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Re: [linuxham] Re: fldigi and globaltuners

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  • Matt Maguire
    ... - try http://hamspots.net/ this will tell you where stations putting out digital signals have been spotted on the bands - 14.070MHz is a good place for
    Message 1 of 7 , Jun 17, 2011
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      On 18/06/2011, at 5:26 AM, dmccasland wrote:

      > Okay, I tried connecting headphone-out to mic-in and got Fldigi (and LinPSK) to work with Globaltuners -- great!
      > I tuned to the bands set designated for data and CW. I could see various things like Morse code and what sounded like PSK31 and RTTY in the waterfall display. I clicked on the waterfall signals with the mouse. Tried various settings like CW (for Morse code) and different PSK and RTTY selections. Only once or twice did it actually decode (once with Morse and another with RTTY, I think). I saw some CQs and call signs. But all I got was random text most of the time (or none). This was mostly at about 0500 UTC with receivers chosen from various locations (USA west, central, east), Hong Kong, and others.
      > Any suggestions about how I could get more signals to decode?
      - try http://hamspots.net/
      this will tell you where stations putting out digital signals have been spotted on the bands
      - 14.070MHz is a good place for PSK31
      - http://hflink.com/olivia/ has some suggestions for Olivia
      - check out the band plan for your country/region (didn't see a callsign in your mail, so not sure where you are based)

      > Another question -- the waterfall display, is that the frequency domain such that zero starts at the receiver's tuned frequency? And thus 2KHz in the waterfall is actually the rcvr frequency + 2KHz?

      This is true if you have your rig on USB (which should be the case for all bands). If you put your rig on LSB, then as you go to the right on your waterfall, you are going *down* from the VFO dial frequency, and a 2kHz audio tone from the radio will represent a signal at (dial_frequency - 2kHz).

      > If so, then does the signal visually displayed at 2KHz have an audio frequency of 2KHz that I hear from the PC speakers?

      Exactly, you get the idea.

      > When I click on that signal in the waterfall, is the software (eg FLdigi) decoding at that frequency and ignoring the other signals that may be present at different nearby frequencies?

      Yes, the decoders filter out the parts of the spectrum that are not interesting.

      > When I hear Morse code, should I always use the CW setting in the rcvr?

      Generally no, use USB. The reason? The USB filter in your radio is generally wider than the CW filter, and so you will be able to see more of the spectrum using USB. Resons you may want to use CW mode:
      - you have strong nearby signals that are activating the AGC in your receiver, which make it difficult to decode your signal of interest. The CW filters may allow you to place the strong signal outside your receiver's passband.
      - if you want to transmit CW, you have a couple of options. The normal case is that the software plays an audio tone into your tranceiver set on USB. However, in some cases you may want the software to key the transmitter while in CW mode. This second option will tend to limit the maximum speed of the CW you can send compared to the first option.

      > And I should always have USB/LSB set above/below 9MHz, unless I want to hear a known AM signal, like a broadcast station ?

      For digi-modes, generally use USB on all bands, even below 9MHz. Many modes will work regardless of USB or LSB, but some such as MPSK16 require USB (ie. they lack the required symmetry)

      > PS I am buying a radio signal book to (re-)learn all this stuff!

      Excellent idea, learning new things is always fun. Enjoy!

      73 de Matt VK2ACL
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