Ships_Cat
Well-Known Member
Quite a number of forumites seem to have SSB transceivers or else mf/hf receivers (or are radio amateurs) and so may be interested in a little FREE but excellent program to forecast propagation. May be especially helpful with the solar cycle at its current low.
I normally use VOACAP which while is about the best is quite complicated to use. However, in the October 2006 QST magazine is a review of a number of simpler programs one of which, HamCAP at www.dxatlas.com (look for it down the left side of the page), is very good, easy to use and FREE (repeating myself /forums/images/graemlins/smile.gif). I have been playing around with it for a few weeks - it also uses VOACAP which the HamCAP site tells you to download and install as well (again is free), but provides a simple (but less versatile) front end to do simple predictions so you don't directly use VOACAP yourself - and can recommend it.
If you don't understand anything about mf/hf propagation then there are a number of sites on the internet which tell how to use HamCAP and what the outputs from it mean. Might make a good winter study for those in the Northern Hemisphere.
For those who try it I would recomend that -
- don't forget to follow the instructions to download and install VOACAP as well (it won't work otherwise)
- in the Settings set the Map Style to "Pseudo" (makes it much easier to read)
- use the instructions on the internet as to where to find the Smoothed Sunspot Number SSN (for those who know of it you don't use the current SN from WWV/WWVH, for example, although if you know what that has hovered around for the last week or so and ignore any sudden peaks use that) to enter on the parameters page. Also, unless you already understand what the K index is don't worry about changing the value from the default (3)
- for power I suggest using, say, 80 watts (even if you have a 150 watt transceiver, also remember that for intelligibility both ways it is the lowest powered station that counts and that will usually be you) or if just interested in receive only use (your power is then irrelevant) 1,000 watts unless you know the actual power of the station to be listened to
- for antennas use 1/4 wl GP (1/4 wave ground plane vertical) as an approximation for both ends (ie the TX and RX antennas, on the antennas page, unless you know better)
- put your lat/long in on the settings page
- for starters use the "Map" output (in Pseudo colour, it's then much clearer), and look for opportunities (time of day/night and frequency, for frequency click the amateur band frequency closest to that which applies (the 3.5, 7, 10, etc on the map page are frequencies in Mhz)) that give the highest positive SNR (signal to noise ratio) at the other station's location - just hover the cursor over that location. Worry about MUF, Long Path, the DX QTH, Kp, etc later when more familiar (unless wise on those things already)
If you know what you are doing, understand a bit about propagation with a tool like HamCAP and have a properly set up station on your boat, it is possible to work shore stations around the world and even mobile ones when conditions are suitable (I have a number of times worked mobile hf stations in UK from here in NZ from our boat even well down in the solar cycle).
But remember, it is not an exact science.
John
I normally use VOACAP which while is about the best is quite complicated to use. However, in the October 2006 QST magazine is a review of a number of simpler programs one of which, HamCAP at www.dxatlas.com (look for it down the left side of the page), is very good, easy to use and FREE (repeating myself /forums/images/graemlins/smile.gif). I have been playing around with it for a few weeks - it also uses VOACAP which the HamCAP site tells you to download and install as well (again is free), but provides a simple (but less versatile) front end to do simple predictions so you don't directly use VOACAP yourself - and can recommend it.
If you don't understand anything about mf/hf propagation then there are a number of sites on the internet which tell how to use HamCAP and what the outputs from it mean. Might make a good winter study for those in the Northern Hemisphere.
For those who try it I would recomend that -
- don't forget to follow the instructions to download and install VOACAP as well (it won't work otherwise)
- in the Settings set the Map Style to "Pseudo" (makes it much easier to read)
- use the instructions on the internet as to where to find the Smoothed Sunspot Number SSN (for those who know of it you don't use the current SN from WWV/WWVH, for example, although if you know what that has hovered around for the last week or so and ignore any sudden peaks use that) to enter on the parameters page. Also, unless you already understand what the K index is don't worry about changing the value from the default (3)
- for power I suggest using, say, 80 watts (even if you have a 150 watt transceiver, also remember that for intelligibility both ways it is the lowest powered station that counts and that will usually be you) or if just interested in receive only use (your power is then irrelevant) 1,000 watts unless you know the actual power of the station to be listened to
- for antennas use 1/4 wl GP (1/4 wave ground plane vertical) as an approximation for both ends (ie the TX and RX antennas, on the antennas page, unless you know better)
- put your lat/long in on the settings page
- for starters use the "Map" output (in Pseudo colour, it's then much clearer), and look for opportunities (time of day/night and frequency, for frequency click the amateur band frequency closest to that which applies (the 3.5, 7, 10, etc on the map page are frequencies in Mhz)) that give the highest positive SNR (signal to noise ratio) at the other station's location - just hover the cursor over that location. Worry about MUF, Long Path, the DX QTH, Kp, etc later when more familiar (unless wise on those things already)
If you know what you are doing, understand a bit about propagation with a tool like HamCAP and have a properly set up station on your boat, it is possible to work shore stations around the world and even mobile ones when conditions are suitable (I have a number of times worked mobile hf stations in UK from here in NZ from our boat even well down in the solar cycle).
But remember, it is not an exact science.
John
