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From: jmorriso@ee.ubc.ca (John Paul Morrison)
Newsgroups: comp.sys.handhelds
Subject: Re: HP48 units bug
Message-ID: <1990Sep25.153857@ee.ubc.ca>
Date: 25 Sep 90 22:38:57 GMT
References: <1990Sep19.024034.15518@mintaka.lcs.mit.edu> <25590059@hpcvra.CV.HP.COM>
Sender: root@fs1.ee.ubc.ca
Reply-To: daveg@ee.ubc.ca
Organization: UBC Electical Engineering VLSI Lab
Lines: 26

Speaking of units, I wonder if the HP48 has support for logarithmic "units"
I don't have a 48, so I really don't know.

What I mean is: can the HP48 work with dB's? When you multiply two
numbers expressed
in dBs, you simply add the two quantities
ie 2 * 2 = 3 dB + 3 dB = 6 dB
but
   1 + 1 = add by POWERS 0 dB and 0 dB = 10log(10**(0/10) + 10**(0/10))
= 3dB (so 0 + 0 = 3 ;-)
There would also be weird things when you considered the original units
and the fact that
your value is in dB. This would be interesting for summing powers of
things in dBm and dBW
that is the power in mW or in Watts. so 1 dBW = 30 dBm.

Just rambling on about effective radiated power...


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