Apparatus for tracking a luminous object

Claim 2

Apparatus for use in tracking a luminous object comprising a photosensitive target, scanning means operable to scan the target to produce an output signal representing illumination thereof, means defining a field of view for the target, a sighting device aligned with the target so that they have a common field of view, a reference mark incorporated in the sighting device so as to be superimposed on the field of view thereof and means operable to adjust the scan so that a predetermined portion thereof can be brought into substantial coincidence with the reference mark in relation to the common field of view.

Claim 3

Apparatus as claimed in claim 1 wherein the scanning means is operable to scan the target along a plurality of parallel lines, the reference mark is a line and the portion of the scan is one line thereof.

Claim 4

Apparatus as claimed in claim 2 wherein the reference line is one of a pair of orthogonal lines and the target is rotatable so that the selected line of the scan can be brought into coincidence with either of the reference lines.

Claim 5

Apparatus as claimed in claim 2 including means to read out the selected line of the scan.

Claim 6

Apparatus as claimed in claim 2 wherein the scanning means includes a vidicon tube incorporating said photosensitive target, an electron gun and line and frame scanning coils, the scanning means further including an oscillator, binary counter coupled to the oscillator and operable to count oscillations thereof, digital-to-analogue converter means coupled between the binary counter and the frame scanning coil, and a line scan generator coupled to the line scanning coil, the apparatus further including storage means, means to select from said output signal a portion representing an image of the object, and gating means having inputs coupled to the binary counter and said means to select and outputs coupled to the storage means and operable to pass the content of the binary counter to the storage means on receipt of said portion representing the image of the object.

Claim 7

Apparatus as claimed in claim 5 including display means and decimal counter means operable to count oscillations of the oscillator, the output of the decimal counter means being gated with the output from said means to select and applied to the display means to display the number of the line scanned when the image of the object is scanned.

Claim 8

Apparatus as claimed in claim 5 including an oscilloscope driven by said line and frame scanning coils and receiving the output signal from the scanning means representing illumination of the target, blanking means to blank a line in the line scan of the oscilloscope and adjusting means operable on the blanking means to blank out that line which is coincident with said reference mark.

Claim 9

Apparatus as claimed in claim 5 including track and store means coupled to said line scan generator and to said means to select whereby the signal output of said track and store means is representative of the location of the image of the object in a direction paraLlel to said reference line relative to the sweep of the line scans on the target, the apparatus further including a servomotor which is sensitive to said signal output of said track and store unit and which is operable to rotate the target about an axis which is perpendicular to said reference line whereby the object is maintained in said field of view.

Claim 10

Apparatus as claimed in claim 5 including blocking means to block said means to select for a predetermined period following receipt of said portion representing an image of the object.

Claim 11

Apparatus as claimed in claim 5 including an arithmetical averaging device having input coupled to said means to select and to said binary counter and operable to take the arithmetic means of the content of the binary counter each time a said portion representing the image of the object is detected over a frame of the scan, said arithmetic mean being passed to the storage means after each frame of the scan.

Claim 12

Apparatus as claimed in claim 1 including means to adjust the target through a desired angle after the reference mark has been aligned with a presurveyed location and measure orientation therefrom.

Claim 13

Apparatus for use in tracking a luminous object comprising a photosensitive target, scanning means for scanning said target so as to produce an output signal representing illumination thereof, means to select from the signal a portion representing an image of the object, assessor means responsive to sensing of the image to asses the brightness thereof, and adjusting means operable to cause adjustment of the output signal from the target in accordance with the brightness of the image.

Claim 14

Apparatus for use in tracking a luminous object comprising a photosensitive target, scanning means for scanning said target so as to produce an output signal representing illumination thereof, means to select from the signal a portion representing an image of the object, assessor means responsive to sensing of the image to asses the brightness thereof, and adjusting means operable to cause adjustment of the output signal from the target in accordance with the brightness of the image.

Claim 15

Apparatus as claimed in claim 12 wherein the assessor means comprises means responsive to the peak value of the output signal, in use the last said means being exposed to the output signal for a time after sensing of the image.

Claim 16

Apparatus as claimed in claim 12 wherein the adjusting means is operable to cause adjustment of the output signal from the target so that the peak amplitude of said portion of the signal after adjustment is maintained substantially constant as the image is scanned repeatedly.

Claim 17

Apparatus as claimed in claim 14 wherein the means to select the portion from the signal comprises threshold means to which the signal is fed.

Claim 18

Apparatus as claimed in claim 14 and including optical focussing means in substantially fixed relationship with said target.

