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US 4,755,994 AGranted
Capacity expander for telephone line
AssigneeRepublic Telcom Systems Corporation
InventorsLester H. Staples, James M. Kresse
Life of this patent
Estimating the term…
Abstract
A private telephone line expander is disclosed which receives two analog voice inputs. Both input signals are digitized, compressed using full period splicing, and converted back to analog for transmission. One is shifted to the upper half of the telephone line bandwidth. The other remains in the lower half. Both are transmitted on the same telephone line. When received both signals are expanded to normal telephone bandwidth and can be connected to two different telephones. DTMF signals are transmitted with each voice transmission.
Claims12
A line expander for a telephone line comprising:
- means for receiving a first analog voice signal;
- means for receiving a second analog voice signal;
- autocorrelation means for determining the pitch periods of said first and second analog voice signals operably coupled to said means for receiving said analog signals;
- voice compression means operably coupled to said autocorrelation means, for compressing said first and second analog voice signals based on their respective pitch periods determined by the autocorrelation means, to form first and second compressed signals having respective bandwidths less than the respective bandwidths of said first and second analog voice signals;
- audio frequency shifting means for shifting the second compressed signal to a frequency band above the first compressed signal;
- and
- means for simultaneously transmitting both compressed voice signals on the same telephone line.
4 more elements
A line expander for a private telephone line comprising:
- receiving means for receiving compressed analog voice signals;
- autocorrelation means, operably coupled to said receiving means, for determining the pitch of the voice signals;
- and
- means operably coupled to said autocorrelation means for expanding the analog voice signals based on the pitch determined by the autocorrelation so that the signals have a bandwidth of normal audio signals,
- said receiving means including means for receiving two or more compressed analog voice signals on the same telephone line.
2 more elements
A line expander for a telephone line comprising:
- receiving means for receiving at least two compressed analog voice signals on the same telephone line;
- filter means, operably coupled to said receiving means, for separating the two compressed voice signals;
- first expansion means, operably coupled to said filter means, for expanding the first compressed voice signal to have a bandwidth of normal audio frequencies;
- audio frequency shifting means, operably coupled to said filter means for shifting the frequency of the second compressed voice signal to base band frequencies;
- second expansion means operably coupled to said audio frequency shifting means for expanding the second voice signal to normal audio frequency;
- and
- first and second phone interface means, respectively coupled to said first and second expansion means, for connecting each of the voice signals to separate telephone lines.
4 more elements
A line expander for a telephone line comprising:
- means for receiving at least one analog voice input;
- autocorrelation means for determining the pitch period of the analog voice input operably coupled to said means for receiving an analog signal;
- voice compression means operably coupled to said autocorrelation means for compressing the analog voice input to form a compressed signal based on the pitch period determined by the autocorrelation means so that the bandwidth of the compressed signal is less than the bandwidth of the analog voice signal;
- means operably coupled to said voice compression means for transmitting the compressed signal,
- said voice compression means including means for splicing successive speech intervals on a variable proportional basis.
2 more elements
A line expander for a telephone line comprising:
- means for receiving at least one analog voice input;
- autocorrelation means for determining the pitch period of the analog voice input operably coupled to said means for receiving an analog signal;
- voice compression means operably coupled to said autocorrelation means, for compressing the analog voice input based on the pitch period determined by the autocorrelation means to form a compressed signal so that the bandwidth of the compressed signal is less than the bandwidth of the analog voice signal;
- transmitting means operably coupled to said voice compression means for transmitting the compressed signal;
- and
- means operably connected to said transmitting means for reducing the frequency of dual tone multiple frequency signals to less than half of the bandwidth of the telephone line.
3 more elements
Dependencies are inferred from the claim text.