Richard Clark wrote:
On 7 Feb 2005 01:44:10 -0800, wrote:
Come listen for yourself...
????? Volume has nothing to do with this!

You could throw a dead carrier and still
have an idea of how close to full quieting you
are....

Obviously your hearing perception exceeds the characteristics of a
larger part of mankind. This makes any claims for someone ELSE to
listen to the difference even more problematic.

Hearing is the poorest measure second only to "seeing" for one self.
Leave this type of testimonial for the Sunday services.


A good receiver actually gives you
TONS of information. You can hear overmodulation,
sideband "splatter" to adjacent channels,
spurious oscillations on other channels,
dead carrier hum in your signal, the overall
intelligibility of your signal and the audio frequency
response (roughly). No field strength meter can
tell you this information!

Bottom line is, human hearing is
the ultimate destination. It can
be more qualitative that quantity.



Slick

On 07/02/2005 4:52 PM, wrote:
Richard Clark wrote:

On 7 Feb 2005 01:44:10 -0800, wrote:

Come listen for yourself...

????? Volume has nothing to do with this!

You could throw a dead carrier and still
have an idea of how close to full quieting you
are....

Obviously your hearing perception exceeds the characteristics of a
larger part of mankind. This makes any claims for someone ELSE to
listen to the difference even more problematic.

Hearing is the poorest measure second only to "seeing" for one self.
Leave this type of testimonial for the Sunday services.


A good receiver actually gives you
TONS of information. You can hear overmodulation,
sideband "splatter" to adjacent channels,
spurious oscillations on other channels,
dead carrier hum in your signal, the overall
intelligibility of your signal and the audio frequency
response (roughly). No field strength meter can
tell you this information!

Bottom line is, human hearing is
the ultimate destination. It can
be more qualitative that quantity.


However, it is exactly these aspects that make human hearing terrible
for side-by-side comparisons like the one initially described by the OP.

There are plenty examples of double-blind tests that indicate that the
participating observer often makes the worst sort of qualitative judgements.

Human judgement is a useful tool, especially when trying to understand
the hard-to-quantify. However, I find it dubious that anyone has ears
good enough to hear the quality of an audio signal that is the result of
+- 1dB of RF gain presented to the front-end. (This is not to say I
think that the OP only used this method to get his/her results.
Clearly, the OP used some sort of methodology to obtain the +1dB gain
claim. I only suggest that we should be critical of qualitative
results that back up the results we want.)

Results to the contrary from a proper double-blind test backed up by
multiple datasets based on what we /can/ measure would convince me
otherwise.

A better qualitative test would be to simply live with the antenna for a
few weeks, and see what DX one could pull in. Again, totally
unscientific; but this is what average radiopersons (like me, I'm
afraid!) have been doing for decades now.

I look at this sort of thing as an example of the "right tool for the
right job."

clvrmnky wrote:


A good receiver actually gives you
TONS of information. You can hear overmodulation,
sideband "splatter" to adjacent channels,
spurious oscillations on other channels,
dead carrier hum in your signal, the overall
intelligibility of your signal and the audio frequency
response (roughly). No field strength meter can
tell you this information!

Bottom line is, human hearing is
the ultimate destination. It can
be more qualitative that quantity.


However, it is exactly these aspects that make human hearing terrible

for side-by-side comparisons like the one initially described by the
OP.

There are plenty examples of double-blind tests that indicate that
the
participating observer often makes the worst sort of qualitative
judgements.



But any radio broadcaster worth his or her
salt will be able to tell APPROXIMATELY how many
watts a signal is producing (or ERP), especially since
we don't have ionospheric skip in the broadcast
band, all line of sight.



Human judgement is a useful tool, especially when trying to
understand
the hard-to-quantify. However, I find it dubious that anyone has
ears
good enough to hear the quality of an audio signal that is the result
of
+- 1dB of RF gain presented to the front-end.


