帮忙翻译--关于信号发生器的(2)

signal is a generator with the longest measuring instruments， as early as the 1920s when the emerging electronic equipment it has. As the communications and radar technology development， 40 in a major test for a variety of standard receiver signal generator so that the signal generator from the qualitative analysis of the test equipment developed into a quantitative analysis of the measuring instruments. At the same time there also can be used to measure pulse circuit or pulse modulator for the pulse generator. Since the early signal generator mechanical structure more complicated， more power， the circuit is relatively simple， relatively slow pace of development. Until 1964 there was the first all-transistor signal generator.

Since the 1960s， since the signal generator with the rapid development of a function generator， this period of analog signal generator use of electronic technology， by discrete components or analog integrated circuits constituted， the circuit structure complicated and can only have a sine Wave， square wave， sawtooth and triangle wave， and so few simple wave， because the analog circuit drift higher， to the extent of output waveform poor stability， but also pose a simulator of the circuit there is a large size， high prices， power-hungry ， And other shortcomings， and to produce more complex waveforms circuit structure is very complicated. Since the 1970s a microprocessor， the use of microprocessors， ADC and DACs， hardware and software to expand the functions of the signal generator， a more complex waveforms. This time the signal generator and more software-based， is essentially a microprocessor on the DAC program control， you can get all kinds of simple wave. Waveform software control one of the greatest shortcomings of the output waveform frequency is low， mainly by the CPU speed of the work of the decision， if you want to increase the frequency can improve the implementation of its software program to reduce cycle time or increase the CPU clock cycle， but these options are limited The fundamental approach is to improve the hardware circuit.

With modern electronics， computers and signal processing technology， such as the development has greatly promoted the digital technology of electronic measuring instruments in the application of the original analog signal processing gradually being replaced by digital signal processing， thereby expanding the signal processing equipment ， Increase the accuracy of the measurement signal， accuracy and speed of transformation， the analog signal processing to overcome the many shortcomings， digital signal generator then developed.

Signal generator is widely used， the wide variety. First of all， can signal generator at GM and dedicated two categories， the main signal generator dedicated to a particular measurement purposes of development， such as the television signal generator， pulse code signal generator， and so on. This generator is subject to the characteristics of the object measured by the constraints of the request. Secondly， the output waveform signal generator can be divided into sine wave signal generator， pulse-wave signal generator， function generator and arbitrary wave generator， and so on. Once again， according to a frequency of methods can be divided into resonant and synthesis of the two. Traditional use of the resonant signal generator， which uses a frequency selective circuit to generate sine vibration， to obtain the necessary frequency. But can also Synthesis technology to obtain the necessary 9 - rate. Frequency of use of technology into the signal generator， often referred to as synthetic signal generator.