Claim 19

Apparatus as claimed in claim 14 wherein the scanning means includes a vidicon tube incorporating said photosensitive target, an electron gun and line and frame scanning coils, the scanning means further including an oscillator, binary counter coupled to the oscillator and operable to count oscillations thereof, digital-to-analogue convertor means coupled between the binary counter and the frame scanning coil, and a line scan generator coupled to the line scanning coil, the apparatus further including storage means, and gating means having inputs coupled to said binary counter and to said means to select and outputs coupled to the storage means and operable to pass the content of the binary counter to the storage means on receipt of said portion representing the image of the object.

Claim 20

Apparatus as claimed in claim 17 including track and store means coupled to said line scan generator and to said means to select whereby the signal output of said track and store means is representative of the location of the image of the object in a direction parallel to said reference line relative to the sweep of the line scans on the target, the apparatus further including a servomotor which is sensitive to said signal output of said track and store unit and which is operable to rotate the target about an axis which is perpendicular to said reference line whereby the object is maintained in said field of view.

Claim 21

Apparatus for use in tracking a luminous object comprising a photosensitive target, means operable to scan the target to produce aN output signal representing illumination thereof, and discriminator means comprising means to assess said output signal and operable to produce output signals representative of the gradient thereof, threshold means coupled to the output of said means to assess and operable to pass to its output only those output signals exceeding a predetermined magnitude in either polarity, holding means operable to hold signals applied thereto at its output for a predetermined period, discriminator gating means operable to produce at its output a gated output signal when signals occur simultaneously at its inputs, first polarity sensitive means connected to the output of the threshold means and operable to pass signals of a first polarity to said holding means, and second polarity sensitive means connected to the output of the threshold means and operable to pass signals of opposite polarity to said first polarity to an input of said discriminator gating means, the output of said holding means being connected to another input of said discriminator gating means, whereby the output signal representing illumination of the target to be responsible for the production of a discriminated output signal must produce at the output of the threshold means a pair of pulses, the first of which is of said first polarity and the second of which is of opposite polarity and occurs within said predetermined period.

Claim 22

Apparatus for use in tracking a luminous object comprising a photosensitive target, means operable to scan the target to produce aN output signal representing illumination thereof, and discriminator means comprising means to assess said output signal and operable to produce output signals representative of the gradient thereof, threshold means coupled to the output of said means to assess and operable to pass to its output only those output signals exceeding a predetermined magnitude in either polarity, holding means operable to hold signals applied thereto at its output for a predetermined period, discriminator gating means operable to produce at its output a gated output signal when signals occur simultaneously at its inputs, first polarity sensitive means connected to the output of the threshold means and operable to pass signals of a first polarity to said holding means, and second polarity sensitive means connected to the output of the threshold means and operable to pass signals of opposite polarity to said first polarity to an input of said discriminator gating means, the output of said holding means being connected to another input of said discriminator gating means, whereby the output signal representing illumination of the target to be responsible for the production of a discriminated output signal must produce at the output of the threshold means a pair of pulses, the first of which is of said first polarity and the second of which is of opposite polarity and occurs within said predetermined period.

Claim 23

Apparatus as claimed in claim 19 wherein the scanning means includes a vidicon tube incorporating said photosensitive target, an electron gun and line and frame scanning coils, the scanning means further including an oscillator, binary counter coupled to the oscillator and operable to count oscillations thereof, digital-to-analogue converter means coupled between the binary counter and the frame scanning coil, and a line scan generator coupled to the line scanning coil, the apparatus further including storage means, and gating means having inputs coupled to the binary counter and to the output of said discriminator gating means and outputs coupled to the storage means and operable to pass the content of the binary counter to the storage means on receipt of a gated output signal from the discriminator gating means.

Claim 24

Apparatus as claimed in claim 20 including display means and decimal counter means operable to count oscillations of the oscillator, the output of the decimal counter means being gated with the output from said discriminator gating means and being operable display the content of the decimal counter means in the display means when a gated output signal occurs at the output of said discriminator gating means.

Claim 25

Apparatus as claimed in claim 21 including track and store means coupled to said line scan generator and to the output of said discriminator gating means whereby the signal output of said track and store means is representative of the location of the image of the object in a direction parallel to said reference line relative to the sweep of the line scans on the target, the apparatus further including a servo-motor which is sensitive to said signal output of said track and store unit and which is operable to rotate the target about an axis which is perpendicular to said reference line whereby the object is maintained in said field of view.

Claim 26

Apparatus as claimed in claim 20 including brightness assessor means responsive to sensing of the image to assess the brightness thereof, and adjusting means coupled to the brightness assessor means and operable to adjust the sensitivity of the photosensitive target to maintain the peak output therefrom constant.