Apparatus and method for generating linearly filtered composite signal

• US 5,555,515 A
• Filed: 07/22/1994
• Issued: 09/10/1996
• Est. Priority Date: 07/23/1993
• Status: Expired due to Term

• Current Assignee: Leader Electronics Corp.
• Original Assignee: Leader Electronics Corp.
• Inventors: Saito, Koichi, Tomita, Hiroyuki
• Primary Examiner(s): Envall, Jr., Roy N.
• Assistant Examiner(s): Ngo, Chuong D.
• Application Number:
  US08/278,909
• Time in Patent Office: 781 Days
• Field of Search: 364/718-722, 364/724.01, 364/728.01, 364/728.02, 364/724.03, 364/724.13
• US Class Current: 708/300
• CPC Class Codes: H04S 1/007 in which the audio signals are in digital form data reduction aspects thereof based on psychoacoustics G10L19/02

Abstract

An apparatus and method for generating a linearly filtered composite signal, wherein the original signal of said composite signal can be divided into a plurality of sequentially arranged original sub-signals. The apparatus having a plurality of memory (1₁, 1₂) which have stored filtered sub-signals y₁ (n), y₂ (n) obtained by linearly filtering the original sub-signals, respectively; an adder (5) for adding data of the sub-signals y₁ (n), y₂ (n) read out from the memory to provide the resultant data y₁ (n)+y₂ (n) to an output terminal of the apparatus; and a controller for controlling timings of providing the data of the sub-signals stored in the memory to the adder. The controller controls such that when a first sub-signal is to be generated, the data thereof sequentially read out from the corresponding memory are provided to the adder, thereby providing the data thereof through the adder to the output terminal, when a second sub-signal is to be generated in place of the first one, during a predetermined time period centered at a switching timing from the first sub-signal to the second one, both of data of the first and second sub-signals read out from the corresponding memory are added at the adder, thereby providing the added data to the output terminal, and thereafter, only the data of the second sub-signal read out from the second memory are provided to the adder, thereby providing the data thereof to the output terminal.

Claims

1. A filtered composite signal generating apparatus for generating a linearly filtered composite signal, wherein the original signal of said composite signal is divided into a plurality of sequentially arranged original sub-signals and intervals between adjacent original sub-signals are within a predetermined time period, and wherein at least one of said sub-signals includes a plurality of selectable patterns, said filtered composite signal generating apparatus comprising:

(a) a plurality of memory means storing filtered sub-signals, including said at least one sub-signal including a plurality of selectable patterns, obtained by linearly filtering said original sub-signals, respectively;

(b) adding means for adding data of said filtered sub-signals read out from said memory means to provide the resultant data to an output terminal of said apparatus; and

(c) control means for controlling timings of providing the data of said filtered sub-signals stored in said memory means to said adding means, said control means including pattern selecting means for selecting one of said plurality of selectable patterns, such that,

when a first filtered sub-signal is to be generated, the data of said first filtered sub-signal sequentially read out from the corresponding first memory means are provided to said adding means, thereby providing the data of said first filtered sub-signal through said adding means to said output terminal,

when a second filtered sub-signal is to be generated in placed of said first filtered sub-signal, during a predetermined time period centered at a switching timing from said first filtered sub-signal, both of data of said first and second filtered sub-signals read out from the corresponding first and second memory means are added at said adding means, thereby providing the added data to said output terminal, and

thereafter, only the data of said second filtered sub-signal read out from said second memory means are provided to said adding means, thereby providing the data of said second filtered sub-signal to said output terminal.

2. An apparatus as set forth in claim 1, wherein said control means comprises address generating means for generating respective addresses of said memory means to read out the data of the respective filtered sub-signals therefrom at predetermined different timings.

3. An apparatus as set forth in claim 2, wherein said address generating means generate the addresses repeatedly, thereby said filtered sub-signals are repeatedly read out from said memory means.

4. An apparatus as set forth in claim 1, wherein

each of said memory means has stored the data of said filtered sub-signal at predetermined addresses and zero level data at the remaining addresses of one filtered composite signal generation cycle;

and

said control means comprises address generating means for generating addresses to said memory means to read out the data from said memory means simultaneously during said generation cycle.

5. An apparatus as set forth in claim 4, wherein said address generating means generate the addresses repeatedly, thereby said filtered sub-signals are repeatedly read out from said memory means.

6. An apparatus as set forth in claim 1, wherein said control means comprises:

address generating means for generating addresses to repeatedly read out said respective filtered sub-signals from said memory means at the same time; and

means for controlling passing/interrupting of said respective filtered sub-signals read out from said memory means to said adding means.

7. An apparatus as set forth in claim 1, wherein

at least one of said memory means has stored data of said filtered sub-signal at predetermined addresses and zero level data at the remaining addresses of one filtered composite signal generation cycle;

and

said control means comprises address generating means for generating addresses having said generation cycle to the memory means which has also stored zero level data to read out the filtered sub-signal data and zero level data therefrom during the generation cycle, and for generating addresses at predetermined timings to the memory means which have stored no zero level data to read out said filtered sub-signals therefrom.

8. An apparatus as set forth in claim 1, wherein

at least one of said memory means has stored data of said filtered sub-signal at predetermined addresses and zero level data at the remaining addresses of one filtered composite signal generation cycle;

and

said control means comprises (1) address generating means for generating addresses having said generation cycle to the memory means which has also stored zero level data to read out the filtered sub-signal data and zero level data therefrom during the generation cycle, and for generating addresses repeatedly to the memory means which have stored no zero level data to repeatedly read out said filtered sub-signals therefrom, and (2) means for controlling the passing/interrupting of the data read out from at least the memory means which has stored no zero level data.

