Invention Grant
US07671778B2 Digital signal processing scheme for high performance HFC digital return path system with bandwidth conservation
有权
数字信号处理方案,用于具有带宽保护的高性能HFC数字返回路径系统
- Patent Title: Digital signal processing scheme for high performance HFC digital return path system with bandwidth conservation
- Patent Title (中): 数字信号处理方案,用于具有带宽保护的高性能HFC数字返回路径系统
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Application No.: US10465326Application Date: 2003-06-18
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Publication No.: US07671778B2Publication Date: 2010-03-02
- Inventor: Mao Zhu Zhang , Robert L. Howald
- Applicant: Mao Zhu Zhang , Robert L. Howald
- Applicant Address: US PA Horsham
- Assignee: General Instrument Corporation
- Current Assignee: General Instrument Corporation
- Current Assignee Address: US PA Horsham
- Agent Larry T. Cullen
- Main IPC: H03M1/58
- IPC: H03M1/58

Abstract:
In a cable return path system, a method for performing digital companding adds a predetermined offset to the digital value to be companded, and employs a modified μ-law or a-law companding technique to obtain a reduced bit length digital value. One embodiment of this modified approach adds a predetermined offset (e.g., 129 for a 12-bit implementation) to the digital value before companding and then employs a two-bit chord and a 5-bit step for the 12-bit implementation. The end result is that the performance metrics are not significantly compromised by this bit reduction when compared to current transmission methods without this technique.
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