Category Archives: Propagation

PropLab 3.1: How Propagation really works

 

Fergana_DK8OK_3DRayTracing

The software’s unique feature is 3D raytracing, showing an anatomy of propagation (see text).

HF propagation software seems to be full of mysteries. But its all about modeling physics. There are several models around, the most prominent surely is VOACAP, followed by ASAPS. VOACAP comes in very many different tastes like e.g. PropMan 2000 or ACE. It often has been coined to be the “Gold Standard” among hams and professionals as well. VOACAP gives reliable results on a statistical base for a month, whereas ASAPS returns propagation based on the current conditions of a day. It also gives propagation for an aircraft en route during its flight and takes at least a bit care of multi-path propagation which may degrade digital modes. Both work offline as online, and they are fast.

[Einen ausführlichen deutschsprachigen Test mit vielen Screenshots und Beispielen habe ich in der Januar- Ausgabe 2017 der Fachzeitschrift FUNKAMATEUR veröffentlicht.]

PropLab is giving you a much smarter view on what is really happening on a specific day and time at a specific path or area. It relies on the International Reference Ionosphere (IRI 2007) and uses the ray tracing technique. In short, PropLab is automatically fetching all relevant space weather data (not just sunspots) from scientific sources of the internet to model the ionosphere with its different “layers”.

You then give in your path, antenna etc. in a well-supported way. After having started “ray tracing”, PropLab lets refract rays at exactly this ionosphere with its high granularity and some real-world effect like tilts of layers which will result in e.g. propagation off the great circle. It will also beautifully show effects like focusing and gray line propagation, including Pedersen’s long ranging ray with time resolution up to one second – rather than one hour as that of VOACAP.

Read more

ASAPS: HF Prediction online & free!

Flight AF 128 from Paris to Beijing: What is they best time/frequency combination to communicate with Stockholm AOCC on HF?

Flight AF 128 from Paris to Beijing: What is the best time/frequency combination to communicate with Stockholm AOCC on HF en route?

 

HF prediction seems to be a somewhat neglected field among short wave listeners, as well as hams. At the same time, some knowledge of how propagation works on specific paths or into defined areas will greatly enhance your hunting success. If you have considered the somewhat flat learning curve of some software as an obstacle, there now is no excuse. With ASAPS’ recently even more improved online services, you are on the sunny side of HF right now.

I had written a short paper explaining how this free service can be used especially for Utility DXing. If you also ever wanted to know the relation of a waste paper basket and multi path propagation, please download this PDF (7 pages, 22 illustrations) here.

Perseus & Markers: Great Tools for analyzing Propagation!

Ionosphäre_CHU

The Perseus SDR comes with a software, where you may define up to eight markers. Each of them measures the level of the signal at distances of 100 ms to 5 seconds and writes it into a CSV file. This is the base for further analyzing these data, i.e. propagation. See such an analysis of the fade-out of CHU on 3.330 kHz on top of this page.

With an (active) antenna delivering a constant antenna factor over specific range – as all professional antennas do, e.g. RF-Systems’s DX-1 – you may also switch to logging the field strength of the signal in dBµV, rather than the input level in dBm.

The first paper presents a general introduction into this concept. It has been translated into English by Guy Atkins.

The second paper, in German, goes more into the depth of analyzing the data. But it’s 13 illustrations will make it under stable also to readers who don’t understand German.

Five Mongolians on Long wave

Mongolia_209_rays_2200

Since I visited Mongolia in 2001, I fell in love with this country. Hence, reception of all their radio stations on long wave caught my double interest. With some help of other listeners, I managed to receive all stations and analyzed their reception. Without any 100 g of Chinggis Khan Vodka, to which I surprisingly bumped into at Sarazul at Warnemünde in late summer 2015 …

Read this paper, to get also some information on how to receive and analyze stations which even might be too weak to hear.

Solar Eclipse 2015: Some signals did improve, some didn’t

23k4

The Solar Eclipse on March 20th, 2015, provided some unique Monitoring opportunities in Europe. It was the first time that broad parts of the spectrum could have been recorded and analyzed even by hams.

I recorded the range from 0 to 2 MHz to analyze the effects of the eclipse on different frequencies: on VLF signals dropped significantly (see the W-shape level of DHO38 on 23,4 kHz above), whereas on medium wave signals did improve.

This paper covers my observations in e.g. 29 illustrations and some audio files.

Caveat: Embedded multimedia content will only work with the most recent version of Adobe`s Acrobat Reader. And you have to save the PDF on your device (hard disk/stick), to make use of these multi-media.

The best Digimodes: Test reveals surprising results

Disturbed

Digital communications with digimodes is a very efficient tool of HF communications. Hams are using RTTY for decades. Since the advent of PSK31 in late 1998, there have been developed a lot of digimodes with special applications in mind. Albeit, RTTY and PSK31 are still very popular.

When I asked myself: “What’s the best mode?”, I couldn’t get a reliable answer. And, really, it depends.

As a result, I made a setup for testing some chat modes on HF channels which are very much different from just flat noisy (AWGN) channels. The results were very much surprising: There are by far better alternatives to RTTY and PSK31 (see table above, reflecting some of the results).

This paper deals with setting up a real-world testbed and presents some results. Anyone is welcomed to replicate the test and/or extend it with other modes. Recent software of W1JHK has made the workflow much easier and faster since then.

Living Sonagram: A revolutionary tool for Monitoring

SOnagram_21

Monitoring of wide frequency ranges can be an art. And hard work, too. The technique ot the “Living Sonagram” makes this task easy:

  • record a frequency range of up to 10 MHz, for e.g. 24 hours or less or more
  • define a range of time ad frequency you want to analyze offline
  • build up the “Living Sonagram”
  • tune. demodulate, and decode in this whole range just with your mouse (see screenshot on top)

You must see this to believe it!

The Software has been developed by Simon Brown.

I wrote this paper as a step-by-step introduction into this technique.

You may also look this video on this topic.

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