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qDF allows a user to enter data from radio direction finding activity,computes target location estimates usingDFLib (using 4 differentestimators), and creates a KML file for plotting the activity inGoogle Earth. It also optionally feeds data to an APRS client via UDPdatagrams (only Xastir has been tested with this capability, as that'sall I use), which can then transmit the data to the APRS RF network oran APRS-IS server.

1. proj.4 libraries and development headers
2. Qt4 libraries, headers, and development programs (moc, etc.)
3. DFLib (which itself requires proj.4, which itself is obsolete ---DFLib has not yet been updated to support versions of proj after6.0, it still uses the old API)

Assuming all dependencies have been installed properly, building qDFrequires only a few steps

mkdir buildcd buildqmake /path/to/qDF/sources/qDF.promake

On some systems, qmake might be called "qmake-qt4".

Execute the "qDF" program created in the previous step. It will popup a main window with a menu bar.

On your first run, choose "Edit->Settings..." and fill in what youneed here. If you're going to be using APRS display, set your callsign, 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 coordinatesystem in the "Geographic Settings" tab. You can also change yourdefault hemisphere if you're not in North America. The most importantsetting here is the default declination, as qDF always treats bearingsyou enter for DF reports as magnetic bearings, and converts them totrue bearings using this setting. All internal calculations are doneusing the computed true bearing --- if you don't get this settingright, 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 greyedout if you try to enter the name of an existing report here, and keepit greyed out until the name is made unique.

Enter the latitude and longitude of the receiver position. This canbe done in one of three formats: decimal degrees, degrees/decimalminute, degrees/minutes/decimal seconds. As soon as you enter adecimal in the deg, min, or sec box, the smaller unit box is greyedout.

Enter the MAGNETIC bearing reported by the DFer directly off of theirmagnetic compass without declination correction. qDF will use yourdefault magnetic declination (from the settings dialog) to convertthis internally to true bearing.

Enter equipment type: Beam (i.e Yagi), Elper (i.e. L-tronics "L'ilL-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 DFerthinks that his equipment gives him high confidence that the bearinghe reports really is the bearing to the transmitter, that's "VeryGood". If the DFer feels that the signal is so weak, or that he hadtrouble pinning down the exact direction, that's "OK." Somewhere inbetween is "Good." These report qualities, combined with theequipment type, are mapped to bearing error standard deviations andused in the statistical estimators (Stansfield and MaximumLikelihood).

As soon as two or more reports are entered, target location estimatesstart showing up in the main window, and start being written to theKML 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 toperiodically re-read the real data, which is in "qDF_GE_data.kml".That way your Google Earth display is kept continuously updated as qDFwrites out more data.

qDF writes out the following information to APRS and KML displays:

1. receiver locations for each report
2. bearing lines from receivers
3. estimated target location for each estimator
4. 50%, 75%, and 95% confidence regions for the Stansfield and Maximum Likelihood estimators