Van's Air Force
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How about receiving APRS in flight?
- Thread starter Davepar
- Start date
Generally speaking a PC and internet connection would be needed in your plane....
it may be possible to use a receiver in your plane to decode nearby stations, however im not sure if this has been done before and it would be limited in usedue it it not being connected to the wider APRS network.
Cheers,
Matt
it may be possible to use a receiver in your plane to decode nearby stations, however im not sure if this has been done before and it would be limited in usedue it it not being connected to the wider APRS network.
Cheers,
Matt
petehowell
Well Known Member
It is very possible
The new tinytrack4 will do it, I think. It might even display targets on your GPS. You would need a hand held radio that will transmit and receive on 144.39 to make this work.
http://www.byonics.com/tinytrak4/
I'll see if Allen will join the thread to explain. The details are beyond me.
The new tinytrack4 will do it, I think. It might even display targets on your GPS. You would need a hand held radio that will transmit and receive on 144.39 to make this work.
http://www.byonics.com/tinytrak4/
I'll see if Allen will join the thread to explain. The details are beyond me.
PaigeHoffart
Well Known Member
Keep in mind that you will hear every ground station within 100-200NM. I think the chances for interference are pretty high. I'd probably grab a handheld and listen to 144.39 airborne before I shelled out the bucks for a TinyTrack4. Having said that, if you use it on a discrete frequency it could be a poor man's ADSB.
Paige
Paige
If you can find a used one of these (Vertex Standard VXA-700), you'd be in good shape. Small, handheld NAV/COM with a 2 Meter amateur band transceiver built in. Looks like the newest version, the VXA-710, doesn't include the 2M transceiver.
Allen has mentioned on other forums that he is working on a MicroTrak version of the TT4 unit with TX/RX capability. I'm sure he'll correct me if I'm wrong, but I thought it was going to be an 8W or 10W version. Just get a UMPC with the maps installed and you should be able to see all packets you can "hear".
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Michael
KB4LFH
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Michael
KB4LFH
Lycosaurus
Well Known Member
AvMap and Kenwood combination
The Kenwood TM-D700A APRS transceiver and AvMap GeoSat5 will do what you want. The handheld version of the Kenwood is the TH-D7A. This link also claims that the EKP-IV supports displaying aprs data as well .... though have not seen it in the specs. Sure would be nice.
http://nwaprs.info/d700avmapgeosatcombo.htm
Also, here's a pdf document reviewing the AvMap G5 for GPRS use:
http://www.geosat.us/AvMapG5QST.pdf
I have a friend who uses the EKP-IV Pro and TH-D7A for CAP type operations in Canada. I'll see what he has to say about the EKP-IV tracking aprs.
Edit: April 9
My friend says his Avmap ekp-IV will not show a track of other stations, but rather, the present (or last transmitted) position of the other aprs devices.
The Kenwood TM-D700A APRS transceiver and AvMap GeoSat5 will do what you want. The handheld version of the Kenwood is the TH-D7A. This link also claims that the EKP-IV supports displaying aprs data as well .... though have not seen it in the specs. Sure would be nice.
http://nwaprs.info/d700avmapgeosatcombo.htm
Also, here's a pdf document reviewing the AvMap G5 for GPRS use:
http://www.geosat.us/AvMapG5QST.pdf
I have a friend who uses the EKP-IV Pro and TH-D7A for CAP type operations in Canada. I'll see what he has to say about the EKP-IV tracking aprs.
Edit: April 9
My friend says his Avmap ekp-IV will not show a track of other stations, but rather, the present (or last transmitted) position of the other aprs devices.
Last edited:
Receiving APRS in Flight
As has been pointed out by others, the Kenwood handheld (and mobile) radios have the ability to display as well as send packets. Last weekend I rode to the Puyallup (WA) hamfest with with KE7KV in his Kenwood HT/AvMap GPS equipped vehicle. With some effort he was able to scroll through a list of stations received on the radio's display. Although he was able to put "target stations" over the moving map on the GPS screen, it seemed like it took an awful lot of keystrokes (some of them on an accessory keyboard he had on a RAM mount) and I decided it was not for me while flying.
On the other hand, Karl Gross, N7MXO-7, has a Kenwood/Garmin setup in his Mooney and once when he heard me talking with Center, he was able to track me while airborne. I'm convinced he could have flown an effective intercept with that setup.
AFAIK, the Kenwood radios are the only "off the shelf" general-purpose solutions right now but the TinyTrak4 with some sort of display may be just the thing in the future.
