Meteor scatter files mid-September 2015

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daveB
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Joined: 07 Oct 2014 16:49

Meteor scatter files mid-September 2015

Post by daveB » 24 Sep 2015 23:32

Since mid-September I've been recording 6 hours or so of the bottom "5" MHz of the band during the small hours and analysing the next day. I've had some interesting results with one highlight being the reception of Belgium via meteor scatter and another highlight being a burst that gave 17 identifiable programmes - with RDS on 5 of the frequencies. Both events on the 24th Sept.

The Belgian reception was from St Pieters Leeuw at 250 km at 05:01BST with VRT Klara on 89.5 and VRT1 on 91.7. Id was from the language and presuming they were sharing a news bulletin. Here's a screenshot of the waterfall highlighting the two stations and a couple of others received in the same burst - these other two weren't identified other than sounding Italian. These are regulars on tropo but at this time they were fairly weak via that mode.
Belgium via Meteor 24-09-2015 0400 UTC.jpg
FMList logs links are below:
http://www.fmlist.org/fm_logmap.php?dat ... L&rxin=ALL
http://www.fmlist.org/fm_logmap.php?dat ... L&rxin=ALL
http://www.fmlist.org/fm_logmap.php?dat ... L&rxin=ALL
http://www.fmlist.org/fm_logmap.php?dat ... L&rxin=ALL
http://www.fmlist.org/fm_logmap.php?dat ... L&rxin=ALL note this was with the FM3 which is beaming north-east but has a poor front/back ratio at the low end and so got Spain as well!

One annoying thing - found out after I deleted the files. There was an issue with the playback set up degrading RDS detection - so I should have got more than I did! In future and I recommend this to everyone if you install a new version of SDR# and plug-ins check the installation is working as well as before. In the past I've found poor RDS sensitivity and had to do a fresh install.

Recording is done using Vasily's plug-in with file format WAV64 with 16bit PCM and 6866Mb file length to give exactly 6 minutes. The schedule starts at 30 seconds before the hour to catch any station ids. I was experimenting with 8-bit PCM recording and found a definite degradation in RDS bit error rate when comparing playback to real-time - so not viable for stretching recording times. On the other hand 16 bit and 32 bit had the same quality as far as RDS sensitivity was concerned - that is once I fixed the issue I discovered. Using Vasily's latest file player 6 minutes is just nice to be able to see enough detail to spot short MS bursts but not needing so many files to be uploaded - it also shows up the aircraft-scatter 'chuff-chuff' phenomenon very nicely.

If nothing else it gives something to do during the days when conditions are flat.
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

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John Faulkner, Skegness
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Location: Skegness, Lincolnshire. JO03dd
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Re: Meteor scatter files mid-September 2015

Post by John Faulkner, Skegness » 25 Sep 2015 01:20

Brilliant stuff Dave. Well done on Belgium via MS. Amazing!

It's great that you are doing all this experimentation with different software and players, bitrates, etc. I just don't have the patience.

Have you thought about trying the FM3 vertical too?

daveB
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Re: Meteor scatter files mid-September 2015

Post by daveB » 25 Sep 2015 08:49

Hi John,
Yes - SDR opens up a whole new aspect of the hobby - not just the logging of more stations. The FM3 vertical is a fixed aerial beam heading 40 deg. I have a 3 ele Moxon vertical mounted beaming east so I will give that a try at some point. My fixed aerial set up is shown in this link: https://uk.groups.yahoo.com/neo/groups/ ... /849261269
Not shown is the rotatable 5 ele 5.5m agl at the bottom of the garden - or the 5 ele beaming 180 deg on the front of the house above the Triax grid TV aerial!
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

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John Faulkner, Skegness
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Re: Meteor scatter files mid-September 2015

Post by John Faulkner, Skegness » 25 Sep 2015 11:48

I didn't know your FM3 was vertical. That's very interesting. You are still able to log the horizontal transmitters well too. I suppose it shows the potential of meteor scatter. i.e. it's not always about what your antenna is doing or what you use.

This might veer very slightly away from the topic, but I always understood that the meteors which cause the scatter are strictly on the horizon. I remember an article which stated this. It also stated that a meteor scatter burning up directly overhead would NOT produce any radio effects. Surely there is still ionisation there and that could be detectable by your antenna. Surely this can't always be the case. Maybe polarisations get skewed a little by meteor scatter. Your comment about meteors coming in off the back due to the poor front-to-back of the FM3, well, it might just be a product of the meteor burning up. How would we know?

I never used to receive a thing on vertical MS and certainly never in any other directions than north-east/east/south-east. This has all changed since I took up MS DXing again a couple of years ago. Lots of vertically polarised signals still get through on the horizontal beam, and vice versa. Hope I'm not waffling too much about this, but MS DXing has to be one of the most fascinating and unpredictable areas of our hobby.

satnipper
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Re: Meteor scatter files mid-September 2015

Post by satnipper » 25 Sep 2015 14:27

I think DaveB made a typo - the FM3 looks distinctly horizontal to me. The Moxon is the one in the vertical plane.

Stuart

daveB
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Re: Meteor scatter files mid-September 2015

Post by daveB » 29 Sep 2015 08:35

Yep - a typo - just spotted the correction
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

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