principles and applications of microearthquake networks

230 A p p et I tli,u
VCO: Voltage-controlled oscillator: An electronic component which converts variations in
signal amplitude to variations in frequency relative to a reference frequency. The converted
signal may then be combined with other converted signals by the frequency division
multiplexing technique.
Vector norm: See Norm of a vector.
vhf: Very high frequency. The band of frequencies from 30 to 300 MHz in the radio
spectrum is referred to as the vhf band.
Voice-grade circuit: Circuit for transmitting voice-frequency signals in the frequency band
from 300 to 3000 Hz.
Vp: P-wave velocity, most often given in kdsec.
Vpp: Volts (peak-to-peak), which is the voltage of a sinusoidal electrical signal as measured
from one peak to an adjacent trough.
V,/V,: Ratio of P-wave velocity to S-wave velocity.
V,: S-wave velocity, most often given in kmlsec.
WWSSN: World-Wide Standardized Seismograph Network (see Oliver and Murphy, 1971)
WWV Call letters for a radio station maintained by the National Bureau of Standards. It
transmits a standard time broadcast, which is coded such that Universal Time Coordinated
can be determined by an appropriate receiver. Broadcast frequencies for WWV are
2.5, 5, 10, 20, and 25 mHz.
WWVB: Call letters for a radio station maintained by the National Bureau of Standards. It
transmits a standard time broadcast at 60 kHz, which is coded such that Universal Time
Coordinated can be determined by an appropriate receiver.