GPSDO für zwei Frequenzen gleichzeitig zwischen 1-100MHz.

  • Tony and what does the signal from the GPSDO generator at 10GHz look like?
    1) Set the frequency on the GPSDO: 25,780.770MHz
    2) Connect the GPSDO generator signal (25,780.770MHz) to the LNB
    3) Connect the LNB to the QO-100 and to the TRX at 435,000.000MHz
    Will the tone of morse signal be clear (ta ti ti ta)?


    73

    Artur

    hello I have not tried 10ghz but would like the wash on 10g with Arduino nano I can not find any project I do not love programming, but some OM can make serket. to do some tests

    73 ik1hgi Tony

  • Tony and what does the signal from the GPSDO generator at 10GHz look like?
    1) Set the frequency on the GPSDO: 25,780.770MHz
    2) Connect the GPSDO generator signal (25,780.770MHz) to the LNB
    3) Connect the LNB to the QO-100 and to the TRX at 435,000.000MHz
    Will the tone of morse signal be clear (ta ti ti ta)?


    73

    Artur

    I tried this long time ago: Remove the built in 25MHz oscillator from the Si5351 breakout board, feed in 10MHz instead. Program the breakout board to output 24 or 25MHz. Works fine as long the multipliers and dividers are integer. No Jitter on the downlink. Program the board to put out odd frequencies like 25.780.770 results in lots of jitter and multiple signals on the downlink , so is not usable.

  • Hi, I will also follow your project.

    as many allready mentioned is de Si5351 not ideal..

    This was my project 1,5 years ago.

    I never solved this problem.

    If you manage a receiption of the beacon with the si5351 as a LO. please inform me...


    I still have the complete GPSDO with the si chip on shelf, waiting for a better time..


    Benno

  • Hello, i`m building up this project and have been running into a strange behavior of the circuit. My Neo-6 isn`t able to get a fix when being near to the Arduino Nano. When removing the Nano i get the red light for a GPS fix in nearly 15 seconds. The circuit produces the desired output of 25MHz and 40MHz, but without the stabilisaton from the GPS. While running this circuit and bringing another Neo-6M (from a clock project) near the circuit he also looses the fix nearly instantly. My workaround of shielding the Neo-6M and separating him from the board and putting ferrite beads into the feeding lines didn`t really help. The modul is getting a fix after a long time but only for a few seconds and loosing it again. In the period when getting a fix the software didn`t recognize this fact. So trying to rise the input voltage an PIN D2 for the Nano with a logic-level shifter didn`t help also.

    The circuit on my self milled board is checked by another OM and prooven as good. Any suggestions for my problem? Thank you in advance...

  • Hi, nice project. I would suggest shielding the adruino and sis boards..


    Not the GPS..


    The wires between GPS and Arduino normally contain not more than 10 Hz. So adding some 1 nf should be sufficient.


    I would be interested in the project because I've not been able to use a sis due to the noise. But adding dividers may be an solution there.


    And one idea to add is a controllable bias.. 12 volt for vertical and 18 volt for horizontal..


    So you can use the board for datv also..


    Or even better.. 2 bias control systems...


    Best regards.


    Benno

  • The picture in Post #29 shows the gps antenna only a short distance from the circuit. If you use an antenna with long cable, does it work?

    I expirienced a similar behavior, but an antenna outside the window with a long enough cable fixed it for me. I can't reproduce it now, because the circuit no longer exists. I use 2 of those instead, one for 10 and another one for 25MHz. YMMV

    73, Martin


    P.S. : If you want to see what your u-blox is doing, connect it to your pc via USB-UART-TTL adaptor and run u-center software by u-blox. This will show you all you need to know. https://u-center2-updates.u-blox.com/u-center2-installer.exe

    A simple terminal program will show status messages after you connect the u-blox. Some u-blox are fake.

    A wealth of information is here: DL7UKM

    Most of it will not apply for you, but there is a lot of useful stuff also.

  • dm4im


    Thank you for your information. The picture in #29 shows the second attempt to solve the problem with the radiation from the SI5351 by using cables to connect the Neo-6M. My previous version was without any cables between the board and the Neo-6M. I have the strong suspicion that something is disturbing the Neo-6M over the VCC and GND lines. Even when the TX connection isn`t plugged in, the GPS don`t get a fix.

    My intention was to build up a cheap GPSD0 which doesn`t need much space. I recognized in post #1 from DL3ED the PCB which showed all the modules well packed without much space between. So i didn`t thought that there would be any problems with the GPS signal caused by the radiation from the SI5351. Maybe DL3ED kann say something how he solved the problem...

  • Update: running into the next issue


    Removing the SI5351 from the main PCB with some wiring between gave better GPS results ending in an fix, but still not constantly and software running with the remark "waiting for GPS". When turning on the circuit without the SI5351 i constantly get a fix after 30 seconds but the software remains in the state of "waiting for GPS". In case of understanding the Arduino code correctly the remark "waiting for GPS" will disappear when the 1Hz pulse signal is recognized at PIN D2 from the Nano. Measuring the voltage with an oscilloscope it got something about 2.5V. Maybe that will be too low but that`s all i get from the Neo-6M, which will might be a cheap china clone.