[CQ-Contest] CW from deep space.

[Bill Coleman]

On 8/6/02 0:51, Guy Olinger, K2AV at k2av at contesting.com wrote:

>What CW or interrupted carrier modes, have going for them from deep
>space, vs. psk31, etc...
>
>Less power consumption transmitting, particularly if one is
>transmitting in packets with self-correction CRC's. Only transmitting
>part of the time. The trick is doing what is necessary to trust the
>zero state.

Guy,

Please name one NASA space mission in the last 40 years that has used 
CW/OOK as a means of information transmission.

The "zero" state is exactly the problem with OOK. That's why it is 
inferior to FSK, PSK or QAM.

Although PSK has a higher duty cycle than OOK, it has a 4 dB advantage in 
the presence of Gaussian noise. One could reduce the power by half (3 dB) 
over an OOK transmitter and still maintain a 1 dB advantage. If the duty 
cycle of an OOK transmitter is 50%, the power consumption would be the 
same, and still the PSK transmitter would have a 1 dB advantage.

OOK doesn't cut the mustard for space communications.




Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901