Communication signal compression system and method

• US 5,072,308 A
• Filed: 11/26/1990
• Issued: 12/10/1991
• Est. Priority Date: 06/21/1989
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: International Mobile Machines Corporation (InterDigital, Inc.)
• Inventors: Lin, Daniel, McCarthy, Brian M., Kurtz, Scott D., Kresse, James M.
• Primary Examiner(s): COLES, EDWARD L
• Application Number:
  US07/617,789
• Time in Patent Office: 379 Days
• Field of Search: 358/426, 358/428, 358/429, 358/433, 382/56, 341/51, 375/122
• US Class Current: 358/426.02
• CPC Class Codes: B60R 15/00 Arrangements or adaptations of sanitation devices
• CPC Class Codes: H04B 1/66 for reducing bandwidth of signals; for improving efficiency of transmission H04B1/68 takes precedence
• CPC Class Codes: H04N 1/41 Bandwidth or redundancy reduction by scanning H04N1/17 ; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00

Abstract

A telecommunication system and method for communicating communication signals between various stations over a selected carrier medium. An improved encoder and method is provided for compressing a communication signal into a selectively formatted encoded signal to facilitate its transmission over the selected carrier medium. The method is particularly useful for encoding fax and modem data signals which do not exhibit the harmonics of a voice signal. A decoder and method for reconstruction of the encoded signal are also provided.

Claims

1. In a telecommunication system for communicating communication signals between various locations over a selected carrier medium wherein the communication signal is compressed to facilitate its transmission over the selected carrier medium and the communication signal is reconstructed after reception, an improved ending method comprising:

transforming the communication signal into two separate components including;

determining the approximate center frequency Ω

of the communication signal,

mixing the communication signal with a selected mixing function of Ω

t to product an in-phase component, and

mixing the communication signal with a selected mixing function of Ω

t to produce a quadrature component; and

quantizing the separated signal components thereby encoding the signal components into quantized signals to produce a compressed encoded signal for transmission over the selected carrier medium of the communication system.

2. An enclosing method according o claim 1 further comprising:

filtering each of the in-phase and quadrature components prior to quantizing to remove from each component'"'"'s frequency domain all frequencies above a selected level.

3. An encoding method according to claim 2 further comprising:

decimate the respective filtered in-phase and quadrature components by a selected factor Prior to quantizing.

4. An encoding method according to claim 3 further comprising:

interpolating the communication signal by a selected factor M'"'"' prior to mixing the communication signal to produce respective in-phase and quadrature components.

5. An encoding method according to claim 4 wherein:

the approximate center frequency Ω

of the communication signal is determined by determining the type of communication signal and assigning a preselected value to Ω

based upon the type of signal.

6. In a telecommunication system for communicating communication signals between various locations over a selected carrier medium wherein the communications signal is compressed into a selectively formated encoded signal comprised of quantized in-phase and quadrature signals to facilitate its transmission one the selected carrier medium and the communication signal is reconstructed after reception, an improved decoding method comprising:

separating the quantized in-phase and quadrature signals of a compressed encoded signal received over the selected carrier medium o the communication system;

determining the approximate center frequency Ω

of the communication signal being decoded;

reconstructing the respective in-phase and quadrature signals by quantized decoding;

mixing the reconstructed in-phase signal with a selected mixing function of Ω

t;

mixing the reconstructed quadrature signal with a selected mixing function of Ω

t; and

combining the two mixed, reconstructed signals to reproduce the decoded, decompressed communication signal.

7. In a telecommunication system for communicating communication signals between various locations over a selected carrier medium wherein the communication signal is compressed to facilitate its transmission over the selected carrier medium and the communication signal is reconstructed after reception, an improved communication method comprising:

transforming the communication signal into two separate components including;

determining the approximate center frequency Ω

of the communication signal,

mixing the communication signal with a selected mixing function of Ω

t to produce an in-phase component, and

mixing the communication signal with a selected mixing function of Ω

t to produce a quadrature component;

quantizing each separated signal component to produce a compressed encoded signal

transmitting the compressed encoded signal over the selected carrier medium o the communication system;

separating the quantized in-phase and quadrature signals of the compressed encoded signal received over the selected carrier medium of the communication system;

reconstructing the respective in-phase and quadrature signals by quantized decoding;

mixing the reconstructed in-phase signal with a selected mixing function of Ω

t;

mixing the reconstructed quadrature signal with a selected mixing function of Ω

t; and

combining the two mixed, reconstructed signals to reproduce the decoded, decompressed communication signal.

