1. APTEM.ru

    I decided to do not participate, because was very unsatisfied with KerberosSDR support/software development. KerberosSDR is abandoned project from the beginning with no support at all. Spent some weeks for running it properly on modern Raspberry models, on laptop with AMD graphics, etc. Android app is old and contains some bugs. No updates available for more than one year or even more. No answers were given to my questions posted on the board for many months. There is no support email available/no responsible person/etc. This is why I worry to participate new projects like this. Project must be well-supported for 3 years as a minimum, like SDR# or something. Some of money must be invested in support, feature development, software development and working information support services. But not just in hardware/PCB & cases bulk ordering/initial software release coding. This is my 5 cents.

  2. perraud

    hello, can you imagine an antenna, a RTL-sdr receiver that follows the 20 Zombies satellites depending on their orbits with a program that scans at the right frequency and at the good period… ?? the Antenna would have to move ?

  3. David Slipper

    If I add a reflector how far below the aerial does it need to be ??
    and does it need to be connected to the coax shielding ??
    Regards, Dave

  4. KB6

    He had me up until the “flashlight scenario” That’s when i knew the jig was up !

    I love a good laugh thanks man I needed that 😉

    Surely you can’t be serious
    I am serious… and don’t call me Shirley!

    ha ha ha

  5. A person

    cool article, and I really am nitpicking here but “communication satellites continually launched by SpaceX since 2015”

    The first Starlink test satellite launch was February 2018

  6. snn47

    Unfortunately it is a bit more complicated, since you forgot to mention the impact of losses/attenuation between signal source (antenna or transmitter) and the sink (receiver or antenna).
    The above assumes that transmission lines like coax cable, chicken wire or waveguide are lossless, in reality losses/attenuation will increase with frequency and vary from cable design to design.
    As consequence the higher the attenuation the lower the meassured SWR or return power will be. If e.g. a cable is long enough to provide attenuation to convert all RF-energy to heat, it doen’t matter if the cable is at the end open, shortened or connected to a any impedance between 0 and infinity, you will always see a SWR of 1.
    Then ther are other effects when the cable length and properties can provide a trasnformation of the sinks impedance, again a shortened or open end coax cable can show a SWR of 1.
    vy 73
    _.. .._. ….. ._.. _.__

    • KB6

      Thank you
      Yes its extremely more complicated then that I was trying to keep it as simple as possible in layman’s terms
      Maybe they should change it to restricted waves instead of reflected ? LOL or just call it Standing Wave Ratio (SWR)
      funny how people actually think that in some weird way RF gets reflected back into the radio down the coax?
      I’m not sure how a transmitter would even see any RF coming back to it as its transmitting (Transmitters do not receive RF) Now if we are talking about (Spurious Radiation) That’s another topic and would go way beyond the scope of this thread I Keep ( RF choke / Balun) on all my coax cables and that has nothing what so ever to do with SWRs !
      Some people even believe that a antenna tuner somehow changes the antenna length Now that’s crazy ! All it dose is change the impedance to something the transmitter can deal with The antenna is still the same exact length with the same SWRs as before and NO the RF power is not returning to the tuner That’s NONSENSE ! However the transmitter is putting out full power and with modern rigs this is a good thing as they automatically back down power with rising SWRs to protect the finals !

      Anyway…. I just wanted to jump in here to make a quick comment about what Sara said “Reflecting RF back into the Pluto SDR”

      Sorry if I offended anyone That was not my intentions


      Mind blowing thought
      When you shine a flashlight at a mirror dose it reflect back into the flashlight ?
      Think about it dose it really ??? or is it just a illusion ?

  7. Jamie

    No, you are wrong, anytime an rf signal encounters a non-perferct match some power is reflected back. This is the entire point of return loss/vswr measurements. They a measure.ent of the ratio of forward to reverse power and are used as an indication of signal path quality.

    • KB6

      I think you misunderstood me?
      If you watch the video again at 7:37 “the rest of it is being reflected back into the SDR” Now that’s just silly!
      The name ” reflected power” is not correct and is probably one of the most misunderstood term in radio

      When the line and load impedances are identical and the SWR is 1, all of the RF power that reaches a load from a transmission line is utilized by that load. When the load is an antenna, the utilization takes the form of EM-field radiation. If the load is a communications receiver or terminal, the signal power is converted into some other form, such as an audio-visual display. If the impedance of the load is not identical to the impedance of the transmission line, the load does not absorb all the RF power (called forward power) that reaches it. Instead, some of the RF power is sent back toward the signal source when the signal reaches the point where the line is connected to the load. This is known as reflected power or reverse power.
      This sounds confusing ? well don’t feel bad it dose to most people 🙂
      I think the best way to explain this without going into a lot of crazy science

