National Research Development Corporation

Qinetiq Limited

Robin Jones

Martin Johnson

Adrian Sean Coffey

Christopher J Oliver

John M Vaughan

Selina A Ballantyne

Michael Alldritt

An apparatus for producing a digital depiction of a signal ( ) which is adaptive to the signal itself. A constant rate sampling means, such as an analogue to digital converter ( ), samples the signal ( ) at a constant rate and produces a first digital depiction ( ) of a signal. A transformation means ( ) is responsive to the first digital depiction ( ) and produces a second digital depiction based on the evolution of the signal. The transformation means may be capable of determining when a predetermined threshold level has been crossed and measuring the time interval between predetermined threshold level crossings. The transformation means ( ) may include a logic arrangement and a timer counter and is run from a clock signal ( ) from the same clock ( ) as drives the sampling means. A method of adapting a conventional ADC ( ) to adaptively sample the signal ( ) by adding a transformation means ( ) run off the same clock ( ) as the ADC ( ) is also provided.

Method and apparatus of producing a digital depiction of a signal

An analogue to digital converter generating at least two threshold levels and a comparator for comparing each of the levels with the input signal and generating a primary digital output signal to provide an indication that the input signal has crossed one of the threshold levels. The converter comprises a timer for determining the elapsed period of time between the input signal crossing a first level and the input signal crossing a second level and for generating a secondary output signal representing the elapsed time, whereby the secondary digital output signal and the corresponding primary output signal are used to provide a digital representation of the analogue input signal. The converter may also comprise a receiver of the primary digital output signal from the comparator and for providing an UP/DOWN digital output signal to indicate in which direction the input signal crossed the threshold level.

Analogue to digital converter and method of analogue to digital conversion with non-uniform sampling

The electrophoretic mobility of cells in a solution is measured by applying an electric potential along a cell. A linescan camera forms an image frame by line scanning the cell in a direction perpendicular to the cell movement. Two such image frames are correlated to determine cell mobility in the interval between the two frames. Each line scanned is processed to indicate detected cells and a digital number obtained. A frame is thus represented by a series of numbers which may be correlated. Alternatively and more simply each line is scanned and the presence of any detected cell represented by a logic ONE so that an image frame is represented by a series of logic ONES and ZEROS for correlation with a later series. Integration of successive mobility measurements improves the observed results. A tag inserter provides a visible mark on a television screen to indicate cells that are detected.

Method of and apparatus for measuring electrophoretic mobility of cells

A method of, and apparatus for, processing a digital electric signal composed of a train of discrete uniformly or non-uniformly shaped pulses to recover spectral information contained in the spacings between the pulses, in which the digital signal is applied to a SAW spectrum analyzer arranged to produce output signals the envelopes of which represent the power spectrum over a selected frequency range of constituent sample lengths of the digital signal, and the required spectral information then derived from these output signals, for example by integration thereof over a period of time. The technique may be used in conjunction with a laser Doppler velocity measurement system in which each pulse of the digital signal represents the detection of a photon scattered from a moving object or particle in a scattering volume illuminated by laser light, the spacing between the pulses containing information regarding the velocity of movement of the object or particles under observation.

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Malvern, United Kingdom

Robin Jones