8. A method according o claim 7 further comprising:

filtering each of the in-phase and quadrature components prior to quantizing to remove from each component'"'"'s frequency domain all frequencies above a selected level; and

filtering each of the mixed, reconstructed signals prior to summing to remove from each component'"'"'s frequency domain all frequencies above said selected filtering level.

9. A method according to claim 8 further comprising:

decimating the respective filed in-phase and quadrature components by a selected factor M prior to quantizing; and

interpolating the reconstructed in-phase and quadrature signals by M prior to mixing.

10. A method according to claim 9 further comprising:

interpolate the communication signal by a selected factor M'"'"' prior to mixing the communication signal to produce respective in-phase and quadrature components; and

decimating the respective mixed and filtered reconstructed in-phase and quadrature signals by M'"'"' prior to summing.

11. A method according to claim 10 wherein:

the approximate center frequency Ω

of the communication signal is determined by determining the type of communication signal and assigning a preselected value to Ω

based upon the type of signal.

12. A signal compression encoder or a telecommunication system for communicating communication signals between various locations over a selected carrier medium wherein the communications signal is compressed to facilitate its transmission over the selected carrier medium and the communication signal is reconstructed after reception, the encoder comprising:

means for transforming a communication signal into two separate components including;

means for determining the approximate center frequency Ω

of the communications signal,

means for mixing the communication signal with a selected mixing function of Ω

t to produce an in-phase component, and

means for mixing the communication signal with a selected mixing function of Ω

t to produce a quadrature component;

means for quantizing each separated signal component into a selected number of levels thereby encoding the signal components into quantized signals; and

formatting means or formatting the quantized signals to thereby produce a compressed encoded signal for transmission over the selected carrier medium o the communication system.

13. An encoder according to claim 12 further comprising:

means for filtering each of the in-phase and quadrature components prior to quantizing to remove from each component'"'"'s frequency domain all frequencies above a selected level.

14. An encoder according to claim 13 further comprising:

means or decimating the respective filtered in-phase and quadrature components by a selected factor M prior to quantizing.

15. An encoder according to claim 14 further comprising:

means for interpolating the communication signal by a selected factor M'"'"' prior to mixing the communication signal to produce respective in-phase and quadrature components.

16. An encoder according to claim 156 wherein:

said means for determining the approximate center frequency Ω

of the communication signal determines the type of communication signal and assigns preselected values to Ω

, M, M'"'"', the level of filtering and the number of quantization levels based upon the type of signal.

17. A signal decompression decoder for a telecommunication system for communicating communications signals between various locations over a selected carrier medium wherein the communication signal is compressed into a selectively formatted encoded signal comprised of quantized in-phase and quadrature signals to facilitate its transmission over the selected carrier medium and the communication signal is reconstructed after reception, the decoder comprising:

format decoding means for separating the quantized in-phase and quadrature signals of a compressed encoded signal received over the selected carrier medium o the communication system;

means for determining the approximate center frequency Ω

of the communication signal being decoded;

quantized decoding means for reconstructing the respective in-phase and quadrature signals;

means for mixing the reconstructed in-phase signal with a selected mixing function of Ω

t;

means for mixing the reconstructed quadrature signal with a selected mixing function of Ω

t; and

means for combining the two mixed, reconstructed signals to reproduce the decoded, decompressed communication signal.

18. A decoder according to claim 17 wherein:

said means for determining the approximate center frequency Ω

of the communication signal determines the type of communication signal and assigns a preselected value to Ω

based upon the type of signal.

