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Thread: Improving Reception

  1. #1
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    Improving Reception

    Hi I have had a Radar box for over five years now, last 2 years it was never used, when I plugged it in a few weeks back I noticed a drastic fall in receiver coverage.

    Thinking it was the antenna or there is just to much traffic and this is causing a reduction in packets decoded, then I recalled the recent installation of two CellPhone masts close to my abode, one at 120m and the other 150m and now thinking these may be the problem.

    I have now invested a DVB-T and Raspbery PI, pretty much the same coverage but now looking at improving my reception area.

    OK when the weather gets better I intend to take a look at the Antenna maybe even raise it a few feet.

    But was also thinking:
    • Wrap the DVB-T in grounded foil.
    • Put ferrite's on the USB and Ethernet cables
    • Add a filter to the antenna feed close to the dongle
    • Move the pi and dongle to the attic when stable and reduce the length of the feeder, maybe eventually a mast head box.


    have I missed anything?

  2. #2
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    i think that about covers it, i would try the filter first over anything else.
    T-EGLF8

  3. #3
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    All your suggestions seem good, however wrapping the dongle in foil is unlikely to have much benefit, nooelec do a decent aluminium box for dongles, however as it is anodised it is not easy to ground well, I lined mine with self adhesive copper RF shielding tape, if you search eBay you can find similar boxes for less than £2 but you would need to do the cut-outs yourself.
    A filter is a good idea, I have got the new FlightAware one (from Amazon) and that with an amplifier (from CosyCave) increased my feed to PlanePlotter by around 50% and gave a big increase in range, I am waiting for the FlightAware pro stick dongles to come back into stock, I use one for my OGN feed and they are very good.
    Definitely put a ferrite on the USB lead, it is probably unnecessary on the Ethernet, but it won't hurt.
    A GOOD power supply is another thing to look at, try for a well built 3 amp one as the noise tends to rise if the psu is running near its rated capacity, a ferrite or even proper filtering on the 5V power cable could help.
    If you have stability problems then try moving the dongle to a powered USB hub as the RPi is not great with power hungry devices, (there is a hardware mod you could try to increase the USB power.)
    Also use wired ethernet if possible as the RPi can be flakey on wifi. (Probably varies depending on the wifi dongle and your router)
    Ben.
    FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

  4. #4
    Captain abcd567's Avatar
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    If you have 2 cell towers at 120m & 150m, then the first thing to do is to add a filter next to the dvb-t dongle.


  5. #5
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    Yes, I have a filter on order but it will take a few days as it is coming from the states.

    So put some foil round the dongle yesterday, to be honest I was not expecting it to do much as the dongle is so small, Was thinking of moving the dongle to to a aluminium diecast box, I think I may have one just the right size when I can find it, can use a short male to female USB lead, that's where I need ferrite's.

    I have on order a 3A 12v to 5v USB module for use in the attic or mast head, and I know all about the problems with switching regulator so may have to build in some smoothing.

  6. #6
    Captain abcd567's Avatar
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    @G8VXY:
    If you have ordered a FlightAware filter, please note it has sma-male connector at one end, and sma-female connector at other end. You will need a mcx-male to sma-male adapter to connect it to generic dvb-t dongle which has a mcx-female socket for antenna connection. Similarly, you will need a sma-male plug to terminate your antenna coaxial cable.

    If you have Flight Aware Pro Stick dvb-t, then it has a sma-female input for antenna, and the FlightAware filter can be directly connected to it without using any adapter. Please see photo in my previous post.
    Last edited by abcd567; 2016-04-29 at 08:06.

  7. #7
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    I already using a short lead SMA 2 MCX

  8. #8
    Captain abcd567's Avatar
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    Wise to use a short lead. A short lead or pigtail of thin cable like RG174 or RG316 is better than a solid adaptor, as it reduces mechanical stress on dvb-t's delicate connector.

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