The new antennas arrived and I experimented with the payload antenna. The base antenna, a Yagi antenna, requires a bit more set up so I haven’t tried it.
I discovered with this experimenting that the radio signal from the DNT900 may interfere with GPS signals. The board was flat and the radio antenna was vertical. I received no GPS data. When I hung the prototype from the top of a ladder (as shown below), I started receiving GPS data after five minutes.
With the data transmission made a little more reliable, I want to try some short distance tests (up to 100 ft). I set up a test in my front yard and powered the base and remote systems. I started receiving battery and temperature data, and GPS after a bit. This is normal while the GPS collects satellite data for a fix.
Suddenly, the base was not receiving GPS data. I went over to the remote and the GPS module indicated a lock (a flashing LED). The following night, I had the same set up. I started receiving GPS data and noted an odd difference in the displayed time. After a few minutes, the base stopped receiving GPS data. With a clue about the time, I reviewed the Arduino code.
The code is designed to send GPS data when the time stamp is different between two sets of GPS data. As it happened, I was crossing midnight during my experiment and that may have been an issue. I also discovered that I had a data type mismatch between the variables used to evaluate the difference in GPS time. After I made the variables the same data type, the base received data consistently and through a midnight.
Lastly, I was able to receive GPS data from 100 ft and farther. I have been using short rubber ducks for this experimenting. I ordered better antennas for the next phase.
Flight Track 1.3
I’ve tracked six or seven flights in the past weeks, and collected information on landing site predictions. After the burst, Flight Track predicts a landing site within an average of three miles of the actual landing site. This means recovery teams have about a half hour to travel to a target landing site.
Flight Track requires wind data (usually from NOAA READY) to make real time predictions however I realized (from some of my designs for Flight Track On Line) that after the burst, Flight Track uses only the wind data gathered during ascent. With this, I altered Flight Track to produce a landing site prediction even when READY data is not available. Expect to see this in Release 1.3!
Lastly, I have prototyped parts of Flight Track On Line and discovered that the parsing of APRS-IS data may skip some packets in Flight Track. This will be corrected in Release 1.3.