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Joe, K7JD
As has been pointed out by others, the Kenwood handheld (and mobile) radios have the ability to display as well as send packets. Last weekend I rode to the Puyallup (WA) hamfest with with KE7KV in his Kenwood HT/AvMap GPS equipped vehicle. With some effort he was able to scroll through a list of stations received on the radio's display. Although he was able to put "target stations" over the moving map on the GPS screen, it seemed like it took an awful lot of keystrokes (some of them on an accessory keyboard he had on a RAM mount) and I decided it was not for me while flying.
On the other hand, Karl Gross, N7MXO-7, has a Kenwood/Garmin setup in his Mooney and once when he heard me talking with Center, he was able to track me while airborne. I'm convinced he could have flown an effective intercept with that setup.
AFAIK, the Kenwood radios are the only "off the shelf" general-purpose solutions right now but the TinyTrak4 with some sort of display may be just the thing in the future.
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Joe, K7JD
GPS, APRS in flight, and Micro-Trak
Bi-directional tracking is a feature that works well with the Kenwood Products. I have a Kenwood TH-D7 and an Avmap GPS receiver that I use for a quick and dirty portable APRS monitoring station. A post above suggested that monitoring all the local transmissions would be overwhelming, but effectively, you would only be aware of those stations that are transmitting on the area of the GPS map-screen you are currently viewing.
The downside to the Kenwood solutions are these: Cost? In excess of $1000.00 using the handheld Kenwood and the Avmap display GPS. Reliability? My Kenwood has died on the bench a couple of times. I would not expect rough use to help much. Many SAR people told me that they gave up on the TH-D7 for just that reason. The mobile radio is more robust, and more expensive. Complexity? If you have trouble programming a Micro-Trak forget about programming a TH-D7!
There are other options. The Byonics TT4 will connect to a hand-held or mobile radio and provide bidirectional tracking with compatible GPS receivers. ( Serial NMEA receivers that accept waypoint uploads- I think that Byon has a list) There are a few companies making competing products in varying stages of development. These are available right now from Byonics. (www.byonics.com)
I am working on developing an integrated product using the Byonics TT4 for a "brain" and a Micro-Trak transceiver. The first product release will be a fixed channel (144.390-the North American APRS channel) transceiver with 8-10 Watts output. The Micro-Trak IV will be able to run any software the TT4 can, so things like airborne digipeating, advanced telemetry capabilities, etc. will be possible. This will (eventually) include sending and receiving airborne E-mail through the APRS network, which as you know is connected to the internet through "I-Gates". ( this will most likely be accomplished using a small LCD display and a mini-keyboard. No PC required)
The price has not been determined, but it is safe to say that it will be more expensive than a Micro-trak 300....
The next generation Micro-Trak TT4 unit will have advanced capabilities, including frequency agility, voice capabilities etc. This will be of more interest to the Ham die-hard APRS guy, and foreign users, than it would be for airborne users ( I would think) since your airplanes are too small to carry a dedicated radio operator....One advantage to a programmable frequency transceiver is that you can set up a temporary system that is not linked to the internet ( away from prying eyes) and will allow you to send many more position reports without conflicting with the main APRS frequency.
Allen R. Lord
VHS Products
Bi-directional tracking is a feature that works well with the Kenwood Products. I have a Kenwood TH-D7 and an Avmap GPS receiver that I use for a quick and dirty portable APRS monitoring station. A post above suggested that monitoring all the local transmissions would be overwhelming, but effectively, you would only be aware of those stations that are transmitting on the area of the GPS map-screen you are currently viewing.
The downside to the Kenwood solutions are these: Cost? In excess of $1000.00 using the handheld Kenwood and the Avmap display GPS. Reliability? My Kenwood has died on the bench a couple of times. I would not expect rough use to help much. Many SAR people told me that they gave up on the TH-D7 for just that reason. The mobile radio is more robust, and more expensive. Complexity? If you have trouble programming a Micro-Trak forget about programming a TH-D7!
There are other options. The Byonics TT4 will connect to a hand-held or mobile radio and provide bidirectional tracking with compatible GPS receivers. ( Serial NMEA receivers that accept waypoint uploads- I think that Byon has a list) There are a few companies making competing products in varying stages of development. These are available right now from Byonics. (www.byonics.com)
I am working on developing an integrated product using the Byonics TT4 for a "brain" and a Micro-Trak transceiver. The first product release will be a fixed channel (144.390-the North American APRS channel) transceiver with 8-10 Watts output. The Micro-Trak IV will be able to run any software the TT4 can, so things like airborne digipeating, advanced telemetry capabilities, etc. will be possible. This will (eventually) include sending and receiving airborne E-mail through the APRS network, which as you know is connected to the internet through "I-Gates". ( this will most likely be accomplished using a small LCD display and a mini-keyboard. No PC required)
The price has not been determined, but it is safe to say that it will be more expensive than a Micro-trak 300....
