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Calibration of Si570

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  • ulidf5sf2002
    Hello, I use PowerSDR-IQ V1.12.20 SV1EIA and the ATTiny with USBtoI2C adapter. I calibrated the Si570 on 3.6Mc as mentioned in message #44. I got the
    Message 1 of 2 , Oct 8, 2009
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      Hello,
      I use PowerSDR-IQ V1.12.20 SV1EIA and the ATTiny with USBtoI2C adapter.
      I calibrated the Si570 on 3.6Mc as mentioned in message #44.

      I got the following:
      Clock Offset: -86950
      Xtall Hz: 114285000
      IF(Hz): 0
      Divider: 4

      If I change to 28.100,000 on display of PowerSDR I get the frequency 28.104,068

      I get the same if I change Xtall:
      Clock Offset: 0
      Xtall Hz: 114214600
      IF(Hz): 0
      Divider: 4

      What's wrong ?

      Many thanks

      73
      Uli
      DF5SF
    • g8voip
      Hi Uli, If you are using one of Fred PE0FKO s versions of the AVR firmware in your USB to I2C interface, there is a calibration function in the firmware, where
      Message 2 of 2 , Oct 8, 2009
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        Hi Uli,

        If you are using one of Fred PE0FKO's versions of the AVR firmware in your USB to I2C interface, there is a calibration function in the firmware, where you use Winrad and calibrate to a known frequency.

        The correction needed is stored in the AVR firmware and applied automatically for every other SDR program you run the hardware with.

        To use that function correctly, you must leave the default Si570 frequency in each SDR program set to 114.285MHz, and no offset or calibration applied.

        If you make any calibration or offset in PSDR-IQ etc, the frequency the program sends to the AVR firmware will have that correction applied first, then the firmware will apply its own calibration to that, so you will have two correction factors fighting with each other, and that would not work.

        I also notice you have the IF set at 0Hz, certainly for RX purposes it is more usual to set it to 9000Hz, and PSDR runs with a 'pseudo' IF, which offsets any noise and hum at the zero point away from the signal you are listening to. Someone will correct me if the same cannot be used for transmit purposes.

        73, Bob G8VOI

        --- In powersdr-iq@yahoogroups.com, "ulidf5sf2002" <uli@...> wrote:
        >
        > Hello,
        > I use PowerSDR-IQ V1.12.20 SV1EIA and the ATTiny with USBtoI2C adapter.
        > I calibrated the Si570 on 3.6Mc as mentioned in message #44.
        >
        > I got the following:
        > Clock Offset: -86950
        > Xtall Hz: 114285000
        > IF(Hz): 0
        > Divider: 4
        >
        > If I change to 28.100,000 on display of PowerSDR I get the frequency 28.104,068
        >
        > I get the same if I change Xtall:
        > Clock Offset: 0
        > Xtall Hz: 114214600
        > IF(Hz): 0
        > Divider: 4
        >
        > What's wrong ?
        >
        > Many thanks
        >
        > 73
        > Uli
        > DF5SF
        >
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