Message-ID: <009001c09166$3f71fae0$7479f5cd@wd4kpd>
From: "David Michael Gaytko" <cn2859@coastalnet.com>
To: rsgb_lf_group@blacksheep.org
Subject: LF: Re: CW-Keying via Soundcard or PC speaker
Date: Thu, 8 Feb 2001 00:29:48 -0000
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good info, but the questions beg to be asked...if audio tones can be used
for afsk on all these digimodes, why not vfsk/dfcw/qrss etc. the audio is
just audio. while i know that there is some small problems with overdriving
the tx and generating spurious tones, why can not vfsk/dfsk use the same
techniques as all the other modes?

i confess i am not a programmer, so dont know about what is involved, but if
one program can do it and not cause problems, then another could also be
made to act the same.

david

-----Original Message-----
From: DL4YHF@aol.com <DL4YHF@aol.com>
To: rsgb_lf_group@blacksheep.org <rsgb_lf_group@blacksheep.org>
Date: Wednesday, February 07, 2001 22:13 GMT
Subject: LF: CW-Keying via Soundcard or PC speaker


>Hello Rik, hello group,
>
>Consider this for 'audio keying' a transmitter to generate CW (morse code
>with
>ON/OFF keying) or DFCW (morse code using AFSK):
>
>As long as you keep the audio frequency higher than half of your
>transmitter's audio bandwith, you will not have problems -whatever waveform
>you are using, because the harmonics of the audio wave would be out of the
TX
>passband. You could even use a square wave (which is the only possibility
for
>the PC speaker).
>
>If you use an audio frequency lower than half of the TX audio bandwith,
your
>signal will be audible on at least TWO frequencies if there is the
slightest
>harmonic distortion. And, on 137kHz, this unwanted emission will most
>certainly be 'out of band'... (made that experience myself a few weeks
ago).
>
>So, if possible, stay above 2kHz, then you don't even need a sine wave.
>
>The problem with Win95 (and later stuff) is, programming the speaker is not
>as easy as under the good ole DOS, because direct access to the hardware
>ports is almost impossible (at least for a 'well behaving' windoze
program).
>
>If necessary, I could include a 'QRSSS' audio keyer in SpecLab, but I guess
>Rik is the 'expert' in this business and I don't want to invent the wheel
>twice.
>
>73's Wolf.
>
>