John Gilbert VK3EDW   IoC 080611

Many thanks to John !
,
For quick reference,  these are his charts



The envelope waveforms are strongly modified by interplanetary scintillation and lane modulation, in a time scale of seconds. Ionospheric scintillation has a longer time scale of minutes.

As we approach Opposition, the interplanetary scintillation pattern on Earth's surface will slow down and then change direction. Early in the observing season the pattern moves East to West. Pulses become longer.
Lane modulation effects should not show this property.
Statistically observers have measured a change in the histogram of pulse durations, due to interplanetary scintillation.

I think I notice longer pulses lately. Is it my imagination ?
We may have to compute some histograms.

Riihimaa 1978, Ap&SS  56, 503


shows the following histograms


Notice how 80-100 days before opposition there are no emission envelope durations longer than 10 sec, but 0-10 days before opposition there are many lasting 10 to 40 sec.

I have plotted some audio waveforms and spectra for the two sound files, which are generally similar



The spectra show a much narrower bandwidth than those I plotted for Ashcraft IoC 080523 and posted earlier:
http://hubbleed.bravehost.com/Ashcraft523/h.html

L burst, for example:


I assume John is using a much narrower audio bandwidth than Tom.
Still, John's spectrum is nearly flat to 2.5 Khz, while Tom's drops 20 db at 3 Khz.
Any other interesting differences ?

Is there a DAM spectrograph in Australia ?  At Culgoora ?

Stay tuned to the decametric band.
Many bursts to you !

Victor