qDF allows a user to enter data from radio direction finding activity, computes target location estimates using DFLib (using 4 different estimators), and creates a KML file for plotting the activity in Google Earth. It also optionally feeds data to an APRS client via UDP datagrams (only Xastir has been tested with this capability, as that's all I use), which can then transmit the data to the APRS RF network or an APRS-IS server.
- proj.4 libraries and development headers
- Qt4 libraries, headers, and development programs (moc, etc.)
- DFLib (which itself requires proj.4, which itself is obsolete --- DFLib has not yet been updated to support versions of proj after 6.0, it still uses the old API)
Assuming all dependencies have been installed properly, building qDF requires only a few steps
mkdir build
cd build
qmake /path/to/qDF/sources/qDF.pro
make
On some systems, qmake might be called "qmake-qt4".
Execute the "qDF" program created in the previous step. It will pop up a main window with a menu bar.
On your first run, choose "Edit->Settings..." and fill in what you need here. If you're going to be using APRS display, set your call sign, the IP address (or DNS name) of the APRS client's server port, and the port number in the "APRS" tab. If you're not using APRS, unclick the "Publish to APRS" checkbox.
Set the magnetic declination, UTM zone, and preferred coordinate system in the "Geographic Settings" tab. You can also change your default hemisphere if you're not in North America. The most important setting here is the default declination, as qDF always treats bearings you enter for DF reports as magnetic bearings, and converts them to true bearings using this setting. All internal calculations are done using the computed true bearing --- if you don't get this setting right, your reports will all be misinterpreted.
You can leave "DF Fix settings" alone for now.
These settings are saved across runs.
Use the "Report->New Report" menu entry to enter DF reports as they come in.
Give your report a unique name. qDF will keep the "Ok" button greyed out if you try to enter the name of an existing report here, and keep it greyed out until the name is made unique.
Enter the latitude and longitude of the receiver position. This can be done in one of three formats: decimal degrees, degrees/decimal minute, degrees/minutes/decimal seconds. As soon as you enter a decimal in the deg, min, or sec box, the smaller unit box is greyed out.
Enter the MAGNETIC bearing reported by the DFer directly off of their magnetic compass without declination correction. qDF will use your default magnetic declination (from the settings dialog) to convert this internally to true bearing.
Enter equipment type: Beam (i.e Yagi), Elper (i.e. L-tronics "L'il L-per"), Interferometer, or Long Baseline Average.
Enter report quality: OK, Good, Very Good. This is a rough, subjective measure of the precision of the bearing taken. If the DFer thinks that his equipment gives him high confidence that the bearing he reports really is the bearing to the transmitter, that's "Very Good". If the DFer feels that the signal is so weak, or that he had trouble pinning down the exact direction, that's "OK." Somewhere in between is "Good." These report qualities, combined with the equipment type, are mapped to bearing error standard deviations and used in the statistical estimators (Stansfield and Maximum Likelihood).
As soon as two or more reports are entered, target location estimates start showing up in the main window, and start being written to the KML and APRS displays.
If you want to look at the KML in Google Earth, open the file "qDF_GE.kml". This is a wrapper file that tells Google Earth to periodically re-read the real data, which is in "qDF_GE_data.kml". That way your Google Earth display is kept continuously updated as qDF writes out more data.
qDF writes out the following information to APRS and KML displays:
- receiver locations for each report
- bearing lines from receivers
- estimated target location for each estimator
- 50%, 75%, and 95% confidence regions for the Stansfield and Maximum Likelihood estimators