      Take a garden hose and put your thumb on it More pressure and less water coming out the end right ? now think about it Is water somehow getting returned to the supply line ?? Nope !
      Now if you look at my (copyed text) above ” Instead, some of the RF power is sent back toward the signal source when the signal reaches the point where the line is connected to the load”
      This is not exactly true however a SWR meter will read it this way and it sure looks like its doing that right??
      Wrong ! there is no power some how magically bouncing back to the transmitter LOL whats actually happening
      is that the transmitter is seeing something other then lets say a 52 ohm load (mismatch) it would need to get rid of the unwelcome power It dose this by dissipating it as heat A light bulb is a good example of this Is the power being returned to the power company for a brighter bulb ??
      signal source = (coax)
      Load = (Antenna)
      There is nothing going back to the SDR however things are heating up fast !
      Hope this helps 🙂

      • snn47

        Unfortunately you will confuse readers not familiar with the basic ubderstanding, which is why I reply to youe examples.
        The comparissions do not reflect the conditions of a RF-generator connected to a complex transmission line which is terminated by some complex impedance ranging from short to open end:
        – the flashlight scenario is not a transmission line scenario since it lacks the tranmission line, since the light is “radiated” in free space
        – Both the garden water house or power line examples are only influenced by resistance, but do not account for the complex impedance. AC power generator behaves different than a RF-generator since it does not rely on impedance matching of the AC lines, but it has also problems when loaded by complex loads.

        • KB6

          What the ??????????????????
          You say I’m confusing? are you trying to make a point ? Flashlight??? What?? Garden hose? What??
          A holiday hoodie whaty?????

          Lighten up dude maybe take chill pill?????? 🙂

          I’m sure your joking right????
          If so that’s ok i can take a joke ha ha 🙂
          I honestly thought you was serious from your first reply but now i see I’ve been had

          You got me 🙂 thanks ha ha ha 🙂 very funny !

          Take care

          • snn47

            @all A simple introduction/explanation to SWR and refelected power can be found in ARRL publications e.g. Understanding SWR by Example


            @KB6 Jamie already made my point, youre wrong power is reflected at points along a cable where a missmatch occurs. If a very short pulse is inserted into a cable the reflections can be seen/meassured in a fast oscillospe, for long cables the time delay is used to identify the distance to those points on a cable.You don’t need detailed (mathematical) explanations, but you need to stick to facts and not confuse people.

            If you use an example to provide a simplified explanation it should match the conditions.

            • Anonymous

              NONSENSE !
              I don’t need to prove a point here as its just basic science !

              Please do some some research before you try to prove something that you cant with some crazy far out theories
              Your not getting it apparently and it becoming even more obvious your just a troll and normally I would just ignore people like you !

              But I just cant stop laughing about that “flashlight scenario”

              Anyway…. go ahead and try to prove the earth is flat and we didn’t go to the moon and Covid-19 is a hoax and so on and so on………..

              This is ridiculous !

              “What we’ve got here is… failure to communicate. Some men you just can’t reach”

  8. KB6

    “Reflecting RF back into the Pluto SDR” ???
    I love your videos sorry I just had to jump in here as your comment is just plan wrong and I’m sure you would agree with me
    RF Energy dose not magically reflect from the antenna The energy is dissipated as heat at the transmitter finals therefore less energy is transmitted at the antenna “there is no such thing as reflected power” all the power from the antenna is transmitted just less then desired with a poorly matched antenna

    Looking forward to your next video
    Nice job 🙂

  9. mg4yi

    Can someone explain to that :
    [2021-11-] ICAO Address: 5438A0 (ADS-B, non-transponder)
    [2021-11-] Air/Ground: airborne?
    [2021-11-] Geom altitude: 90500 ft
    [2021-11-] CPR type: Airborne
    [2021-11-] CPR odd flag: even
    [2021-11-] CPR latitude: (110505)
    [2021-11-] CPR longitude: (41447)
    [2021-11-] CPR decoding: none
    [2021-11-] NIC-B: 0
    [2021-11-] NACp: 11
    [2021-11-] SIL: 2 (p <= 0.001%, unknown type)

  10. G1RNB

    Interesting device…

    What I hope is that Caribou have concentrated on frequency stability.

    Everything else can be improved by external filters and Amplifiers of various types, you get the idea.

    However, if you wander about the band as your device warms up and cools down, it’s pretty much an unusable toy.

    Interested to follow the development.

    • Truth

      > However, if you wander about the band as your device warms up and cools down, it’s pretty much an unusable toy.