19. A communication station of a telecommunication system for communicating communication signals between various stations over a selected carrier medium wherein the communication signal is compressed into a selectively formatted encoded signal to facilitate its transmission over the selected carrier medium and the communication signal is reconstructed after reception, the communication station comprising:

at least one signal compression encoder including;

means for transforming a communication signal into two separate components including;

means or determining the approximate center frequency Ω

of the communication signal,

means or mixing the communication signal with a selected mixing function of Ω

t to produce an in-phase component, and

means for mixing the communication signal with a selected mixing function of -106 t to produce a quadrature component;

means for quantizing each separated signal component into a selected number of levels thereby encoding the signal components into quantized signals;

formatting means for formatting the quantized signals to thereby produce a compressed encoded signal for transmission over the selected carrier medium of the communication system; and

at least one signal decompression decoder including;

format decoding means for separating the quantized in-phase and quadrature signal of a compressed encoded signal received over the selected carrier medium of the communication system;

means for determining the approximate center frequency Ω

'"'"' of the communication signal being decoded;

quantized decoding means or reconstructing the respective in-phase and quadrature signals in accordance a selected number of quantization levels;

means or mixing the reconstructed in-phase signal with a selected mixing function of Ω

'"'"'t;

means for mixing the reconstructed quadrature signal with as elected mixing function of Ω

'"'"'t; and

means for combining the two mixed, reconstructed signals to reproduce the decoded, decompressed communication signal.

20. A plurality of communication stations according to claim 19 comprising a telecommunication system wherein one of said stations is a base station.

21. A communication station according to claim 19 wherein:

said at least on signal compression encoder further comprises means of filtering each of the in-phase and quadrature components prior to quantizing to remove from each component'"'"'s frequency domain all frequencies above a selected level; and

said at least one signal compression decoder further comprises means or filtering each of the mixed, reconstructed signals prior to summing to remove from each component'"'"'s frequency domain all frequencies above a selected filtering level.

22. A communication station according to claim 21 wherein:

said at least one signal compression encoder further comprises means for decimating the respective filtered in-phase and quadrature components by a selected factor M prior to quantizing; and

said at least on signal compression encoder further comprises means for interpolate the reconstructed in-phase and quadrature signal by a m prior to mixing.

23. A communication station according o claim 22 wherein:

said at least one signal compression encoder further comprises means or interpolating the communications signal by a selected factor M'"'"' prior to mixing the communication signal to produce respective in-phase and quadrature components; and

said at least one signal compression decoder further comprises means for decimating the respective mixed and filtered reconstructed in-phase and quadrature signals by m'"'"' prior to summing.

24. A communication station according o claim 23 wherein:

said at least one encoder'"'"'s means or determining the approximate center frequency Ω

o the communication signal determines the type o communications signal and assigns persecuted values to Ω

, M, M'"'"', the level of filtering and the number of quantization levels based upon the type of signal; and

said at least one decoder'"'"'s means for determining the approximate center frequency Ω

of the communications signal determines the type of communications signal and assigns preselected values to Ω

'"'"', m, m'"'"', the level of filtering and the number of quantization levels based upon the type of signal.

25. A communications station for a telecommunication system for communicating communication signals between various stations over as elected carrier medium wherein the communications signal si compressed into a selectively formatted encoded signal o facilitate its transmission over the selected carrier medium and the communication signal is reconstructed after reception, the communication station comprising:

a plurality of signal compression encoders and signal decompression decoders for encoding and eroding a selected type of signal;

means for selecting one of said encoders for processing a signal to be transmitted in accordance with the signal type;

means for selecting one of said decoders for processing a received signal in accordance with the signal type;

at least one of said signal compression encoders including;

means for transforming a communication signal into two separate components including;

means for mixing the communication signal with a selected mixing function of Ω

t to produce an in-phase component where Ω

is a preselected value, and

means for mixing the communication signal with a selected mixing function of Ω

t to produce a quadrature component;

mean for quantizing each separated signal component into a selected number of levels thereby encoding the signal components into quantized signals;

formatting means for formatting the quantized signals to thereby produce a compressed encoded signal for transmission over the selected carrier medium of the communication system; and

at least one of said signal decompression decoders including;

format decoding mean for separating the quantized in-phase and quadrature signals of a compressed encoded signal received over the sleeted carrier medium of the communication system;

quantized decoding means of for reconstructing the respective in-phase and quadrature signals in accordance with the gain component and a selected number of quantization levels;

means for mixing the reconstructed in-phase signal with a selected mixing function of Ω

'"'"'t where Ω

'"'"' is a preselected value;

means for mixing the constructed quadrature signal with a selected mixing function of Ω

'"'"'t; and

means for combining the two mixed, reconstructed signals to reproduce the decoded, decompressed communication signal.

26. A plurality of communications stations according to claim 25 comprising a telecommunicating system wherein one of said stations is a base station.

