Polar Diagram - how is it calculated?

[Dean]

Just to clarify - network flights display the * on my settings but I was definately only on a harware connection.

[EK01]

Tarbat - good point, I'd forgotten about the preference for the *, but then the OP does say that he was using only the hardware not the network.

EK01 - I'm not certain of what you're saying, but my view is that if even a single position fix is received then that position should be part of the polar plot. It doesn't matter that the aircraft may have timed out without being tracked further.

Brian,
What I mean  is that if an aircraft is at low level it will still plot within the extent of your current polar diagram but it will not increase the extent of the current polar diagram as it will most likely timeout. However if the aircraft is at a higher level then its signals will be picked up by the RB for a longer length of time therefore it would be more likely to further extend your current polar diagram before timing out.

Ian

[Fenris]

Ah right, I see what you mean.

Well in this case an aircraft with some trail points on the map is clearly being received locally but despite being outside the current polar diagram limits it has not caused the polar diagram to extend to its position.

I think that's incorrect.

[AirNav Support]

Dean,

Are you 100% sure that network flights weren't on and the asterix removed.

As the trail plots are almost the same distance apart, which would suggest they are network flights (when you downloaded the next update)

If not its unsual to say the least

[hofs]

Hello
Do networkflights change the polar diagram or only the local flights from my own antenna ?
I am asking this because my polar diagram is changed enormously after i am using realtime network for two weeks .
Fred

[Fenris]

Hello
Do networkflights change the polar diagram or only the local flights from my own antenna ?
I am asking this because my polar diagram is changed enormously after i am using realtime network for two weeks .

It should only be local flights, the whole point of the polar diagram is to show you what you are likely to see without using network information.

If network flights are changing the polar diagram then it must be a bug.

[tarbat]

If network flights are changing the polar diagram then it must be a bug.

Yes, its a bug that Airnav are trying to fix
http://www.airnavsystems.com/forum/index.php?topic=3498

[Fenris]

If network flights are changing the polar diagram then it must be a bug.

Yes, its a bug that Airnav are trying to fix
http://www.airnavsystems.com/forum/index.php?topic=3498

I get an error message from that link, it seems to be telling me that I may not be allowed to view it.

[Dean]

I've double checked and as the 2 screen grabs below show when I use the network then those flights are clearly shown with the *.

On Piccy 1 there is a non network KLM flight showing which isn't adding to the plot.

On piccy 2 another (albeit short lived) flight EZY40GF is clearly shown approaching Leicester which would be a correct path between Stanstead & Edinburgh.

As with my earlier comment these are appearing in MyLog so should only be hardware flights. I guess it's back to my original question to AirNav Support - is there a minimum time / height etc on a flight before the polar plot updates?

[EK01]

I've double checked and as the 2 screen grabs below show when I use the network then those flights are clearly shown with the *.

On Piccy 1 there is a non network KLM flight showing which isn't adding to the plot.

On piccy 2 another (albeit short lived) flight EZY40GF is clearly shown approaching Leicester which would be a correct path between Stanstead & Edinburgh.

As with my earlier comment these are appearing in MyLog so should only be hardware flights. I guess it's back to my original question to AirNav Support - is there a minimum time / height etc on a flight before the polar plot updates?

Dean,
My understanding is that it would be based on line of sight and therefore the height of your antenna. In other words, the higher your antenna, the more signals are picked up by your RB from a particular aircraft and hence the further your polar diagram will extend. That would also hold true for the length of time a particular aircraft would remain in your MY Flights before timing out. However, even if you have your antenna placed high up on the roof, for example,  it would still be affected by high buildings, trees, etc in the area which is why polar diagrams often plot much further in one direction than in another.

Ian

[bratters]

Flights come and go Dean and you will find "black holes" in odd areas across the country.

For example I pick up most flights heading to EGNX (my nearest airport) as they cross the south coast. You would think that I could then follow them all the way north but that rarely happens. The flights will come and go due to drops in altitude and changes of course, either of which are sufficient to temporarily mask the signals behind an intervening object or geographical feature.

[Fenris]

With respect folks, those factors are not relevant.

If an aircraft is ever picked up at any position for long enough to receive the ADS-B position information and hence be displayed on the map, the polar plot should extend to that point.

In Dean's case, that does not appear to be happening for local flights.

[EK01]

With respect folks, those factors are not relevant.

If an aircraft is ever picked up at any position for long enough to receive the ADS-B position information and hence be displayed on the map, the polar plot should extend to that point.

In Dean's case, that does not appear to be happening for local flights.

Brian,
That is correct but if the particular aircraft reaches a distance point or drops to an altitude below line of sight then the ADSB signals would not be received by the RB  although the aircraft might still appear on the map before timing out. The polar diagram would therefore not extend. Dean, what you could do is go into 'preferences' and extend the RB local time out settings which would then allow for any short breaks in ADSB signals due to temporary obstructions, etc and allow the signals to be re picked up when the aircraft is in the clear again without timing out which may then help with the extension of the polar diagram by that particular aircraft.

[Fenris]

My view is that the timeout should not affect it, the polar diagram does one thing only, which is to show the *maximum* distance that an aircraft has been received at a given azimuth.

It matters not if the same aircraft disappears from view closer to you, it has still been received at the original position and that should be marked.

2.01 acted exactly like this, a single trail point would be included in the polar diagram.

[FACTflights]

I know this is an old topic, but I found some of the comments very intersting, and therefore felt that I should share my experience.

I use a small UHF discone antenna.  The furthest point of my polar diagram is 208nm.

I have compared the altitude and the distance of the aircraft over the past few years.

My findings are that the aircraft takes longer to reach a certain altitude in the summer than in the winter.

I have also found that the aircraft seems to climb out of the discone's polarisation pattern at a certain altitude. Which happens sooner in winter than in summer.

It then follows that the longer the aircraft stays below that altitude the further it is plotted in the polar diagram.

Question:  Would the slower climbing of the craft in summer have something to do with the density of the air?