      Where are you getting that from, I looked at the BOM and schematic and I see the total opposite.

      I looked up the BOM and checked what they are using and it is two oscillators: a 0.5 ppm 26MHz TCXO for where it is important on the analogue side of the board and then a 50 ppm 125MHz XTAL for the digital side of the board where it is not going to improve the quality of the signal after it has been captured. As long as it is good enough to meet digital timing requirements it is good enough.

      Analogue side (e.g. Modem with ADC and DAC)
      26 MHz TCXO Oscillators XTAL OSC TCXO 26 MHz Clipped Sinewave 0.5ppm -40C +85C 2.5x2mm, 1.6-3.6V

      Digital side (e.g. FPGA):
      SG-8018CG 125.0000M-TJHSA3
      Standard Clock Oscillators SG-8018CG 125.0000M-TJHPA3: MHZ OSC 1.8V 3.3V +/-50PPM -40C +105C O/E 250TR
      SG-8018CG 125.0000M-TJHPA3

      • G1RNB

        It’s just that I noticed that both the TXCO,s face the CPU of the PI and are near the Caribous FPGA, which I know can get very hot.

        If both of those units are mounted in a airtight case it may be a problem…

        • Truth

          The TCXO will maintain +/-0.5ppm over its entire operating temperature range from -40°C to +85°C, so it should be fine and if the check the position it is basically above the hdmi connector. The crystal oscillator is 125.00 MHz +/-50ppm over its entire operating temperature range from -40°C to +105°C and to be honest when the signal is digital as long as it meets the digital timing requirements all is good. But yes it does appear to be directly over the RPI CPU. The interesting part is the iCE40 LP Series Ultra Low-Power FPGA Family (which at power up uses a peak of 30mA peak at 1.2 volts ~ 36mW) will not generate much heat itself but it is sitting directly over the RPi CPU, but as long as it’s junction temperature is inside the range –55 °C to 125 °C it is all good. So the parts of the circuit that are least effected by temperature have been placed directly over the hottest part of the RPi.

          If any electronics are mounted in an airtight case without cooling there is one long term effect – shorter life time for the hardware (ref: “10°C rule”- from the “Arrhenius equation” is the usual “Every 10°C increase in temperature reduces the life of electronics by half”). The two big enemies of most electronics lasting longer than about 20 years are temperature followed by electrolytic capacitors (They have a useful and a shelf life of ~20 years).

    • Dave H

      The photo shows it mounted on a Pi Zero, but all the Pi models (except the Pi Pico) have the same expansion connector so it should connect to any of them. Any Pi model that can run the software they said is compatible should work.

      • Paddy

        If you click on the crowdsupply link in the article, past half way down on the webpage page is a link to the Datasheet and page 14-15 of that shows the GPIO pins used which is more than 26 so that means that the oldest boards with only 26-pin headers will not work at all. But any with the 40 pin header should all work since the header was standardised.

  11. Thom

    I also am looking at a boat application. A sailboat so slow moving. I see an issue with passive on the move because you are changing direction and dont have a direct point to the transmitter unless you built in a tracking device. I understand WIfi signal range is minimal, however what if we used a mono pulse in the 25-27 mghz range (Citizens Band Radio) in the legal 5 watts or say even up to 100 wats with a linear amplifier?

    • Seasalt

      The reason I chose a 2.4ghz pulse ie Microwave was in my mind the seawater around the boat would absorb the signal and any object on the ocean would reflect the signal.

      I thought that would sort of be a double win and make a cheap radar idea work better.

  12. JTC

    Hi there, I’ve had a V3 RTL-SDR for a couple of years now. Love it! I’ve gotten a lot of use out of it. I was wondering if a V4 RTL-SDR is planned and if so, what improvements will be made to it?

  13. Allan

    Over time, SDR Sharp has become more bloated and difficult to install with each successive
    version. Now Windows 11 is here, on both X86 and ARM based systems and I’ve been trying for several days to get Zadig and SDR Sharp working with my RTL-SDR/820T USB dongle. Everything worked fine in Windows 10 64 bit. The folks at AirSpy need to come up with a COMPLETELY NEW installer that just does everything as far as installing drivers, configuring them, etc. Too many hoops to jump through getting this software to actually WORK, when there are so many other software packages out there that work without all of the fussing and fidgeting around with drivers, having to read tutorials, watch videos, config stuff, etc. All the user should have to do is plug their RTL-SDR into a USB port and run the installer – ONCE. Release an installer that can do this and you WILL sell more product.

  14. Blurryface

    Would love to see this plug-in for SDR++ or SDR#. I don’t see myself using SDRUno EXTIO very often–just not a fan of the interface.

