In a message dated 11/5/03 7:14:45 AM Eastern Standard Time,
btippett@alum.mit.edu writes:
>>
For sake of argument,
assume my TX bandwidth is set to 1800 Hz. If I am
transmitting my 1500 watts into an 1800 Hz BW, does this
mean I would be 3 dB stronger than someone transmitting
his 1500 watts into a 3600 Hz BW?
<<
Maybe not exactly 3 dB, we are dealing with distribution of the voice
spectrum and power applied to it, but close. Factors like TX passband,
compression
and equalization - tailoring to operators voice for maximum "punch" or
intelligibility and then on the RX side the same chain contributes to the
effective
transfer of voice information.
If the band of frequencies that do not contribute much to the intelligibility
is transmitted, than the power is "wasted" (for DXer or contester wanting to
brake the pileup). Seems that the best range for the average "good" voice is
between 300 to 2100 Hz, that is 6 dB bandwidth of 1800 Hz. 1600 Hz is still
comfortable, but one has to carefully tailor the bandpass and equalization to
take advantage of it and not to chop off valuable part of spectrum and impact
intelligibility. This will also help the other side to maximize the QRM
fighting
and digging out in weak signal situations.
Compression here plays big role. We hear some signals in the contests that
are louder when not talking, huge roar of background fans. Audio is so
distorted
that you have use your DSP and ESP to figure out the callsign. That is
transmitting own QRM rather than concentrating power on transmitting useful
voice
information.
Dave Heil had article on the subject in old Radiosporting about fitting the
microphones to voice and filtering bandwidth.
Yuri, K3BU.us
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