reception

[oldun666]

Hi, can somebody point me in the right direction please, my setup consists of a radar rama antenna, and a good lengnth of mini 8 coax, because i have my setup in a front downstairs bedroom, and can only fit the antenna on the back of the building, the cable  has to come through two walls, ie outside and inner, the antenna is on a pole next to the gutter and the tip level with  the apex, would i benefit with a Watson radar extender, or a mast preamp ?  thank's jeff.           ps i have tried to send a polar diagram , if it works

[oldun666]

i forgot to say that is with a moonraker MRP 2000 in line by my reciever, i dont get to many my flights, am i set up right ? without the preamp, hardly any my flights thank's again  jeff.

[neroon79]

Hi Jeff,

what's your total cable lenght between Antenna and Radarbox?

I fear, that you would have the most benefit, if you change on a cable like the one in my proflile.

Yours has a attenuation of about 36db per 100m @ 1000MHz mine has abaout 6db /100m @ 1000MHz (ADS-B is 1090MHz) therefore many of the signals your atenna is picking up will get lost in the thermal noise of your cable. Means the received signal don't  get through to your receiver.

Ingo

[oldun666]

Hi ingo, roughly speaking its about 35 to 40 ft, what i was thinking of doing is puting my box in the other room wher the coax comes in and taking about 20 ft off, and puting in a 5 mtr  usb repeater cable. thank's  jeff.

[Runway 31]

Hi Jeff,

The cable length isn't excessive but I believe the cable could be  the problem as Ingo details and you may in my opinion be better off getting a low loss cable such as Westflex than using the one that you are.

Another factor regarding reception is what is around you as you will only pick up aircraft the antenna can see.  What is your location like, high buildings, hills, being in a valley, nearby trees etc can all impact on your range and reception is they stop the antenna seeing the sky maybe in the one direction.

Alan

[neroon79]

Hi Jeff,

I did some calculation and, clear line of sight implied, you may get an 15% increase in reception range, if you would change to 4,5m of low loss cable with 10dB/100m attenuation instead of your currently used cable with 36,7dB/100 attenuation.

About Antenna: 1,3dB more gain --> 16% more range (clear line of sight and airframe above horizon implied)

Remark: It's a rough calculation. Real results can (will) differ.

Preamp: If you want to use a preamp you should use a narrow band preamp specially designed for 1090MHz reception. With a wide band amp like you stated you can reduce the signal quality of weak 1090MHz ADS-B signals due to intermodulation effects with other received frequency/signals in the cable. With narrow band amps designed for ADS-B reception only the 1090MHz gets full amplification other frequencys get less amplification or in best case even attenuation.

Ingo

[oldun666]

gutten taag, ingo, thank you for the reply, i went to my friends house on fri 21/11, before i perchased my airnav, i asked him to keep a look out for a decent 1090 mhz antenna, i told him of the difficulty i was having, and he said he had something for me, ( i had forgotten all about it ) and he produced a second hand watson radar extender, when i got back, luckily there is scaffolding around my building, so i was up and changed it. I came back in to test, and as if by magic my flights went from 15 to max 89 last night, 35 wthout preamp, thank you for the trouble you went to ingo, so it looks like a vote for the watson radar extender over the radar rama adsb. this is the new polar diagram.   thank you to all. 73 

[Runway 31]

Glad you are happy Now Jeff.  Maybe if you could get it a wee bit higher up the pole you could get better coverage to the south east.  Guess it will be the roof but looking good.

Alan

[neroon79]

Hi Jeff,
no trouble was caused. It was a hugh bit of own curiosity to figure out, how many influence the attenuation of cable could have. Did some calc with my own cable and came to the conclusion that I haven't wasted money five years ago.

Glad to hear your that your reception has improoved (understatement). Make sure, that the connection between antenna and cable (preamp if used and cable) as much waterproof as possible. Moisture in the connection can cause much more attenuation as any cable.

Ingo

[oldun666]

hi Alan, i would love to know what that is, it's not the roof, because the antenna is on the south side lol, i have had a look on google maps and cant see anything that would stop it, mind you there is a massive fir tree about 50 ft away, but i dont think that would do it ?. i am happy now though, just on my way out to buy a chainsaw lol.

[Runway 31]

Yes Jeff it will be the tree, chainsaw will do it!!

Alan

[neroon79]

Alan, a chainsaw that's not nice... The poor tree ;-)

My reception range reaches from EDDV to over the netherlands, but only in the winter. From late spring to late autumn it was blocked by chestnut trees. Too bad that they got ill and were cut down this summer...

Ingo

[Runway 31]

Hanging my head in shame, poor tree.

Alan

[oldun666]

Hi all, Alan, i have managed to raise the antenna about 3 ft, this is my polar diagram after about 14 hrs. once again thank's to all for your help.

[RodBearden]

I'd just like to remind folk about the HeyWhatsThat site for predicting/assessing your potential coverage - my original post about it is here: http://www.airnavsystems.com/forum/index.php?topic=3335.msg31610#msg31610

Post #6 has a link to my instructions on how to use its features (I hope it's still up-to-date). EDIT - it still works fine :-)

It's great fun, and produces amazing results.