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How far it can receive?

V

Vlad

Well Known Member
In Eastern Europe there is no APRS. But there is very strong desire to create a network. Airplane park is expanding, GA-friendly legislation is under construction and pilots like the idea of low cost trackers.

I was asked by a knowledgeable and capable gentleman couple of questions I would like to post here. Though I educated myself on the subject and will be installing a tracker on my RV, I am not sure I know precise answers.

Those who have their own iGates - at what maximum range you were able to receive YOUR beacons? What altitude were you flying? I would like to know practical digits if any.

What's your coupled (home station and airborne tracker) hardware technical data? Power, antenna etc? Pictures of typical home stations would be excellent to see.

How much internet traffic do you use while running iGate?

Sam, Mike, Ted, Brett your input is very valuable. Others APRofesSors' help appreciated.
What would be your suggestion for pioneers ready to conquer undisturbed airband in low populated area?
 
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Vladyspassky said:
In Eastern Europe there is no APRS. But there is very strong desire to create a network. Airplane park is expanding, GA-friendly legislation is under construction and pilots like the idea of low cost trackers.

I was asked by a knowledgeable and capable gentleman couple of questions I would like to post here. Though I educated myself on the subject and will be installing a tracker on my RV, I am not sure I know precise answers.

Those who have their own iGates - at what maximum range you were able to receive YOUR beacons? What altitude were you flying? I would like to know practical digits if any.

What's your coupled (home station and airborne tracker) hardware technical data? Power, antenna etc? Pictures of typical home stations would be excellent to see.

How much internet traffic do you use while running iGate?

Sam, Mike, Ted, Brett your input is very valuable. Others APRofesSors' help appreciated.
What would be your suggestion for pioneers ready to conquer undisturbed airband in low populated area?
Click to expand...

Vlad, my knowledge of iGates is pretty limited, a ham with extensive background in APRS would be a better resource.

I don't know how to give you precise numbers on iGate range since there are so many variables. Tracker power, antenna, altitude and terrain will have a huge impact on how far away a ground station can receive a beacon. For the ground station, antenna height, type, quality of receiver and terrain will likewise result in so many variables that a hard and fast answer is impossible.

I can tell you, however, that on occasion my tracker has been received by digipeaters more than two hundred miles distant, and a couple of times over three hundred miles away, this with the plane less than 3000' AGL. No doubt reliable service would not be expected at such range, but line-of-sight can cover quite a large area. But...........if you desire good performance near the ground for potential search-and-rescue, you need digipeaters that are fairly well populated.

I probably didn't tell you anything you didn't already know, but best wishes to your comrades who are APRS pioneers in eastern Europe. Suggestions? Get the iGAte/digipeater antennas as high as possible and encourage as many participants to install iGates as you can. There is little substitute for dense station population. To your advantage is the fact the only APRS stations will be your aircraft so the freq should be uncluttered and range will be maximized.

I trust you have seen the sticky in the forum on setting up an iGate:

http://www.vansairforce.com/community/showthread.php?t=30180
 
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Sam Buchanan said:
I can tell you, however, that on occasion my tracker has been received by digipeaters more than two hundred miles distant, and a couple of times over three hundred miles away, this with the plane less than 3000' AGL. No doubt reliable service would not be expected at such range, but line-of-sight can cover quite a large area. But.........
snip

Suggestions? Get the iGAte/digipeater antennas as high as possible and encourage as many participants to install iGates as you can. There is little substitute for dense station population.
Click to expand...



Thank you Sam. This kind of answer I was looking for. Waiting for guys with own iGates to chime in.

Yes I have read the thread couple times and gave them brief summary.
 
My experience

Although I run an I-gate in my home office I am no expert on the subject neither. I totally agree with what Sam said about range, etc. Following is my setup:

I use a little hand held radio: Yaesu VX3R that is a total overkill. I am cheap and use the sound card interface. I brought a project box from Radio Shack to house the interface (see below).

APRS%20radio.JPG


I use an very old PC that still have a serial port to run AGW Packet and UI-View software packages.

