Propagation

This page is a 'primer' for APARC members. It is 'work in progress' and liable to have significant changes. Please use it as a starting point for your own investigations.

Hourly Area Predictions

Hourly Area Predictions are produced by Space Weather Services, Bureau of Meteorology, Government of Australia gives a near-real-time view of the f0F2 conditions affecting the UK (London).

For fuller information please visit the webpage (link) where you can select other locations.

HAP Chart © Copyright Commonwealth of Australia 2016, Bureau of Meteorology.

Local Area Mobile Predictions

This LAMP Chart is intended for use by UK Cadet Forces [presumably for 5MHz portable communications]. While precise data may need to be re-interpreted for Amateur Radio use the general principles do apply and illustrate changes on useable frequencies during the day.

For fuller information please visit the webpage (link) where you can select other locations.

LAMP Chart © Copyright Commonwealth of Australia 2016, Bureau of Meteorology.

Current British & Global K & Kp Geomagnetic Indices

Recorded at UK Observatories by the British Geological Survey

Visit

http://www.geomag.bgs.ac.uk/education/current_activity.html

Note on K & A Indices

K & A Indices give a 'health check' on the geomagnetic stability of the ionosphere. /font> As a general rule, lower values indicate more stable conditions which usually lead to 'better' (more predictable) MF & HF conditions.

'K' values represent an average of rolling 3 hourly measurements at specific locations; 'Kp' values are similarly obtained but values are averaged across the globe. So, K / Kp values indicate the extent of hourly fluctuations in the earth's geomagnetic field (see note below).

'A' values indicate the daily trend in geomagnetic variations. They are an average of eight 'K' values: that means they are a 24 hour rolling average. 'Ap' values are average values for the globe.

Together, K & A (Kp & Ap) Indices indicate the 3 hour vs 24 hour fluctuations in geomagnetic conditions. Values of less than K = 3 and A = 6 indicate 'settled' conditions that may give good propagation.

The British Geological Survey also produce a K(UK) value is a daily average of indices measured at 3 UK Geomagnetic Observatories (Lerwick, Eskdalemuir, Hartland).

G3YLA Real Time Propagation

A very useful interactive website provided by Meteorologist Jim Bacon G3YLA - This site includes foF2 observations from Chilton & RAF Fairford (UK) and Dourbes (Belgium). The additional stations give a broader picture of conditions across the UK and the 'Lowlands'.

However, there is a problem with the new upgraded site with the sizing/scaling of the chart which can make it cluttered and virtually unreadable, so you may need to change your display zoom level to 90% or similar.

http://www.propquest.co.uk/graphs.php

Critical Frequency, MUF & Ionograms, foF2 & Ionosonde Data

The UK Solar System Data Centre (see below) produces real-time ionosonde data every 10 minutes throughout the day using the UKSSDC Chilton Ionosonde. An example is given below.

The ionosonde data is available in a number of formats including ionograms (see below) and tables. This information is very helpful in determining likely current HF propagation conditions across the UK and also helps work out the prevailing 'skip distances' for, say, 40m contacts. The conditions affecting other bands can also be deduced. As with other examples on this site, the information may need further personal research in order to fully understand what the data shows and how to best use it.

Example of an ionogram from UKSSDC Chilton

The horizontal axis is the frequency of the ionosonde sweep (MHz); the vertical axis is the height in km.

Explanation of Ionograms

The coloured lines/zones represent electron densities at different heights (vertical axis) and the horizontal axis is the frequency of transmission by the ionosonde. The curves and cusps on the lines indicates zone of reflection and the values are used to compute the tabular information on the left hand side of the chart. The tabular information is primarily what we are interested in.

Annotated hypothetical example ionogram

Note: an asymptote is a straight line that continually approaches a given curve but does not meet it at any finite distance.

Longer explanations of ionograms

See the UKSSDC explanation (click the diagram or go to:

http://www.ukssdc.ac.uk/ionosondes/ionogram_interpretation.html

For another explanation of ionograms see this NOAA page:

https://www.ngdc.noaa.gov/stp/IONO/ionogram.html

UKSSDC (Chilton) Ionosonde Data

To access the Chilton ionograms registration is required. Use of the data for purposes other than research, or for re-publication, may require a licence. The Ionograms (and other charts) can be found at:

http://www.ukssdc.ac.uk/cgi-bin/digisondes/cost_database.pl

Registration can be done at:

http://www.ukssdc.ac.uk/cgi-bin/wdcc1/userreg.pl

UK Solar System Data Centre, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX.

Propagation Predictions

ITURHFProp

This up-to-date application produced by the ITU is the successor to the VoACAP Propagation Prediction suite (see below). It gives predictions of path reliability based on 'standard' seasonal and daily variations - however these do not include short term variables such as geomagnetic storms and sunspot activity. The ITURHFProp program incorporates current information about prevailing solar trends.

http://www.predtest.uk/

VOACAP (Voice of America Coverage Analysis Program)

This has been overhauled recently to make it much more useful. The original VoACAP application is still available online. It provides predictions of path reliability based on 'standard' seasonal and daily variations - however these to not include short term variables such as geomagnetic storms and sunspot activity. Functionally it is very similar to the ITURHFPROP software but has a more useable interface, better tools and a much nicer interface in PARC's opinion.

https://www.voacap.com/hf/index.html