US3900844A — Analog and digital data interconversion system

Claim 1

Independent Claim 253 words

Apparatus for interconverting analog and digital signals comprising, in combination: a source of clock pulses; a cycle strobe pulse source for giving a strobe pulse output after each predetermined number of clock pulses; an n-bit, 2''s complement counter giving a first count output which cyclicly passes through a range of values extending from a maximum to a minimum; a (n-1)-bit, magnitude-only counter giving a second count output which cyclicly passes through a range of values extending from a maximum to a minimum; means connecting said counters for simultaneous actuation by said clock pulses; means for presetting said counters to maximum values in response to said strobe pulse output; a bipolar digital-to-analog converter giving an analog output determined in magnitude by the second count output and in sign by a sign bit from said n-bit counter; and a converter channel including first and second converting means each receiving the first count and analog outputs, said first converting means for receiving an input digital signal and including means comparing the input digital signal with the first count output and giving an output signal determined by the value of the analog output at the time the first count output becomes equal to the input digital signal, said second converting means for receiving an input analog signal and including means comparing the input analog signal with the analog output and giving a digital output signal determined by the value of the first digital output at the time the analog output becomes less than the input analog signal.

Claim 2

Dependent Claim 253 words

Apparatus for interconverting analog and digital signals comprising, in combination: a source of clock pulses; a cycle strobe pulse source for giving a strobe pulse output after each predetermined number of clock pulses; an n-bit, 2''s complement counter giving a first count output which cyclicly passes through a range of values extending from a maximum to a minimum; a (n-1)-bit, magnitude-only counter giving a second count output which cyclicly passes through a range of values extending from a maximum to a minimum; means connecting said counters for simultaneous actuation by said clock pulses; means for presetting said counters to maximum values in response to said strobe pulse output; a bipolar digital-to-analog converter giving an analog output determined in magnitude by the second count output and in sign by a sign bit from said n-bit counter; and a converter channel including first and second converting means each receiving the first count and analog outputs, said first converting means for receiving an input digital signal and including means comparing the input digital signal with the first count output and giving an output signal determined by the value of the analog output at the time the first count output becomes equal to the input digital signal, said second converting means for receiving an input analog signal and including means comparing the input analog signal with the analog output and giving a digital output signal determined by the value of the first digital output at the time the analog output becomes less than the input analog signal.

Claim 3

Dependent Claim 134 words

Apparatus according to claim 1 including: a plurality of converter channels having first and second converting means each receiving the first count and analog outputs and an input digital signal, including means comparing the input digital signal with the first count signal and giving an analog output signal determined by the value of the analog output at the time the first count signal becomes equal to the input digital signal; and a plurality of converter channels having first and second converting means each receiving the first count and analog outputs and an input analog signal, including means comparing the input analog signal with the analog output and giving a digital output signal determined by the value of the first count output at the time the analog output becomes less than the input analog signal.

Claim 4

Dependent Claim 108 words

Apparatus according to claim 1 in which said first converting means includes: a buffer register arranged to be set in accordance with the input digital signal; a digital comparator connected to receive the first count output and the output of said register, and to give a further output when the inputs thereto become equal; and an analog gate connected to receive the further output and the analog output, for giving an analog output signal determined by the value of the latter at the time when said inputs to said digital comparator become equal, which does not thereafter change as the analog output contiNues through its cycle of values.

Claim 5

Dependent Claim 23 words

Apparatus according to claim 3 in which said buffer register is loaded with said input digital signal concurrently with resetting of said counters.

Claim 6

Dependent Claim 69 words

Apparatus according to claim 1 in which said second converting means includes: a sample-and-hold circuit; an analog comparator comparing the output of said sample-and-hold circuit with the analog output and operating to give a control output when the latter becomes smaller than the former; a buffer register; and means setting said reegister in accordance with the value of the first count output at the time said analog comparator operates.

Claim 7

Dependent Claim 46 words

Apparatus according to claim 5 in which said clock pulse source also supplies delayed pulses, and in which said second converting means further includes logic means actuated by said delayed pulses for preventing said register from being set except at the time said analog comparator operates.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-08-18	1979-02-17	1979-08-19	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-08-18	1983-02-17	1983-08-19	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-08-18	1987-02-17	1987-08-19	$7700.00	Window Closed / Lapsed

Analog and digital data interconversion system

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