No Radarbox ADS-B reception within approximately 15NM (including overhead)

[KBOS]

Hello:

I am writing at the suggestion of AirNav Support to see if any other users have encountered my issue.

I do not recive any aircraft from the North to East SouthEast at all.  Even though the Atlantic Ocean is 2 miles away with countless aircraft visibly operating either to or from the EU in that airspace.  A very small sample of aircraft are received from the Northwest, but would quickly be lost.

Most importantly, NO ADS-B aircraft were received overhead or within approximately 15nm.  Signals of aircraft approaching from the South or Southwest are lost at about 25-30nm and sometimes closer at 15nm, even though they continue to fly past my home at FL350+ and some directly overhead.   Mode-S aircraft are received.

The Aircraft tracks that are received are intermittent as there have been multiple gaps in their trails.  A plane would stop in one location even though altitude updates continue and then it appear further away 20+nm gaps.

My antenna is outside and 20 ft above the ground with an unlimited view of the West Northwestern to Southeastern skies.  There are trees to the East, but that should not be an issue with line of sight.  It is not uncommon to visibly see multiple flights to and from Europe operating within 50nm at one time  (thanks to the contrails). 
 
I am able to pick up aircraft that far away from the S/SW, but lose contact as they approach.  One interesting point to note is that flights coming from over the Atlantic do not appear until they cross land 15nm SE of me most at FL330+ (there have been a few exceptions of which appeared about 5-10nm from the shoreline). 
 
A plane would stop in one location even though updates continue and then it appear further away (position does not update even though altitude does).  An example would be an aircraft that appeared coming off the Atlantic at FL350 (18nm SE of me) and would be tracked for about 10nm to the West only to freeze and not update its position until about 30nm away.
 
KBOS-Boston Logan (a busy International airport) is about 5nm to the North.  Runway 4R ILS approaches are in my line of sight and aircraft often fly directly overhead or within 5nm as they intercept the ILS approach.  Many of these flights are of EU origin, BAW, VIR, DHL, EIN etc.  Also, international flights at FL350 or higher often cross the BOS VOR of which is 5nm away.  None of these flights are displayed ever, that is until they are SW about 25+nm away. 
 
As I said, I can see many of these EU flights operating (FL350 to FL410) within 50nm and the flights that intercept the ILS are visible at about 3,000 feet either overhead or within 5nm and again, my atenna is outside. 

I have attached a screenshot of my Polar image.

I am running a Pentium 4 1.2GHz with 256MB RAM with Windows XP Serv Pk 2.

I have installed the Beta version 1.01 patch with the same results.  My PC is rebooting periodically since the install, of which the frequency was greater when I was not online.  I had advised support of this issue as well.

I am very troubled by this issue and would greatly appreciate any thoughts/comments on how to remedy my situation.

Best regards,

Michael

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[AirNav Support]

Hi KBOS,

Can we have a bit more information about the antenna, is it the default antenna how is it connected to the RadarBox? Also is it higher than any other buildings around.

Furthermore can you confirm that to North West where there is no reception there is either high ground or heavily populated with buildings above the antennas line?

[Roadrunner]

Hi KBOS,

Can we have a bit more information about the antenna, is it the default antenna how is it connected to the RadarBox? Also is it higher than any other buildings around.

I would also ask, being on the coast, are there any Radio beacons or other equipment that might be sending signals out to sea and along the coast, and creating a wall of electrical signal/interference to RB. Just a suggestion as it does seem strange. One would normally expect unrestricted access to aircraft flying over the see with no buildings or trees.  Also do you know anyone with an SBS1 and have they the same problem.

[KBOS]

Hello AirNav Support:

My two story building is behind the antenna, of which blocks from (compass heading) 300 degrees WNW to 120 degrees ESE.  I am on the second floor and am using the default antenna, of which is 4 feet from the ANRB on an outside window sill.

There are houses behind me to the NW but nothing higher than my own.  KBOS is 5nm to the NNW with no significant obtacles, with the exception of a 40 ft hill with houses about 1.5 nm away and then spits of land and open water to the airport from there.

In reference to the antenna's unobstructed view of the sky from the ENE to the NNW, please note the following views by compass heading:

ESE 120 to 150 degrees: there is a house about 80 feet away that blocks the sky by 15 degrees elevation.  Closer trees obstruct to 45 degrees.  

ESE/SSW 150 to 210 degrees:  There is a close two story house that blocks the sky up to 30 degrees elevation.

SSW/WSW 210 to 240 degrees:  Distant houses and building block the sky by 15 degrees.  Aircraft intercepting the KBOS ILS are easily within view in the sky.

