Uncategorized

0 comments

  1. snn47

    Unlike other article on ARS technical this article is cherry picking what it needs to support the headline, but lacks some important facts necessary for the understanding ILS-system. Therefore the ars technica article and the post on RTL-SDR needs to be revised and amended in explanations, why the proposed jamming is very hard to unlikely to achieve in reality, even though it sounds plausible, when demonstrated on a test bench.

    Both ILS-LLZ- and ILS-GP-Receiver of an aircraft derive the information fly left/right (ILS-LLZ) and fly lower/higher (ILS-GP) from the difference in Depth Of Modulation (DOM) between the 90 Hz and 150 Hz tone of the Amplitude Modulation in relation to the carrier received.

    However the Difference in DOM between the 90 Hz and 150 Hz tone of the AM received by the ILS receivers exists in space, is not generated as AM in the ILS-LLZ- and ILS-GP-transmitter.

    – The difference in Depth Of Modulation (DOM) between the 90 Hz and 150 Hz modulation of the Amplitude Modulated ILS-LLZ and ILS-GP signal signals varies in space and therefore with the 3d position of an aircraft.
    – ILS-LLZ and ILS-GP transmitter generate only signals with a constant Depth Of Modulation (DOM).
    – The varying DOM of the 90 Hz and 150 Hz in space requires for generation several signals (with and without carrier, CSB and SBO) which are feed through elaborate phase and amplitude shifting networks to feed a minimum of 3 ILS-LLZ and ILS-LLZ-antennas.

    The aircraft ILS-LLZ- and ILS-GP-Receiver receives the
    – ILS-LLZ 90 Hz signal is stronger, when an aircraft flies left of the RWY center line
    – stronger for the 150 Hz signal, when the aircraft is flying right of the center line.
    – For an aircraft flying directly on the extended center line the Difference in DOM is 0, because both 90 Hz and 150 Hz have identical DOM.
    – ILS-GP is similar and differs only in so far that the 90 Hz is the signal above, and the 150 Hz the signal below the Glide slope.

    It is not easy to estimate the volume of space of and consequently volume of possible interference such a proposed transmitter can create, because it will differ among other factors with the interferers location, antenna pattern and EIRP it will create compared to signal in space generated by the ILS-LLZ- and ILS-GP-antenna/-EIRP pattern and the varying aircraft 3d-position in relation to the interferer and ILS-LLZ and ILS-GP.

    The Instrument Landing Systems (ILS) is standardized by ICAO since 1949 in Annex 10 and related documents and consists of
    – ILS-Localizer (ILS-LLZ) providing fly left/right for the aircraft to maintain the extended Runway (RWY) center line (108 -112 MHz)
    – ILS-Glide-Path (ILS-GP) providing fly lower/higher Glide-Slope normally of 3° ending at the touchdown (329-335MHz)
    – Outer-, Middle- and Inner-Marker identifying distance to the touchdown (75 MHz) and/or
    – Distance Measuring Equipment (DME (960 – 1215 MHz) which can replace or augment the Marker

  2. Tim_rtd

    I recently had an event in which I lost audio on my openweb server sound . My IT guy said to go into the chrome settings, content settings, sound and then add your website to alow sound. Worked for me..

  3. bobcat

    Using the Farnham WebSDR interface i see the waterfall but cannot get any sound.Im using chrome browser HTML5 win7 so what is the problem im having.how do i resolve this?.

  4. tony

    is there a version of SDR# i can download with the plug in manager already installed OR a version with all the plug ins install and I can delete the ones I want….
    No matter what I try I can get a plug in to install..
    Please I know ,I know , do this follow this tutorial belive me I,ve spent days…….

    • Timothy Roberts

      Tony, I don’t think any repo like areas have what you’re asking. I will tell you a couple things. You don’t need a plugin manager at all, and SDR# has evolved to where older plugins no longer work with newer release SDR# builds.
      Look for Valisi’s plugin website. You may need to turn on Russian translate.

  5. Microbob

    Is there a way of observing a much wider frequency range in the spectrum window? I need to search for offending transmitters that may be putting out huge sidebands that are interferring with normal WFM signals. The main spectrum window is always less than 2MHz wide. I’m looking for something like 50 to 100MHz wide.

  6. Comment

    The OM and telecommunications legislation derives from agreements of the Second World War … of course there have been additions and the OM world has supported these phases but perhaps it is time to change to have social benefits and not just economic ones.

    .. America and further duties on intellectual property ….

  7. WacKEDmaN

    US law is a bit poo!
    here in AU we are allowed to receive and demodulate/decode anything…its just illegal do anything with the information we find..

  8. Chris

    What is here happend? Where have to be the File right now?
    CMake Error: The current CMakeCache.txt directory /home/geeko/rtl-sdr/pkg-rtl-sdr/CMakeCache.txt is different than the directory /home/geeko/pkg-rtl-sdr where CMakeCache.txt was created. This may result in binaries being created in the wrong place.

