Claims
- 1. A digital attenuator comprising:
- first and second pattern shift circuits;
- means for branching an input compressed PCM signal to each of said pattern shift circuits;
- said first pattern shift circuit having means for shifting the branched input PCM signal to the lower side by a predetermined number of bits from one bit to five bits;
- said second pattern shift circuit having means for shifting the branched input PCM signal to the lower side by a predetermined number of bits, from one bit to five bits, which differ from those in the first pattern shift circuit;
- a first adder for adding the outputs from said pattern shift circuits to provide an attenuated PCM signal; and
- a selector for selecting the input PCM signal when no attenuation control signal is applied to the selector, or selecting the attenuated PCM signal when an attenuation control signal is applied to the selector, as the output signal.
- 2. A digital attenuator comprising:
- first, second and third pattern shift circuits;
- means for branching an input compressed PCM signal to each of said pattern shift circuits;
- said first pattern shift circuit having means for shifting the branched input PCM signal to the lower side by a predetermined number of bits, from one bit to five bits;
- said second pattern shift circuit having means for shifting the branched input PCM signal to the lower side by a predetermined number of bits, from one bit to five bits, which differ from those in the first pattern shift circuit;
- a first adder for adding the outputs from the first and second pattern shift circuits;
- said third pattern shift circuit having means for shifting the branched input PCM signal to the lower side by a predetermined number of bits, from one bit to five bits, which differ from those in the first and second pattern shift circuits;
- a second adder for adding the output of the first adder with the output from the third pattern shift circuit to provide an attenuated PCM signal; and
- a selector for selecting the input PCM signal when no attenuation control signal is applied to the selector, or selecting the attenuated PCM signal when an attenuation control signal is applied to the selector, as the output signal.
Priority Claims (1)
Number |
Date |
Country |
Kind |
48-113109 |
Oct 1973 |
JPX |
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Parent Case Info
This application is a continuation-in-part of co-pending application No. 701,574 filed July 1, 1976, now U.S. Pat. No. 4,115,785, said co-pending application being a continuation of prior co-pending application Ser. No. 507,812, filed Sept. 20, 1974, now U.S. Pat. No. 4,004,140.
US Referenced Citations (6)
Continuations (1)
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Date |
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507812 |
Sep 1974 |
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Continuation in Parts (1)
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Number |
Date |
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701574 |
Jul 1976 |
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