Raspberry / Orange Pi not starting


After burning an image to an SD card, the processor does not start.

Solution 1

Very often, it is a weak 5v supply that is the source of this blockage. Change the power supply to a model that provides a little more than 5v (5.1v to 5.3v) and that’s fine.

Solution 2

Twice I had corrupted files on the SD card. You must either:

  • redo the image
  • update/rewrite the sources in the /var/www/html folder via an SSH connection. Do not forget to open the rights on the files.



A bad connection between the Raspberry and the PC can give a choppy transmission with loss of audio signals.


Try switching to wired ethernet. In version 4.5, the size of the input buffer will be increased to 2s max to better absorb these bit rate bursts. This brings delay, but in the event of a good link, the size of the buffer gradually decreases to around 200ms.

Hack RF One or Pluto


Crashes or connection difficulties.

RX or TX led of the Hack RF not on.


There are 2 potential sources of difficulty.

  • A poor quality power supply. Change power supply for your processor and Hack RF. Differences are visible between an output at 5v or rather 5v3.
  • The quality of the USB cable. The flow being important, there can be cuts with badly shielded cables. Try other cables.

Remember to take a look at the “Tools” page to check that all USB devices are visible.

HackRF One and RTL-SDR


HackRF and RTL-SDR conflicts. The HackRF does not transmit. The 2 SDRs using the same drivers, the Raspberry does not know which is the transmitter.


Change the order of the USB ports or preferably put in the TX.js configuration file the last 4 digits of the HackRF serial number.



The Pluto is visible in the list of devices connected via USB, but the TX or RX LED does not turn green.


In the Tools page, do a Pluto Reboot

Try also:
– Unconnect and reconnect the Pluto
– Reboot the Raspberry Pi
– Change the USB cable
– Add a 5V power supply to the Pluto

Frequency-unexpanded Adalm-Pluto

For unmodified Adalm Plutos that cannot go below 325MHz, you need to correct the startup frequency value in GNU Radio which are around 144MHz and put them around 434 MHz. Version Remote SDR 4.5 and below.


The system does not start at the correct frequency in reception and no transmission.


Open GNU-Radio and load the files pluto-rx_sanw_v3.grc and pluto_tx_ssbnbfm_v3.grc. In the properties (right click), put a frequency around 434,000,000 Hz for the following blocks:

Once modified, save the files and generate the executable files in python by pressing the small screen. Close the application and relaunch Remote SDR.

Local Storage

Remote SDR saves your last chosen configurations, such as USB mode, frequency band, audio level etc., in the local storage area of the web browser. This allows you to find the configurations when your system restarts.

Locally stored settings page in browser console (Ctrl+Shift+I)

The web page loads incompletely due to errors, the SDR RX On light does not turn green. This follows an update, changes to the configurationRX.js or configurationTX.js files.

Inconsistent page after loading

Go to the “Tools” page and select “Reset Local Storage in browser” at the bottom of the page. This resets all initial settings and avoids configuration conflicts.

If the “Tools” page does not load correctly, go to the console (Ctrl+Shift+I) and clear all settings under the application/local storage tab.

Please note, following a “Reset Local Storage in Browser”, the “Access Key” key must be returned to the “Settings” page to be able to send. By default, it is equal to ‘1234’ unless there is another value in the /remsdr/AccessKey.txt file.

Cache Memory


The page loads incompletely due to errors, the SDR RX On light does not turn green. This follows an update and cached data of the browser in an old version not compatible with the rest.


It is necessary to force the reloading of all the files by the browser. Press CTL-F5 repeatedly.

19 thoughts on “Troubleshooting”

  1. Hallo Andre:

    I have great problems with my Raspbbery PI 2Gb and Adalm Pluto Plus to get work.
    I have never seen a green RX or TX “LED”.
    When I write the correct IP adress in form, then the screen will “flasch” and the IP adress in “Parameter” will clear automatically. In tools the RX were listed under UDB devices correctly.

    I have tested with LAN connection and:

    WIN7 + Chrome with changed Flags and Firefox
    Linux MINT with Firefox

    Raspi 4B 2 Gb Image 4.4 and 4.5 with:

    Pluto PLUS: Analog Devices, Inc. PlutoSDR (ADALM-PLUTO)
    Realtek Semiconductor Corp. RTL2838 DVB-T
    Dexatek Technology Ltd. DK DVB-T Dongle

    All tested with different USB Wires on USB 2.0 and USB 3.O.

    What’s going wrong here?

    best regards

    73, de OE1NHU

    Apache Server Errors:

    [Thu Nov 18 17:44:21.435836 2021] [mpm_event:notice] [pid 5167:tid 3069936064] AH00489: Apache/2.4.51 (Raspbian) configured — resuming normal operations
    [Thu Nov 18 17:44:21.436310 2021] [core:notice] [pid 5167:tid 3069936064] AH00094: Command line: ‘/usr/sbin/apache2’
    [Thu Nov 18 17:48:48.866212 2021] [mpm_event:notice] [pid 5167:tid 3069936064] AH00492: caught SIGWINCH, shutting down gracefully
    [Thu Nov 18 17:48:48.967744 2021] [mpm_event:notice] [pid 5653:tid 3069239744] AH00489: Apache/2.4.51 (Raspbian) configured — resuming normal operations
    [Thu Nov 18 17:48:48.968244 2021] [core:notice] [pid 5653:tid 3069239744] AH00094: Command line: ‘/usr/sbin/apache2’
    [Thu Nov 18 17:53:20.943948 2021] [mpm_event:notice] [pid 5653:tid 3069239744] AH00492: caught SIGWINCH, shutting down gracefully
    [Thu Nov 18 17:53:31.305453 2021] [mpm_event:notice] [pid 618:tid 3069915584] AH00489: Apache/2.4.51 (Raspbian) configured — resuming normal operations
    [Thu Nov 18 17:53:31.315798 2021] [core:notice] [pid 618:tid 3069915584] AH00094: Command line: ‘/usr/sbin/apache2’
    Traceback (most recent call last):
    Traceback (most recent call last):
    File “/var/www/html/cgi-bin/”, line 23, in
    File “/var/www/html/cgi-bin/”, line 23, in
    s.connect((HOST, PORT))
    s.connect((HOST, PORT))
    ConnectionRefusedError: [Errno 111] Connection refused
    ConnectionRefusedError: [Errno 111] Connection refused
    Traceback (most recent call last):
    File “/var/www/html/cgi-bin/”, line 23, in
    s.connect((HOST, PORT))

    ….. and so on.

    1. Stefan

      Go on the Tools Page

      1) Do you see the Pluto when you « List USB Devices » ?
      2) Is the pluto responding when click on « Pluto Help »?
      3) Reset Local Storage in Browser
      4) Open the browser console Ctrl+Shift I, to see the error messages
      5) Don’t use Firefox. Use only Chrome or Edge

      Hope you do not have the same issue as an other OM last week. One file on the SDcard was corrupted. After reinstalling the source everything was OK.

      If you still have an issue. I can control your PC with the « Remote Assistance » of windows to inspect the Raspberry.


      1. Hallo Andre:

        3) Reset Local Storage in Browser

        Was the correct answer! Now it works fine!

        73, de Stefan OE1NHU

  2. Hallo Andre from Vienna:

    I have seen in the docs that Orange Pi can connect via WLAN.
    Is this on an Raspi also possible? And how?
    Were perfect for working on Fieldday.

    73, de OE1NHU

    1. This is also possible on Raspberry.
      You switch to root:
      sudo su
      then in the terminal you type:
      Go to System menu, you will find the WIFI

      Be careful. If the Audio Signal is not good enough, you will have an audio not fluid.

  3. Hello André,

    first of all: a very big thanks for making this project available to us. I am really impressed by all the work that you have done!

    I have a working QO100 ground station with ADALM Pluto that I use with SDR console in full duplex configuration.
    It consists of a Pluto + GPSDO for TX stability, a 2.4 GHz preamp plus an SG labs PA. Combined with a BullEye LNB and the tracking of the beacons for RX stability this is working fine.
    The Pluto I have is the latest revision with separate clock input so it was easy to add the GPSDO.

    I have setup your latest Raspberry Pi image and I am able to listen to the QO100 downlink via the browser. But I do have an issue with the TX of audio.

    I am wondering if there is a way to get some more insights on the configuration that your software sends to the Pluto for TX. I have the impression something is off there, but I don’t know exactly where to look to troubleshoot it.

    When I connect the TX output of the Pluto to a spectrum analyser, and I select the 70 cm band for TX then I see an output when I enable ‘TX audio’ + 800 Hz tone. The output of the tone is however always on 434.430 MHz, no matter where I set the TX frequency.

    When I select the 23 cm band I see no output at all on the analyser.

    I would appreciate it very much if I could debug this further. Do you have any pointers for me so that I know where to start?

    Thanks a lot,
    Lieven ON8HZ.

    1. Lieven

      This morning, I did the test, connecting a Pluto Old generation Rev:B) on Remote SDR version 4.5. I used simply the 2 small antennas of the Pluto;
      On 70cm and 23cm, it works fine.

      With the Pluto, be careful that you cannot change the TX frequency while you are transmitting. It’s not the case with a Hack RF.

      Open the browser console, Ctrl-Shift I and ave a look on any error messages.
      Do also a reset of the Pluto as proposed in the Tools page.

      If you do not succeed, I can take the control of your PC and have a look.
      I already did that with other OM. We can arrange that in private via Email. at


      1. Hello André,

        thank you for your fast reply.

        I have verified the browser console > no errors are visible there. A reset of the Pluto does not bring any improvement.

        Using the 2 small antennas of the Pluto I don’t get any signal in the spectrum view, not on 70 cm and not on 23 cm. The only thing I can verify if that if I enable TX on 70 cm with the tone generator active I see energy in the spectrum at 434.430 MHz with a spectrum analyser.

        I just reverified that the exact same hardware setup is working as expected with SDR console (full-chain TX+RX via the satellite), so it must be a software detail somewhere.

        I appreciate it very much that you would want to take a look from remote, I will send you an email to arrange the details.

        Kind regards,
        Lieven ON8HZ

        1. The source of the issue is the startup frequency of GNU-Radio around 144MHz not compatible with a non Frequency-extended Pluto. The solution is explained above. Will be modified in Version 5 of Remote SDR.
          André F1ATB

          1. André,

            thanks again for taking the time to look into this together with me. Looking forward to making some QSO’s over QO100 via remote SDR this weekend!

            Lieven ON8HZ

  4. Hello André,

    I recently installed your latest Remote SDR (v.5 and updated it to the newest one yesterday).
    First of all, thank you for this very useful documentation.
    It works with Adalm Pluto, but when I switch to SDRplay RSP2 it doesn’t work.
    The virtual LED on the website tells me the Pilot is green, but the RX LED is red.
    I checked with tools and RSP2 is visible and I have correct communication.
    But the waterfall is not working.
    Can you can fix it or I should buy a broken (worse) version of SDRplay like RSP1 🙂
    RSP2 works with SDRConsole without any problems.
    Thank you
    If it makes any sense, I noticed that in the status bar on the website the tx LED is green and it does not turn off (red) even in the configuration I checked it with Pluto for none.

  5. Hello André
    thank you very much for the great software from Remote SDR.
    Very nice interface and easy to use intuitively.
    Now unfortunately a small problem has occurred. I use a RPI4 (2GB) together with an Adalm Pluto, but it was no transmit operation possible. only if I deactivate the Pluto in the settings under RX configuration, the transmitter is working. now I use as a receiver a RTL stick, but it would be nice if send and receive with the Pluto would be working. Any idea?

    Vy73 de Hermann DB7GV

    1. Hermann
      Remote SDR, installed on a RPI4, works with a Pluto in RX and TX. I have one in front of me working perfectly.
      – Set the access key to 1234
      – Select Pluto in the RX configuration table
      – Select Pluto in the TX configuration cable.

      Now , if it is not working, this is often the case with the Pluto.
      Try the following solutions:
      – In the tools page “Reset the Pluto”
      – Unconnect and reconnect the Pluto
      – Reboot the Raspberry Pi
      – Change the USB cable
      – Add a 5V power supply to the Pluto
      – Work at 432 MHz or higher if you have not modified the frequency range of the Pluto

      It must work.

      Good luck

      Good lu

  6. Dear André
    Thank you very much for your quick reply.
    Meanwhile I could solve my problem. The error is on my ADALM-PLUTO itself.
    With another PLUTO-device the software works UFB.
    VY73 de DB7GV

  7. Dear Andre’,
    I would like to come back to my previous problem with the TX function of Adalm Pluto.
    I have made the tests with two different Pluto. One is Rev.B the other Rev.C borrowed from a friend. With the rev.C RX and TX works UFB. With the Rev.B transmit is only possible if in the RX settings the Pluto is disable, or I use a RTL-Stick as receiver.
    Now I have tested both Pluto with SATSAGEN, and big surprise, full duplex with simultaneous RX and TX works with both Pluto without any problems.
    also when I call the Pluto Info under Tools-remote Sdr, the output is 100% identical for both.
    I use the Remote SDR v5.0 image for Raspberry Pi 4B from your github site.
    Now I am really despairing.
    VY73 de Hermann DB7GV

    1. Go to the Tools page. Click on Look for Updates and update the version to the latest 5.07. In version 5.04, I have corrected a bug on Pluto TX.

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