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Re: [linuxham] 100% cpu, and any chance of stereo output

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  • 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 1 of 2 , Jul 1, 2008
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      >>>>> 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.

      Stelios, M0GLD.
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