Release date:2020-06-22
With the increasing call for the construction of a safe city, traditional technology has been difficult to meet the needs of the security market, from analog to digital, from the standard clear to hd to super clear, from video monitoring to cloud monitoring, the security industry big data wave came, smart overwhelming.
I believe you are not unfamiliar, from the beginning of contact with the computer can see this product. It is often mentioned in daily news or newspapers. When there is a car accident, robbery or burglary, the first thing that comes to mind is to check whether there is CCTV recording what happened. The photos will be one of the best pieces of evidence in a lawsuit. Can realize these functions, in fact, by vibration is a tiny semiconductor, crystal vibration has a vital role in the field of security, such as surveillance cameras crystals is one of the most commonly used items in 12 MHZ, his role is the main circuit is to provide a stable clock signal frequency, for control circuit, the effect is very important, it also relates to whether the product to be able to run, especially for the CPU still plays an important role, semiconductor applications in camera to produce stable frequency model to provide accurate signal screen.
Crystal oscillators play a specific role in applications. Clock sources of microcontrollers can be divided into two categories: clock sources based on mechanical resonance devices, such as crystal oscillator and resonant slot; RC (resistance, capacitance) oscillator. One is an oscillator configuration suitable for crystal and ceramic resonator channels. The other is a simple discrete RC oscillator. Oscillators based on crystal and ceramic resonators usually provide high initial accuracy and low temperature coefficients. RC oscillators can and cost less, but are usually less accurate over the entire temperature and operating supply voltage range (accuracy of 5% to 50% of the nominal output frequency). Its performance is affected by environmental conditions and circuit element selection. The component selection and layout of oscillator circuit should be taken seriously. Environmental factors that affect oscillator operation include: mechanical vibration and shock, humidity, and temperature. These factors increase the output frequency, increase instability, and in some cases cause the oscillator to shut down. Using an oscillator module can avoid most of these problems. These modules have built-in oscillators that provide low-resistance square-wave output and are capable of operating under certain conditions. The two most common types are crystal oscillator modules and integrated RC oscillators (silicon oscillators). The crystal oscillator module provides the same precision as the discrete crystal oscillator. The silicon oscillator is more accurate than the vertical RC oscillator and in most cases provides the same precision as the ceramic resonator channel.
In fact, crystal vibration is a combination of passive and active crystal vibration. Passive Crystal Crystal (Crystal), also known as to rely on other internal oscillation circuit chip, passive Crystal Crystal are mainly quartz and two kinds of ceramic, quartz Crystal with high precision, and the active Crystal oscillation circuit, needs electricity to work alone, called active Crystal Oscillator (Oscillator), under normal circumstances, the working state of active crystals will be more stable. In the sound card design, only a few sound CARDS use active crystal vibration. What is the difference between active crystal vibration and passive crystal vibration? Depending on the number of pins, the vibration of active crystals is usually 4, and that of passive crystals is 2.