I live in a hilly area three miles from the Ohio River. Most of the hills are about 400 agl. My house is half way to the ridge and back to the steep hill. This part of the town is surrounded three sides by the hills. So, unless you are directly over me, my radio does not receive you. An old ham friend works in the county got permission to put an antenna on top of the antenna tower that is on top of the county building/court house. It is still a few hundred feet lower than hill tops, but at least in a more open area. He put a digi in the county basement. My I-gate picks up his signal and put it on the internet. It uses very little bandwidth (being in a low traffic area, it uses a few byte a minute for the digi ID. Even in a high traffic area it uses very little.). We have the only digi/I-gate in the county. Our airport is 7 nm away in another valley. Most of the time my MicroTrak 300300 mw signal can not be picked up while flying pattern. However, at 3,000' it has been picked up hundreds miles away. My MicroTrak setup can be found here.

Conclusion: 1. You can setup an i-gate for little money. 2. Put the antenna as high as you could. 3. In areas of few i-gates/digis use a more powerful transmitter.


Ted
 
Thank you Sir

tc1234c said:
I live in a hilly area three miles from the Ohio River. Most of the hills are about 400 agl. My house is half way to the ridge and back to the steep hill. This part of the town is surrounded three sides by the hills. So, unless you are directly over me, my radio does not receive you. An old ham friend works in the county got permission to put an antenna on top of the antenna tower that is on top of the county building/court house. It is still a few hundred feet lower than hill tops, but at least in a more open area. He put a digi in the county basement. My I-gate picks up his signal and put it on the internet. It uses very little bandwidth (being in a low traffic area, it uses a few byte a minute for the digi ID. Even in a high traffic area it uses very little.). We have the only digi/I-gate in the county. Our airport is 7 nm away in another valley. Most of the time my MicroTrak 300300 mw signal can not be picked up while flying pattern. However, at 3,000' it has been picked up hundreds miles away. My MicroTrak setup can be found here.

Conclusion: 1. You can setup an i-gate for little money. 2. Put the antenna as high as you could. 3. In areas of few i-gates/digis use a more powerful transmitter.


Ted
Click to expand...

This kind of information they are looking for.
 
It is very difficult as others have stated to determine the actual distance mostly due to the large number of iGates available. While an igate may have heard you 300 miles away, one of the hundred other igates that did are the ones that you see got credit in the raw packets. The only way to really know is to have someone watch there igate window that shows the rf to internet traffic. This shows everything heard and gated to aprs. Then fly your plane far away and see what shows on the screen and determine the last position distance. There is a way to log it, but it would be a pain to translate the GPS coord on the packet to distance. But it could be done.

Next week I have a flight of 15 headed out over the gulf to Key West Friday 1300ish eastern. Open water distances might give a clue. But we wont be more than 70 miles from shore.

Let me noodle on this a bit. Could probably set up my igate to log me on the trip south and see. It would be a good test.
 
Will monitor your group Mike

I have sent your call sign to the guys who are interested in network. They will be watching you too. Thanks for contributing.
 
OK I have a plan for you.
Before I leave my house for a trip on Feb 6th, Ill turn the logging feature on.
Ill be gone for 3 days. SO as to prevent monster logs, Ive set up a scheduled reboot routine for the server hours after I leave.

Looking at the iGate server logs. It does not log the GPS position. here is a snip of what it does log:
===
2009-02-01 13:05:13 START UTC
2009-02-01 13:05:15 08:05:14R KJ4G>S0RU5Y,KD4MOJ-7*,WIDE1*,W4GR*,WIDE2 Port=1 <UI R Len=42>:
`p.)l#Wj/]"4+}JUS' PASSIN' THROUGH . . .
2009-02-01 13:05:15 08:05:14R KJ4G>S0RU5Y,KD4MOJ-7*,WIDE1*,W4GR*,WIDE2 Port=2 <UI R Len=42>:
====
I have saved an actual .txt file log for you to view so you can see what it does. You can find it here.
Since the server time stamps it, we will be able to coorelate from my APRS track and this iGate server log data to see when I was heard last. I believe this will be an effective solution for you and fairly scientific. Both the aprs server and mine are synced with the atomic clock, so our times are accurate. The latency between transmitions, igates, and the APRS servers is not material for this granularity of data we need.

