> I may be missing something here, but how are the newer rigs generating
> FSK ? Are they shifting xtals or just sideband tones ?
Depending on the design they are using different approaches ... some
are generating audio tones (at a fixed level relative to the carrier
oscillator into the balanced modulator), some are directly shifting
the frequency of the carrier oscillator (a synthesizer, not a crystal)
and one is directly generating the FSK signal using DSP at a low IF.
73,
... Joe, W4TV
On 8/23/2011 6:06 PM, Ed wrote:
> On 08/23/2011 05:53 PM, Larry Gauthier (K8UT) wrote:
>> In theory the transmitted signals are the same.
>> In practice they are often very different.
>>
>> As others have pointed out, many AFSK operators overdrive their mic inputs,
>> or transmit audio tones whose frequency is so low that the second (and third
>> and fourth) harmonics fall within the bandpass of the transmitted sideband
>> signal. The result is broad, splattering signals or signals with multiple
>> spikes beyond the primary RTTY signal. It's not a pretty sight, and the
>> receiving end definitely knows the difference.
>>
>> -larry
>> K8UT
>
> I may be missing something here, but how are the newer rigs generating
> FSK ? Are they shifting xtals or just sideband tones ?
>
> Ed W3NR
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