Sam Buchanan
been here awhile
It borders on geekiness, but there are ways to find out how the little pink dots found their way from our APRS tracker to the computer monitor. This can provide interesting data on how well our system is transmitting and the general state of coverage in our area.
All my APRS flights so far have been within 50 miles of DCU, my home 'drone. There is an iGate (direct portal to the APRS internet system) only 13 miles SE of DCU that has been capturing most of my beacons. But for some reason, the iGate (N8DEU-5) was down during yesterday's flight so I got an insight into coverage without the local iGate snagging most of my beacons.
Here is the flight:
DCU is at the bottom of the frame, the figure eight was flown over my hometown. By clicking on any of the dots the beacon info can be seen:
Take a look at the data in the bubble:
NT4UX-2 was the first station to hear this particular beacon. We can find the location of NT4UX-2 by entering the call sign "NT4UX" in the call sign search box at the upper left-hand corner of this look-up page: http://www.qrz.com/
NT4UX is a station located in Mt. Juliet, TN. When NT4UX received the beacon from the Micro-Trak in N399SB, it rebroadcast it and the bounce was then received by K4CP. Where is K4CP? Using QRZ.com again we find K4CP is located in Monterey, TN, about 70 miles east of Mt. Juliet. This station is an iGate which relayed the beacon info to the aprs.fi internet server which then displayed it on our monitor just seconds after the beacon was transmitted from N399SB.
There is more info to be gleaned from this flight. By hitting the "Station Info" link on the map page, we find this nugget:
This record shows the most distant stations that heard N399SB during the flight. Notice that NT4UX was 148.1 miles from the plane, and I was only 1900' AGL at the time, with hilly terrain between the plane and NT4UX. This beacon was received 148 miles distant with only 300mw power.
The other stations referenced give us this data:
KG4NRC; 91.5 miles, Nashville, TN
N4XWC; 109.8 miles, Warrior, AL
Not bad for low altitude, a little 300mw transmitter, and a homemade antenna! N399SB was working an area 260 miles in width.
The "Raw Packets" link on the map page provides data for every beacon sent on the flight. Here is an excerpt:
Most of this data is self-explanatory; notice the series of characters near the end of each line. This is the GPS data translated into MIC-E format. This format is better for our use because it results in a much shorter packet than having the GPS data in text form sentences as it comes out of the GPS NMEA stream.
It is obvious the APRS protocol is quite clever, and having access to the full data makes the process even more interesting and educational. This provides us a way to see how well our system is performing and which stations in our area are capable of receiving and relaying distant beacons.
It's also interesting to know the map display we are using originates on a server in Finland!
All my APRS flights so far have been within 50 miles of DCU, my home 'drone. There is an iGate (direct portal to the APRS internet system) only 13 miles SE of DCU that has been capturing most of my beacons. But for some reason, the iGate (N8DEU-5) was down during yesterday's flight so I got an insight into coverage without the local iGate snagging most of my beacons.
Here is the flight:
DCU is at the bottom of the frame, the figure eight was flown over my hometown. By clicking on any of the dots the beacon info can be seen:
Take a look at the data in the bubble:
NT4UX-2 was the first station to hear this particular beacon. We can find the location of NT4UX-2 by entering the call sign "NT4UX" in the call sign search box at the upper left-hand corner of this look-up page: http://www.qrz.com/
NT4UX is a station located in Mt. Juliet, TN. When NT4UX received the beacon from the Micro-Trak in N399SB, it rebroadcast it and the bounce was then received by K4CP. Where is K4CP? Using QRZ.com again we find K4CP is located in Monterey, TN, about 70 miles east of Mt. Juliet. This station is an iGate which relayed the beacon info to the aprs.fi internet server which then displayed it on our monitor just seconds after the beacon was transmitted from N399SB.
There is more info to be gleaned from this flight. By hitting the "Station Info" link on the map page, we find this nugget:
This record shows the most distant stations that heard N399SB during the flight. Notice that NT4UX was 148.1 miles from the plane, and I was only 1900' AGL at the time, with hilly terrain between the plane and NT4UX. This beacon was received 148 miles distant with only 300mw power.
The other stations referenced give us this data:
KG4NRC; 91.5 miles, Nashville, TN
N4XWC; 109.8 miles, Warrior, AL
Not bad for low altitude, a little 300mw transmitter, and a homemade antenna! N399SB was working an area 260 miles in width.
The "Raw Packets" link on the map page provides data for every beacon sent on the flight. Here is an excerpt:
Most of this data is self-explanatory; notice the series of characters near the end of each line. This is the GPS data translated into MIC-E format. This format is better for our use because it results in a much shorter packet than having the GPS data in text form sentences as it comes out of the GPS NMEA stream.
It is obvious the APRS protocol is quite clever, and having access to the full data makes the process even more interesting and educational. This provides us a way to see how well our system is performing and which stations in our area are capable of receiving and relaying distant beacons.
It's also interesting to know the map display we are using originates on a server in Finland!
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