Both signals are generated by the microprocessor,
which has enough troubles doing just one, hence the
programming restriction that only lets you choose one
or the other.
They both modulate the VCO. CTCSS is a continuous
sine-wave, DCS is a continuous binary coded
square-wave with varying positive and negative pulse
widths. IF you could generate both, or feed both to
the VCO, at the same time, you'd end up with a mixing
situation, where you would end up with both
fundamental signals plus the sum and difference. The
CTCSS would interfere with the DCS and vice versa. The
sum and difference would also get into the mix. The
poor microprocessor in the receiver, attempting to
locate, lock on, and recognize/decode the signals
would see a constantly changing input and just say
"fuggedaboudit". Even two discrete decoders would have
problems. However a vibrating reed might have some
luck with the CTCSS, but not much you can do about the
DCS as it always requires some complex electronics or
software algorithm to be decoded.
Nothing says you can't send either signal to the VCO
based on what the receiver is hearing. Just not both
at the same time.
Bob M.
======
--- ku4zs1 <[EMAIL PROTECTED]> wrote:
> Is it possible to run CTCSS and DCS at the same time
> on a
> transmitter? Aside from the fact that most radios
> will not allow you
> to select both at the same time (I will be using an
> outboard DCS
> encoder and the built in CTCSS encoder). I am not
> sure if they are
> capable of both running at the same time. Thanks.
>
>
> Rusty Coleman
> KU4ZS
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