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Thread: NooElec with small antenna ---> FA Pro Stick + FA 1090 Antenna = worse results?

  1. #11
    Captain abcd567's Avatar
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    The Flightaware stand alone filter is an LC filter.
    The Pro Stick + (Blue) has an integral SAW filter.

    A Cavity filter will sure give precise and narrow band width, but cost $100 to $150(6 to 10 times the cost of LC or SAW filter).

    In my case, Flightaware's $15.50 LC filter did the job well.
    In few very severe noisy location, a costly cavity filter may needed. On ebay 1090 Mhz SAW filter are available for around $20, and may be good, but I did not try these.

  2. #12
    Captain Anmer's Avatar
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    Have you tried the Pro Stick with your previous antenna and vice versa? The existing DVB-T "dongle" with the FlightAware antenna?

    You don't mention what coax cable you're using?
    Mike


    www.radarspotting.com

    Radarspotting since 2005

  3. #13
    Captain abcd567's Avatar
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    LC FILTER SCHAMETICS

    UNBALANCED LC LADDER



    BALANCED LC LADDER



    FLIGHTAWARE FILTER INSIDE




    HUNGARIAN FILTER WITH TAI-SAW CHIP
    US $19.99 http://www.ebay.com/itm/112472645896




    CHINESE FILTER
    US $28.95 http://www.ebay.com/itm/331993013752
    Passband : 1086 ~ 1094 MHz (Not mentioned what type of filter is inside. Seems to be a TAI-SAW Chip, but not sure.)







    TAI-SAW FILTER CHIP






  4. #14
    Captain abcd567's Avatar
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    Flightaware antenna is a high gain antenna (6 dBi), while mag mount whip antenna supplied with DVB-T is a low gain (1.5 ~ 2 dBi)

    The Flightaware antenna therefore picks much more Cell Phone signals, and overloads the rf preamp chip if a filter between antenna and ProStick is not used.

    TEST-1: Comparison of Cantenna (Gain ~2 dBi) vs Flightaware Antenna (Gain 6 dBi) WITHOUT FILTER and with Generic DVB-T

    .







    TEST-2: Comparison of a Spider Antenna (Gain ~2 dBi), and Flightaware antenna (Gain 6 dBi) With ProStick/ProStick Plus



  5. #15
    Captain abcd567's Avatar
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    TEST-3: Flightaware Antenna and Pro Stick/ProStick Plus with Attenuators
    Gain Setting throghout the experiment = 38.6 dB











  6. #16
    Flight attendant Strix technica's Avatar
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    Quote Originally Posted by abcd567 View Post
    A Cavity filter will sure give precise and narrow band width, but cost $100 to $150
    This cavity filter goes for €42 incl. VAT (which you won't pay if you're outside of the EU) so no, they don't all cost thee figures or substantially more than a SAW filter.

    Doubtless you can spend hundreds on them, but the same goes for nearly anything.

  7. #17
    Flight attendant Strix technica's Avatar
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    Quote Originally Posted by abcd567 View Post
    TEST-3: Flightaware Antenna and Pro Stick/ProStick Plus with Attenuators
    Gain Setting throghout the experiment = 38.6 dB
    Adding pads (attenuators) to a system that includes amplifiers (actually two in this case, up to +70 dB or more in aggregate) is counterproductive, to say the very least.

    Signal lost in the pads can never be recovered, where injected noise is roughly proportional to the gain you use plus a bit more, therefore all you will accomplish is to decrease your SNR.

    If the problem is intermodulation noise, then use a decent, low-insertion loss bandpass filter before the first LNA rather than pads. Then set the gain to avoid overdriving anything.

  8. #18
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    Thanks for all the replies!

    I do have the blue stick - connected directly to the Pi. Pi is powered by a suitable high amperage power supply. The 16" cable between the pi and the antenna is a good quality one.

    I ordered the FA 1090MHZ filter to put in front of the stick which should be here on Wed, I will update with those results. I do have quite a few Zigbee sensors around the house - 902-928mhz, perhaps those are interfering?

    Anyway, if the FA filter helps out, maybe I'll invest in a better one.

  9. #19
    Flight attendant Strix technica's Avatar
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    Quote Originally Posted by klinquist View Post
    I ordered the FA 1090MHZ filter to put in front of the stick which should be here on Wed, I will update with those results.
    That's a bit of a pity because the bandwidth of that filter seems too wide to exclude GSM signals, which means a negative result won't necessarily prove much. I know they're more expensive, but a SAW or better still a cavity filter would probably have been a better choice. If you have the option of returning the filter and ordering a SAW filter (from China, if you must), that might be a better idea.

    On the other hand, if the BP filter in the Pro+ is after the LNA, it might help a bit to filter pre-LNA, even if the bandwidth is too wide.

    Quote Originally Posted by klinquist View Post
    I do have quite a few Zigbee sensors around the house - 902-928mhz, perhaps those are interfering?
    Hard to say. I'm unsure what ZigBee's maximum power output is, but it's probably in in the 50-100 mW range. That's tiny compared with GSM base stations, OTOH, your ZigBee transmitters are that much closer and inside your house, at which point the inverse square law comes into play.

  10. #20
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    Ok, I just *also* ordered a SAW filter from Hong Kong .

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