Improvements relating to electrical pulse generating circuit arrangements

... 760,834. Pulse generating circuits. BRITISH THOMSON-HOUSTON CO., Ltd. March 3t, 1955 [April 1, 1954], No. 9615/54. Class 40(6) A pulse generating circuit comprises a normally conducting control valve and a normally non-conducting pulse generator valve which are connected in a flip-flop type circuit so that when a trigger pulse is applied the control valve is cut-off and the pulse generator valve conducts until after a period determined by a resonant circuit it is cut-off by the control valve conducting again. The Figure shows a circuit for generating pulses having a duration determined by the period of resonant circuit LCI. Control valve V2 is normally conducting and pulse generator valve V1 cut-off. When a positive trigger pulse is applied at terminal A valve V2 is cut-off at its cathode and V1 starts to conduct; resonant circuit LC1 "rings " due to the applied trigger pulse and when the grid potential of valve V2 has risen sufficiently due to the " ring- ing" voltage V2 conducts and V1 ...

Improvements in and relating to recurrent generators

... 741,580. Pulse generating circuits. BRITISH THOMSON-HOUSTON CO., Ltd. April 12, 1954 [April 10, 1953], No. 9798/53. Class 40 (6). A system for generating a train of pulses comprises two pulse generators, each of which will produce an output pulse having a delay with respect to a triggering input pulse which is variable as a function of the phase and number of oscillations produced by an oscillatory circuit in each generator; the generators operating alternately by causing each output pulse from each generator to effect the triggering of the other generator. Fig. 2 shows a pulse generating system comprising two pulse generators 10, 11 each of which, as shown in Fig. 1, comprises an exciting circuit 1 which is triggered by an input pulse at terminal 4 to initiate a train of oscillations from resonant circuit 3, the same pulse also switching out of circuit the damping circuit 2. The train of oscillations is fed to variable phase shifter 5, counter or frequency divider 6 and pulse-forming circuit ...

Improvements in and relating to electrical timing circuits

741,587. Phase difference measurements. BRITISH THOMSON-HOUSTON CO., Ltd. Oct. 19, 1953, No. 28802/53. Class 37. [Also in Group XL (c)] Relates to a system for adjustably delaying a marker pulse a relative to a triggering pulse P, the marker pulse being used as a brilliance or deflection range marker on a cathode-ray tube radar display or as a triggering pulse for initiating a succeeding cycle, thereby generating a pulse train having a continuously-variable and accurately known recurrence period as disclosed in Specification 741,580, [Group XL (c)]. According to the present invention the trigger pulse initiates a train of oscillations of period T in a generator 1 which is applied in series to a phase shifter 2, a pulse generator 9, and a plurality of counting stages, 4, 6, 8, each counting stage being adapted to produce a pulse output after a selectable number x of input. pulses and thereafter an output pulse after each group of a predetermined number y of input pulses (x less than y) so that the first output pulse from the nth counter is delayed relative to the triggering pulse P by an integral number N of periods T equal to x 1 +(x 2 Îy 1 )+(x 3 Îy 1 x y 2 )+ . . . +(x n Îy 1 Îy n Î ... Î y n-1 ) plus a fraction α of a period T determined by the setting of the phase shifter. Preferably the first output pulse from the final counter (i.e. the marker pulse a) cuts off the input to the counting chain until the next triggering pulse P occurs. When setting the counters, x 1 is made equal to the remainder obtained on dividing N by y 1 , the resultant quotient being N1; x 2 is made equal to the remainder obtained on dividing N1 by y 2 and so on. Fig. 4 lines B, C, D and E show respectively the input pulses to counters 4, 6 and 8 and the output pulse a from counter 8 for a selected example in which N=138, y 1 =y 2 =5 and y 3 =6 so that the selected values of x 1 , x 2 and x 3 are 3, 2 and 5 respectively. Each counter may be of the type in which the counting factor is ...

Improvements relating to radar display systems

... 894,126. Radar. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Oct. 15, 1959 [Oct. 15, 1958], No. 32936/58. Class 40(7). A radar true motion C.R.T. P.P.I. display system comprises a rotatable transparent cursor 5, Fig. 1, mounted in front of the display screen and carrying a plurality of parallel lines 4 and means for causing an electronic bearing marker 2 to be produced on the screen in a direction parallel to the lines 4, one end of the marker originating at the spot 1 corresponding to the position of the craft carrying the radar. As shown the electronic marker 2 is generated by contacts 9, Fig. 2, which are closed and during each aerial rotation of a cam 8 driven by the output from a differential gear 6 when inputs are coupled respectively to the frame of the rotatable cursor and the rotating scanning coils 7. Alternatively the cam 8 is driven directly by the scanning coils 7 and the contacts 9 are mounted on the frame of the cursor. Reference has been directed by the Comptroller to Specification ...

