Custom unit definitions for GNU Units

.units.dat

# Custom unit definitions for GNU Units
# http://www.gnu.org/software/units/

# The bel was defined by engineers of Bell Laboratories to describe the
# reduction in audio level over a length of one mile. It was originally
# called the transmission unit (TU) but was renamed around 1923 to honor
# Alexander Graham Bell. The bel proved inconveniently large so the decibel
# has become more common. It is used in various to contexts to report a
# signal's power relative to some reference level.

bel(x)  [1;1] 10^(x);    log(bel)    # Basic bel definition
dB(x)   [1;1] 10^(x/10); 10 log(dB)  # Basic decibel definition
dBW(x)  [1;W] dB(x) W ;  ~dB(dBW/W)  # Reference = 1 W
dBk(x)  [1;W] dB(x) kW ; ~dB(dBk/kW) # Reference = 1 kW
dBf(x)  [1;W] dB(x) fW ; ~dB(dBf/fW) # Reference = 1 fW
dBm(x)  [1;W] dB(x) mW ; ~dB(dBm/mW) # Reference = 1 mW
dBmW(x) [1;W] dBm(x) ;   ~dBm(dBmW)  # Reference = 1 mW

# When used to measure amplitude, voltage, or current the signal is squared
# because power is proportional to the square of these measures.  Usually 
# defined for a root-mean-square measurement.

dBV(x)  [1;V] dB(0.5 x) V ;  ~dB(dBV^2 / V^2)           # Reference = 1 V
dBmV(x) [1;V] dB(0.5 x) mV ; ~dB(dBmV^2 / mV^2)         # Reference = 1 mV
dBuV(x) [1;V] dB(0.5 x) microV ; ~dB(dBuV^2 / microV^2) # Reference = 1 microvolt

# Referenced to the voltage that causes 1 mW dissipation in a 600 ohm load:
dBu(x)  [1;V] dB(0.5 x) sqrt(1 mW * 600 ohm) ; \
                        ~dB(dBu^2/sqrt(1 mW * 600 ohm)^2)
dBv(x)  [1;V] dBu(x) ;   ~dBu(dBv)  # Synonym for dBu

# Commonly used for sound pressure level measurements, reference = 20 uPa:
dBSPL(x) [1;Pa] dB(0.5 x) 20 microPa ; ~dB(dBSPL^2 / (20 microPa)^2)

# Numbers
eleven                  11
twelve                  12
thirteen                13
fourteen                14
fifteen                 15
sixteen                 16
seventeen               17
eighteen                18
nineteen                19

# The actual character is not on my keyboard
u-                      micro

# Unofficial abbreviation
RMB                     CNY

readme.md

Maybe this should be merged into Proposed changes to GNU Units database