Variable digital automatic gain control in a cordless direct sequence spread spectrum telephone
First Claim
1. In a direct sequence spread spectrum communication link, a digital automatic gain control circuit connected to receive in-phase and quadrature baseband signals that have been converted to digital format, the digital automatic gain control circuit comprising:
- means for generating a discrimination signal from the received in-phase and quadrature baseband digital signals; and
means for multiplying the generated discriminator signal by a first gain constant during signal acquisition and a second different gain constant during signal tracking.
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Accused Products
Abstract
A cordless telephone system connectable to the public switched telephone network having a base station and one or more handsets communicating with the base station by an RF link utility time division duplex direct sequence spread spectrum modulation technique, having a digital variable rate automatic gain control loop. The gain is varied by changing the scale factor for the discriminator output. A high gain scale factor is used during signal acquisition. When the signal has been acquired, a low scale factor is utilized during signal tracking. The controller in the base station and in the handset causes gain use of the different scale factor at the appropriate time.
43 Citations
24 Claims
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1. In a direct sequence spread spectrum communication link, a digital automatic gain control circuit connected to receive in-phase and quadrature baseband signals that have been converted to digital format, the digital automatic gain control circuit comprising:
- means for generating a discrimination signal from the received in-phase and quadrature baseband digital signals; and
means for multiplying the generated discriminator signal by a first gain constant during signal acquisition and a second different gain constant during signal tracking. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- means for generating a discrimination signal from the received in-phase and quadrature baseband digital signals; and
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10. In a direct sequence spread spectrum communication link, a digital automatic gain control circuit connected to receive in-phase and quadrature baseband signals that have been converted to digital format the digital automatic control circuit comprising:
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means for generating a discriminator signal from the received in-phase and quadrature baseband digital signals; and means for multiplying the generated discriminator by a high gain constant during signal acquisition, and by a low gain constant after signal acquisition and during signal tracking. - View Dependent Claims (11, 12)
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13. In a cordless telephone having a base station connectable to a switched telephone network and at least one handset, said base station and handset communicating over a radio frequency link utilizing time division duplex direct sequence spread spectrum modulation, a digital automatic gain control circuit, in said handset and in said base station, each connected to receive the digital in-phase and quadrature baseband signals received over the radiofrequency link, the digital automatic gain control circuit comprising:
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means for generating a discriminator signal from the in-phase and quadrature baseband digital signals; and means for scaling the discriminator signal by a first gain constant during acquisition and a second different gain constant during tracking. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification