Electronic memory unit
First Claim
1. A method of processing at least one time varying electrical signal, the method including the steps of:
- sampling the signal to provide a succession of sample values;
sensing a rate of change of the signal;
converting the sample values to digital form;
writing the digitized sample values into an electronic memory device at a writing rate; and
simultaneously reading out previously stored sample values from the memory at a rate which is different from the writing rate;
said writing rate being automatically variable in response to the sensed rate of change of the signal.
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Accused Products
Abstract
In an electronic memory unit for processing a pair of transient electrical signals prior to recording by an XY plotter, a random access memory receives digitized samples of the signals at a dynamically variable rate which is determined by the rate of change of the input signals. The said rate is controlled by sampling decision circuits which sense the difference in level between successive samples. The stored samples are read out of the memory to digital-to-analogue converters at a rate which is suited to the characteristics of the XY plotter connected to the outputs of the unit thereby enabling rapidly changing signals fed to the inputs of the unit to be recorded accurately without wasteful use of memory capacity.
37 Citations
11 Claims
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1. A method of processing at least one time varying electrical signal, the method including the steps of:
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sampling the signal to provide a succession of sample values; sensing a rate of change of the signal; converting the sample values to digital form; writing the digitized sample values into an electronic memory device at a writing rate; and simultaneously reading out previously stored sample values from the memory at a rate which is different from the writing rate; said writing rate being automatically variable in response to the sensed rate of change of the signal. - View Dependent Claims (2)
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3. A method for recording two time-varying electrical signals in the form of a graph in which the level of one signal is plotted as a function of the level of the other, the method including the steps of:
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(i) sampling both signals at a single, variable sampling rate, which rate is increased in response to an increase in the rate of change of either of the said signals; (ii) converting the samples of both signals to a digital form; (iii) writing the digital sample values into the memory; (iv) simultaneously with steps (i) to (iii) above, reading out stored sample values from the memory at a readout rate which is different from the said sampling rate; (v) converting the read out sample values into two analogue output signals representing the two time-varying electrical signals; and (vi) feeding the output signals to a recording instrument, whereby the recording element of the instrument moves in an X direction in response to the level of one of the output signals, and in a perpendicular Y direction in response to the level of the other output signal. - View Dependent Claims (4, 5, 6, 7)
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8. An electronic memory unit comprising:
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(i) input signal sampling means for sampling a time-varying input signal; (ii) analogue-to-digital conversion means connected to the sampling means for converting the samples into digital form; (iii) difference determining means for determining the incremental difference in level between adjacent sample values; (iv) an electronic memory stage linked to the analogue-to-digital conversion means and controllable simultaneously to store and read out digitized sample values, the rate of storing samples being controlled automatically by the said difference determining means and related to the rate of change of the input signal, and the readout rate being different from the rate at which samples are entered for storage; and (v) digital-to-analogue conversion means linked to the electronic memory stage for converting the values read out from the electronic memory stage into analogue form. - View Dependent Claims (9, 10, 11)
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Specification