Aircraft dropping off - reception issue or something else?

[airdata]

I have had my radarbox now for almost 1 year and am very happy with it.  I have a WiMo antenna setup on the roof and having been up there myself there is no line-of-sight issue. 

There is a large area (of rectangular shape) which starts from only 7 miles from my location and extends beyond where aircraft are never shown on the map.  The aircraft stay on the "My Flights" list and get updated every second.  Once the aircraft go beyond this "box" area, they re-appear and I can track them until the signal is lost due to distance and line-of-sight.  Attached is my polar diagram with the large block highlighted in yellow.  You can see it is a rather large chunk of airspace.

Airnav responded quickly stating is was "a phenomenal of reception".

Does anyone else out there have similar issues?

[Fenris]

So, is this area *exactly* rectangular? If so then I cannot imagine it can be due to  terrain and your antenna placement, it has to be something programmatic.

Do you ever see aircraft there at any altitude?

One possibility is that if you are sharing on the network and there are no other NZ sharers covering that area that other RB users could comment on whether they see the shared aircraft on their map.

I note however that your MyFlights list is not showing any ADS-B tracks, so the network sharing is not going to be a lot of use as it won't place these on the map.

Which version are you using? If v2.01 then maybe you could try v3.01 beta, or a later one if it gets released soon as Airnav are suggesting it will.

[AirNav Support]

The software version would have no affect in making that area seen. If degraded signal is being recieved from that area there is nothing the RadarBox can do.

[Fenris]

The software version would have no affect in making that area seen. If degraded signal is being recieved from that area there is nothing the RadarBox can do.

While I see what you're saying Airnav, I can't imagine how such an area in a given direction can be obscured at short range but not at longer range.

I think we need more information to work out what is happening here.

I wondered if it could be down to the plotting algorithm not working for certain latitude and longitude, or maybe plotting the aircraft somewhere off the map. It's very strange....

[airdata]

Thanks for the replies so far.  To clarify further, aircraft in the rectangular area always remain on the "my flights" list but no aircraft ever show their position in that area regardless of altitude.  An overflight at FL350 will dissappear at 6NM from my location just as an aircraft at 3500ft will do as well.  This has been the case with the supplied aerial as well as the external one.  I tried the supplied one at Auckland airport as well and again nothing was received in that rectangular area. 

Latitude/Longitude for this area is between 35°30' and 36°50' South and between 172°10' and 176°10' East.

The next thing I'll try after the new version is taking it with me into the rectangular zone to see what happens - but this will be several weeks away...

[Fenris]

Airdata

Do they aircraft that disappear still show the blue globe to indicate that they are transmitting ADS-B position?

If they do then it points towards software I would have thought.

I assume you have all the filtering turned off as well?

[EK01]

Or a movement of the Bermuda Triangle to a rectangle at Auckland !

[pjm]

The next thing I'll try after the new version

Let us know how it goes with the new version.

[airdata]

Airdata

Do they aircraft that disappear still show the blue globe to indicate that they are transmitting ADS-B position?

If they do then it points towards software I would have thought.

I assume you have all the filtering turned off as well?

When the aircraft reaches the rectangular area the ADSB blue globe shows.  The aircraft position then becomes stationary and the globe still shows.  After several minutes the globe and the position disappear (probably a software correction once the trail line reduces to nothing).  Once out of the rectangular area, both the globe and aircraft position re-appear.

Personally, I don't believe this is a signal strength issue but something else.  From the responses so far it does not appear to be happening to anyone else's radarbox...

[DaveReid]

Thanks for the replies so far.  To clarify further, aircraft in the rectangular area always remain on the "my flights" list but no aircraft ever show their position in that area regardless of altitude.  An overflight at FL350 will dissappear at 6NM from my location just as an aircraft at 3500ft will do as well.  This has been the case with the supplied aerial as well as the external one.  I tried the supplied one at Auckland airport as well and again nothing was received in that rectangular area. 

Latitude/Longitude for this area is between 35°30' and 36°50' South and between 172°10' and 176°10' East.

The next thing I'll try after the new version is taking it with me into the rectangular zone to see what happens - but this will be several weeks away...

The fact that it's a rectangular area, i.e. similar in shape to the cells used for position encoding (albeit much smaller) strongly suggests a decoding bug, which in turn suggests that your RadarBox installation has somehow become corrupted (since you seem to be the only user affected that we've heard about).

If I were you, I would try completely uninstalling and reinstalling RB - I'm very surprised AirNav haven't already suggested this.

[airdata]

Thanks for the replies so far.  To clarify further, aircraft in the rectangular area always remain on the "my flights" list but no aircraft ever show their position in that area regardless of altitude.  An overflight at FL350 will dissappear at 6NM from my location just as an aircraft at 3500ft will do as well.  This has been the case with the supplied aerial as well as the external one.  I tried the supplied one at Auckland airport as well and again nothing was received in that rectangular area. 

Latitude/Longitude for this area is between 35°30' and 36°50' South and between 172°10' and 176°10' East.

The next thing I'll try after the new version is taking it with me into the rectangular zone to see what happens - but this will be several weeks away...

The fact that it's a rectangular area, i.e. similar in shape to the cells used for position encoding (albeit much smaller) strongly suggests a decoding bug, which in turn suggests that your RadarBox installation has somehow become corrupted (since you seem to be the only user affected that we've heard about).

If I were you, I would try completely uninstalling and reinstalling RB - I'm very surprised AirNav haven't already suggested this.

I have previously done a full uninstall and re-install (including removing items from the registry) but this didn't make any difference.  The dropouts have been there since when I got the radarbox so it's not a recent development.  I intend to do a full uninstall and install the new version when it does come out but I am not holding out a great deal of hope after everything I have tried out so far...

[tarbat]

Can you turn on the Lat/Long lines on the map and see if they line up with your box.  My rough calculations put the box at:
Top-Left: S 35.000  E 172.000
Bottom-Right: S 37.000  E 176.000

It may that this is some obscure program problem.

[airdata]

Can you turn on the Lat/Long lines on the map and see if they line up with your box.  My rough calculations put the box at:
Top-Left: S 35.000  E 172.000
Bottom-Right: S 37.000  E 176.000

It may that this is some obscure program problem.

Can you turn on the Lat/Long lines on the map and see if they line up with your box.  My rough calculations put the box at:
Top-Left: S 35.000  E 172.000
Bottom-Right: S 37.000  E 176.000

It may that this is some obscure program problem.

OK, I have taken another screenshot with the latitude/longitude lines on.
They are parallel to the box but not exactle at full degree intersections.

[Jeremy]

Can you do a 3D polor diagram using the software that was suggested a few weeks ago. Iwonder if your RF path is is being distorted by a reflection causing an interference shadow of some sort?
J.

[airdata]

Can you do a 3D polor diagram using the software that was suggested a few weeks ago. Iwonder if your RF path is is being distorted by a reflection causing an interference shadow of some sort?
J.

I  haven't installed 3D as I don't have the need for it.  In any case, all aircraft disappear in this area regardless of altitude and all re-appear once they leave this area.  So I doubt that a 3D polar diagram will highlight anything I am not already aware of...  I also don't think the laptop can keep up with the 3D as its resources are limited.  It also doesn't explain why aircraft in the same rectangular area remain invisible when the radarbox is at a different location (i.e Auckland Airport rather than my house).