Loading ...
Sorry, an error occurred while loading the content.

100% cpu, and any chance of stereo output

Expand Messages
  • phluffy2002
    Two questions: I ve been using fldigi with sdr-core and jack (and a softrock 6.2tx/rx), using oss2jack and the fldigi OSS mode. No problem, so I thought I d
    Message 1 of 2 , Jun 30, 2008
    • 0 Attachment
      Two questions:

      I've been using fldigi with sdr-core and jack (and a softrock
      6.2tx/rx), using oss2jack and the fldigi OSS mode. No problem, so I
      thought I'd try to simplify, and use portaudio direct to jack. It
      works, however fldigi (2.10.3) takes all the spare CPU (all the
      select() calls return immediately). It didn't do this with OSS. Is
      there some magic I've missed to avoid busy wait?

      Quite separately, I get very odd results trying to get a clean tx
      signal - imagine bpsk at 1KHz center in fldigi, but say +20 KHz in the
      sdr. I can tune out the -20 KHz image fine, but I get two sidebands at
      +- 1KHz around the center frequency, each about -20dB down. I wonder
      if it's because fldigi seems to only generate a mono output, and
      sdr-core wants an I&Q pair. Has anyone tried getting fldigi to emit
      I&Q - I'm happy to dive into the code, but I'd rather not duplicate
      existing work.

      Any ideas welcome - I want to get a Linux tx/rx setup using the
      softrock and open software, as it would help to keep the proper ham
      spirit alive. Happy to share as far as I've got if anyone's interested
      - getting ptt signalling working was fun...

      73s

      G8SQH
    • Stelios Bounanos
      ... You shouldn t have to do anything special, as there is no busy waiting in fldigi s audio backend. Unless there s a weird bug somewhere! I too have used
      Message 2 of 2 , Jul 1, 2008
      • 0 Attachment
        >>>>> On Mon, 30 Jun 2008 23:59:12 -0000, "phluffy2002" <djch-linuxham@...> said:

        > Two questions:
        > I've been using fldigi with sdr-core and jack (and a softrock
        > 6.2tx/rx), using oss2jack and the fldigi OSS mode. No problem, so I
        > thought I'd try to simplify, and use portaudio direct to jack. It
        > works, however fldigi (2.10.3) takes all the spare CPU (all the
        > select() calls return immediately). It didn't do this with OSS. Is
        > there some magic I've missed to avoid busy wait?

        You shouldn't have to do anything special, as there is no busy waiting
        in fldigi's audio backend. Unless there's a weird bug somewhere!

        I too have used fldigi with sdr-core and a softrock (rxtx v6.1). The
        CPU load goes up, but it certainly doesn't reach 100% for a single
        fldigi instance.

        I just tested the latest svn revision of java-sdr with the (upcoming)
        fldigi-3.0 code, and the load only climbed to about 25% on an old 2.8GHz
        Pentium 4. About the same with fldigi-2.10.

        Are you using the latest version of dttsp? Are the jack ports connected
        correctly? Is jackd configured with a reasonable number frames per
        period? Fldigi only uses the left input channel, so you might save some
        cpu cycles by leaving the right channel disconnected.

        > Quite separately, I get very odd results trying to get a clean tx
        > signal - imagine bpsk at 1KHz center in fldigi, but say +20 KHz in the
        > sdr. I can tune out the -20 KHz image fine, but I get two sidebands at
        > +- 1KHz around the center frequency, each about -20dB down. I wonder
        > if it's because fldigi seems to only generate a mono output, and
        > sdr-core wants an I&Q pair. Has anyone tried getting fldigi to emit
        > I&Q - I'm happy to dive into the code, but I'd rather not duplicate
        > existing work.

        Isn't this (I&Q generation) what dttsp is for? IIRC, the sdr-core
        channels are as follows:

        il, ir: i/q input from sound card
        al, ar: accessory (non-i/q) input (mic or fldigi)
        ol, or: non-i/q output (spk or fldigi)
        tl, tr: transmit (i/q) output to sound card

        Fldigi has two output channels, normally both carrying the same signal.
        If you are using the CW QSK or RTTY pseudo-FSK features, that data then
        goes to the right channel. As with the input, you probably want to leave
        the right channel disconnected.


        73,
        Stelios, M0GLD.
      Your message has been successfully submitted and would be delivered to recipients shortly.