SAT Controller SDR Nano

  • SAT Controller SDR Nano

    With the "SAT Controller SDR Nano" a simple NB station for QO-100 can be realized. The software image include current Raspberry Pi operating system (Raspbian Stretch with desktop), a preinstalled SDR receiver (GQRX) and a control software.

    Image 1: Block diagram (with additional SDR stick for software drift correction)

    Image 2: Main screen (GQRX and SAT Controller SDR Nano)

    Image 3: Lock to master signal (Es'hail-1 beacon, default setting)

    As transmitter a FT-817 (via USB/TTL converter like CP2102) and a up-converter MKU2424 (via USB/RS232 converter like FTDI) can be connected. PTT input (from the transmitter) and output (to the up-converter) is possible via the handshake lines. For this the up-converter requires an additional transistor. Receive only operation is also supported.

    The image runs at Raspberry Pi 3B+ with the official 7" touch display of the foundation. Other displays/monitors are possible (maybe some adjustments are needed). For the two receivers (GQRX + drift correction) SDR sticks with rtl-sdr support can be used. Myself prefer NooElec NESDR Nano3 with 0.5 ppm TCXO because they fit perfectly to the small Raspberry.

    Some things should be noted before operation:

    1. Lock to master signal

    First, the system must be set to a reference signal (menu item "Lock", right mouse button). This is used to calculate the actual LO frequency and as master signal for the software drift correction. Default setting is beacon of Es'hail-1 (menu item "Master"). With the preset RF frequency you have to adjust the peak in the audio spectrum to 1.5 kHz.

    This process must be repeated occasionally if the LO frequency has drifted too far away. If you have problems, you should experiment with the parameters and possibly restart the program (unfortunately this function is not perfect at the moment).

    2. Adjust beacon frequency

    Fast fine adjustment is possible with a beacon signal in NB passband (button "Adjust"). Default setting is CW beacon of QO-100 transponder (menu item "Beacon"). With the preset RF frequency you have to adjust the peak in the audio spectrum to 1.5 kHz.

    This procedure should be performed before each operation (after a short warm-up phase). Because the SDR software sometimes shows errors of some 100Hz. This often happens when you restart GQRX, change frequency ranges or if you tune via the big frequency indication digits. For tuning it will be better to use the mouse wheel and/or place mouse pointer to desired frequency in the waterfall. The fine adjustment should be checked regularly. In the future hopefully this step can be omitted.

    3. TX offset

    Now the TX offset should be set (menu item "Offsets"). Alternatively, the offset can also be adjusted via a frequency tuning on the SDR or on the transmitter (previously unlock tuning knob) during transmission. For this the "Auto tracking" function have to be activated.

    The remaining functions hopefully are self-explanatory. But please note: The basic functions are given, but there are still errors. Because it's just a quick, stupid and dirty solution (I am only a little hobbyist and not an engineer).

    Important: The respective license terms apply. All the software comes without any warranty and without special support.

    Frank, DL3DCW


  • Maybe your downloaded file is corrupt. Here no problems on different systems and with different ZIP-Tools. I also tested 7-ZIP.

    Same problem on OSx with Keka. Getting an error. But also getting the img file with 1,32GB. How big is the org. img??

  • I had also no problem with download and unzip.

    WinRar-ZIP download 2.147.629 KB

    If the download is finished you will see 2.0/2.0 GB below the filename.

    You must wait until this information below the file is gone.

    I just tested it a second time and it works perfect.

    For unzipping i use a quite new l Winrar

  • SAT Controller SDR Nano - Troubleshooting

    1. Decompressing .zip file fails

    Please use an other unzip tool. Some programs have problems with big file size.

    2. Wrong locale, timezone, keyboard, WiFi settings

    Adjust localisation settings (Preferences/Raspberry Pi Configuration/Localisation).

    3. Warning "Crash detected" at SDR Receiver (GQRX) start

    You can ignore this message. It takes no effect.

    4. Warning "No connection" at SAT Controller start

    Please start SDR Receiver (GQRX) before you start SAT Controller and/or enable remote control interface in GQRX (Tools/remote control).

    5. Value “RX ERR” jumps or frozen

    Switch off “Drift correction” and repeat “Lock” procedure. If this takes no effect restart program and/or reboot raspberry because this function is not perfect at the moment. You also should experiment with the "Master" parameters. The defaults are set to Es'hail-1 beacon because this will work fine in most cases.

    6. Control transmitter (FT-817)

    Via USB/TTL converter (like CP2102) you can control transmitter (FT-817). For this connect RXD/TXD signals crossover and PTT GND output from CAT/ACC socket to DCD input of USB/TTL converter.

    7. Control up-converter (MKU2424)

    Via USB/RS232 converter (like FTDI) you can control up-converter (MKU2424). For this connect RXD/TXD signals crossover and DTR output from USB/RS232 converter via external NPN transistor to PTT input of up-converter.

    8. Transmitter (FT-817) can not be switched on

    Please close "SAT Controller", switch on transmitter (FT-817) and then restart "SAT Controller".

    9. Audio volume during own transmission

    TX audio volume can be set independent from RX audio volume. This is useful for avoid echoes via the transponder. You can adjust TX audio volume via the volume slider during own transmission.

    10. USB sockets occupied

    In some cases all USB sockets may be occupied with SDR sticks and USB converters. Additional mouse and/or keyboard you can also connect via Bluetooth. Then you don't need an external USB Hub.

    11. Operating digimodes

    The easiest way for digimodes is a seperate computer. For RX you can use the audio output from Raspberry and for TX the DATA socket of FT-817. For this connect DATA IN and PTT to the transmitting computer. In the future there will be a solution to operate digimodes directly from the Raspberry.

    12. Touch-only operation

    Touch-only operation will be optimized in the future. At the moment a mouse with mouse wheel is useful. For normal operation no keyboard is required. In some cases you can use the software keyboard (Accessories/Keyboard) or remote control via VNC from a desktop computer.

    Will be continued ... ;)

  • SAT Controller SDR Nano - CAT interface

    For connecting FT-817 (CAT/ACC socket) you can use USB/TTL converter below (CP2102). Very nice: All handshake signals are available. It also works fine as PTT output from a seperate digimode computer. For this only one external diode in series is required to connect DTR signal to PTT input (DATA socket) of FT-817.