Posts by SV1BDS

  • Voice Rx level sensitivity testing

    Quote from PA1EJO

    Results of the ZRO beacon test, I submitted 18 but want to remark that not all pulses are sent at a predictable strength, for a next test maybe try a 1000 tone and ask people how many tones they heard?

    Hi Ernst,

    You are my mind ! The WAV files have been normalized but I have thought that a more accurate test will be to say the level and then a tone or CW Vs for example is transmitted. Update: for award some unknown ham radio words can be transmitted for example.

  • Voice Rx level sensitivity testing

    Hi,


    In order to measure each user, its Rx sensitivity, without any instruments, numbers is transmitted as voice from 0 to 30, each one with a variable attenuation equal to the number transmitted. So a bigger number possible to be read, is mean a more sensitive Rx system exists.

    The test is to be transmitted at Sunday 27/6/21 from 05:00-17:00 UTC at 10.489.940. It consists from a Voice ID and 0-30 level transmission in 3 dB steps, repeated 3 times and then a final voice ID is to be send. Each sequence will start every 10 minutes and holds about 2:25 minutes.


    A vote exists to compare the results.

  • Voice Rx level sensitivity testing

    Hi,

    A common QO100 NB user question is: what my Rx sensitivity? What is the minimum signal I can receive? This is not always easy to be measured. This need has to cover this test.

    The approach is to transmit numbers as voice 0 to 30, each one with a variable attenuation equal to the number transmitted. So a bigger number possible to be read, is mean a more sensitive Rx system exists.

    Also every one is happy with its system. But it could be very useful for all of us to compare our Rx sensitivity with others. So a Vote will be opened to get relative results.

    The test is planned to be transmitted at Sunday 27/6/21 from 05:00-17:00 UTC at 10.489.940. It consists from a Voice ID and 0-30 level transmissions (update) in 3 dB steps, repeated 3 times and then a final voice ID is to be send. Each sequence will start every 10 minutes and holds about (update) 2:25 minutes.

  • Voice Rx level sensitivity testing

    DB2OS is there any objection to operate the voice beacon at 27/6 from 5:00 UTC to 17:00 for example and open a vote that users can enter the maximum number entered, in order to have a comparison of received sensitivity? Each Tx holds 1-2 min. Repetition details can determined. If this service is to be included in the QO100 services any personal help is available.

  • Voice Rx level sensitivity testing

    Hi,

    A user service for the NB seems feasible to be done that will transmit audio files that will contain the Tx dB level (if calibrated can be how dB is down from the beacons ). This will be useful for someone to test his Rx sensitivity. A similar approach has been discussed before using CW. It can be implemented using GNURadio.

  • First QO 100 test tx

    Hi,

    I am not absolutely sure about your point.

    So I will try. I believe that QO100 gives new ways of consindering ham radio communication. In early ham radio HF days Tx and Rx rigs was separated. This is similar to having a separate uplink and downlink in QO100. But it is operational. Later HF transceivers had large VFO drifting relative to modern ones. But stable design permits now narow data modes. The most HF operators here compare QO100 to a VHF repeater. My point is there a nice bird in the sky. We use it just as a SSB repeater? Ham radio is just a free channel? Now a child can communicate with his phone along the world. What is our added value to today communication world community? A few Hertz's in stability? We have a gift in the sky. How we use it to give back to world community that gives us the frequencies?

  • First QO 100 test tx

    Quote from 2E0ILY

    If I tune to 10.489749895 I am dead on the middle beacon. So what's that 105 Hz off? All told, is that considered OK for a GPS locked LNB and Pluto? I really don't know what to expect if I am honest....

    Yes it seems similar to mine measurements.

  • First QO 100 test tx

    Hi,

    The method I use is to measure the frequency offset that provides the Costas Loop Block of GNURADIO. But it needs proper scailing in order to measure Hz. I can measure at the same time the 750 QPSK beacon and if I want I can Tx at a free frequency and measure also mine. I Tx also BPSK similar to 750 signal but with random data. The values are compared to Doppler calculations. In previous tests Doppler calculations was outside GNURADIO. Now can included in it if desired.

  • First QO 100 test tx

    2E0ILY How many Hz is away the beacons? From my measurements a range of 30 Hz is due to Doppler effect and a few decades Hz may be exists due to QO100 Lo accuracy. Totally about 100 Hz max is observed recently. If your reception is more maybe LNB is not locked.

  • Where can I buy a TCXO

    In order to have as good accuracy as possible, a R trimmer must be used to set it exactly at 10 MHz. The R trimmer must be a multi turn one and be powered from a very good (without noise) source that provides 4-5 V. I want to make such a no GPSDO module and I plan to use an existing 4.096 V reference.