| 摘要 |
A radio transmission system of the suppressed carrier type incorporating means for correcting frequency errors. The transmission circuit can include the usual components which first produce a carrier wave, an upper sideband, and a lower sideband. The carrier wave and one of the sidebands are eliminated and only the desired sideband is radiated. The transmitter also incorporates a highly selective circuit which substantially reduces the amplitude of all audio frequencies below about 350 hertz. This frequency characteristic is used as a frequency reference to regenerate the carrier wave in the receiving system. Since low frequencies of 350 hertz are not present in voice waves at all instances, a storage circuit is employed to store a control voltage during the absence of low frequency sounds which would have the identifying frequency step.
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