9. An apparatus as set forth in claim 1, wherein said control means comprises:

address generating means for generating addresses to repeatedly read out data of said sub-signal from at least one of said memory means for a filtered composite signal generation cycle and to read out data of said filtered sub-signals at predetermined timings from the other memory means; and

means for controlling passing/interrupting of the data read out from the repeatedly addressed memory means.

10. An apparatus as set forth in claim 1, wherein

the number of said sub-signals is three or more;

at least one of said memory means has stored data of said filtered sub-signal at predetermined addresses and zero level data at the remaining addresses of one filtered composite signal generation cycle; and

said control means comprises (1) address generating means for generating addresses having said generation cycle to the memory means which has also stored zero level data to read out the filtered sub-signal data and zero level data therefrom during the generation cycle, for generating addresses repeatedly to at least one of the memory means which have stored no zero level data to repeatedly read out data of said filtered sub-signals therefrom, and for generating addresses at predetermined timings to the other memory means to read out the data of said filtered sub-signals therefrom, and (2) means for controlling the passing/interrupting of data of the repeatedly read out sub-signal from the memory means which has stored no zero level data.

11. An apparatus as set forth in claim 1, further comprising:

input nodes and an output node associated with said adding means,

output selecting means for selectively connecting one of said input nodes and said output node of said adding means to said output terminal of said apparatus, and

means for controlling the operations of said output selecting means and said adding means such that only for said predetermined time period centered at the sub-signal switching timing, it renders said adding means active and said output selecting means to connect the output node of said adding means to the output terminal of said apparatus, and for the other time period, it renders said output selecting means to selectively connect one of said input nodes of said adding means to said output terminal in accordance with the filtered sub-signal to be generated.

12. An apparatus as set forth in claim 1 wherein at least one of said intervals between said adjacent original sub-signals is null (zero).

13. An apparatus as set forth in claim 1, wherein said pattern selecting means comprises upper address generating means for generating upper bits of addresses of the memory means storing the sub-signals having said patterns.

14. An apparatus as set forth in claim 1, wherein

the memory means storing the sub-signals having said patterns consists of a plurality of memories respectively storing said patterns, and

said pattern selecting means comprises alternative selection gate means disposed between said memories and said adding means for alternatively connecting one of outputs of said memories to said input node of said adding means.

15. A filtered composite signal generating method for generating a linearly filtered composite signal, wherein the original signal of said composite signal is divided into a plurality of sequentially arranged original sub-signals and intervals between adjacent original sub-signals are within a predetermined time period, and wherein at least one of said sub-signals includes a plurality of selectable patterns, said method comprising the steps of:

(a) providing a plurality of memory means storing data of filtered sub-signals obtained by linearly filtering said original sub-signals, respectively, said sub-signals including said at least one sub-signal having a plurality of selectable patterns;

(b) reading out data of a first filtered sub-signal from a first memory means and outputting it from an output terminal;

(c) selecting a signal pattern from said plurality of selectable patterns;

(d) reading out data of said first and a second filtered sub-signals from said first and a second memory means during a predetermined time period centered at a signal switching timing from said first filtered sub-signal to said second filtered sub-signal, adding the read out data, and outputting the resultant data from said output terminal; and

(e) thereafter, reading out the data of said second filtered sub-signal from said second memory means and outputting it from said output terminal.

18. A method as set forth in claim 15 wherein at least one of said intervals between said adjacent original sub-signals is null (zero).

19. A method as set forth in any one of claims 15-18, wherein said pattern selecting step is executed by addressing upper bits of addresses of the memory means.

20. A method as set forth in any one of claims 15-18, wherein

said memory means storing said filtered sub-signal having said patterns comprises a plurality of memories, which have respectively stored said patterns, and

said pattern selecting step is executed by alternatively selecting outputs of said memories.

16. A filtered composite signal generating method for generating a linearly filtered composite signal, wherein the original signal of said composite signal is divided into a plurality of sequentially arranged original sub-signals and intervals between adjacent original sub-signals are within a predetermined time period, and wherein at least one of said sub-signals includes a plurality of selectable patterns, said method comprising the steps of:

(a) providing a plurality of memory means respectively storing data of filtered sub-signals obtained by linearly filtering said original sub-signals at predetermined addresses, and zero level data at the remaining addresses of a filtered composite signal generation cycle, said sub-signals including said at least one sub-signal having a plurality of selectable patterns; and

(b) selecting one of said plurality of selectable signal patterns;

(c) reading out data of said filtered sub-signals and zero level data from said memory means simultaneously, adding the read out data, and outputting the resultant data from said output terminal.

17. A filtered composite signal generating method for generating a linearly filtered composite signal, wherein the original signal of said composite signal is divided into a plurality of sequentially arranged original sub-signals and intervals between adjacent original sub-signals are within a predetermined time period, and wherein at least one of said sub-signals includes a plurality of selectable patterns, said method comprising the steps of:

(a) providing a plurality of memory means storing data of filtered sub-signals obtained by linearly filtering said original sub-signals, respectively, said sub-signals including said sub-signals including said at least one sub-signal having a plurality of selectable patterns;

(b) selecting one of said plurality of selectable signal patterns;

(c) repeatedly reading out data of the filtered sub-signals from all the memory means, simultaneously;

(d) transferring the read out data of said first filtered sub-signal, and outputting it from an output terminal;

(e) transferring the read out data of said first a second filtered sub-signals from said first and a second memory means during a predetermined time period centered at a signal switching timing from said first sub-signal to said second filtered sub-signal, adding the transferred data, and outputting the resultant data from said output terminal; and

(f) thereafter, transferring the read out data of said second filtered sub-signal from said second memory means and outputting it from said output terminal.