Improvements relating to voltage stabilising arrangements

... 780,747. Automatic voltage control systems. BRITISH THOMSON-HOUSTON CO., Ltd. July 15, 1955 [Aug. 3, 1954], No. 22514/54. Class 38 (4). In a voltage-stabilizing network a series valve V3 is controlled by the output of a twostage direct-coupled amplifier V1, V2 responsive to voltage differences between a reference source Vo and a tap on a potentiometer P1 connected with resistors across the network output Vo which is to be stabilized with variations in supply V1. The amplifier response to fluctuations in Vo is improved by a negative feedback coupling between the anodes of the amplifier pentodes, the consequent drop in overall gain being partially compensated by running valve VI as a " starved " pentode with high anode load and low screen potential, whereby its gain is considerably increased. A theoretical analysis is given of the gain and response characteristics of this type of amplifier.

Improvements in and relating to electric pulse gating circuits

... 729,293. Pulse circuits. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 2, 1953, No. 33508/53. Class 40 (6). In a circuit for selecting a train of pulses having a frequency which is a sub-multiple of that of an input pulse train the first pulse of the input train initiates a timing period during which period pulses are selected from the train and passed to an output channel, the next pulse in the input train initiating a subsequent period. The Figure shows a pulse selecting or gating circuit comprising a valve V1 connected in a Miller integrator circuit and a gating circuit comprising cathode coupled triodes V2a, V2b to the cathodes of which a train of negativegoing pulses is fed. Initially the control grid of valve V2a is biased to a voltage midway between the upper and lower voltages which the screen grid of valve V1 acquires during the operation of the Miller circuit so that initially the grid of V2a is at a higher voltage than that of V2b and the first negative-going pulse of the input train ...

Improvements relating to control apparatus for cathode ray tubes

... 812,953. Automatic current control systems. BRITISH THOMSON-HOUSTON CO. Ltd. June 27, 1956 [May 12, 1955], No. 13773/55. Class 38 (4). [Also in Group XL (c)] The part of the beam current that passes between the apertured accelerating anode and the screen of an electrostatically focused cathoderay tube is maintained constant by automatically controlling the control grid bias. The system is particularly applied to multiple tube radar displays. The potential of the graphite coating G of the tube is used as a measure of the beam current and is applied to the control grid of a transitron oscillator VI so that as the beam current increases the amplitude of oscillation decreases. The output of the oscillator is rectified at D1, D2 to provide the bias for the grid of the cathode-ray tube and is in the sense to reduce the beam current as the bias decreases. For a multi-tube display, Fig. 1 (not shown), each tube is provided with its own bias oscillator, and individual brightness control, e.g. RV1 ...

IMPROVEMENTS IN OR RELATING TO FREQUENCY RESPONSIVE APPARATUS

... 1277208 Automatic frequency control systems; radar ASSOCIATED ELECTRICAL INDUSTRIES Ltd 2 Oct 1969 [2 Oct 1968] 46810/68 Headings H3A and H4D A frequency responsive apparatus comprises a signal generator 11, a frequency multiplier 12 and a frequency discriminator 8 for controlling the generator 11 so that the multiplied generator frequency is maintained at a constant non-zero difference with respect to an input signal from a source 7, i.e. a radar transmitter. A radar apparatus incorporating the above set-up may also include data pick-off or processing circuitry 5 to which direction data is applied via a transducer (not shown) from a physically scanning radar array aerial 1 and a correction unit 6 to which data from a circuitry 5 and a signal from generator 11 (proportional to radar beam squint angle) are applied to obtain the radar beam direction. The combined oscillator-multiplier 11 and 12 may be employed as the local oscillator in a radar receiver.

Improved means for deriving a direct from an alternating voltage

... 689,996. Automatic control systems. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 18, 1951 [Jan. 8, 1951], No. 519/51. Class 38 (iv). An alternating voltage developed across an impedance is converted into a proportional direct voltage by alternately earthing opposite ends of the impedance at the frequency of the alternating voltage, the ends of the impedance being connected to a point between which and earth the direct voltage is obtained. The earthing means may be commutator or other synchronous switches, but preferably comprise sets of diode valves. When the alternating voltage reverses in phase, the rectified direct voltage changes in sign. As shown, the alternating voltage (which may be modulated as indicated at B, Fig. 2, and reverses in phase as it passes through zero amplitude) is developed across the secondary coil 10 of an input transformer which is connected at its ends to earthing switches 12. Each of these comprises parallel pairs of series-connected diode valves. The series pairs ...

