[RTTY] The Problem with AFSK ...

[Joe Subich, W4TV]

On 1/19/2013 1:25 PM, Gedking at aol.com wrote:
 > No compression and watch the ALC to much drive is a no no.

Doesn't mean a thing if the level going into the mic jack is
already too high for the microphone preamplifier.  Most rigs
that use dynamic mics (Kenwood, Yaesu, Ten-Tec) will clip in
the mic preamp if they get much more than 10 mV peak.  The
stock dynamic mics are generally 2 to 3 mV.  When they get
hit with the 4V P-P (or more) output of a sound card, the mic
preamps are very good harmonic generators.

73,

    ... Joe, W4TV


On 1/19/2013 1:25 PM, Gedking at aol.com wrote:
> No compression and watch the ALC to much drive is a no no.
> ED
>
>
> In a message dated 1/19/2013 1:21:18 P.M. Eastern Standard Time,
> lists at subich.com writes:
>
>
>>   I think you are confusing technology with operator skill.
>
> No, I'm  viewing the entire "system" ... you're very correct that it's
> relatively  easy to generate a cleaner signal *from the sound card* in
> AFSK but there  are so many more opportunities to screw it up in the
> interfacing and so  many do screw it up.  It only takes a little bit
> of listening to any  of the digital bands/modes to hear all kinds of
> *rotten signals* (with  respects to HPM).
>
> While there is nothing that the sound card developer  can do, FSK is
> done in the transceiver so although the implementations may  not be
> the best, there is very little (perhaps some severe common mode  RF
> feedback) that can be done that will make it worse - unlike  the
> hundreds of improperly adjusted or connected sound cards we hear  on
> a regular basis.
>
> As transceiver makers move sound cards into the  rig, it will be easier
> (perhaps) to generate clean AFSK and other audio  based digital modes.
> However, there is no reason not to expect (and lobby)  those same
> manufacturers to make use of the DSP modulation capabilities in  their
> new rigs to generate equally clean FSK.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 1/19/2013 12:50 PM, Peter Laws  wrote:
>> On Sat, Jan 19, 2013 at 11:00 AM, Joe Subich, W4TV  <lists at subich.com>
> wrote:
>>
>>> This behavior is all to  typical of AFSK signals where the audio is
>>
>>
>> I think you  are confusing technology with operator skill.
>>
>> I have no doubt  that W7AY can put out a cleaner RTTY  signal using
>> AFSK than I  can with my IC746Pro running FSK, but FSK is a LOT harder
>> to screw  up.
>>
>> Any mode that requires that an audio signal be fed to a  transceiver is
>> just begging to be screwed up ... and often is, as  you've just
>> reported!
>>
>> But that's not the fault of AFSK  - that's the fault of the  operator.
>>
>>
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