AirNav Systems Forum
AirNav RadarBox and RadarBox24.com => AirNav RadarBox and RadarBox24.com Discussion => Topic started by: jonjorobb on February 14, 2010, 03:26:59 PM
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Hello,
I have been using my supplied antenna in the loft for quite some time now, And I have been looking to get better results. As I don't have a step ladder, I place the antenna on top of a tower of DVD Cases to get it as High as possible, with a Tin box and the antenna at the top.
Today I decided to try and get the antenna as high a possible - I added more DVD's to the Tower and it was as high as I could get it. I left it there, and came back a few hours later. I know you should leave polar diagrams to develop, but I have had my Radarbox for over a year so I know where my range is good, and where it is bad.
I got a shock when I saw the results. With my previous set-up I was receiving flights from over 120NM away. With the antenna as high as possible, only 80NM. I inspected the loft with a torch and there does not seem to be anything in the antenna's way at that height, so I was confused of this.
I then decided to grab a Quality Street tin and lower the Antenna to its original position in the loft. Its been running like this for less than 15 minutes and I've already broken some personal records, Aircraft from EGNT climbing out from the P18 for example, I'm picking them up a lot earlier. Another example is Aircraft on the N601 descending into EGPH, there dropping from my reception allot later. I need to let the Polar Diagram develop, But so far the results look much more promising.
So remember, Height isn't always everything!
Jonjo
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Jonjo - I don't understand the mysteries of loft placement of antennas either. I've posted elsewhere about similar experimentation that I tried, moving the blooming thing all over the length, breadth and height of the loft.
It worked well in one place, so-so in another and badly in a third but to no discernible pattern. In the end and totally by chance I hit the spot, up shot the number of flights, and I haven't touched it since.
I seem to recall many years ago doing similar experiments with an indoor biscuit tin mounted loft scanner and getting similar results.
There must presumably be some logical explanation but it is baffling.
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Yes Bratters, it really is odd!
Anyway, I don't think I dare touch it ever again!
Jonjo
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I tried the same to try and improve my contacts, but with the same results. It took me a couple of weeks of going into the loft to get the same position as before with cries from my wife "Not again, haven't you got it right yet?" I daren't try again.
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I find your and jonjo's posts very reassuring bearcat.
I seriously thought I was going barmy.
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Hi
What were you using for a ground plane before using the the sweet and biscuit tin lids?
Dudley
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This Halo 3 collectors edition tin http://www.videogamesblogger.com/wp-content/uploads/2007/03/halo-3-collectors-edition-box-big.jpg
I found it on the pavement on my street! It was an improvement on the supplied disc.
I have another Quality Street tin, putting that below it as well wont make a difference will it?
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I used to have an externally mounted antenna but found reception just as good with my loft mounted mag whip, although I have found Cadbury's Roses tin lid gives me better reception than quality street did ;-)
Seriously my polar diagram is little different than it was with my external antenna although I am on a hill.
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I used to have an externally mounted antenna but found reception just as good with my loft mounted mag whip, although I have found Cadbury's Roses tin lid gives me better reception than quality street did ;-)
Seriously my polar diagram is little different than it was with my external antenna although I am on a hill.
Always prefered Roses myself.
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Bit of horse muck round it. better still!
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I bought a 5m active USB cable to try it out.The aerial is about 10Ft higher in the loft but my polar diagram is still rebuilding but does not seem to cover as much of an area as previously. Should I leave it to let the polar diagram build up, remove the USB cable & revert back to old set up, or try repositioning the aerial? Choices choices.
I have tracked some transatlantic flights on the new set up & the disappear far quicker with the new set up, is this something that will improve if I leave the polar diagram to populate?
Any advice appreciated.
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I bought a 5m active USB cable to try it out.The aerial is about 10Ft higher in the loft but my polar diagram is still rebuilding but does not seem to cover as much of an area as previously.
When you say the aerial is 10 feet higher in the loft, where was the aerial before? What are we comparing with what?
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Best is to try several locations in the loft, give "SBS-1 Meter Lite" a try, it gives faster a clue how much traffic is coming in.
