Ionograms

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Oblique sounders such as the one at Inskip are usually used at the remote end of the path to produce ionograms. We use them differently for the single frequency plots that are shown here, but we can also use them in the manner intended. ChirpView has a facility to allow this. The following plot is an oblique ionogram of Inskip done at 1234z on 11 December 2002.

Ionogram 1234.bmp (192054 bytes)

The plot began at 4.5MHz with the F layer. The critical frequency is about 11MHz with backscatter above that frequency. Inskip seems to miss some frequencies, hence the gaps. This plot was done by simply manually switching my receiver in 100kHz steps at 1 second intervals as the sounder progressed through the bands. Quick and effective!

 

1757 Inskip.bmp (192054 bytes)

The  ionogram above started at 2MHz and is also of Inskip. Taken at 1757 it shows the E layer up to just over 3MHz (FoE about 3.1MHz) and the F layer up to 6MHz FoF about 6.1MHz).

040103-1739-Inskip.bmp (192054 bytes)

The ionogram above was an early result of using special rig control software by G3WGV. The horizontal line at 0ms is the groundwave from Inskip. The trace between 2 and 5MHz are F layer returns. The double penetration frequencies (about 4.2 and 5 MHz are caused by the extraordinary ray refelcting from higher frequencies than the ordinary ray. The same effect causes the ordinary ray to be lost first on the Dopplergrams elsewhere on this site. This ionogram was done at 1739 local time.

040103-1410-Inskip.bmp (192054 bytes)

This ionogram from Inskip was taken at 1415 local time. Note how much higher the MOF is at this time (12.2MHz). A nice plume of backscatter can be seen as the skipzone edge increases in distance beyond the MOF.

040103-1840-Inskip.bmp (192054 bytes)

It's always fun to have something a bit mysterious. This Inskip ionogram done at 1840 local show some odd returns at 12-15ms. I have no idea what they are!

040103-1308-250-600.bmp (192054 bytes)

This ionogram is from a much more distant Chirpsounder and is pretty typical. Here the LOF is 10MHz and the MOF is 22MHz. The best frequency (strongest returns) is about 19MHz. Sadly the resolution of my system is insufficient to show any fold-back features with this distant signal.

 

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