WSW/NNW 240 to 300 degrees:  Distant buldings obstruct the view by 5 to 10 degrees elevation.  Aircraft on the KBOS ILS fly easily within view and aircraft operating at high altitudes can be seen up to 50nm away.

The only beacons I am aware of are the Boston VOR 5nm to the NNW and the Runway 4R Outer marker beacon 5nm from the 4R threshold of which is a few nm to my WNW.

I do not know any users of the SBS1 as I thought that the US release was scheduled for next year; I could be wrong. 

Thank you

[jmhayes]

I do not know any users of the SBS1 as I thought that the US release was scheduled for next year

I've had one in San Francisco since November of 2005.

[KBOS]

Thank you for the post jmhayes.

At the request of Air Nav Support please refer to my further information and comment if you can.  Thank you.

-------------------------------------

I have more to add after some observations.

Landing at KBOS not plotted on map (no position info received)  logged in My
Log:

Flight EIN133  Aircraft EI-JFK  Route: EIDW-EINN-KBOS
First  received on log at 6000 feet inbound to KBOS (Contacted Boston
TRACON).   Last report to 450 feet altitude on Final approach Runway 33L.

Flight EIN137  Aircraft EI-DUB  Route: EIDW-KBOS
First  received on at 6000 feet inbound to KBOS (Contacted Boston TRACON).   
Followed to 650 feet altitude on Final approach Runway 27.

Outbound from KBOS not plotted on map (no position info received)  Logged in
My Log:

Flight DLH423  Aircraft D-AIKC  Route: KBOS-EDDF
First  received at 1750 feet outbound from KBOS (Contacted Boston TRACON).
Last report at 14100 altitude (Handover from TRACON to Boston Center).

Logged in My Log not plotted on map (no position info  received):

Flight BAW64J  Aircraft G-BNWR  Route:  EGLL-KEWR
First  received at FL360 68nm ENE from my location.  Last report at 16000
altitude  40nm WSW of my location. Passed 5nm from my location at FL230 over the BOS  VOR

Flight DLH414  Aircraft D-AIKI  Route:  EDDM-KIAD
First  received at FL380 50nm ENE from my location.  Last report at FL380
75nm WSW  of my location.  Passed 5nm from my location at FL380 over the BOS  VOR

These flights were logged in My Log and were plotted on map briefly:

Flight VIR45  Aircraft G-VHOT  Route:  EGLL-KJFK
First  received at FL360 20nm SE from my location.  Last report at FL360 30nm
SSW  of my location.  See Attachment.

Flight DLH410  Aircraft D-AIHP  Route:  EDDM-KJFK
First  received at FL380 20nm SE from my location.  Last report at FL340 30nm
WSW  of my location.  See attachment.

This aircraft was logged in My Log and was plotted on map, but there was a gap of 50nm:

Flight MON364  Aircraft G-SMAN  Route:  KSFB-EGNT
First  received at FL390 40nm SW of my location.  Last report at FL390 30nm N
of  my location.  There was a gap in position reporting for 50nm even  as
other data was received; this resulted in the gap in plotting.  Passed 5nm from my location at FL390 over the BOS VOR.

Thank you.


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[Allocator]

Hello AirNav Support:

My two story building is behind the antenna, of which blocks from (compass heading) 300 degrees WNW to 120 degrees ESE.  I am on the second floor and am using the default antenna, of which is 4 feet from the ANRB on an outside window sill.

KBOS,

This is the effect I get when I have the RB antenna on a window sill at work with the building blocking the sky in one direction.



You can see that I get excellent coverage to the SE, but coverage to the NW is very poor.

The picture below is from home where the antenna is in the clear, but is slightly lower that the ridgeline of the roof which is to the NW of the antenna.  Although the all-round coverage is much better, I still have a blind spot to the NW.  Your polar diagram does show an extream case of poor coverage to the NE and E, but I think that this is caused by the screening of your building.  Can you install RB on a laptop and try a different location, or install it on another computer where the antenna can have a better view of the sky?  I have been using the SBS-1 for over a year, and I can assure you that when there are leaves on the trees that are 50 feet away, my reception signal is reduced!



Take a look at this thread where I compare the coverage of the SBS-1 and Radarbox - two different bits of kit, but very similar coverage.

http://www.airnavsystems.com/forum/index.php?topic=177.0

all the best

Allocator

[palmar]

Have you really seen any of these flights with your own eyes?
EVERYTHING that you cannot see with your eyes at the location of the antenna cannot be received by RB. Mode-S waves are strictly line of sight.
A flight at FL230 at 50NM from you is behind a building of same height and is HIDDEN for the antenna.

