On 2006-09-13, Radium wrote:


Easy for you to ask. I doubt any store has the device. And the
equipment required to amplify .00000000001 dB to an audible level would
take up the entire room.


There is no such thing as a .00000000001 dB signal

Whats stops a .00000000001 dB signal from existing?

Nothing, it's just indistinguishable from a 0db signal.

In other words it's about half the amplitide of a 3db signal...

It's a logarythmic scale.

Bye.
Jasen

jasen wrote:

On 2006-09-13, Radium wrote:

Easy for you to ask. I doubt any store has the device. And the
equipment required to amplify .00000000001 dB to an audible level would
take up the entire room.


There is no such thing as a .00000000001 dB signal

Whats stops a .00000000001 dB signal from existing?

Nothing, it's just indistinguishable from a 0db signal.

In other words it's about half the amplitide of a 3db signal...

It's a logarythmic scale.

Bye.
Jasen


No, without a reference, its use is meaningless. He was trying to
use dB for an absolute signal level, not a ratio.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

"Telamon" wrote in message
...
My point was that some otherwise ambiguous dB scales (at least one) have
a
defined absolute basis.

Like Michael stated dB is a logarithmic reference-less ratio value.

So what is acoustic dB?
http://home.new.rr.com/trumpetb/audio/dBexamp.html
SPL, I should say.

There it lies, x dB on the left scale.

Tim

--
Deep Fryer: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

Tim Williams wrote:

"Telamon" wrote in message
...
My point was that some otherwise ambiguous dB scales (at least one) have
a
defined absolute basis.

Like Michael stated dB is a logarithmic reference-less ratio value.

So what is acoustic dB?
http://home.new.rr.com/trumpetb/audio/dBexamp.html
SPL, I should say.

There it lies, x dB on the left scale.


That is a SPL chart with the dB levels referenced to 0 dB SPL =
0.0002 µbar.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Tim Williams wrote:

"Telamon" wrote in message
...
My point was that some otherwise ambiguous dB scales (at least one) have
a
defined absolute basis.

Like Michael stated dB is a logarithmic reference-less ratio value.

So what is acoustic dB?
http://home.new.rr.com/trumpetb/audio/dBexamp.html
SPL, I should say.

There it lies, x dB on the left scale.


Read this Sound Level Meter manual if you want to understand that
chart.

http://rsk.imageg.net/graphics/uc/rsk/Support/ProductManuals/3304050_PM_EN.pdf


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

"Michael A. Terrell" wrote:

That is a SPL chart with the dB levels referenced to 0 dB SPL =
0.0002 µbar.

errrr,,, excuse me ...but....

scratches head trying to see

since when has a fraction of microBar had any effect
on an rf link using any sort of modulation ?

\g\g\g\g (zpk) wrote:

"Michael A. Terrell" wrote:

That is a SPL chart with the dB levels referenced to 0 dB SPL =
0.0002 µbar.

errrr,,, excuse me ...but....
scratches head trying to see
since when has a fraction of microBar had any effect
on an rf link using any sort of modulation ?


ahhh..now i see where uBars come in...

ok..

caryy on.

Brian Reay wrote:
"Mike Gathergood (G4KFK)" wrote in message
oups.com...
Radium wrote:
What is FEC?
Forward Error Correction. Google it :-)


Just to add to Mike's comment, FEC works by send the same message several
times- in simple terms, in the hope that one with get through correctly.

You may want to read up on Viterbi, Sequential, Turbo Product Codes
(TPC) and Low Density Parity Check (LDPC) forms of FEC to see how they
work and see if that statement still holds true!

It's truly amazing how many errors Turbo codes and LDPC codes can
actually correct even with only an additional 5% of error correction
coding on top of the data stream in some cases!