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Examples of Sound Obtained During a Typical, Minor, One-Evening Tropospheric Duct ('Lift')

(The most common sort heard in the United Kingdom!)

Click on each of the examples in turn to hear the appropriate example. You will need RealPlayer version G2 or later to play the clips. (Click the picture below to download it if you don't have it - free!)

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Some visitors might remember that this file and its audio clips used to be in a .zip archive. Click here if you really want to download it and have copies of the recordings in .wav format in the 'old-fashioned' way!

Times given (UTC/GMT) are approximate. Sunset on this date was at 18:56 UTC, the lift started shortly afer this time.

Example 1
At the start of a lift, sound may become distorted as the atmosphere is unstable. This may also occur at dusk or dawn as the change between night and day is quite major for the troposphere. The effect heard here is normally called 'fading' (19:30)

Example 2
The sound will probably then settle, but at a weaker volume. (20:00)

Example 3
After this stage, the volume may increase slightly, but this increase may be accompanied by some more minor fading. (21:00)

Example 4
I have no idea why, and I have not found a reference to it in any book, however the sound levels often decline shortly after reaching this first peak. I can only assume, that it is related to the atmosphere again adjusting to the night-time conditions. (21:15)

Example 5
It should then be seen that the sound levels again increase. On the way to obtaining this level, there may well be some very slow fading, perhaps taking five to ten minutes between peaks of signal strength. (21:45)

Example 6
The signals should then gradually increase in strength, and will probably reach a peak just over three hours after night-fall. This was recorded at the start of such a peak. (22:35)

Example 7
After this, signals will fall surprisingly rapidly, and it may be that within thirty minutes, all traces of the station have disappeared. This clip was recorded only about ten minutes after the one in example 6 and, although it may sound as strong, this was the peak's end. (22:45)

Identifying French Stations at Night
This is actually quite easy, since all Radio-France Local Stations broadcast the same music programme, inserting their own station name and either a freqency or other sentance during the introduction to every third or fourth song. For examples click here or here:
"Mettez les voiles - Radio France Normandie-Caen"
(Set the sails - Radio France Normandy Caen)
"Radio France Normandie-Caen - Tout le temps"
(Radio France Normandy Caen - All the time)

Note: These are all excerpts taken from Radio France Normandie-Caen (102.6MHz) on the evening of 15 Mar 99 at my home near Plymouth and were all recorded at the same audio level. Equipment used for reception was nothing more than a normal 'ghetto blaster' with its built-in telescopic aerial. Obviously, being recorded from a radio station, all execpts are copyright. I hope that copyright owners will accept the scientific nature with which this presentation is intended. Please email me, however, if you would like the material to be removed.