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Old 22nd August 2012, 07:24 PM
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Grahame Hutchison Grahame Hutchison is offline
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Default ADS-B Long Range Plots

When I had a look at the PlanePlotter tracks sourced from my ADS-B receiver today, there were several good tracks out past 300nm to the northeast.

The track through DRUMO (29° 30' 19S 157° 36' 41E) was by Emirates B777-31HER A6-ECI on route from Auckland to Brisbane, and I just happened to be watching while it was displayed. The Start Position was S29 48.6 E158 11.1 and End Position S29 40.3 E157 55.3, some 421.1nm and 414.9nm from my receiver respectively.

If I can track down the other five or six plots outside the 300nm, I will post the details.

While I was writing this post, I had another look at RadarBox and there was a plot out at 435nm to the east. There must be something in the air this evening.

SQLite view of the A6-ECI record in the database.


PlanePlotter screenshot of today's plots.
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Old 22nd August 2012, 07:44 PM
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Another plot was PBN154 Fiji-Sydney operated by ZK-PBM out at 431.3nm.



Next up was ZK-OJN out at 360nm.



ZK-PBG from Brisbane to Dunedin out at 299.9nm.



N171UA from San Francisco out at 369.4nm right through to 28.2nm and 2975ft



ZK-ZQA from Auckland to Brisbane out at 432.8nm.


Just had another look and there is another flight tracking Northwest-Southeast out at 444nm.

So far today there have been 15 flights received out past 300nm - just love these conditions.
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Last edited by Grahame Hutchison; 22nd August 2012 at 08:24 PM.
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Old 23rd August 2012, 01:24 PM
Mike Scott Mike Scott is offline
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Default Going Tropo !!!

The enhanced reception distances you are seeing is the result of tropospheric ducting...it happens at all RF frequencies and results in varying conditions for both transmission and reception of rf. When you mentioned "something in the air" you were in fact right !!!

We have the same thing happen in ham radio with our repeater systems (Vhf and UHF) where all of a sudden we start hearing stations a long way away and getting interference from stations on the same freq that we don't normally hear....good example is all of a sudden somebody on one of the high hills or mountains around here (PHNL) can work somebody in California direct with a handheld radio....a distance of some 2300 miles...it might only happen for a few minutes...might last for an hour.

The frequency that ADS B operates (1GHZ) is less prone than some of the lower freqs but it does still happen resulting in reception over much larger distances.....then you look again 5 or 10 mins later and its gone....maybe even a few minutes later.... Tends to happen more at certain times of the year. Also happens with TV signals if you have an off air antenna rather than cable...all of a sudden you start seeing stations from a long way away that normally you don't see.

http://en.wikipedia.org/wiki/Troposp...pheric_ducting

This is a segment from the page below provided by a radio amateur working with ADS B propagation etc

Quote:
"In the spirit of Amateur Radio (well, one of the spirits) I decided I needed a bigger antenna, with more gain. I constructed a 16-element coaxial Co-linear (~12-dBd?), and mounted it 3 metres above the top of my 144 MHz array – about 14.5 metres above ground level. After a short (3.5 metre) run of SCF12-50 heliax, a VK5EME kit dual-stage Pre-amplifier (MGF1302 followed by an ERA-1) provides a boost before the signal hits the run of LDF4-50 to the receiver. Maximum range observed reliably so far is 225 nm (416.7km), with aircraft flying at high altitude (38,000-40,000 feet), though instances of greater distance have been observed as we enter late spring and come under the influence of tropospheric “ducting”.
I decided that wasn’t enough, so I built a 28-element T-boom Yagi. This has a calculated gain of 16.7-dBd. Admittedly I lose the omni-directionality of the co-linear, but I was more interested in maximizing my forward view".
http://www.qsl.net/vk3bjm/ads-b.htm

Some good charts directly related to ADS B here
http://my.pinkfroot.com/forum/topics...ge-direct-adsb

Sorry to be so Geeky tried to keep the explanation short but its quite a complicated and involved topic.

Regards

MS
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Old 23rd August 2012, 06:59 PM
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Grahame Hutchison Grahame Hutchison is offline
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Thanks for the info and link Mike, very interesting. There are definitely days when reception is extended significantly.

A few more good plots today out to the northeast, and a host of dot plots directly to the east, which I believe is the
suspect LAN CC-CQC. The most distant LAN plot was out at 535nm.



ZK-OJG may have operated Christchurch-Brisbane (after an earlier Melbourne-Christchurch sector) at a range of 496.1nm (to be confirm).
ZK-OKA operating Brisbane-Auckland at a range of 436.2nm.



9V-SVE operating Auckland-Singapore at a range of 444.2nm
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Last edited by Grahame Hutchison; 23rd August 2012 at 07:21 PM.
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Old 23rd August 2012, 07:23 PM
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Michael Dawson Michael Dawson is offline
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Grahame,

You would have got the Dunedin flight as Misly is one of it's waypoints before hitting BNE area. Having done that flight a few weeks ago, this and the Queenstown flight are from quite southerly reaches. The Dunedin flight tracks overhead Queenstown in both directions.

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Old 23rd August 2012, 07:32 PM
Henning S Henning S is offline
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Yesterday in the evening (around 11pm) I had an awesome reception of AIS messages. I thought that the marine authority was testing a new AIS repeater or something like that. Never had so many ships on my screen before. But maybe it was also related to this In-The-Air thing.
Now the reception is normal again... unfortunately...
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Old 23rd August 2012, 10:58 PM
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Quote:
Tropospheric Ducting http://en.wikipedia.org/wiki/Troposp...pheric_ducting

Tropospheric ducting is a type of radio propagation that tends to happen during periods of stable, anticyclonic weather. In this propagation method, when the signal encounters a rise in temperature in the atmosphere instead of the normal decrease (known as a temperature inversion), the higher refractive index of the atmosphere there will cause the signal to be bent.
I guess the warm northwesterly winds over the last two days might be part of the reason.

Thanks Michael, on some of the flights there is just not quite enough information to identify the Aircraft and Flight No. The last ACARS report for ZK-OJG had it going into Christchurch. ZK-PBG from Brisbane to Dunedin via MISLY was a nice lateral plot at 300nm.
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Last edited by Grahame Hutchison; 23rd August 2012 at 11:12 PM.
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Old 29th August 2012, 05:44 PM
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Looks like there is something in the air again, good plots out between NATLI and DRUMO ...

Emirates Auckland-Brisbane flight UAE435 operated by A6-ECI, out at 342nm (633km).

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Old 30th August 2012, 08:54 AM
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Still some good ADS-B plots this morning, maybe the warm air from Queensland moving down towards New Zealand.
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Old 6th September 2012, 09:03 AM
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The long range reception definitely follows the warm westerly/northwesterly winds. Reception out to the northeast increased to just on 900km.

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