Improvements relating to radar display systems

... 877,159. Radar. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Dec. 1, 1959 [Oct. 15, 1958], No. 32935/58. Class 40(7) In a ship-borne radar with a true motion PP and CRT display, when the spot representing the position of the ship crosses a selectable one of four imaginary threshold lines AB, CD, EF and GH, Fig. 1, defining a square symmetrical with respect to the screen, the spot is automatically reset to a diametrically opposite position, outside the square, the selected threshold line being selected automatically and continuously in accordance with the instantaneous heading # of the ship. As described the north threshold line AB is selected if the ship's heading is within the sector bounded by the directions NW and NE and the other threshold lines are selected in a corresponding manner. As shown in Fig. 2 the ship spot is displaced in accordance with the movement of the ship by applying shift voltages V N and V E to orthogonal shift coils 6 and 7. A sine-cosine potentiometer 1 set in accordance ...

Improvements relating to radar display systems

Improvements in and relating to goniometers

... 710,890. Photo-electric goniometers. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 17, 1952 [Oct. 23, 1951], No. 24728/51. Class 40 (3) A goniometer comprises a cathode ray tube on the screen of which is a circular trace, a mask angularly positioned in accordance with the angle to be indicated and an aperture in the mask positioned on the circumference of the trace so that the intersection of the trace and the aperture produces a light pulse which is detected photo-electrically and the phase of which relative to the sinusoidal wave producing the trace is a measure of the angle to be indicated. As shown, sinusoidal voltages differing in phase by 90 degrees are applied to plates 10 of cathode ray tube 1 to produce a circular trace (shown dotted). Mask 2 positioned in accordance with the angle to be indicated by means of gearing, carries an aperture 3 positioned at the radius of the trace so that when the spot passes beneath the trace light reaches a photo-cell 4 which produces an output pulse which ...

Improvements relating to the display of information in code

... 712,985. Television. BRITISH THOMSONHOUSTON CO., Ltd. Jan. 23, 1952 [Feb. 20, 1951], No. 4114/51. Class 40 (3). [Also in Group XL(c)] In television apparatus for the display of coded image information in which the in formation is derived by means of a signal-generating system, e.g. a monoscope or flying-spot scanner, the signal obtained from the system is mixed with a further signal from a second signal-generating system and the combined signal passed through an amplifying channel possessing a characteristic such as to invert the sense of the signal voltage from the first signal-generating system when a signal voltage of a predetermined value is obtained from the second signal-generating system whereby the information conveyed by a particular image may be increased. As shown in Fig. 1 image information derived from the signal plate 12 of a monoscope 10 is reproduced on a cathode-ray tube 11. The two tubes are scanned in a common raster in synchronism by means of unit 14 applying signals ...

Improvements relating to closed loop television systems

... 917,197. Radar. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. March 16, 1961 [March 16, 1960], No. 9320/60. Class 40 (7). [Also in Group XL (b)] In an auto-follow radar system employing a closed loop television system comprising a television camera " seeing " through a sighting telescope mounted on the radar aerial and supplying video signals to a television picture reproducing tube at a stationary observation position, displacement of the target from the intersection of the telescope cross-wires (as seen in the reproduced picture) due to acceleration errors in the servo systems controlling the aerial movement (as distinct from noise errors) may be measured by producing a visual mark the rectangular co-ordinates of which are determined by the azimuth and elevation servo error voltages. Since the visual mark is displaced from the intersection of the crosswires, automatically, in accordance with acceleration errors, the remaining error, i.e. that causing displacement between the target and the visual ...

Improvements relating to interference suppression

... 929,360. Radar; radio receiving systems. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Dec. 4, 1952 [Dec. 4, 1951], No. 28425/51. Drawings to Specification. Classes 40 (5) and 40 (7). In a radar receiver consisting of a number of I.F. amplifiers, interference is suppressed by switching off the amplifier in the pass-band of which the interference frequency lies. The amplifiers have different pass-bands, in the region of the pulse carrier frequency, and are switched in and out of circuit either manually in response to a visual indication of the interference frequency, or automatically in response to the amplitude of the interference.

Improvements in voltage regulating apparatus

683,100. Automatic voltage control systems. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 23, 1951, No. 4455/51. Class 38 (iv). To maintain the output voltage of a D.C. supply constant, the rectified output of a thermionic oscillator is connected in series with the supply to variably boost the supply voltage ; the amplitude of the oscillations being controlled according to the output voltage. Variations in output voltage are applied through condenser 10 to the grid of an amplifier 13 directly coupled to the grids of a multivibrator 18, 19 to control the output which is coupled by transformer 26 to an amplifier 27, and this amplified output is coupled by a transformer 8 and rectifiers 9 in series with the positive line 3, 1. The output of the oscillator is rectified at 30 and a part fed back to the grid of valve 13 to stabilize the mean amplitude of these oscillations.