[Roadrunner]

Have you really seen any of these flights with your own eyes?
EVERYTHING that you cannot see with your eyes at the location of the antenna cannot be received by RB. Mode-S waves are strictly line of sight.
A flight at FL230 at 50NM from you is behind a building of same height and is HIDDEN for the antenna.

That is not strictly true. I can see aircraft up to 200 miles away on my SBS1 and Radar boxes but I cant see them with my naked eyes - would that I could. What is true is that the space between the antenna (RB or SBS1) and the object (aircraft) must be clear of any obstructions then the device can see it. This then falls away due to the earths curvature.

[AirNav Support]

Whats intresting is here, is that is it:

1.) Line of sight issues
2.) The European Flights mentioned are turning off ADS-B or do not have it
3.) A bug in the system
4.) Any other antenna close by
5.) All of the above

As mentioned in his earlier post, he is getting Mode-S messages from aircraft on approach (down to 700ft) however no ADS-B. Can someone confirm those aircraft he has mentioned have been picked up in Europe using ADS-B?

[Allocator]

Another issue is where is the nearest Mode S capable radar on the ground.  In the UK, not all of the area radars are Mode S equipped, so I believe that without the radar sending out the the request for a Mode S response, you won't get anything from the aircraft.  I could be wrong here, but this is how I understand how it works.

None of the following aircraft appear in MyLog

EI-JFK
EI-DUB
D-AIKC
G-BNWR
D-AIKI

However, I have all of these aircraft in my SBS-1 Reporter log with full position information, so does this mean that RadarBox is not picking up the position information for these aircraft for some reason?

[Roadrunner]

Whats intresting is here, is that is it:

1.) Line of sight issues
2.) The European Flights mentioned are turning off ADS-B or do not have it
3.) A bug in the system
4.) Any other antenna close by
5.) All of the above

As mentioned in his earlier post, he is getting Mode-S messages from aircraft on approach (down to 700ft) however no ADS-B. Can someone confirm those aircraft he has mentioned have been picked up in Europe using ADS-B?

I can confirm that the aircraft mentioned in one of the messages EI-JFK, EI-DUB, D-AIKC, D-IAKI, G-BNWR, G-SMAN are all in my lists and transmit Mode-B all the time

[flightchecker]

Hi KBOS,

Can we have a bit more information about the antenna, is it the default antenna how is it connected to the RadarBox? Also is it higher than any other buildings around.

I would also ask, being on the coast, are there any Radio beacons or other equipment that might be sending signals out to sea and along the coast, and creating a wall of electrical signal/interference to RB. Just a suggestion as it does seem strange. One would normally expect unrestricted access to aircraft flying over the see with no buildings or trees.  Also do you know anyone with an SBS1 and have they the same problem.

Hello Roadrunner
That is indeed a phenomenon which is independant of whether receiving ADS-B signals by means of RB or SBS-1. It is noticed here at the continent too, if “looking” across the north sea and towards the UK.
An assumption, but just an assumption is, that multipath reception could be the reason for extinguishing the transponders signals, or at least degrading their strenght to an amount, that a receiver is unable for evaluation.
Multipath reception might be experienced due to signals reflected from the sea’s surface (even  “rough” by waves, thus having a positive influence on “scattered” reflections) that are “out of Phase” due to their longer way of travel, as compared to signals that travel directly from the airplanes antenna to that of the receiver. Signals out of phase to each other tend to extinguish themselves, at least partially.

As I said, its an assumption, and maybe somebody does have a better explaination. In no way, radio beacons or any other kind of nautical / aeronatical Radio Aid will be the reason.
There are well known “local” reception problems caused by wireless networks / consumer- as well as amateur electronics etc. If  operated in the neighbourhood they may  interfere with the ADS-B receiver, thus causing partial blackouts for instance.
An interesting theme, maybe to keep an eye on it, may be there are some other comments to this.
 
Kind regards

Karl

[tvcmh]

I've experienced a similar situation.  I recently used my RadarBox at Las Vegas Intl airport.  Many ADSB equipped departing flights did not show up until they were at least 10+ miles from the airport.  I was in an observation lot within direct line-of-site of the runway and the (default) antenna was mounted on top of a vehicle.  I know I was getting some sort of contact from these planes since their Mode S was received and their altitudes displayed but no position data was available until several minutes after departure.

[AirNav Support]

Hi tvcmh,

Was the same occuring for arriving flights?

We have contacted few other customers who are in the US and they don't seem to have this issue so it may be location related.

Also KBOS did send some further pictures to us which did show ADS-B aircraft landing however there position data was offset.

Any other US users?