27. A communication station according to claim 25 wherein:

said at least one signal compression encoder further comprises means for filtering each of the in-phase and quadrature components prior to quantizing to remove from each component'"'"'s frequency domain all frequencies above a selected level; and

said at least one signal compression decoder further comprises means for filtering each of the mixed, reconstructed signals prior to summing to remove from each component'"'"'s frequency domain all frequencies above a selected filtering level.

28. A communication station according to claim 27 wherein:

said at least one signal compression encoder further comprises means for decimating the respective filtered in-phase and quadrature components by a s elected factor M prior to quantizing; and

said at least one signal compression decoder further comprises means for interpolating the reconstructed in-phase and quadrature signals by m prior to mixing.

29. A communication station according to claim 28 wherein:

said at least one signal compression encoder further comprises means for interpolating the communication signal by a selected factor M'"'"' prior to mixing the communication signal to produce respective in-phase and quadrature components; and

said at least one signal compression decoder further comprises means for decimating the respective mixed and filtered reconstructed in-phase and quadrature signals by m'"'"' prior to summing.

30. A communication station according to claim 29 wherein:

said encoder selecting means determines the type o communication signal and assigns to said at least one encoder preselected values for Ω

, M, M'"'"', the level of filtering and the number of quantization levels base upon the type of signal; and

said decoder selecting means determines the type of communication signal nd assigns to said at least one decoder preselected values for Ω

'"'"', m, m'"'"', at the level of filtering and number of quantization levels based upon the type of signal.

31. A telecommunication system for communicating communications signals between various stations over a selected carrier medium wherein the communication signal is compressed into a selectively formatted encoded signal to facilitate its transmission over the selected carrier medium and the communication signal is reconstructed after reception, the system comprising:

a first station having at least one signal compression encoder including;

means for transforming a communication signal into two separate components including;

means for determining the approximate center frequency Ω

of the communication signal,

means for mixing the communication signal with a selected mixing function of Ω

t to produce an in-phase component, and

means for mixing the communication signal with a selected mixing function of Ω

t to produce a quadrature component;

means for quantizing each separated signal component into a selected number of levels thereby encoding the signal components into quantized signals; and

formatting means for formatting the quantized signals to thereby produce a compressed encoded signal for transmission over the selected carrier medium of the communication system; and

a second station for receiving the compressed encoded signal from said first station having at least one signal decompression decoder including;

format decoding means for separating the quantized in-phase and quadxature signals of a compressed encoded signal received over the selected carrier medium of the communication system;

means for determining the approximate center frequency Ω

of the communication signal being decoded;

equalize decoding means for reconstructing the receptive in-phase and quadrature signals;

means for mixing the reconstructed in-phase signal with a selected mixing function of Ω

t;

means for mixing the reconstructed quadrature signal with a selected mixing function of Ω

t; and

means for combining the two mixed, reconstructed signals to reproduce the decoded, decompressed communication signal.

32. A telecommunication system according to claim 31 wherein one of said stations is a base station.

33. A telecommunication system according o claim 32 wherein:

said at least one signal compression encoder further comprises means for filtering each of the in-phase and quadrature components prior to quantizing to remove from each component'"'"'s frequency domain all frequencies above a selected level; and

said at least one signal compressing decoder further comprises means for filtering each of the mixed, reconstructed signals prior to summing to remove from each component'"'"'s frequency domain all frequencies above said selected filtering level.

34. A telecommunication system according to claim 33 wherein:

said at least one signal compression encoder further comprises means for decimating the respective filtered in-phase and quadrature components by a selected factor M prior to quantizing; and

said at least one signal compression decoder further comprises means for interpolating the reconstructed in-phase and quadrature signals by M prior to mixing.

35. A telecommunication system according to claim 34 wherein:

said at least one signal compression encoder further comprises means for interpolating the communication signal by a selected factor M'"'"' prior to mixing the communication signal to produce respective in-phase and quadrature components; and

said at least one signal compression decoder further comprises means for decimating the respective mixed and filtered reconstructed in-phase and quadrature signals by M'"'"' priro to summing.

36. A telecommunication system according to claim 35 wherein:

said means for determining the approximate center frequency Ω

of the communication signal determines the type of communication signal and assigns preselected values to Ω

, M, M'"'"', the level filtering and the number of quantization levels based upon the type of signal.