On Oct 14, 2006, at 3:44 PM, Anthony W. DePrato WA4JQS wrote:
>> No, RTTY is a binary (two state) mode, but it is not digital, any
>> more
>> than CW is.
>
> SNIP
> Bill:
> tell it like it is brother. guess when they lowered the theory to get
> a ticket they just put rtty and cw into that other word so the new
> guys would not get cornfused hi
What hams call "CW mode" is really modulation that uses OOK (on-off
keying) or ICW (interrupted continuous wave) to pass information
through an HF channel. Amateur "RTTY mode" uses FSK as the
modulation process.
In the presence of noise in the HF channel, both of them can be
characterized by such things as bit, character and symbol error rates
(BER, CER, etc). Analog voice modes are characterize somewhat
differently (A-weighted SNR is one example).
So, call them whatever you like. When I write implement the
decoders for them, I treat them as modes that have discrete symbols
and therefore optimize the filters, demodulators and slicers with BER
in mind. Unless people start calling them discrete signaling modes,
I will keep calling them "digital modes."
The channel for CW and RTTY is continuous, but the information being
exchanged is discrete.
73
Chen, W7AY
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