[RTTY] RTTY spectrum analysis article

[Joe Subich, W4TV]

Chen,

> If the radio manufacturer did the right things, their noise floor can
> be as low as any external sound card, and probably better

Therein likes the rub.  Some manufacturers are simply summing the
output of their codec with the microphone chain - no switching so
the mic is active at all times!  Unless the user is careful to unplug
the mic (and any external audio hardware) when using the codec, he's
right back into the soup.

Yes, a manufacturer can (hopefully) design the external codec to insure
that it is not possible to overdrive the balanced modulator but again
if he's still using an analog balanced modulator (as many are) one has
issues of carrier balance and carrier placement which effect transmit
quality.

73,

    ... Joe, W4TV