  15. Duncan Thomas

    Are there any other details on the database? I might have a go at reverse engineering the plugin since the code is fairly simple, but an API doc would be easier. Google isn’t finding me anything

  16. Joseph Corrigan

    I am looking to start a project based around a Software Defined Radio device (e.g., Hack RF One) untethered to home base. I want to monitor Cellular signals here in the Northeast USA. If I can get any feedback on what I need to buy that would be great. E.g., the antenna, CPU, software., etc. I have a very portable cheap laptop in the Gateway (GWTC116-2 with an Intel Celeron(R) N4020 CPU at 1.10 GHz with 4GB RAM) at my disposal for a display/CPU but was not sure it will be suitable in processing such high frequency signals? I have watched many videos on the subject and read many blogs which gives me a sense processing cellular signals digitally on SDR devices does not require super fast CPU processing speeds. Is there any advantages in running it on a , e.g., Raspberry Pi, creating a self contained unit with its own display? RE powering it I have an inverter installed in my van where I will be running it from. I have had some trouble running some electronic laden tools (Fein Multi-purpose tool will not run) from my Power Drive 3000W inverter. I was told I should possibly try deep cycle batteries as base power for the inverter vs the standard truck (Ford Van) batteries in order to get cleaner more universally usable power. In short I am looking for a reliable cheap alternative to buying a costly portable spectrum analyzer. The granularity of the signal is not that important (for now), detecting just basic signal strength is fine. My price range is $1000-$1500 for this project. I recently purchased a Hakko FX951-66 soldering station and AmScope SM-4NTP-144 7X-45X to make it seems like I know what I am doing, so if soldering is needed I can give it a try. Thank you to the hacker community here, and elsewhere, for inspiration.

  17. BlurryFace

    I got SDRUno EXTIO to work, but I can’t figure out how to activate plugins. I even downloaded the latest build with community plug-ins. Perhaps this is a limitation of the ExtIO version?

  18. beta-tester

    oh, it is running directly on the PlutoSDR ?! very interesting.
    thank you for the link and information, i’ll give it a try soon.

  19. Tomasz Lemiech

    dumphfdl 1.2.0 released.


    – Noise floor and signal level estimates are now computed and printed in
    message headers.
    – Added –freq-as-squawk option which uses squawk field in the Basestation feed
    to convey HFDL channel frequency on which the position information has been
    – The program can now decode data from I/Q samples piped onto standard input.
    This allows interoperation with I/Q data sources like GNURadio or KiwiSDR.
    – Added `–read-buffer-size` option for setting input buffer size when decoding
    from an I/Q file or from standard input.
    – Slightly better sensitivity.



  20. Keith Taylor

    Well, I made this antenna using the supplied info. It’s great at long distances i.e 2500 kim, but absolute rubbish at ranges around 500 km, with very deep nulls of 25dB or more.

    I’ve spent three weeks playing with it. Some days I get a full pass with only 3 or 4 dB nulls. The next day, it is back with deep nulls, even though I have not changed anything, But there are so many variables that I find it impossible to optimise the performance.

    Time to build a QFH antenna methinks, unless anyone has any ideas of how I can fix this double X.

    • Johnathan

      Go with qhf I took mine down not long after building it and replaced it with one made of copper refrigerant tubing. Don’t use coax IMO. Not very rigid and constantly had to dink with it. The copper one I made is still in service and haven’t touched it since install.

  21. Ed Montaigne

    On my nanovna when you are in menu mode, whatever you touch, it activates the choice below it…not the one you touched. makes it impossible to select the choice on the top of the menu bar

  22. KC1UA

    I’m interested but can’t see myself using it in a mobile environment, and my house is surrounded by trees. That said I do have a 50′ tower for amateur and monitoring antennas. Are there any recommendations for mounting this antenna in such a manner, hardware, etc., and obviously LMR400 or an equivalent low loss cable would be a must. Before I fabricate something myself, looking for any ideas. Thanks.

  23. Nelson

    Hello !
    I purchased this device to be used with my Malahit DSP 2 (original from Russia), but it is not working….
    I cannot contact the seller because I get a error message from the site when I try to send a message.
    Could the seller contact me to tell me what I am doing wrong ?

  24. Dave H

    How sharp is the filtering at the high end of the frequency range? Would this antenna work reasonably well to receive weather ballon radiosondes at 1676 – 1682 MHz?

  25. Richard Riley

    If there’s anyone trying on testing, that was bullseye, you can run tsdrpp after install from the .deb file on the releases page but you probably have to find and install (dpkg -i)


    I normally dont like doing this, but it worked without any hiccups.