Propagation

[m5aec]

is there a way to show Long path/short path statistics?

[CT1BXX]

Hi,
As far as i know no!
I had already thought about writing this on the forum.
Let's see if we have any more comments.

[DF5WW]

Hi Nando,

think you´re right. Log4OM is using VOACAP propagation with simple dipole and 100 watts.
No changes possible in the setup so no LP/SP stats are possible (now). Maybe a feature
for the future ?

[m5aec]

thanks and sorry I had read about simple dipole, which is of course both long and short path.
It would be good for the future to have both, as in DX Summit.
Barrie M5aec

[ah6fx]

M5AEC,

I could not resist jumping in and commenting on your question about the Log4OM2 propagation tool [SP/LP issue] which interfaces with VOACAP. I am not a Log4OM team member, but have been a Log4OM user for maybe 10 – 15 years or more. Log4OM creator Lele IW3HMH and I in about 2014, discussed incorporating a propagation capability into Log4OM. Maybe as a result of that – emphasize maybe - he and the team … I am sure Terry did yeoman’s work, developed the VOACAP interface we enjoy today.

Excuse me because you asked for the time … and I am telling you how to build a watch. BUT … I regularly use VOACAP (Voice of America Coverage Analysis Program ) Coverage Area Maps as a tool for visualizing band openings from our shacks to various DX regions. VOACAP is the result of over 50 years of HF research and development. Many consider it as the most professional HF system performance prediction tool. It is used for frequency planning by Voice of America and a number of other international broadcasters and institutions all over the world. So what does that mean to us the average Log4OM2 user … it means we have instant access the perhaps the world’s standard for HF propagation forecasting via Log4OM. It is the Rolls Royce of prop tools.

Although not real-time, VOACAP is statistically based and very accurately simulates HF propagation conditions. Out of sight and out of mind, VOACAP software incorporates various data elements and produces a propagation picture in world map, and other formats. The smoothed sunspot number is the only solar weather parameter used in the VOACAP algorithm. The map does not show current conditions. Instead, the map displays a pictorial estimation of reliable communications circuits from our shack to locations throughout the world. The estimate produces a propagation picture that holds true for the entire month for a particular frequency range at a particular hour. Of course there are natural occurrences which VOACAP does not model since it is not real-time. Some of these natural occurrences include propagation immediately before, during, and after sunset and sunrise especially on the low bands. Also consequences of current geomagnetic storms or peculiarities in the polar zones are not modeled. Even though not real-time, after over 30 years of VOACAP use, I find it very accurate predicting HF conditions.

VOACAP gets my vote as the best propagation tool available to ham radio operators.

Now addressing your desire for long path and short path predictions … see the actual VOACAP tool at http://www.voacap.com . Be sure to read the tutorial if you are unfamiliar with VOACAP. You will find the short path – long path capabilities. I understand your desire for long path predictions in Log4OM … I am sure it can easily be incorporated into Log4OM2 by the talented team … but perhaps there is little demand for this snap shot since most hams are not avid DXers such as yourself who desire that data. Frankly, I use a large loop antenna and I am equally weak in all directions, but I pay attention to the stations who are working the DX via long path. Recommend going to the VOACAP website for the LP capability. I have the VOACAP website book marked in my browser for quick reference.

Since I am a “propagation hound” I find the “Reliability” data on the cluster page one of the most useful Log4OM tools. Further, I find the “Circuit Reliability” subtab in the “Propagation” tab very useful and accurate. I am sure those tabs are inter-related. They summarize VOACAP data and give us in one look, a percentage of success for working specified stations in certain regions of the world. That is really the bottom line: what are our chances of working that station.

Lastly, thanks to Jari Perkiömäki OH6BG and others for making possible and maintaining the various versions of VOACAP.

Danny
AH6FX/W4 – Virginia, USA

[IW3HMH]

Hi Danny,
Log4OM voacap engine is based on the engine created in Delphi by Alex VE3NEA (the OMNIRIG guy), built starting from fortran VOACAP sources.
Alex developed this engine some years ago, and will not mantain it anymore (but, luckily, it's open sourced)
His engine is amazingly fast but, other than not mantained anymore, does not support different antenna types.

I asked Alex for more antennas some days ago, and he politely refused, but provided a text file with some instructions on how to implement different antennas into voacap engine.
Unluckily i'm not so skilled in delphi, so actually i must rely on what we have. Maybe one day someone will take care of that project and will improve further, but actually it's not on my path.
The alternative is to use the "default" voacap engine but this will be really slow compared to the actual module

[ah6fx]

Great to hear from you again Lele. Hoping all is well with you and yours.

Understand what you say. I am going way back in VOACAP history. As I recall off-hand, propagation guru George Jacobs [W3ASK ... he may be SK but QRZ does not show him SK] at VOA contracted out for the development of a tool which became VOACAP. My great long time friend Dan Ferguson - K4VOA took over some of George's responsibilities when George retired, and has had some involvement with it. Dan was the frequency manager for VOA for many years.

Too bad about the current state of VOACAP. Have you contacted Jari Perkiömäki OH6BG, who I picture as one of the prime engineers and developers/maintainers behind VOACAP today? He assisted me writing two propagation articles which were actually more about VOACAP than HF propagation. Let me know what Jari says. If necessary I can contact Dan Ferguson - K4VOA and maybe we can find someone to assist you.

Have a great day.

Danny
AH6FX/W4 Virginia, USA

[ah6fx]

Lele,

A follow-up from my last to you. As you know, Alex's "VOACAP" engine version was embedded in his HAMCAP or DX Atlas, etc. which he developed many years ago based on the open source VOACAP code. They are great tools and I used them sometimes in parallel to VOACAP.

Check out the VOACAP users manual. You can select various antennas ... antenna heights ... station power, etc. including SP / LP which was the original question from the M-station. [[[If you incorporate more VOACAP data into Log4OM2 ... the antenna, antenna height, etc info seems to belong in "set up" under a new set up section for propagation tools ... even though some of this info is already in "Program Configuration."]]] All the subtabs under the main Propagation tabs are also data views per VOACAP. That is why I thought your prop data was based moreso on VOACAP. But since Alex uses the VOACAP source code, no wonder they are very similar.

Recommend contacting Jiri. He is a great guy.

Danny
AH6FX/W4 Virginia, USA