Will this work for you?
 
Update,
I have found a good method for trapping the data. UI-view has a log feature by call sign. This allows me to weed out all but the call sign I want to see. COol!:cool:I have a routine running on the APRS server to move the log files over to my webserver and I turned on directory browsing for you to be able to file list the directory. With this you can now go to http://mstewart.net/super8/aprs/data/ and see the data files.

So this is what we will do. Friday morning Feb 6th, ~0830 eastern, I launch out of Atlanta and by the time I hit Key West Ill be a flight of 15 rv's.:eek: On my way out of Atlanta, my packets for N687MS should be logged on the aprs server, and then every 5 minutes, the file is moved over for you to see on my web server with the link above. The first time stamp in the log file is UTC, the second my local eastern time. With these times it will be easy to coorelate my position from the APRS site and my iGate stamp and see how far I can be seen from my own iGate.

Ill do a test run Thursday afternoon locally to verify operation.

This will be an excellent test.

Also during this trip, as we go feet wet over Marco Island Fl, we will get further and further from land and an iGate on shore ~1330 Eastern. While these distances are not far, it will be another interesting data point for a transmitting distance. We RTB Sunday morning and I Immediately get on a cow hearding plane for 2 weeks overseas. I wont be able to work the data while Im gone BUT YOU GUYS CAN! I made all the info available to you to putz with it.

If there is something else you would like to see please let me know. I hope this works! I have logged some locals APRS data and it seems to work just fine. Everything is running automatic and unattended.

Best,
 
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Ready to monitor

Kahuna said:
Update,


So this is what we will do. Friday morning Feb 6th, ~0830 eastern, I launch out of Atlanta and by the time I hit Key West Ill be a flight of 15 rv's.:eek: On my way out of Atlanta, my packets for N687MS should be logged on the aprs server, and then every 5 minutes, the file is moved over for you to see on my web server with the link above. The first time stamp in the log file is UTC, the second my local eastern time. With these times it will be easy to coorelate my position from the APRS site and my iGate stamp and see how far I can be seen from my own iGate.
..........
This will be an excellent test.

Also during this trip, as we go feet wet over Marco Island Fl, we will get further and further from land and an iGate on shore ~1330 Eastern. While these distances are not far, it will be another interesting data point for a transmitting distance.
.........

Best,
Click to expand...

Great info Mike!
 
There is a new feature on aprs.fi that might provide some value to your question.

Open up aprs.fi in an area and zoom out. Select 6 hours so there are a lot of tracks. After the page is finished updating when you roll over a point, it will draw a line to the igate that posted the packet to the internet. If it goes through a digi it will post both paths.

igateused.jpg


This is snowing the station KQ4AZ-1 being igated by an igate quite a distance away.

I was playing with this the other day and saw a packet from a Heli go out and hit an digi 120+ miles away then got sent to an igate that was about 100+ miles away.

Doug
 
Will also be tracking N996JP for distance

To provide further data points, N996PJ, RV-6 owned and operated by James Clark, will also be launching Friday morning out of Columbia SC with his APRS. He is with another group of Team RV'ers headed for Key West. I often gate packets from that distance(150 miles) so we should also see his packets on my igate in the logs I HOPE! Ive provided seperate files for both James in N996PJ and me in N687MS. Both should be seen for some distance into central and southern GA by my iGate server.

And with any luck, at 1400 eastern Friday, you should see the 2 planes converge in the Keys, one from the North, one from the east, rendezvouing just east of KEYW. Each plane represents flights of 8 coming together for one flight which Ill lead into KEYW for the appropriate announcement pass over Mallory square( you know, the pass where we announce that we have arrived to take over the island for the weekend!) and initial to pitchout into KEYW.

You will see 2 folders. A history view folder and a log folder.

The history folder contains data that will look familiar to you in a format that you will recognize. The log folder has less recognizable data structures. These files have a structure designed specifically for playback in the uiview program that many of our iGates use. Im showing you both format types just cause I can. But for the lay person, use the history folder. Got an iGate and want the log file for playback? Then by all means use the log files.

As I mentioned before, Friday these files will be updated every five minutes as they get copied over for you to see from the APRS iGate server.

