. I have tried APRS and had great success. We may or may not have had an advantage, we were using Kenwood TH-D7s and the Garmin GPS Etrex series. The etrex series is not limited, i believe anyway. The cheapest model is the the Etrex, little yellow unit. I personally have the Etrex Legend, the blue one, i am able to download topo maps onto my GPS of anywhere in the US, alittle more expensive though. It tracked our aircraft with no problem and we didn't need an external antenna.
Best of luck to you, email me if you'd like at AJMJr910@aol.com
73
AJ, N1ZWL
C/ Major
Cadet commander
Burllington Composite Squadron
NER-VT-005[/QUOTE]<span id='postcolor'>
Sir,

Arn't TH-D7's Non Compliant?

remember... always check to make sure it is compliant





-KD7LDH

[KD5LJH]

all this stuff is mighty fine and dandy, anyone got a answer to my previous post of this thread?

[N3HGB]

You can try http://www.tapr.org/~kh2z/aprsplus/
A google search on APRS will keep you busy for days.

[KD5LJH]

Thanks I appreciate the information. I'm sure it will be put to good use.

73

[N7BRJ]

Excellent thread! #I have 3 comments.

1st, I fly with a Garmin GPS III Pilot, PicoPacket TNC, Kenwood TH-F6 (non CAP use) and a ni-cad battery pack to run it all. #Both antennas are of low profile, external mag-mount, high wind speed variety. #Works like a champ and other than the config process before taxi/takeoff, I never again have to touch that system at all or until landing. #I mount all components and cables such that the only part I see is the dash mounted Garmin. #If there are any problems, I have a readily available main power switch/breaker to shut it all down. #The battery pack includes a higher current, fast blow fuse to prevent problems caused by any accidental short circuits. #All active components are configured to power up into proper operation when power is turned on.

2nd, I have noted that when using an external GPS antenna on top of the aircraft, I get a better look angle to all available satellites thus providing a somewhat better EPE or more accurate position info. #However, considering the average speed of the aircraft compared to a lower EPE obtained with a dash or rear window mounted antenna, top mounted antennas are in reality only marginally better than an antenna mounted inside the cabin.

3rd, APRS-like technology is exploding into many types of commercial and government applications. #Why?? #Because when used properly, it adds an entire level of productivity and reliability. #So there is every reason to believe it will do the same for SAR and other similar applications. #Systemic knowledge by field or mobile users is not actually necessary.

Gary Memory, N7BRJ
CAP, 2LT for 20 years running

[ae4ym]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (kf5jq @ Mar. 11 2003,09:05)</td></tr><tr><td id="QUOTE"></span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (wa9svd @ Mar. 11 2003,02:17)</td></tr><tr><td id="QUOTE">inexpensive or older GPS units are not able to operate accurately over 100 MPH; not a problem with your Cessna, but it could be an issue with other planes. #[/QUOTE]<span id='postcolor'>
Why is this not a problem with a Cessna 172S? The cruise speed is 120 knots (132mph) Va is 109 knots (120mph) and I have gotten ground speeds of over 180mph.

Ground speed is really what we are more concerned with when it comes to the 100mph problem with older units but since most planes can easily have a ground speed of over a 100mph this is a problem for most airplanes.

Scott[/QUOTE]<span id='postcolor'>
Yeah, that one got me too! http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

[ae4ym]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (KD7LDH @ Mar. 16 2003,16:46)</td></tr><tr><td id="QUOTE">Sir,

I must disagree about your comment about APRS on our aircraft.... I find it super important!

Here in AZ wing all our APRS is out of the way and is completly automated (infact most pilots don't even know they have APRS) - When the master switch is on the APRS tracker and Digipeater activate.... #

-I can see where your coming from - Just make it automatic and it is no longer a safety concern....

Oh yeah, APRS I found is great for reporting a find (location) because here in AZ wing all the newsrooms have scanners


# # # # # # # # # # # # # # # # # # # # #-KD7LDH[/QUOTE]<span id='postcolor'>
If the pilots don't know they have it, are they transmitting without a license in those planes?