Page 2 of 4 FirstFirst 1234 LastLast
Results 11 to 20 of 31

Thread: expierence with receiver Navilock GNS ADS-B ??

  1. #11
    Captain Anmer's Avatar
    Join Date
    Apr 2010
    Posts
    1,384
    Thanks for the confirmation that you are working for GNS.

    Why didn't you include the SBS-3 in your comparative tests? And what results were you comparing?

    In all my tests, the only valid result is how many aircraft can be tracked off the same antenna. So far, the SBS-3 and Beast are way ahead of everything else.
    Mike


    www.radarspotting.com

    Radarspotting since 2005

  2. #12
    Passenger
    Join Date
    Nov 2012
    Location
    Melbourne, Victoria, Australia
    Posts
    49
    Quote Originally Posted by Mike View Post
    I have tried 3 of them and sent them back as they didn't work.
    We can recommend 4 receivers, and specially the first 2 are very good.
    http://www.flightradar24.com/hardware
    G'Day Mike.
    Can you tell me what type & gender is the antenna socket on the 5890 please ?
    Thanks, Greg.

  3. #13
    Captain Anmer's Avatar
    Join Date
    Apr 2010
    Posts
    1,384
    Quote Originally Posted by GregHudson View Post
    G'Day Mike.
    Can you tell me what type & gender is the antenna socket on the 5890 please ?
    It's an MCX female connector:

    http://en.wikipedia.org/wiki/MCX_connector
    Mike


    www.radarspotting.com

    Radarspotting since 2005

  4. #14
    Passenger
    Join Date
    Nov 2012
    Location
    Melbourne, Victoria, Australia
    Posts
    49
    G'Day All.
    Ignorance is bliss - which is why I'm so happy... BUT...

    With regards to DVB-T dongles not being able to receive data fast enough, I find that difficult to understand.
    They are built to receive Digital TV Broadcasts, which, I believe range from 1.5 to 3 Gbps depending on broadcast type.
    I believe each ADS-B transponder is transmitting at 1Mbps which, by my calculation, means we should be able to ident 1,500 to 3000 aircraft (visible to antenna) at any one time.
    (source - ADS-B for Dummies by European Organization for the Safety of Air Navigation)

    As stated, I'm ignorant... But assuming my research is correct, and a laptop can display a Full HDTV signal, it should have no trouble decoding data streams from several hundred aircraft simultaneously.

    Comments please anyone ?

    Regards, Greg.
    Last edited by GregHudson; 2012-11-27 at 20:40.
    GNS 5890 (German), 2 x DVB-T Dongles (China / USA), Mobile One SAN-1090 external base antenna (Australian), Heliax coax (USA).
    HDSDR, Plane Plotter (full version, but not working), adsbScope, Virtual Radar.

  5. #15
    Passenger
    Join Date
    Apr 2012
    Posts
    16
    Greg....
    this really a good question.
    I have seen some recommendations for DVB-T dongles.
    It´s correct that you can receive data with SDR dongles on 1090 Mhz.
    I made also some experiments and first I do not understand why the framerate is sooo bad.
    Add the end it has something to do with the concept of the receiver or better with the modulation.
    ADS-B is PWM modulated.
    Mostly for DVB-T QPSK modulation is used means there is more information (higher bitrate) inside the signal
    IQ receiver are used ect. the PLL inside can be slow, but for ADS-B you need a very very fast PLL
    actual there is also no SDR on the market which has such kind of fast PLL.
    Thats the reason why the ADS-B receiver concept should be a non PLL design.
    So with SDR concept you will loose a lot of information (frames)
    and the framerate for SDR based tuners is only 5f/s.
    So reception of ADS-B data with SDR design is a kind of playing lotto ;-)....you can be lucky if you receive some frames.

