Cisco GS7000 Installation And Operation Manual page 241

schemes can be represented.
QPSK
quadrature phase-shift keying. A phase modulation technique for representing digital
information. QPSK produces four discrete states, each state representing two bits of
information.
R
RCM
reverse configuration module.
RCVR
receiver.
reverse path
Signal flow direction toward the headend.
RF
radio frequency. The frequency in the portion of the electromagnetic spectrum that is above
the audio frequencies and below the infrared frequencies, used in radio transmission systems.
RFI
radio frequency interference.
RMA
return material authorization. A form used to return products.
RX
receive or receiver.
S
S/N or SNR
signal-to-noise ratio. The ratio, in decibels, of the maximum peak-to-peak voltage of the video
signal, including synchronizing pulse, to the root-mean-square voltage of the noise. Provides
a measure and indication of signal quality.
SA
system amplifier.
Glossary
221