terms, a signal at is equivalent to a sine wave signal with a peak amplitude (VPK) of approximately , or any general signal at root mean square (VRMS). A signal at is equivalent to a sine wave signal with a peak amplitude of approximately , or any general signal at approximately 1.228 VRMS. Peak-to-peak (sometimes abbreviated as p-p) amplitude (VPP) refers to the total voltage swing of a signal, which is double the peak amplitude of the signal. For instance, a signal with a peak amplitude of has a of . The line level signal is an alternating current signal without a DC offset, meaning that its voltage varies with respect to signal ground from the peak amplitude (for example ) to the equivalent negative voltage (). Impedances A line driver is typically used to drive line-level analog signal outputs. As cables between line output and line input are generally extremely short compared to the audio signal wavelength in the cable, transmission line effects can be disregarded and impedance matching need not be used. Instead, line level circuits use the impedance bridging principle, in which a low impedance output drives a high impedance input. A typical line out connection has an output impedance from 100 to , with lower values being more common in newer equipment. Line inputs present a much higher impedance, typically or more. The two impedances form a voltage divider with a shunt element that is large relative to the size of the series element, which ensures that little of the signal is shunted to ground and that current requirements are minimized. Most of the voltage asserted by the output appears across the input impedance and almost none of the voltage is dropped across the output. The line input acts similarly to a high impedance voltmeter or oscilloscope input, measuring the voltage asserted by the output while drawing minimal current (and hence minimal power) from the source. The high impedance of the line in the circuit does not load down the output of the source device. These are voltage signals (as opposed to current signals) and it is the signal information (voltage) that is desired, not power to drive a transducer, such as a speaker or antenna. The actual information that is exchanged between the devices is the variance in voltage; it is this alternating voltage signal that conveys the information, making the current irrelevant. Line out