This plugin can be used to generate a heat map based on RF channel power. Channel power is measured as average power, maximum peak power, minimum peak power as well as pulse average power (i.e. average power above a threshold).
To view the Heat Map visually, the [Map Feature](../../feature/map/readme.md) should be opened. If using the 3D map, it is recommended to set the Terrain to Ellisoid (as the heat map is 2D).
To record data for a heat map, a GPS is required, and Preferences > My Position should have "Auto-update from GPS" enabled.
(E.g. on Linux: export QT_NMEA_SERIAL_PORT=/dev/ttyACM0 or /dev/ttyUSB0 on Windows: Set QT_NMEA_SERIAL_PORT=COM5 via Control Panel)
This requires the Qt serialnmea plugin, which is not available in the libqt5positioning5-plugins package on Debian / Ubuntu.
It can be downloaded for Ubuntu/x64 from http://sdrangel.org/downloads/libqtposition_serialnmea.so and should be installed in usr/lib/x86_64-linux-gnu/qt5/plugins/position/.
This custom build of the pluging also allows setting the baud rate via the QT_NMEA_SERIAL_BAUD_RATE option (which is not supported on Windows nor Mac).
On Android, GPS setup should be automatic. GPS position updates may stop on Android when the screen is off. To keep the screen on, press the View > Keep Screen On menu.
<h3>1: Frequency shift from center frequency of reception</h3>
Use the wheels to adjust the frequency shift in Hz from the center frequency of reception. Left click on a digit sets the cursor position at this digit. Right click on a digit sets all digits on the right to zero. This effectively floors value at the digit position. Wheels are moved with the mousewheel while pointing at the wheel or by selecting the wheel with the left mouse click and using the keyboard arrows. Pressing shift simultaneously moves digit by 5 and pressing control moves it by 2.
<h3>2: Channel power</h3>
Average total power in dB relative to a +/- 1.0 amplitude signal received in the pass band.
<h3>3: Level meter in dB</h3>
- top bar (green): average value
- bottom bar (blue green): instantaneous peak value
- tip vertical bar (bright green): peak hold value
<h3>4: BW - RF Bandwidth</h3>
Bandwidth in Hz of the channel for which power is to be measured.
Time period overwhich the channel power is averaged. Values range from 10us to 10s in powers of 10. The available values depend upon the sample rate.
<h3>8: THp - Pulse Threshold</h3>
The pulse threshold sets the power in dB for which the channel power needs to exceed, in order to be included in the pulse average power measurement.
<h3>9: TX - Enable Transmitter</h3>
When checked, enables the position of the transmitter of the signal being mapped to be set and its transmit power level. This enables range and path loss calculations.
<h3>10: Transmitter Latitude</h3>
Specifies the latitude of the transmitter in decimal degrees, North positive.
<h3>11: Transmitter Longitude</h3>
Specifies the longitude of the transmitter in decimal degrees, East postive.
<h3>12: Transmitter Power</h3>
Specifies the power of the transmitter in dB.
<h3>13: Set Transmitter Position</h3>
When clicked, sets the transmitter position (10, 11) to the current position.
<h3>14: Min - Colour Map Mininimum Power</h3>
The colour map minimum power field, specifies the power in dB, below which, power measurements are not plotted on the heat map, and above which are plotted using the colour map (16).
The colour map maximum power field, specifies the power in dB, above which, all power measurements are mapped to the highest entry in the colour map (16).
Selects the colour map used to linearly map power measurements between the minimum (14) and maximum (15) fields to the colour of pixels that will be plotted on the map.
<h3>17: Latitude</h3>
Displays current latitude in decimal degrees. North positive.
<h3>18: Longitude</h3>
Displays current longitude in decimal degrees. East positive.
<h3>19: Range</h3>
Displays the range from the current position to the transmitter position in metres or kilometres.
The following figure shows the difference between average power, max peak power, min peak power and pulse average power, when the averaging time is over the full time of the graph.