The next generation Micro-Trak TT4 unit will have advanced capabilities, including frequency agility, voice capabilities etc. This will be of more interest to the Ham die-hard APRS guy, and foreign users, than it would be for airborne users ( I would think) since your airplanes are too small to carry a dedicated radio operator....One advantage to a programmable frequency transceiver is that you can set up a temporary system that is not linked to the internet ( away from prying eyes) and will allow you to send many more position reports without conflicting with the main APRS frequency.
Allen R. Lord
VHS Products
PaigeHoffart
Well Known Member
Just to clarify...Your receiver will be hearing everything within line of sight on 144.39. It doesn't matter what map you're looking at. If two stations transmit at the same time, the data packets will collide and both beacons will be lost. If there are 10 stations, no problem, if there are 200, we have a problem. Why would two stations transmit at the same time? Because they are probably at an elevation of 3' AGL and they can't hear each other. Unfortunately, if you're at 10,000' you're going to hear everything.
BTW, the other issue with hearing all of this congestion is that your tracker is waiting for a break in the action to transmit its packet. Imagine being in a crowded room, and you're unable to speak until everyone else is quiet.
Unfortunately, in some areas of the country APRS is a victim of its own popularity.
Here's one example of APRS congestion with only 50 stations:
http://mm.aprs.net/map.cgi?map=APRSworld&lat=41.02117&lon=-96.36550&call=*&range=1
For you guys in Fort Worth, I didn't bother counting:
http://www.findu.com/cgi-bin/map-near.cgi?zip=76137
Ok, enough with the doom and gloom. There are things that can be done to reduce the congestion.
1) Transmit less often (smart beaconing)
2) Reduce the number of digi's in your path (WIDE 1-1, 2-1, don't use RELAY)
3) Use a shorter beacon (mic-e compressed)
(Of course, this is a community effort)
How will it work in flight? Hard to tell.
Paige
Davepar
Well Known Member
The Seattle area looks similarly crowded, but the timestamps indicate they aren't all transmitting right now. I took all the APRS stations near Seattle and put them into Excel and sorted by last update. Only 13 transmitted within the last 5 minutes. Doesn't sound like many collisions to me.
Isn't there something in the packet that indicates the vehicle type? We could filter on airborne vehicles.
I figured it was a long shot, but it sounds possible. I think many of the handheld GPS units can display traffic from a 327 transponder or other device. We should be able to fake that protocol pretty easily.
A side question on the WIDE 1-1, 2-1 path setting. Does that affect the ability for the packet to get onto the internet? I don't care how many digipeaters it goes through. I just want it to show up on a map on the web.
Dave
Isn't there something in the packet that indicates the vehicle type? We could filter on airborne vehicles.
I figured it was a long shot, but it sounds possible. I think many of the handheld GPS units can display traffic from a 327 transponder or other device. We should be able to fake that protocol pretty easily.
A side question on the WIDE 1-1, 2-1 path setting. Does that affect the ability for the packet to get onto the internet? I don't care how many digipeaters it goes through. I just want it to show up on a map on the web.
Dave
PaigeHoffart
Well Known Member
Yes, but collision wise it doesn't matter, the interference occurs at the RF level.
That sounds very reasonable. Its been a few years since I lived in a congested area; maybe the new path types have paid off. With the old RELAY, WIDE, WIDE your beacon went out, and was immediately repeated by multiple digis. A receiver in the house would be receiving about 80% of the time. The other thing to note about the statistics off the web is that you will never see a collision, it will never be decoded.
The short answer is no, that is if the i-gate hears the signal directly. If the i-gate isn't within line of sight, then increasing the number of digis that it goes through gets you a better chance of eventually being seen by an i-gate.
Paige
Sam Buchanan
been here awhile
That is precisely the setup used in the default config of the Micro-Trak.
There is a great deal I don't know about packet protocol. This link will answer some of your questions and provide far more info than you probably wanted to know:
http://web.usna.navy.mil/~bruninga/aprs/fix14439.html
(By the way, Mr. Bruninga is the fellow who invented APRS)
Bottom line, we don't want to have more bounces in our beacon than absolutely necessary. The congestion problem increases exponentially when unneeded hops occur. The "WIDEn-N" protocol is designed to reduce congestion and seems to be providing good results for those of us using it.
