Phase-locked loop

A phase-locked loop or phase lock loop (PLL) is a control system that generates an output signal whose phase is related to the phase of an input signal. While there are several differing types, it is easy to initially visualize as an electronic circuit consisting of a variable frequency oscillator and a phase detector. The oscillator generates a periodic signal. The phase detector compares the phase of that signal with the phase of the input periodic signal and adjusts the oscillator to keep the phases matched. Bringing the output signal back toward the input signal for comparison is called a feedback loop since the output is "fed back" toward the input forming a loop.

Keeping the input and output phase in lock step also implies keeping the input and output frequencies the same. Consequently, in addition to synchronizing signals, a phase-locked loop can track an input frequency, or it can generate a frequency that is a multiple of the input frequency. These properties are used for computer clock synchronization, demodulation, and frequency synthesis.

PLL (disambiguation)

PLL may refer to:

PLL-05

The PLL-05 is a Chinese self-propelled gun-mortar in use by Chinese mechanised infantry formations. Conceptually it is similar to the Russian 2S23 "Nona-SVK" (the turret and weapon system of the 2S9 Nona mounted on a BTR-80 chassis) three of which China purchased for evaluation; at one time it was reported that China would purchase 100 of the Russian vehicles however this failed to occur, nor does it appear that there was a formal transfer of technology to China. The Chinese system features a longer barreled weapon mounted on the Type 92 variant of the WZ551 armored personnel carrier.

The gun-mortar is a lighter and more compact artillery piece than the traditional gun-howitzer at the expense of maximum range, and which has the advantage of better accuracy, higher rate of fire and capability of direct fire in comparison to standard infantry mortars.

Description

The main armament of the PLL-05 is a 120mm gun-mortar in a turret capable of 360° traverse, this turret being mounted on a 6x6 WZ551 armored personnel carrier chassis. The mortar has an elevation range of -4 to +80 and is capable of both direct and indirect fire. It is fitted with a semi-automatic loader and can be fired in fully automatic, semi-automatic and fully manual modes, the maximum rate of fire being around 8-10 rounds per minute, with a sustained rate of fire being about 4-6 rounds per minute. Ammunition capacity is 36 rounds and include indirect fire mortar bombs and direct fire anti-tank rounds, maximum range with standard mortar bombs being about 9km. Secondary armament is a QJC-88 12.7×108mm heavy machine gun mounted on the turret roof. The crew of four consists of the vehicle commander, gunner, loader and driver. Mobility of the PPL-05 is similar to that of that base WZ551 and the vehicle can swim by way of two rear mounted propellers.