4am Propagation VK6RSX Dampier 50.304MHz beacon to Perth

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4am Propagation VK6RSX Dampier 50.304MHz beacon to Perth

Postby VK6DVR » Wed Jul 15, 2015 10:34 pm

VK6RSX Dampier 50.304 MHz beacon to VK6DVR Perth Propagation at 4am WAST 13-Jul-2015

I was scanning the Argo software waterfalls from the other morning and found 4-minutes of really strong signals that didn't look or sound like MS at all.

4-minutes of Argo software waterfall

4-minutes of VK6RSX Dampier 50.304 MHz beacon - Which Propagation modes do we have in this recording at 4am WAST 13-Jul-2015?

View the YouTube screencast video I made from the .WAV file: https://youtu.be/Z6Jw5DUc1pU
The movie has been sped up about 2.5 times, so it's not too long to watch.

4-minutes of video showing S9++ peak around middle of recording

So, which one could it be?

1: Aircraft Enhancement (AE): Specular Reflections from the body/wings of two fly-in/fly-out large-body jets angled at ascent/descent and maybe near to each end of the flight path from Karratha/Perth between 04:15 and 04:20 am on 13-Jul-2015. Trouble with it being AE, is that there doesn't appear to be any evidence of Doppler-shift in the signals recorded.

2: Reflections from an orbital pass of the ISS at 400-km above the earth. (unsure, needs checking, never heard of it - is it possible under certain angles of the dangle?).

3: Meteor-scatter (MS - unlikely as signal presents the wrong signature, ie there was no pancake splash effect at the start).

4: Tropo-scatter (1,236km path may be a bit longish, no Hepburn Charts evidence).

On Jul 13th, there is just a surface trough running down and off the West coast.
On Jul 13th, there is just a surface trough running down and off the West coast.

5: Sporadic-E (does Es form this strongly at this low-mid latitude at this time of the year?).

The main consensus of opinion so far, seems to point to signals having the characteristic fading pattern of Sporadic-E.

From: Roger Harrison, VK2ZRH - "Lesson for the Day" (thanks, Roger).

Danny, It sounds distinctly like sporadic E to me, with that characteristic fading pattern.

Sporadic E is not unusual at this time of year, around the Winter solstice. Es can occur at *any* time of day or night, as the Sun does not generate the ionisation, wind shear in the E-region "sweeps up" metallic ions (chiefly iron and magnesium), compressing them into a thin, dense layer at around 95-120 km.

73, Roger VK2ZRH

6: Multi-object/Multi-path combination of various propagation modes (unlikely).

7: Two instances have now been seen at around the same time of the morning (within the hour) and requires further comparisons and analysis.

The movie has been sped up about 2.5 times, so it's not too long to watch.

Please get back to me with your thoughts on which propagation mode you see. I'm very curious.

PS: Scroll down my website and checkout the VK6RSX beacon photos and also click on the Meteor trail right up top.

VK6DVR Danny Robinson | VHF Weak-signal & Meteor-Scatter on 6-Metres | Perth, W.Australia: http://goo.gl/9fncQ1


73's Danny VK6DVR
Last edited by VK6DVR on Fri Jul 17, 2015 4:55 pm, edited 3 times in total.
Danny Robinson, VK6DVR
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Re: 4am Propagation VK6RSX Dampier 50.304 MHz beacon to Pert

Postby VK2KRR » Fri Jul 17, 2015 2:24 pm

Hi Danny,
Saw other email, but hav a chance to reply here.

I'd say the propagation was a period of Sporadic E.

Up until I put my 10m yagi up, I'd been monitoring 6m WSPR for a long time, day and night. There has been a number of occasions where I have received the VK4TVL 6m WSPR signal in the early morning hours, also heard into Sydney etc.

I'd say it would be similar to this. :thumbup:
Leigh VK2KRR
The Rock Hill, NSW

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Re: 4am Propagation VK6RSX Dampier 50.304 MHz beacon to Pert

Postby VK3QI » Fri Jul 17, 2015 2:35 pm


Have you looked at the IPS ionograms for 2000z on 12 July (presumably that is what you mean when you say 4 a.m. on July 13th)?

Perth, Darwin and Learmonth would be the ones to look at to see if there was any anomalous reflections at that time.

see: www.ips.gov.au and the HF section.


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Re: 4am Propagation VK6RSX Dampier 50.304MHz beacon to Perth

Postby VK0JJJ » Wed Aug 05, 2015 2:46 pm

Hi Danny,

Pretty sure the propagation you heard was Sporadic E.
I used to live in Karratha for 15 years and its amazing how often the path between Dampier and Perth is open on 6m.
This can occur any time of the day or night and throughout the whole year.
I used to have a lot of fun on this path using WSJT/FSK441 on both 6m & 2m too.
The trans-equatorial propagation to the North from Dampier is awesome, but that's another story.
Thanks for the interesting discussion and recording.

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