SYNTHESIS OF DIGITAL SIGNALS CORRESPONDING TO SELECTED ANALOG SIGNALS

• US 3,742,197 A
• Filed: 01/14/1972
• Issued: 06/26/1973
• Est. Priority Date: 01/14/1972
• Status: Expired due to Term

• Current Assignee: GEC Plessey Telecommunications Limited
• Original Assignee: Uwe A. Pommerening
• Inventors: Pommerening, Uwe A.
• Primary Examiner(s): Morrison, Malcolm A.
• Assistant Examiner(s): Malzahn, David H.
• Application Number:
  US05/217,988
• Time in Patent Office: 529 Days
• Field of Search: 235/152,197 328/14 332/11 325/38B
• US Class Current: 708/271
• CPC Class Codes: G06F 1/022 Waveform generators, i.e. devices for generating periodical functions of time, e.g. direct digital synthesizers G06F1/025, G06F1/03 take precedence
• CPC Class Codes: H04J 3/12 Arrangements providing for calling or supervisory signals
• CPC Class Codes: H04Q 1/4575 which are transmitted in digital form

Abstract

Digital signals for use in a time-divided multiplex signalling system are synthesized directly in digital form. Binary signals indicative of the differences between the values of successive time-spaced samples of preselected analog signals are fed through gates to an up-and-down accumulator under control of a counter and phase and polarity discriminators. The output of the accumulator at any instant represents the algebraic sum of all previous signals received by it. The preselected analog signals are preferably of the kind that can be represented by the sums of one or more simple trigonometric functions, so the sample values need be calculated only for a quarter wave.

Claims

1. An electrical tone synthesizer for generating digital signals corresponding to an analog tone signal comprising:

a. a multi-stage binary up-and-down accumulator, b. means for producing predetermined binary signals representing the calculated differences between successive time-spaced samples of the analog tone signal without reference to an analog signal, and c. means for applying binary signals produced by said producing means to said accumulator for up-and-down adding at periodic intervals, whereby the output of said accumulator consists of binary signals indicative of the quantum values of the successive calculated samples.

2. A tone synthesizer according to claim 1 in which said binary signal producing means includes means to produce difference signals in binary form indicating value differences between successive samples taken over only one half wave interval of a simple analog tone signal representable as a sine wave, and also includes means for reversing the algebraic sign of addition of said accumulator at the end of each half wave of the simple analog tone signal.

3. A tone synthesizer according to claim 1 wherein said producing means comprise an encoder and a counter connected to set said encoder in response to received timing signals such as framing pulses derived from a pulse code modulated digital signalling system.

4. An electrical tone synthesizer for generating digital signals corresponding to an analog signal representable as the sum of a plurality of simple sine waves comprising, a. a multi-stage binary up-and-down accumulator, b. means for producing predetermined binary signals representing the calculated differences between successive time-spaced samples of each simple sine wave component of the analog signal without reference to an analog signal, and c. means for applying the signals produced by said producing means to said accumulator for up-and-down adding at periodic intervals, whereby the output of said accumulator consists of binary signals indicative of the quantum values of the sum of the calculated values of all the simple sine wave components.

5. An electrical tone synthesizer for generating digital signals corresponding to preselected analog signals comprising:

a. a multi-stage up-and-down accumulator, b. means for producing predetermined binary signals representing the calculated differences between successive time-spaced samples of each of the analog signals without reference to an analog signal, c. means for applying signals produced by said producing means to said accumulator selectively on a time-shared basis for up-and-down adding at periodic intervals, separately adding the predetermined binary signals for each one of the analog signals, d. registers equal in number to the preselected analog signals, and e. gate means connecting said registers to said accumulator in predetermined time-spaced order relative to the operation of said applying means so that the outputs of said registers are respectively indicative of the quantum values of the successive calculated samples of the different analog signals.

6. An electrical tone synthesizer for generating digital signals corresponding to analog signals that are representable as the sums of simple sine waves comprising:

a. means for producing predetermined space divided binary signals indicative of the differences in value between successive time spaced samples of each of the simple sine waves without reference to an analog signal, b. an accumulator, c. means for applying signals produced by said producing means to said accumulator in predetermined sequence, d. registers equal in number to the digital output signals to be generated, and e. means connecting the output of said accumulator to said registers and transferring signals selectively back and forth between said accumulator and said registers in predetermined timed relationship to the operation of said applying means to cause said accumulator to add the respective components of the output signals on a time-shared basis and to store the sums in the respective registers during intervals between additions.

7. An electrical tone synthesizer according to claim 6 arranged for operation in a pulse code modulated, time division multiplex signalling system of the kind having a repetitive time frame including a predetermined number of individual signal intervals, said synthesizer including synchronizing means to operate it synchronously with the frame and individual signal intervals of the signalling system.

8. An electrical tone synthesizer for generating digital signals corresponding to an analog tone signal for pulse code modulated systems of the type that transmit a plurality of sequential channels of information in recurring frames, said synthesizer comprising:

a. a multistage binary up-and-down accumulator, b. counter circuit means for counting frames, c. decoder means responsive to the output of the final stage of said counter circuit means for counting frames and producing phase signals indicative of the relationship between the recurrent frames and the instantaneous phase of the analog signals that are to be represented by digital signals, d. encoder means including an encoder for each analog signal that is to be represented, e. said counter means and said decoder means being connected to set said encoder means so that its output consists of predetermined binary signals representing the calculated differences between successive time spaced samples of the analog signal, and f. means for applying the output signals of said encoder means to said for applying the output signals of said encoder means to said accumulator of up-and-down adding at periodic intervals, whereby the output f said accumulator consists of binary signals indicative of the quantum values of the successive calculated samples.