-1 dB at 100 watts is about 79 watts, so
yeah, most people with a good receiver aren't
going to hear the difference. But some
people very familiar with the signal might
notice the difference.

-2 dB at 100 watts is about 63 watts, which
most people should notice, especially on the
fringe of the service area.

-3 dB is 100 versus 50 watts, and no
**** there's an audible difference!





(This is not to say I
think that the OP only used this method to get his/her results.
Clearly, the OP used some sort of methodology to obtain the +1dB gain

claim. I only suggest that we should be critical of qualitative
results that back up the results we want.)


+1 dB was what our theoretical
difference was, but it may have been more.

Sorry, but we don't have a huge VHF anechoic
chamber, and the proper signal strength meter
to do this properly!





A better qualitative test would be to simply live with the antenna
for a
few weeks, and see what DX one could pull in. Again, totally
unscientific; but this is what average radiopersons (like me, I'm
afraid!) have been doing for decades now.


Like i said, I would love to have a
big VHF anechoic chamber, and place each antenna
on a rotor, and measure every 2 degrees or so,
with the proper uV/meter equipment, but
we don't have the $$ for that. Most people
don't, i don't know anyone who does.

It may be unscientific, but in a certain
way NOT, because you can get field reports from
many people, who all have different receivers,
and different antennas on their cars, etc... so
the results are more of an averaged response.

Bottom line is, is the signal more
intelligible and listenable?


Slick

On 8 Feb 2005 18:49:05 -0800, wrote:

-3 dB is 100 versus 50 watts, and no
**** there's an audible difference!

Only to a piece of toast.

On 8 Feb 2005 18:49:05 -0800, wrote:

+1 dB was what our theoretical
difference was, but it may have been more.


First the average reciever will not see the differnce unless right at
the threshold of detection (MDS). The only place I've seen a 1db
difference that was detectable is in really weak signal systems.
In those systems the 1DB differnce cosses the threshold from just
noise to marginally detectable. Such as EME or my favortie mode
troposcatter.

The average FM broadcast system TX and RX runs at high power because
the average FM rx has limited sensitvity due to the required wide
bandwidth. Those recievers require a much larger signals to hit an
acceptable signal to noise and rarely can differentiate between
a 1db difference.

Sorry, but we don't have a huge VHF anechoic
chamber, and the proper signal strength meter
to do this properly!

Measuring 1db difference does not require all of that. As to a
propper field strength meter, specify a brand. They are not rocket
science and are easy to build. If you really want to see something
attend a Central states VHF society antenna gain test. They usually
hit .1db or better accuracy and have tested Jpoles. The results of
past years are posted at their site.

http://www.csvhfs.org/CSVHFANT.HTML

I'll point you to the 2004 results and specifically to the 144mhz
section where a Jpole entered scored a -2.8db gain compared to
a reference dipole (0db)

These things are easily tested and easy to verify. If your trying
to resolve to bettern than .1DB that may be harder but,
3DB is easy and tends to jump at you.


Allison

wrote:
On 8 Feb 2005 18:49:05 -0800, wrote:

+1 dB was what our theoretical
difference was, but it may have been more.


First the average reciever will not see the differnce unless right at
the threshold of detection (MDS). The only place I've seen a 1db
difference that was detectable is in really weak signal systems.
In those systems the 1DB differnce cosses the threshold from just
noise to marginally detectable. Such as EME or my favortie mode
troposcatter.

The average FM broadcast system TX and RX runs at high power because
the average FM rx has limited sensitvity due to the required wide
bandwidth. Those recievers require a much larger signals to hit an
acceptable signal to noise and rarely can differentiate between
a 1db difference.


Then we agree. Most listeners
will not notice a 1dB difference.




These things are easily tested and easy to verify. If your trying
to resolve to bettern than .1DB that may be harder but,
3DB is easy and tends to jump at you.

3 dB? 100 watts versus 50?

Yeah, I should hope so!



Slick