The Solartron Electronic Group Limited

Anthony John Ley

Eric Metcalf

Michael Cedric Jeffery

Apparatus for measuring the phase difference between two electrical signals Asin (wt+.theta.), Bsin (wt+.phi.), given a reference signal Vsin wt generated by the apparatus, comprises a phase lock loop for generating a clock frequency f = 360F where F is the frequency of the reference signal. This clock frequency f is then used to tune a 360 stage CCD transversal filter which is used to filter successively the two first-mentioned signals, whose phase difference is then measured by a zero intercept system. The clock frequency f is used to give phase difference in degrees. The phase lock loop comprises a 90-stage CCD to which the reference signal is applied. The output of the CCD is applied to one input of a phase sensitive detector whose other input is connected to receive the reference signal, and the control signal produced by the phase sensitive detector controls a voltage controlled oscillator whose output is applied to the clock input of the CCD.

Phase measuring apparatus

In a spectrum analyzer, the analogue signal to be analyzed is periodically sampled and digitized, and the digit samples are formed into R successive arrays each containing 2N successive samples and each overlapping the previous array by 50%. The forward Fourier transforms of each array are then successively formed, and an array of 2P complex points is formed from the result of each transform, where L-P/2 and L+P/2-1 are the points which represent the upper and lower limits of a Vernier band to be studied in detail and each array extends from points L-P to L+P-1 (i.e. each array is twice the width of the Vernier band, and the Vernier band is symmetrically disposed therein): additionally, each array for which L and R are odd is complemented. The arrays thus formed are then each multiplied by a window function (effectively equivalent to a band pass filter), and the result is subjected to the inverse Fourier transform to form respective further arrays of 2P points. The central points (from P/2 to 3P/2-1) of each of these further arrays are allowed to build up into a continuous array, and the M most recent points, where M is twice the required number of points in the Vernier band, are subjected to the forward Fourier transform to form M complex points, of which the middle points (from M/4 to 3M/4-1) are the desired result. This analyzer has the advantage that the Vernier band can be digitally positioned anywhere in the frequency band covered by the first forward Fourier transform.

Signal processors

The analogue storage circuit includes a charge transfer device such as a charge-coupled device (CCD) and a quantizing circuit. The charge transfer device is arranged to shift an analogue signal from its input to its output, the analogue signal being subject to a change in magnitude during such shifting. The quantizing circuit receives the analogue signal from the output of the charge transfer device and quantizes that signal at a respective one of several substantially discrete levels. The quantizing circuit is arranged to apply the quantized analogue signal to the input of the charge transfer device, whereby in operation the analogue signal is circulated round the loop defined by the charge transfer device and the quantizing circuit. The quantizing circuit is further arranged to quantize the analogue signal, upon each subsequent receipt thereof, at the same one of the discrete levels. The storage circuit is provided with an input for introducing the analogue input signal to be stored, into the loop defined by the charge transfer device and the quantizing circuit.

Growing community of inventors

New Canaan, CT, United States of America

Anthony John Ley