    regards

    Bill

  6. #16
    Passenger
    Join Date
    Apr 2012
    Posts
    16
    @Anmer,
    I can not say if SBS-3 is far away, because I do not have tested this receiver.
    Fact is that the GNS5890 has no limitation regarding frame rates as long they are not overlapping.
    As you may know app. 20% of frames are overlapping this is the reason why the GNS5890 has in the middle 20-30% lower frame rate than the beast has.
    Sometimes if we are lucky we have the same high framerate but not stable...reasonly because of lucky moments with only a few overlapping frames.
    but......
    Is this really an indication or more or less a theoretic thing ???
    You can imagine that if we miss two frames in a second because of overlapping we will catch it in the next second.
    So what ? It doesn´t matter.
    At the end of the day the most important thing is to receive all transponders.
    Missing overlapping frames is not a big issue.
    Missing frames which are not overlapping is an issue !
    This is what happend with SDR receivers or with MicroADSB and Radarbox, because of RF design and/or slow decoder firmware.
    Second thing is missing frames because of donought effect (bad RF design or better Gain control)

    What do you think ?

    regards

    Bill

  7. #17
    Passenger
    Join Date
    Nov 2012
    Location
    Melbourne, Victoria, Australia
    Posts
    49
    G'Day Bill.
    I have my GNS 5890 up & running today, and seen frame rates up to 4900 (depending on traffic of course).
    There may have been higher rates, but I didn't see them.

    There also doesn't appear to be any discernible donut effect that I've heard about. I've had planes flying directly over head today, and visible on screen 100% of the time).
    Range seems to be approx 200NM.

    Regards, Greg.
    GNS 5890 (German), 2 x DVB-T Dongles (China / USA), Mobile One SAN-1090 external base antenna (Australian), Heliax coax (USA).
    HDSDR, Plane Plotter (full version, but not working), adsbScope, Virtual Radar.

  8. #18
    Passenger
    Join Date
    Jul 2010
    Posts
    19
    I assume you mean 4900/min? The Beast can do 4900/sec.

    As you are aware RTL1090 software can handle DVB-T dongles easily. With proper gain settings you can expect 1/3 of the Beast data rate (benchmarked by F5ANN), which is not too bad.

    ADS-B (you mean Mode-S) is not PWM but PPM. To decode PPM there is no PLL needed (for what?). The dongles data rate is limited by the USB channel and the PC processing speed of samples, nothing else.

    I am surprised...

    Mike: I would suggest that hardware sales persons should not be allowed to talk badly about competitors here.

    Thanks
    Andy
    jetvision.de

  9. #19
    Passenger
    Join Date
    Nov 2012
    Location
    Melbourne, Victoria, Australia
    Posts
    49
    G'Day Andy.
    Yes, you are correct, the highest frame rate I had seen at the time was 4900 per Minute.
    This has now increased to 6700 / min (observed).

    I'm a newbie, so I don't really know if the above figures are good, bad or irrelevant.

    I believe Bill was trying to explain why a DVB-T Dongle, with decoding software running on a PC was going to be slow - although to be honest, I don't really understand either his response, or your comments to him.
    I need an explanation in laymans terms ! ;-)
    Please read my 'ignorance is bliss msg 4 or 5 msgs up, & see if you can explain it to me.

    My DVB-T dongles still haven't arrived yet, so in preparation, I am now on your website examining the RTL1090 software you mentioned.

    Also, I believe the GNS 5890 does not have what they call 'expensive' FPGA ? circuitry (whatever that is).
    Whereas the Beast does have it, and I assume this is why it costs more than my Laptop !

    However, that doesn't mean I won't buy a Beast as well... After watching a series of videos on YouTube, it doesn't appear to be as difficult to build as I first imagined.
    Indeed just 2 days ago I went out and bought a more powerful soldering iron, some flux, and solder - in preparation for purchasing a Beast. BUT...

    If, as Bill implies, I'm receiving 'enough' data to display a decent amount of tracking / aircraft movement using the GNS, then maybe a Beast isn't required.

    The reason I bought the GNS was totally because of the price, not based on the framerate.

    Regards, Greg.
    (A user, with no vested interests)
    Last edited by GregHudson; 2012-12-05 at 23:11.
    GNS 5890 (German), 2 x DVB-T Dongles (China / USA), Mobile One SAN-1090 external base antenna (Australian), Heliax coax (USA).
    HDSDR, Plane Plotter (full version, but not working), adsbScope, Virtual Radar.

  10. #20
    Super Moderator
    Join Date
    May 2011
    Location
    T-NZCH1, PP:PH New Zealand
    Posts
    5,002
    Depends on your target rates really. Beast is good in EU/UK where there are 200 or so contacts at one time. Whereas here and aus where you may only get 20-30 it could be fine to use a lower model decoder.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •