NB Station for Es'hail-2

  • Features of "SAT Controller SDR Nano":

    • Compact stand alone design
    • Internal miniatur speaker
    • LNB/PTT(+/-) supply output
    • Touch operation possible
    • LAN/WLAN/Bluetooth (mouse/keyboard/speaker) on board
    • RX audio muting or damping during transmission
    • Up converter status readout (via RS232/DATA)
    • Synchronize RX/TX frequency on demand (via CAT/ACC)
    • Free SD card image available (like HAMServerPi)
    • ...

    So far at least my first moderate wishes/ideas ;)

  • At the moment everything looks very good. I'm excited.

    As long as the rx signal drifts by a few kHz (see main waterfall), the demodulated audio signal only drifts by a few hertz. And all that with so little effort.

    Only one additional SDR stick and a small software tool is required. All on one raspberry. Not more. Perfect.

    If everything works fine i will create a sd card image for raspberry pi (like HAMServerPi). That makes it a little bit easier.

    Alternatively everyone can create his own solution for other systems by using/modificating the files/sources from sd card image. And makes it better then i can do ;)

  • The described raspberry with touch display works not only as a stand alone SDR receiver for NB downlink, it also takes the drift correction and control the TX chain. First, a Yaesu FT817 transceiver (connection via CAT) and a Kuhne MKU2424 Up converter (connection via RS232) will be used for the uplink.

    So only a mouse click on a free frequency or a CQ call in the waterfall is needed and the TX automatically adjusts to the appropriate uplink frequency. Additionally there are some useful functions/tools planned.

    If the raspberry solution works well in practical operation and the software is more user friendly i will provide a memory card image and a manual / circuit board as soon as possible. But please be a little bit patient. Its only my hobby ;)

  • If the raspberry solution works well in practical operation and the software is more user friendly i will provide a memory card image and a manual / circuit board as soon as possible. But please be a little bit patient. Its only my hobby ;)

    Very interesting solution. You can show CPU performance and I / O Statistics?

  • SAT Controller SDR Nano

    In the last days i have spend some time for optimizing my little raspberry setup. Now the software drift correction also works fine with weak master signals like the lower engineering beacon at 10-12dB S/N.

    The screenshot above shows beacon drift over 1h (main waterfall). During the whole time the demodulated audio output was absolutely constant and without any disturbing drift, clicks, chirps or noise.

    It can be used any stable signal as master for software drift correction. The signal is chosen in the waterfall and used on simple mouse click. That's all. Now there is no drift anymore!

    Remember: The software drift correction cyclic measures the drift of a master signal with a second SDR stick and adjust the LO frequency of the SDR program. So only a standard LNB (PLL recommended) is needed.

    The software drift correction allows very simple and stable station setups without any LNB modifications like TCXO, OCXO or GPSDO etc.

    User interface of “SAT Controller SDR Nano” software

    • RX QRG - Receiver frequency (downlink)
    • RX ERR - Receiver error (drift)
    • TX QRG - Transmitter frequency (uplink)
    • TX ZF - Transmitter ZF frequency
    • Adjust - Choose master signal for drift correction
    • Drift Correction - Switch on/off drift correction
    • RX - Indicates RX or TX operation
    • Tune - Switch on TX for tuning or offset align
    • Auto Tracking - TX frequency will be tuned automatically
    • OK - Indicates status of up converter (SWR, temperature)

    Pictures of “SAT Controller SDR Nano” hardware

    The software drift correction is integrated in the “SAT Controller SDR Nano” device. Based on Raspberry Pi with touch display this is the main part of my Es'hail-2 NB station.

    It handles some useful jobs:

    • Control SDR software (GQRX via TCP interface)
    • Control transmitter (FT817 via CAT interface)
    • Control up converter (MKU2424 via RS232 interface)

    Features of “SAT Controller SDR Nano”

    • Compact stand alone design
    • Touch operation possible
    • Single 12V DC supply
    • Internal miniature speaker
    • Supply output for LNB/PTT
    • USB/LAN/WLAN/Bluetooth
    • Miniature and quiete CPU fan

    Functions of “SAT Controller SDR Nano”

    • Software drift correction (via 2nd SDR stick)
    • RX audio damping or muting during TX
    • Tune function for align TX power/offset
    • Auto tracking of TX frequency (via CAT)
    • Up converter status readout (via RS232)

    Now i am waiting for official opening of Es'hail-2 NB transponder to do some "live" tests and more optimations. I am very exited ;)

  • It really is a nice piece of work!

    When it works well in practice there undoubtedly will be some efforts to make it work with only a single RTL stick and some integration of the drift correction within gqrx or operating in a separate program that receives a copy of the I/Q data.