Digital apparatus for waveform measurement
First Claim
1. In waveform measurement apparatus including means for taking a time sequence of voltage samples of a signal, and means for displaying the sampled voltages to provide a representation of the signal, the improvement comprising:
- means for taking the voltage samples at random times for providing a scattered display to prevent aliasing when the signal includes frequency components greater than half the sampling frequency.
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Abstract
Digital instrumentation for waveform measurement including method and apparatus for providing irregularly spaced sampling times to prevent misleading visual patterns of coordinate points due to the presence of signal frequencies above the Nyquist frequency. The method and apparatus includes means for plotting coordinate points having abscissa positions corrected according to actual irregular sampling times, method and apparatus whereby irregularities are repeated for each signal sweep, and method and apparatus utilizing a bit reversal system to achieve the irregularly spaced sampling times.
34 Citations
12 Claims
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1. In waveform measurement apparatus including means for taking a time sequence of voltage samples of a signal, and means for displaying the sampled voltages to provide a representation of the signal, the improvement comprising:
- means for taking the voltage samples at random times for providing a scattered display to prevent aliasing when the signal includes frequency components greater than half the sampling frequency.
- View Dependent Claims (2)
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3. In digital apparatus for analog waveform measurement including signal input means, signal sampling means for taking a plurality of voltage samples of a signal, memory means for storing the sampled voltages, digital address counter means for controlling the memory means, and coordinate display means connected to the memory means for displaying sampled voltages, the improvement comprising:
- timing control means connected to the sampling means for taking the plurality of sample voltages at sequential irregularly spaced time intervals, to prevent aliasing effects.
- View Dependent Claims (4, 5, 6, 7)
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8. In digital apparatus for analog waveform measurement including signal input means, signal sampling means for taking a plurality of voltage samples of a signal, memory means for storing the sampled voltages, address counter means for controlling the memory means, and coordinate display means connected to the memory means for displaying sampled voltages, the improvement comprising:
- timing control means connected to the sampling means for taking the plurality of sample voltages at irregularly spaced time intervals, to prevent aliasing effects;
further counter means connected to the address counter means, means for entering at least a portion of the state of the address counter means into the further counter means in reverse order of bit significance; and
means connecting the further counter means to the timing means for controlling the spaced time intervals between sample voltages according to the count time of the further counter means. - View Dependent Claims (9)
- timing control means connected to the sampling means for taking the plurality of sample voltages at irregularly spaced time intervals, to prevent aliasing effects;
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10. In the method of measuring waveforms with digital apparatus comprising the steps of taking a sequence of voltage samples of a signal, storing the sampled voltages, and displaying the sampled voltages on a coordinate display, the improvement comprising:
- controlling the storing and displaying of sampled voltages with a counter;
deriving irregular time intervals from the states of the counter;
taking the voltage samples at said irregular time intervals; and
displaying the voltage samples at times related to the irregular times between intervals. - View Dependent Claims (11, 12)
- controlling the storing and displaying of sampled voltages with a counter;
Specification