Are we geeking out yet?:eek:I do believe we are! Experimentals RV's rock!
Best
 
I set up a page, for everyones viewing pleasure, that will track both Mike and James (and any other aircraft in formation that have APRS).

http://www.numacon.com/whereisdoug/mike.cgi

I have it set to show other stations on the page at the same time, this will allow users to roll over their track points and see where they igated to.

Since these are showing other stations, the aircraft will not show up until they turn on their beacons.

Doug
 
A while ago I created a thread about APRS here http://www.reaa.ru/cgi-bin/yabb/YaBB.pl?num=1232816008/0 and now getting it updated with new info from Mike. Posted Doug's double map window too, thanks Doug!

Mike can you post GO - NO GO here before your takeoff? Or PM me from your cell I repost on reaa.ru
Russia covers eleven time zones and some people asked to wake them up when you launch.
 
You can now see Mike and James converging in Southern Florida. There are several other RVs in the flight(s) that have APRS. Kind of neat to watch in near real-time.
 
Looks like they are below reach of any iGates now. Does somebody know if they landed? Please update. World is watching...
 
Some things to consider.

The first Digi that they are all using is over 80 miles away. From there depending on the both the set up of the digi and the tracker itself the packet may only hop one more time.

I have seen some paths that the first hop is to a digi 80 miles away then an igate another 80 miles away.

The power output of each aircraft is not known. You can probably tell that N275RV is a low power transmitter, as we are not seeing any traffic in the keys. Last reported position being about 40 miles north of the keys.

On the ground they are probably limited by power output, and non optimal antenna placement/orientation.

Overall I think the tracking down to the keys was successful and a good test of the distance you can expect.

Doug
 
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Airborne Digi

Too bad that neither unit had a digipeater on board! I bet the air-to-air range of even the smallest tracker would be pretty good. One of these days I will get one of my MT-TT4's to Sam and/or Pete and they can test the theory.

Allen
VHS
 
APRS

VHS said:
Too bad that neither unit had a digipeater on board! I bet the air-to-air range of even the smallest tracker would be pretty good. One of these days I will get one of my MT-TT4's to Sam and/or Pete and they can test the theory.

Allen
VHS
Click to expand...

Leaving Mike's link on Doug's front page and signing onto the aprs.fi web site and then plugging Mike Stewarts N687MS call sign in; he was tracked all the way from Atlanta to Key West. There was coverage across the water from when he left offshore in Southwest Florida to Key West with only a few missed packets here and there.

I've seen much worse coverage in Central Miss.!
 
Kahuna said:
Update,
I have found a good method for trapping the data. UI-view has a log feature by call sign. This allows me to weed out all but the call sign I want to see. COol!:cool:I have a routine running on the APRS server to move the log files over to my webserver and I turned on directory browsing for you to be able to file list the directory. With this you can now go to http://mstewart.net/super8/aprs/data/ and see the data files.

So this is what we will do. Friday morning Feb 6th, ~0830 eastern, I launch out of Atlanta and by the time I hit Key West Ill be a flight of 15 rv's.:eek: On my way out of Atlanta, my packets for N687MS should be logged on the aprs server, and then every 5 minutes, the file is moved over for you to see on my web server with the link above. The first time stamp in the log file is UTC, the second my local eastern time. With these times it will be easy to coorelate my position from the APRS site and my iGate stamp and see how far I can be seen from my own iGate.

Ill do a test run Thursday afternoon locally to verify operation.

This will be an excellent test.

Also during this trip, as we go feet wet over Marco Island Fl, we will get further and further from land and an iGate on shore ~1330 Eastern. While these distances are not far, it will be another interesting data point for a transmitting distance. We RTB Sunday morning and I Immediately get on a cow hearding plane for 2 weeks overseas. I wont be able to work the data while Im gone BUT YOU GUYS CAN! I made all the info available to you to putz with it.

If there is something else you would like to see please let me know. I hope this works! I have logged some locals APRS data and it seems to work just fine. Everything is running automatic and unattended.

Best,
Click to expand...


