My before and after ADB-S comparisons
 

Hi All, well I got my radarbox back from Airnav, I did a screen shot comparison from stock antenna to external antenna.

This really highlights the difference between the 2.

I will also post a screen shot with the LMR400 coax and another 20 feet of height as soon as i get my cable. At the moment the antenna is using cell foil cable, antenna is 4 feet from rooftop, elevation of 60mASL but with clear horizon view about 320 degrees.

Now I have the box back ill be feeding the radar box network :)

yes, big difference with external; mine has suffered some static issues so only picks up close stuff now.

Still helped me overseas when at airport hotels!

exact same thing that happened to mine and a mates box, im told to put a DC block in line...anyone else doing this?? How have you protected your radar box??? Seems weird that the box itself doesn't have some form of protection.

ok so spread is looking pretty good, I still think i need a better antenna! the radar rama is just making 200nm.

http://i1244.photobucket.com/albums/.../2ndaugust.gif

Hi Brad,

Thanks for the plot. Looks good.

What's your visual range of sight like in the West? Many obstructions? There's other factors that could limit it's range too... length of cable run (shorter the better), the use of connectors (less the better).... and would you believe, as reported in the UK, TREES.

I'd suggest 200nm range is pretty good from in the suburbs. To be honest, unless you're extremely high and have got an absolute clear outlook over the ocean, you'll be hard pressed to get in the 250nm range or even further like Grahame.

Suggest you attend to the above and report back. Else, couple your LMR400 with the DPD Antenna Grahame imported. I know Steve in Sydenham is potentially interested in a similar antenna, so maybe you can do a deal together?

If you see no difference with an alternate antenna, you might have some obstruction out on the horizon that you just can't see. Remember, the further the aircraft away, the lower it is on the horizon.

Keep us posted and if you need any other help don't hesitate to ask.

Not sure if it's been mentioned elsewhere, but as ADS-B is line of sight (basically the same as a VHF signal), the theoretical range can be worked out by the following:

Theoretical Range = √1.5 x Aircraft Height Above the Antenna

Eg. √1.5 x 30,000ft = 212Nm's

Then as has been pointed out above, that's all dependant on site error's of your aerial as well. Plus the cableing, etc. It doesn't take much for a weak signal that far out, to then be shielded by a tree, or a distant hill.

Mick

Thanks for the input Floody!

Here's a brilliant document from a well respected SBS enthusiast who talks about theoretical range and formulas etc. Of course some of us experience better range than the theory, but it depends on the circumstances. Check it out, it's a good read, even for the non technical.

http://www.homepages.mcb.net/bones/S..._Reception.htm

Thanks for the ADS-B range article Kurt, very interesting.

I am running Planeplotter alongside AirNavSystems RadarBox and only plot my ADS-B and ACARS reception. This is today's plot, and the two tracks way out to the east are at 439nm and 557nm respectively. I have had a quick look through the ACARS logs looking for position reports at E162deg, but could not find any. Next up will be a check of the RadarBox logs.

The 557nm plot may be an aircraft flying between Asia and NZ as the track angle is very north/south.

http://www.16right.com/MessageBoard/...r 20120803.jpg

thanks for the info, yeah I think id like to try another antenna.

this is the view from my roof

http://www.youtube.com/watch?v=mux1I...ature=youtu.be

Brad, your antenna position is really awesome! Couldn't be much better. Maybe you can cut down some of the trees. ;-) I am really jealous!