Topband: Digital mode spurious issues

[Guy Olinger K2AV]

It's really not any different.  The question is whether the levels and
output are engineered clean, and KEPT that way.  That can be done
completely internally to a TRX and maintained.  But when the (audio
baseband) signal is generated external to the radio then all of the issues
of off-level-for-optimum-signal, or distortion supplied to the radio, come
into play, and quite often the issues are unknown or undetected.

The best thing is for all modes to be generated in TX DSP (not baseband),
but that is a journey not sure many transceiver manufacturers are willing
to make. Elecraft does it for some modes in the K3.

73 & HNY
Guy


On Tue, Dec 31, 2013 at 1:08 PM, Richard (Rick) Karlquist <
richard at karlquist.com> wrote:

>
>
> On 12/31/2013 7:13 AM, Tom W8JI wrote:
>
>>
>> Collins got burned by this. They tried running a pure audio tone into
>> the SSB transmitter of the early S line to generate CW. The FCC (back
>>
>
> How is this different than RTTY using the AFSK method?
> In my FT-1000D, if you try to use FSK mode for RTTY it
> turns out that the rig is still running AFSK, using
> an internal audio source.
>
> Rick N6RK
>
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