The software will create a time- and day-specific bandscan of any shortwave segment including a signal strength prediction (the dB column):

For example for North Germany, 31.7.2005, no Threshold, 100 sunspots looking like this
(the real application has colours, I just didn't manage to get a coloured screenshot):

with frequency analysis over 24 hours

How to make it work

What I provide is only the browser. You need the file ILGATEXT.ZIP (ILGSTEXT.TXT) which is not officially available anymore.

• Download ILGSTEXT.TXT and put it into the directory C:\dx\ (must be this path!)
• Download SWBRWS.ZIP and unzip it into C:\dx\
• Execute SWBRWS32.EXE

System requirements

Not much. This should even work on a 286-PC as it is written in Pascal, still using MSDOS. For the graphics, a EGA/VGA-card is required. Unfortunately I don't know if OS released later than Windows 98 would fully support the MSDOS-standard and graphics driver. It is possible to make it work under XP but may be a bit tricky.

Colums:

• Frequency
• Special Status (I=inactive, N=non-confirmed, E=Estimated, P=Planned)
• Special mode (N=Digital, L=LSB, U=USB, S=Reduced carrier 12dB, T=Reduced Carrier 6dB)
• Programme
• Power kW
• Transmitter Site
• Language
• Times of current broadcast
• Preduicted signal Strength in dB (SKP: skip too short, qth?: transmitter coordinates unknown)

Some background information about the propagation analysis: I searched the whole internet for a more-or-less simple algorhythm that calculates the signal strength on shortwave. Unfortunalety there was no free source code. The only thing available were 2 old Basic and Fortran files: Micromuf and Minimuf. They only calculate the lowest and highest usable frequencies. Micromuf even has an error calculating the LUF - any code you find on the net will have that included. I tried to solve that problem, after all Minimuf worked better. That was the algorhythm used in my Shortwave Browser 2. But it wasn't good enough. So had to develop something on my own.

The propagation analysis works as follows: The initial signal strength is detemined by the transmitter power and the direction into which the transmitter antenna is beaming. Then signal travels in many hops to the receiver. On each hop, the intensity of the E- and F-layer of the ionosphere are determined by the position of the sun and the sunspot number. Each time the distance from signal to sun-in-zenith-point is being taken. This gives a value for the light and darkness. The lighter it is, the higher are the E- and F-MUF (all this can be roughly traced in the details mode). The F-Layer has a 2 hour delay effect because the high bands stay open long after dusk, whereas before dawn they can't be used. Around the equator the F-MUF stays very high until midnight, then it drops fast till sunrise. Around the pole, the F-layer is minimized.

So the length of each hop is determined by the F-intensity, the attenuation by the total number of hops, the frequency and the intensity of the E-layer. If the F-intensity isn't strong enough (F-MUF too low), no reception is possible. If the hop distance is too long and there is only one hop, it will give out the message 'SKP', whereas in the graph the signal is attenuated. Often you can pick up these signals by so-called backscatters, sometimes even quite strong, but usually with echoes becuase of the multi-path reception.

If you like you can adjust the city data (coordinates) in the DAT-file.

The next thing I'm thinking about is a long-path analysis.

Please mail me if you're interested in the Pascal-source code. The lentgth of each hop is determined by the F-MUF

Questions? Corrections? Ideas? Comments?
Mail me: PeerAxel@aol.com

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