Oscillator frequency and Modulator Frequency?
时间：04-05
整理：3721RD
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I have doubt,i.e; while using encoder ex:HT12E we use some oscillator........while transmitting it we use some RF module ex:TX433
Q1) does the oscillator in the both encoader and oscillator should same?if same why?if not,why?
Q2)Why we require an ocillator in the encoader ?
Q3) How the modulator and encoader's frequencies & oscillator related ?
Q4) how to selest the frequency of the oscillator,i.e; parameters?
Thank you.
http://en.wikipedia.org/wiki/Shannon...artley_theorem
Q1) does the oscillator in the both encoader and oscillator should same?if same why?if not,why?
Q2)Why we require an ocillator in the encoader ?
Q3) How the modulator and encoader's frequencies & oscillator related ?
Q4) how to selest the frequency of the oscillator,i.e; parameters?
Thank you.
no for sure it isn't the same. the oscillator at the encoder is used as a digital clock and consequently determines the speed of operation of the encoder. modulator and encoader's frequencies aren't really related. The encoder give the baseband data which is modulated by the modulator on a certain carrier (frequency).
For your knowdge:
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Nyquist rate [edit]Main article: Nyquist rate In 1927, Nyquist determined that the number of independent pulses that could be put through a telegraph channel per unit time is limited to twice the bandwidth of the channel. In symbols, where fp is the pulse frequency (in pulses per second) and B is the bandwidth (in hertz). The quantity 2B later came to be called the Nyquist rate, and transmitting at the limiting pulse rate of 2B pulses per second as signalling at the Nyquist rate. Nyquist published his results in 1928 as part of his paper "Certain topics in Telegraph Transmission Theory."