Using the logs from my iGate server, I was heard on the way out ~160nm @9k'AGL. On the return it was 180nm also at ~9k' agl. So the distance averaged 170NM. 8w transmitter Jpole in the tip. Not bad.
Flight of 16 arrived on time and we had absolutely no fun at all.
This was a fun test.
Best,
 
Good job Mike and all!

You were being watched by pilots in Eastern Europe, Central Asia and Far East. One guy based in Asia referred to your flight as " grown men are playing with their toys". You were up over Everglades at that time.

Special thanks from a team based in Ukraine. They are in the process of planning an APRS network. Every year they do a formation X-country flying under the banner of AOPA-Ukraine, covering all the country and (not) having fun in Crimean Peninsula. They hope one of those days you will be watching their team broadcasting near real time.

Good job Mike!
 
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Kahuna said:
Using the logs from my iGate server, I was heard on the way out ~160nm @9k'AGL. On the return it was 180nm also at ~9k' agl. So the distance averaged 170NM. 8w transmitter Jpole in the tip. Not bad.
Flight of 16 arrived on time and we had absolutely no fun at all.
This was a fun test.
Best,
Click to expand...

Looks like you had a great track (and trip!). The largest of the few gaps I saw were no more than six minutes and interestingly it seems those gaps were filled when you were flying the opposite direction in the same area. Perhaps the gaps were due to network congestion or maybe some shadowing from the antenna. But I suspect network glitches accounted for most of the lost packets.

All in all, a very impressive demonstration of the APRS net! You have a very solid tracker installation. Thanks for sharing. :)
 
Using a standard Comm antenna for APRS

I am using an external unmodified aviation comm antenna for my 300 MW APRS xmitter. In spite of the freq mismatch I am pleased with its performance. If you zoom in on Hillsboro arpt in this link you will see that it tracks right to my hangar. I also have the added benefit of hooking up my hand held comm if I need to.

http://aprs.fi/?call=n623rs&mt=m&z=11&timerange=3600
 
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638RS said:
I am using an external unmodified aviation comm antenna for my 300 MW APRS xmitter. In spite of the freq mismatch I am pleased with its performance. If you zoom in on Hillsboro arpt in this link you will see that it tracks right to my hangar. I also have the added benefit of hooking up my hand held comm if I need to.

http://aprs.fi/?call=n623rs&mt=m&z=11&timerange=3600
Click to expand...

That may very well be the ultimate APRS antenna installation for our RV's. If pilots know they can use the "APRS" antenna for backup com ops that might convince more folks to go with an external antenna. This is definitely a great option for APRS installations in certificated aircraft. Adding a com antenna should be a very minor paperwork hurdle (but will need to use an FAA/PMA approved antenna).

Very inexpensive antennas here: http://www.aircraftspruce.com/catalog/avpages/stainlessantenna.php

VHF_antennas.jpg


A couple of our local APRS'ers are using the 04517 unit with very good results.

Hmm...will have to try using the old King KX99 handheld navcom on my homemade APRS external whip next time I'm at the airport. :)
 
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Sam,

The 05417 is the one I am using. It is mounted on the belly across from my high priced comm antenna with a coax to a B&C connector between the seat cushions.
 
Paul Stratman sent me this site that measures digipeater distances received. Another data set to use. While this is not maximum, you can see some long distances in there.
 
Ive been paying attention recently to my APRS distances when airborn. Since I have my own i-gate, I can log myself at my i-gate and see how far away I can pick myself up. Climbing through 15k' for the low 20's on 6/27/2009, ive been seeing myself between 170nm and 220nm.

Altitude definately matters. in the 8k' range, i receive myself ~150nm.
15k' ~160nm
26k' 240nm

Ive been surprised by this data and I can not explain it. I would think line of sight is line of site. Perhaps its the j-pole orientation in the wingtip?

Not sure.
The distances are just fine. Ive just been curious about it so Ive been logging myself as I commit aviation.
 
Kahuna said:
Ive been paying attention recently to my APRS distances when airborn. Since I have my own i-gate, I can log myself at my i-gate and see how far away I can pick myself up. Climbing through 15k' for the low 20's on 6/27/2009, ive been seeing myself between 170nm and 220nm.
Click to expand...

Just curious: How much xmit power on your APRS? 8W? 300mW?
 
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