You can find the program here: http://jetvision.de/bstchart/SBS1Meter.zip
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I bought a 5m active USB cable to try it out.The aerial is about 10Ft higher in the loft but my polar diagram is still rebuilding but does not seem to cover as much of an area as previously.
When you say the aerial is 10 feet higher in the loft, where was the aerial before? What are we comparing with what?
Bratters it was in the loft previously, the radarbox sat on my comp desk with the aerial cable running into the loft. Now the Radarbox is in the loft connected via 5m cable to PC. The additional cable lets me elevate the aerial by approx 10 ft.
Jannuh I will try that cheers.
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Brimon - yes, this really encapsulates the "loft" problem and the thread title "height isn't everything".
While the extension USB gives you the freedom to move box and aerial about, it doesn't help finding that elusive "sweet spot" is. Not necessarily high, not necessarily central, not necessarily anywhere in particular.
There's really no advice I can give you, it defies logic and is purely down to trial and error.
Best I can say is Good Hunting.
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Further to the above, I checked the aerial effectiveness purely by MyFlight numbers and distances.
Easier if you can co-opt an observer!
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Brimon - yes, this really encapsulates the "loft" problem and the thread title "height isn't everything".
While the extension USB gives you the freedom to move box and aerial about, it doesn't help finding that elusive "sweet spot" is. Not necessarily high, not necessarily central, not necessarily anywhere in particular.
There's really no advice I can give you, it defies logic and is purely down to trial and error.
Best I can say is Good Hunting.
Thanks for that Bratters, will trial & error basically. I am just concerned that rather than positioning I losing distance because of the length of cable now involved between the Radarbox & PC.
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Thanks for that Bratters, will trial & error basically. I am just concerned that rather than positioning I losing distance because of the length of cable now involved between the Radarbox & PC.
No, not if I understood you correctly. The length of your USB cable is immaterial in terms of degrading signals; it's aerial cable that is responsible for signal loss.
I'm currently using around 12 metres of USB, but the aerial cable is the supplied one. Signals were never better.
Do let us all know how you get on and whether you can come up any "scientific" theory for siting your aerial in the optimum position - if and when you find it.
(I find a stack of cardboard boxes and biscuit tins come in handy)
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The length of the USB cable is more likely to introduce power problems resulting in RB disconnecting due to lack of power. I'm not sure why the maximum length of a 'normal' USB cable is set at 5M though - could that be a power issue?
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Brimon seems to be using 5mtr active Allocator.
Both my 5 mtr active cables came with a further 5 mtr of "normal" cable thus giving a 10 mtr functional run which the manufacturers virtually guarantee to be effective. I haven't tried stretching to 15 mtr but I would anticipate that would be a bridge too far and my 40 feet is pushing the limit. Still, it's a helluva of a lot better than 40 feet of aerial.
I suppose the conclusion is that for non-active USB cable 5 mtr is the effective limit.
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Brimon seems to be using 5mtr active Allocator.
Both my 5 mtr active cables came with a further 5 mtr of "normal" cable thus giving a 10 mtr functional run which the manufacturers virtually guarantee to be effective. I haven't tried stretching to 15 mtr but I would anticipate that would be a bridge too far and my 40 feet is pushing the limit. Still, it's a helluva of a lot better than 40 feet of aerial.
I suppose the conclusion is that for non-active USB cable 5 mtr is the effective limit.
Bratters I am indeed using 5m active. Thanks for comments regarding cable not affecting signal. I don't know about a "scientific" solution.
I did think about putting the wife in the loft holding the aerial in various positions
for the weekend, don't think she'll be too keen though.
Appreciate the reply's by everyone, thats what makes this a very good forum,Cheers.
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I use the Cat 5 USB extender that gives me up to 50m extension - and it provides the power faultlessly as well :-)
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I think one of the reasons my loft aerial performs nearly as well as when I had it on the roof is the shorter antenna cable length used in the loft meaning less signal loss.
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I ag
I think one of the reasons my loft aerial performs nearly as well as when I had it on the roof is the shorter antenna cable length used in the loft meaning less signal loss.
You are right, antenna as high as possible and antenna co-ax as short as possible - it just has to be the best solution.