Features of the analog voice
The analog is defined as a signal that has amplitude or frequency continuously and smoothly diverse. What a person says, and everything else you hear, that is in the analog form, and the early telephone systems were analog too. Analog signals are often represented as smooth sine waves, but they express and other signals are more complex than that, since they contain many frequencies. The figure in the analog voice measurement section shows the typical distribution of energy in the voice signals.
The vertical axis is relative energy and the horizontal not horizontal axis is frequency. The figure in the analog voice measurement section shows that speech frequencies that contribute to speech can range from below 100 hertz to over 6000. However, most of the energy required for intelligible language is contained in a frequency band between 200 and 4000.
To eliminate unwanted signals (noise) that may disturb conversations or cause errors in control signals, the circuits that carry the telephone signals are designed to pass only certain frequencies. The frequency ranges are passed that are reputed in the pass band. Zero to 4000 hertz are the pass band of a channel of the VF channel-one of the Voice of the telephone system. (Sometimes this band is called a message channel.) Bandwidth is the difference between the upper limit and the lower limit of the pass band. Therefore, the bandwidth of the VF channel is 4k hertz. However, voice transmission does not require the entire VF channel. They restrict the band of passage of the Voice to 300 to 3300 hertz. Therefore, any signal continued the telephone circuit that is within the range of 300 to 3300 Hz is called an in-band signal. Any signal that is not within the 300 to 3300 Hz bands, but is within the VF channel, is called an out of band signal. All vocal signals are in-band signals. Some some signaling trans-missions are in -band and some are out of band.
The analog is defined as a signal that has amplitude or frequency continuously and smoothly diverse. What a person says, and everything else you hear, that is in the analog form, and the early telephone systems were analog too. Analog signals are often represented as smooth sine waves, but they express and other signals are more complex than that, since they contain many frequencies. The figure in the analog voice measurement section shows the typical distribution of energy in the voice signals.
The vertical axis is relative energy and the horizontal not horizontal axis is frequency. The figure in the analog voice measurement section shows that speech frequencies that contribute to speech can range from below 100 hertz to over 6000. However, most of the energy required for intelligible language is contained in a frequency band between 200 and 4000.
To eliminate unwanted signals (noise) that may disturb conversations or cause errors in control signals, the circuits that carry the telephone signals are designed to pass only certain frequencies. The frequency ranges are passed that are reputed in the pass band. Zero to 4000 hertz are the pass band of a channel of the VF channel-one of the Voice of the telephone system. (Sometimes this band is called a message channel.) Bandwidth is the difference between the upper limit and the lower limit of the pass band. Therefore, the bandwidth of the VF channel is 4k hertz. However, voice transmission does not require the entire VF channel. They restrict the band of passage of the Voice to 300 to 3300 hertz. Therefore, any signal continued the telephone circuit that is within the range of 300 to 3300 Hz is called an in-band signal. Any signal that is not within the 300 to 3300 Hz bands, but is within the VF channel, is called an out of band signal. All vocal signals are in-band signals. Some some signaling trans-missions are in -band and some are out of band.
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