The decibel is a rather ridiculous method to measure rf power. Indeed, the
decibel is designed on the human ear, of all things. While this can be
justified for audio work-its' justification in radio takes a "stretch of
sanity" (akin to "a leap of faith" in religion) to justify.



The large unit is the "Bel", and is a measurement (guess really-although
someones' guess has become standardized and now defined in math) of a sound
increase of twice as loud (twice as loud = "One Bel")-as detected by the
human ear. The Decibel is one-tenth of a Bel (One Decibel = smallest sound
increase which can be detected by the human ear).



In many ways the Bel/Decibel is much like time-they don't really exist.



Warmest regards,

John

On Sat, 21 May 2005 12:29:20 -0700, "John Smith"
wrote:

The decibel is a rather ridiculous method to measure rf power. Indeed, the
decibel is designed on the human ear, of all things. While this can be
justified for audio work-its' justification in radio takes a "stretch of
sanity" (akin to "a leap of faith" in religion) to justify.

So Brett,

Do you watch the Radio with the volume turned down?

73's
Richard Clark, KB7QHC

Richard:

Well, it does need to be turned up a bit...

HEY!!! This knob ain't marked in Bels, how will I know how much to turn it
up... and my hearing is not quite what is was as a child--is the Bel
measurement in "Child Bel", "Adult Bel" or "Senior Bel"--yanno--this all is
quite confusing... is there a Bel Chart I can use to extrapolate from?
frown

Warmest regards,
John

"Richard Clark" wrote in message
...
On Sat, 21 May 2005 12:29:20 -0700, "John Smith"
wrote:

The decibel is a rather ridiculous method to measure rf power. Indeed,
the
decibel is designed on the human ear, of all things. While this can be
justified for audio work-its' justification in radio takes a "stretch of
sanity" (akin to "a leap of faith" in religion) to justify.

So Brett,

Do you watch the Radio with the volume turned down?

73's
Richard Clark, KB7QHC

What would you use?

I'd suggest that the root reason for choosing the name is irrelevant to
its continuing use. If what you say is correct it has obviously been
redefined by those that use it.. One might even call it evolution!

I have always thought it as "relative to". ie 0dBm=1mW for general RF
use. One can define and tune a radio's "levels" using one unit of
measure for all. eg;

+60dBm = 1kW
-117dBm = a pretty good FM receiver
-142dBm = about the limit for voice SSB/good preamp human ear use on 2M
-174dBm = thermal noise on earth at 1Hz bandwidth

These numbers then make path loss calculations predictions easier as
well. One just adds the gains (eg antenna) and subtracts the losses (eg
feedline and path) to get the RX level. The "margin" between that and
the RX level can then be used to make judgements about error rates over
the path.

Please come up with a viable alternative.

Cheers Bob VK2YQA


John Smith wrote:
The decibel is a rather ridiculous method to measure rf power. Indeed, the
decibel is designed on the human ear, of all things. While this can be
justified for audio work-its' justification in radio takes a "stretch of
sanity" (akin to "a leap of faith" in religion) to justify.

I look at it as pretty worthless--mainly followed for historical reasons...
looks important--avoids real world data... I do care about volts/amps/watts
and signal densities though...

I just increased my transmitter power by 10db... how many watts per/cm. is
the near field density power at my antenna now? How many more watts increase
has been affected in the input to the final? ... no way to tell...

I just turned up my volume control knob from "4" to "5" position--how much
of an increase in input power to the audio amp have a affected? How many
watts are now flowing into my speaker? This is just about as useful...

Warmest regards,
John

"Bob Bob" wrote in message
...
What would you use?

I'd suggest that the root reason for choosing the name is irrelevant to
its continuing use. If what you say is correct it has obviously been
redefined by those that use it.. One might even call it evolution!

I have always thought it as "relative to". ie 0dBm=1mW for general RF use.
One can define and tune a radio's "levels" using one unit of measure for
all. eg;

+60dBm = 1kW
-117dBm = a pretty good FM receiver
-142dBm = about the limit for voice SSB/good preamp human ear use on 2M
-174dBm = thermal noise on earth at 1Hz bandwidth

These numbers then make path loss calculations predictions easier as well.
One just adds the gains (eg antenna) and subtracts the losses (eg feedline
and path) to get the RX level. The "margin" between that and the RX level
can then be used to make judgements about error rates over the path.

Please come up with a viable alternative.

Cheers Bob VK2YQA


John Smith wrote:
The decibel is a rather ridiculous method to measure rf power. Indeed,
the decibel is designed on the human ear, of all things. While this can
be justified for audio work-its' justification in radio takes a "stretch
of sanity" (akin to "a leap of faith" in religion) to justify.

On Sat, 21 May 2005 13:09:07 -0700, "John Smith"
wrote:

This knob ain't marked in Bels

Do you stumble on sidewalks that aren't marked in inches?

73's
Richard Clark, KB7QHC

On Sat, 21 May 2005 14:28:23 -0700, "John Smith"
wrote:

I just increased my transmitter power by 10db... how many watts per/cm. is
the near field density power at my antenna now?

Brett,

You are yelling as loud as ever, but you don't know how many watts
per/cm. Doesn't stop you does it? --- back off about 40dB and no one
would notice the difference in irritation. Now THERE'S a mystery!

73's
Richard Clark, KB7QHC

Not if I first convert everything to meters and centimeters... however,
then I must convert them back to get anything useful... however, after much
practice with watts and db's I am quicker!!!!

Warmest regards,
John

"Richard Clark" wrote in message
...
On Sat, 21 May 2005 13:09:07 -0700, "John Smith"
wrote:

This knob ain't marked in Bels

Do you stumble on sidewalks that aren't marked in inches?

73's
Richard Clark, KB7QHC

SCREAMING???? Gees Richard, just hit the volume control by accident--went
up 20+ db before I could get ahold of it and crank it about minus 15 db back
down... however, I guess it does, kinda, matter what watts were set before
the accident... but then who knows now--maybe it doesn't matter...

Warmest regards,
John

"Richard Clark" wrote in message
...
On Sat, 21 May 2005 14:28:23 -0700, "John Smith"
wrote:

I just increased my transmitter power by 10db... how many watts per/cm. is
the near field density power at my antenna now?

Brett,

You are yelling as loud as ever, but you don't know how many watts
per/cm. Doesn't stop you does it? --- back off about 40dB and no one
would notice the difference in irritation. Now THERE'S a mystery!

73's
Richard Clark, KB7QHC