VOAAREA Case: RUV Gufunes
This is a case study that tries to guestimate the coverage area of Icelandic National Broadcasting Service (RUV), based on information provided in Radio Nederland's recent article on the station. It also serves as a practical example of how to use VOAAREA even if some of the critical input parameters are missing; in RUV's case, the exact transmitting antenna setup.
Collect all necessary input data
Start by reading the RNW (Radio Nederland) article on RUV, http://www.rnw.nl/realradio/features/html/iceland020111.html. Look for the following data:
- transmitter coordinates
- transmitter power
- times & frequencies of transmission
- transmitter antenna
- antenna beams
Enter the input parameters
- Launch VOAAREA.
- Set Parameters to REL (Circuit reliability). It predicts us the percentage of the days in the month that the REQ.SNR will be met.
- Set Path to Short (Path).
- Set Coefficients to CCIR (Oslo).
- Set Method to 20 (Auto Select).
- Enter the transmitter coordinates: Latitude 64N05, Longitude 21W51, Name GUFUNES.
- Enter Plot Center. Click "Set to transmitter". Then select appropriate X-range and Y-range values. Test your map by viewing the map only (Run > Map only) until you are happy with it. Our values were: Xmin -2000, Xmax 4500, Ymin -3000 and Ymax 2500.
- Enter Groups values. The first Europe transmission takes place at 1215-1300 UT on 13865 kHz so enter 13 as the time and 13.865 as the frequency. The second transmission takes place at 1755-1825 UT on 11402 kHz. Enter 18 UT and 11.402. The month is January (1) and the SSN (the monthly smoothed sunspot number) is estimated to be 110.
- Enter System values. Man-made Noise 145, minimum take-off angle 3 degrees, required reliability 90%, required SNR 67 dB-Hz (a value representing a reasonable grade of service), multipath power tolerance 3 dB, max time delay 0.1 ms.
- Ensure the Fprob values are 1.0 / 1.0 / 1.0 / 0.0.
- Set the transmitter antenna (Tx antenna). This is the trickiest part. Launch the HFANT program. Open the Sample.07 file (a sample Rhombic antenna) from the Samples directory. Set the height above ground to 27 meters (as discussed in the article). Run Plot patterns > Vertical to see the take-off angle. Set the frequency to 13.865 (MHz). The best angle is at 8 degrees and the directivity gain is quite high. Still, let us try with this one. Save the new antenna model under a different name. Enter the new name by pressing "File name" button. Then click "<<Save as.." button to really save it.
- Now press the "Tx Antenna" button on the VOAAREA main screen. Press "Transmitter Antenna" button to select your newly-saved antenna. Set the design frequency to zero. Set the main beam to 125 degrees, and the power to 70% of 10 kW, ie. 7 kW. This is because we assume some line losses.
- Rx antenna. Accept the default SWWHIP.VOA antenna.
As a result, the VOAAREA main input screen should look like this:
Run the prediction
- Choose Run > Calculate > Save{temp.VOA}/Calculate.
- To plot the map after calculations, choose Run > Plot results.
- Open the first file to be plotted: File > open TEMP.VG1.
- If you do not wish to change the default colours or values, just choose Plot to > Window.
- To view the 18 UT map, first Exit the current map, and choose File > Open > temp.vg2.
Voila!
This is approximately what you should see (I have changed some of the default colours for my maps):
13 UT - 13865 kHz 18 UT - 11402 kHz Legend