  9. Pawelr98

    Recently I built a somewhat similar upconverter using ech81 heptode-triode. Triode works as Meissner (aka Armstrong for US people) oscillator (LO) while heptode works as mixer and RF amp. G3 tied to Triode grid, G1 is RF input. Vacuum tube upconverters have massive signal levels so they cannot really be plugged in directly. It peaks my RTL-SDR input even when beeing couple meters apart(small antenna provided with generic RTL-SDR). Around 200V anode, G2+G4 at around 85V. Triode anode at around 60V. Cathode at ground level. LO at around 11MHz, bringing some HF signals into RTL-SDR low-end usable range.

  10. keyle

    thanks ,,, its realy work well with low snr ! i test it and successfully done .
    i test window version but not got any decoding becouse its low signal , this is realy good and better and work with low snr . very thanks ..

  11. phil

    I have a cordless digital phone which claims to operate on 1.8-1.9 ghz. I intend to check the base station frequency. Is it common for them to be insecure?

    • Harold Giddings

      At that frequency if you were looking at a dect cordless phone.

      It is completely insecure but it is digital instead of analog, it used to be that you needed a $300 device with a modified driver to listen into these calls but now you can use a relatively inexpensive SDR and some software like gr – dect2 and listen to them all the same.

      Technically it supports encryption but I have never once seen a single dect phone use it.

      The chances of somebody listening to your calls are slim but very possible, a good rule of thumb is that if it is wireless it is extremely vulnerable to interception.

  12. Steve Olney

    After 20 months of daily observations of the Vela Pulsar, on the 1st February, 2019 my HawkRAO system detected a ‘glitch’ in the pulsar. AFAIK this is a first for an amateur radio astronomer.

    On the 1st February 2019 at 14:09 (UTC) Vela ‘glitched’ (refer to ATel #’s 12466, 12481 & 12482).

    This glitch (~ 2.5 ppm jump) was clearly seen in HawkRAO data in the MJD 58516 and following observations.

    The purpose of the observations has now evolved from waiting to detect a glitch, to ongoing observation of the post-glitch behaviour.

  13. Rodney Yeo

    Is FlightAware 1090Mhz Antenna electrically shorted at the center element to the outer element. I want to use RTL-SDR Triple LNA+ Filter with Bias-T and RTL-SDR version 3 dongle with it, will it work?

  14. Rodney Yeo

    If you want it to load at boot up via rc.local or crontab… do add a sleep 10 timer else it will fail to work!

    — BOF biast.sh —
    #!/bin/bash
    sleep 10
    service dump1090-fa stop
    cd ~/rtl_biast/build/src
    ./rtl_biast -b 1
    service dump1090-fa start
    — EOF biast.sh —

  15. Mike

    100 hundred years ago and a warship in the harbor would deliver a powerful measured but convincing message to the ruling parties involved. The Barbery Pirates learned the hard way, let’s hope that this is not needed again.

  16. John

    Thanks for the information but the link link to the video has been unavailable for a very long time. It would have been helpful to include some rudimentary written instructions. This is a ‘how-to’ after all?

  17. Richie. HJ

    I wonder if someone could help me. I’m failing to run my RTL-SDR on my Motorola Z3 mobile phone. The driver tells me, “No compatible devices found.” The RTL-SDR works well on the laptop.

    I can use a whole host of apps and programmes using a NooElec R820T on the phone

    What am I missing?

    If something’s could please provide an answer, suggest something else to try or point me in the direction of a FAQ answer or blog, I would be most appreciative.

    de G0RHJ

    • RichieHJ

      I suspect that it could be a power issue. That is, the RTL-SDR needs more power than the phone can provide. Would a OTG Power Cable be the answer?

  18. Chaq

    I need help! On the config Menu (cog icon) for the RTL-SDR (USB), the options for choosing my device are grey out, I can´t select anything, I already change the drivers with zadig, and reinstalled SDR#. I´m using the Nooelec NESDR smart dongle.

  19. jeff

    i have the v3 dongal and get good reception on 40/20m.would getting a ham it up .make any difference
    or should i just stay as i ham .i like hf dxing .from the uk….

    • James Johnson

      As I understand the only reason to get “ham it up” is to hear frequencies below 25 MHz. If you already hear the 40 M band then you already have those frequencies.

  20. Yarda

    It seems the bias tee is supported by the upstream librtlsdr and osmosdr, could you update the instructions to cover it? For librtlsdr there is usually the -T option, e.g.:
    # rtl_fm … -T
    to activate the bias tee

    For the osmosdr the option “bias” can be used in the device string, e.g.:
    rtl=0,bias=1