GNS 5890 or not?

[colin1951uk]

Hi, a new member here after a bit of advice.

I've only just recently got into aircraft tracking using a a cheap dongle and accompanying stock small portable antenna that came it (bought from Amazon for ten quid and I'm sure you will all know about these.)

I live about half a mile north of Southampton (EGHI) airport on the second floor of a five storey building that runs north to south. Being so far from the roof I'm limited in what I can do with the antenna but I have got a small balcony and with an extension lead can get the antenna outside and stuck onto a baking tray (incedentally the antenna has been trimmed to 69mm as I read it is a good length for quarter wave reception of ads-b .) So all a bit primitive but it does work quite well.

To the west of me and going away from the building I can get aircraft tracking out towards the Atlantic for about 250km but to the East where I'm blocked by the building I'm limited to about 130km (and that's assuming flying at at an altitude of 30,000ft as reception tapers off at lower altitudes.) North/South of me varies but the farthest I've achieved is 140km. Any traffic into EGHI I can obviously get but that is mostly none ads-b equipped aircraft (Dash8 etc) although the odd charter flight does have it.

Now I was wondering whether I could do any better with a GNS 5890 (the cheapest next logical step up for me) as it is a dedicated ads-b receiver and not a hacked dongle which I'm guessing is nowhere near as sensitive as any custom built ads-b receiver.

Or might I be better off staying with the dongle and getting a proper ads-b tuned antenna which would be almost as expensive as the 5890?

Bearing in mind the problem I've got with the antenna location I'm not sure I would benefit from either of the two options but being new at this game I'm looking for advice about this just in case I might surprise myself.

So any comments that can help me decide on what to do to improve my situation (or not) would be appreciated.

Cheers...Colin

[Anmer]

Welcome.

As far as I can tell, the GNS5890 is basically a "dongle" - SDR radio and decoding software.

In a comparative test, my "dongle" performed as well as a GNS 5890.  I don't see the point in upgrading.

The important component is the antenna and where it can be placed to receive maximum messages.  From your post, you have worked out your options which are limited to the east.

If I were to upgrade, I'd check out eBay for a used SBS-1, any version will do but the SBS-1e or 1eR are more "sensitive".  You could pick one up for around GBP £100 or a bit more.  The one I bought 9 years ago is still working great.

Or stick with what you have.

[IanH]

See my comments here

http://radarspotting.com/forum/index.php/topic,4357.0.html

about the micro ADSB which is similar to the GNS 5890.

Basically it confirms Anmer's comments. But whether you can pick up a SBS-1e(r) for £100 is down to luck, ie no one else is bidding for it on eBay 

[colin1951uk]

Ok well thanks for the input and I may as well stay as I am for a while then as  there's no point in spending money if it's not going to make much of an improvement.

I've had a look at SBS and it appears tasty but it is old (or version 1 is anyway) and I wonder if it would run with Windows 7. Kinetic don't have a driver for it on their downloads page or I couldn't find one anyway so that is something I need to research more. But even so I'll keep an eye on Ebay and if a bargain appears I'll take a shot at it as I still have XP tucked away somewhere.

I think I'll try and do something with my antenna though. Maybe I can try and fix it on a long pole and push it out a lot further from my apartment. It may make a difference away from the bricks and mortar and if it does it might be worth getting a decent twig from Jetvision or whoever and get something setup outside permanently (something I can't do with the tiny magnetic portable as it isn't weatherproof.)

Might be worth trying a couple more of the dongles to (Jetvision and Cosycave?) just to see if there's a bit more sensitivity reception wise in these little bits of kit. They're so cheap you can't lose really.

Anyway I'm still learning so I'll keep trying different things to find the best arrangement for my location 

[IanH]

You just missed an SBS-1er on eBay that went for £139. 

Basestation software runs on Windows 7 no problem. The early SBS-1 that connect via USB need the FTD2 driver (I think). 2014 version for Win7/8 is here: http://www.ftdichip.com/Drivers/D2XX.htm

I doubt the there is much difference in dongle sensitivity - they are all based on the RTL2832U chipset and mass-produced. The R820T version improved on the E4000 version.

The antenna is where you are going to see most improvement - I might just try a dongle on  my new aerial installation for comparison  (see TMRF1090 thread).

I bent some copper wire to this pattern  and got good reception:
http://www.tech-software.net/1090_ant_02.JPG
http://www.airlomba.net/index.php?pag=projects&projpg=coli1090

The cost of getting them on the roof meant that I decided to go with a ready-built model but might be worth trying.

[viking9]

Colin,

If you can't get your antenna in a position to see to the East perhaps you should consider suscribing to PlanePlotter;

http://www.coaa.co.uk/planeplotter.htm

Tom

[EGTE24]

I doubt the there is much difference in dongle sensitivity - they are all based on the RTL2832U chipset and mass-produced. The R820T version improved on the E4000 version.

The differences between DVB-T dongles isn't huge, but there are some variations. I've accumulated half a dozen dongles and have been running some side-by-side comparison tests by using an antenna splitter to feed the signal from a single antenna to two dongles, each feeding a separate instance of dump1090, then into VRS to produce polar plots (example attached - dongle #1 blue outline, dongle #2 pink outline). The overall max range is short due to the test antenna (a simple dipole) being indoors, against a window and only 7ft agl, however it's adequate for test purposes.

The differences in range between dongles is subtle (and inconsistent), however I've also observed variations in signal strength, numbers of a/c received and how quickly they're picked up or dropped.

[Anmer]

Welcome and thanks for sharing your experience.

What were you using to split the antenna signal?

[EGTE24]

Thanks for the welcome

The antenna splitter I'm using is this: http://www.ebay.co.uk/itm/F-Type-Screw-Connector-Splitter-For-Virgin-Cable-Sky-Satellite-2-way-/271313781710?pt=UK_Sound_Vision_Other&hash=item3f2b8fc3ce

I've just started running a comparison with another dongle, which is showing a significant improvement in range - I'll post a polar plot image after it's been running for 24 hours, if it's of interest.

[Anmer]

Thanks.

I found that using a simple splitter tended to favour one receiver against the other.  It's easy to check by swapping them around.

[EGTE24]

A fair point and one I hadn't considered - I'll let this test run 24 hours, then swap round and give it another 24 hours before posting results.

[EGTE24]

Well, a fairly conclusive difference in performance and range between the two dongles under test - see the polar plots below - the outline colours are for the same dongle in each image, i.e. blue=dongle#1, pink=dongle#2, but the antenna feeds were swapped halfway through the test to compensate for any bias in the antenna splitter.
For me, this clearly demonstrates that dongle #1 (http://ebay.eu/1vo2to5) significantly outperforms dongle #2 (http://ebay.eu/1vo2Fnx)