Modulator utilizing high and low frequency carriers
First Claim
1. A low carrier-leak voice-frequency signal translation circuit which comprises:
- a source of low-frequency carrier signals;
a source of high-frequency carrier signals in which the frequency is very high with respect to that of said low frequency signals;
balanced modulation means responsive to signals from said low-frequency and said high-frequency sources for translating voice-frequency signals to a pre-determined plurality of positions in the frequency spectrum in an output signal thereof with substantially suppressed low frequency carrier; and
,means for selecting a desired one of said frequency spectrum positions in said output signal.
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Accused Products
Abstract
To minimize carrier leak in the modulation of voice frequencies to the desired line frequency for a carrier system, a first balanced modulator is operated at a low frequency where low carrier-leak modulators may be constructed and a second balanced modulator, directly coupled to the first, is employed. The modulation frequency of said second modulator is very high compared to that of said low-frequency modulator. The sideband obtained from the second modulation stage is remote from said high-frequency carrier and a band-pass filter selects the desired sideband and substantially eliminates the high-frequency carrier and the other sideband. Thus, only a low amplitude of carrier leak is present which may cause interference with other channels.
105 Citations
5 Claims
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1. A low carrier-leak voice-frequency signal translation circuit which comprises:
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a source of low-frequency carrier signals; a source of high-frequency carrier signals in which the frequency is very high with respect to that of said low frequency signals; balanced modulation means responsive to signals from said low-frequency and said high-frequency sources for translating voice-frequency signals to a pre-determined plurality of positions in the frequency spectrum in an output signal thereof with substantially suppressed low frequency carrier; and
,means for selecting a desired one of said frequency spectrum positions in said output signal. - View Dependent Claims (2, 3, 4, 5)
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Specification