Posts by SV1BDS


    There are two practical solutions ways.

    One modified LNB with internal TCXO and with external source of 25 MHz.

    At external source you can apply in theory TCXO, but then there in no reason not to put it inside.

    With an OCXO instead of TCXO, you have better stability. With a GPSDO you have also better accuracy.

    The price for the better performance is cost.

    You must define what solution is acceptable for you.


    Every oscillator drifts. So what drift is acceptable for you?

    By the way one that does not drift at all is one that is referenced by a Cesium reference, but I imagine that this is a solution not acceptable economically by you.


    When active in 2.4&5.5 GHz WLan world I have built a software that says with recorded voice the RSSI (S meter), permiting easy antenna alligment. The SDR console programmer seems that does not accept ideas for implementation. I have start implementing one in gnuradio. Is that of general interest?

    Hi George:

    Not problems with work in full-duplex mode. If it is possible, pleaae, send me code for work and paly with it.

    73,s de Jabi, ea2aru.

    Hi Jabi,

    The code is not operational yet, it is still under develpment.

    As soon as I have one, I will publish it here.

    Hi Jabi,

    In order to operate this mode every station partitipating (can be more than two) must have full duplex capability i.e. to be able to hear his own transmission. All the stations use the same frequency USB. In an typical QSO each one pass the microphone to another one. In this mode all can speak together like a telephone call. In order to have same audio level, all must reduce their power to reach the lowest stations level. The produced QSO is without over. Callsigns must announced every some minutes as laws require. There is a habit to try to work as a half duplex but all must overcome this. It is very helpful to interrupt the others if you didn't understand something or you have a phone ringing. It is a more live way of communication similar to a telephone one or a chat one as more than two can participate. The drawback is that you hear your voice. Headphones is mandatory in order not loop voice and also you have to adjust the audio in order not confused from your voice. The drawback is that you hear your own voice but work is in progress to overcome this. I do tests at 950 and also I am QRV at this frequency. Hope all this helps.


    A new algorithm tested on the air which has faster convergence and is less CPU intensive, producing delay calculation within +-10 Hz. BPSK beacon is used for coarse frequency setting.


    Two probes has been built with similar results.

    SWR is under 1.5 up to 12 GHz and less than 3 at 12-16 GHz. Linearity vs frequency is in a ratio of 1:2 max. It can not compared with an IC one but for such a cost is an interesting solution. I use 1206 for 100 ohm and 0805 for 1K and 1n.


    Some notes regarding RF probe:

    The 2*100 ohm alone have less than 1.5 SWR up to 11 GHz. Adding the diode the SWR is affected. A isolation resistance maybe a solution. A second diode providing negative voltage can increase the dynamic range 6 dB more in the lower limit. My thought is that a doubler, as described in application note, stress the second diode at twice the voltage! An op amp circuit has designed to convert symmetrical voltage to half in order to be measured by a microcontroller ATMEGA8 and powered and provide measured voltage to USB serial. Double diode exists in a small extra price.

    27/4/2022 7:Min UTC

    Min: 36 Az: -3.1 Doppler: 1433 Hz Distance : 761926 Km Time: 2.542 sec

    Min: 37 Az: -2.7 Doppler: 1344 Hz Distance : 761924 Km Time: 2.542 sec

    Min: 38 Az: -2.4 Doppler: 1255 Hz Distance : 761922 Km Time: 2.541 sec

    Min: 39 Az: -2.0 Doppler: 1166 Hz Distance : 761919 Km Time: 2.541 sec

    Min: 40 Az: -1.7 Doppler: 1077 Hz Distance : 761918 Km Time: 2.541 sec

    Min: 41 Az: -1.3 Doppler: 988 Hz Distance : 761916 Km Time: 2.541 sec

    Min: 42 Az: -1.0 Doppler: 899 Hz Distance : 761914 Km Time: 2.541 sec

    Min: 43 Az: -0.6 Doppler: 810 Hz Distance : 761913 Km Time: 2.541 sec

    Min: 44 Az: -0.3 Doppler: 720 Hz Distance : 761911 Km Time: 2.541 sec

    Min: 45 Az: 0.1 Doppler: 631 Hz Distance : 761910 Km Time: 2.541 sec

    Min: 46 Az: 0.4 Doppler: 542 Hz Distance : 761909 Km Time: 2.541 sec

    Min: 47 Az: 0.8 Doppler: 452 Hz Distance : 761908 Km Time: 2.541 sec

    Min: 48 Az: 1.1 Doppler: 363 Hz Distance : 761908 Km Time: 2.541 sec

    Min: 49 Az: 1.4 Doppler: 273 Hz Distance : 761907 Km Time: 2.541 sec

    Min: 50 Az: 1.8 Doppler: 184 Hz Distance : 761907 Km Time: 2.541 sec

    Min: 51 Az: 2.1 Doppler: 94 Hz Distance : 761906 Km Time: 2.541 sec

    Min: 52 Az: 2.5 Doppler: 4 Hz Distance : 761906 Km Time: 2.541 sec

    Min: 53 Az: 2.8 Doppler: -84 Hz Distance : 761906 Km Time: 2.541 sec

    Min: 54 Az: 3.2 Doppler: -174 Hz Distance : 761907 Km Time: 2.541 sec

    I will try using homebrew 10 GHz transverter in Rx only.

    A RTL stick will be used for Rx DL0SHF.