Patent GB-860837-A (GB)
Title: Improvements in telemetering systems
IPC: G01S13/46
Filed: 1958-11-05
Abstract: 860,837. Direction angle telemetering apparatus. UNITED STATES OF AMERICA, SECRETARY OF THE ARMY OF. Nov. 5, 1958 [Nov. 5, 1957], No. 35574/58. Class 40 (1). [Also in Group XL (c)] A telemetering system applied to radio direction-finding apparatus in which a line is produced on a cathode-ray storage tube of which the angle indicates the direction of the signal, has further means for generating a constant rate circular scan on the cathoderay tube which gives outputs when the beam crosses a datum position and the position of the line, means for generating timing pulses and a counter for counting the number that occur between the time the circular crosses the datum position and the time it crosses the line position. The apparatus may be for determining the bearing of an atmospheric electrical disturbance detected in a meteorological observation post. A crossed-loop aerial AE, Fig. 1, produces outputs from each loop proportional to the sine and cosine of the direction of the atmospherics signal. These signals are amplified to produce horizontal and vertical beam control voltages at 10 Kc/s. which are in phase but of amplitude depending on the direction of the signal. The beam is therefore caused to traverse a straight line, the angle of which represents the direction of the signal. There are also generated for application to the control plates of the cathode-ray tube, sine-wave voltages at 100 c/s and 90 degrees out of phase so that the beam moves in a circle at 100 revolutions per second. Switching means is provided to cause the beam to move in the direction indicating line and in the circle alternately, the straight line trace being made for about 5 milli-seconds. This is shown in Fig. 5 as the writing time, the beam then being switched back to the circular trace and completing the remainder of its course. The bearing of the signal picked up is # but since the circular scan and the line scan are independent the writing time may be in any position on the circle. The cathode-ray tube target consists of a mosaic of sensitive cells. As the beam traverses the circular track it generates a " video " signal where it crosses the line position because the charge on the target is different at this point. The angle # of the direction line is now represented by the timing between this signal and a pulse occurring at the datum position. The timing generator 300 comprises an oscillator and frequency divider and pulse forming circuits so that a pulse train of frequency 100 c/s is produced, Fig. 4 (D). These pulses are differentiated (E) and clipped to produce datum pulses which with the negative video pulse are as shown at G, Fig. 4, are applied to a trigger which is set by the datum pulse and unset by the video pulse. The output, which is as shown at H, is applied to close a diode gate which is normally open and connected to a source of 25.6 Kc/s. pulses. The reception of an atmospherics signal during a circular scan produces a video signal not during that scan but during the following scan and the time between the beginning of the scan t21 and the video signal t22 is proportional to the angle. During a complete circular scan 256 pulses are generated each representing an angle of about 1.41 degrees. These angle pulses are applied to a binary counter comprising eight trigger stages, counting up to 256. While no atmospherics signal is received the angle pulses flow into the counter which accordingly counts up to 256 and returns to zero at the beginning of each circular scan. The triggers are in any case reset to zero at the beginning of a scan by reset pulses F, Fig. 4. When an atmospherics signal is received a timed video pulse causes the trigger output H to become negative and the gate is closed to prevent further angle pulses reading the counter. The counters are reset at time t31, Fig. 4, and simultaneously the setting of each stage is transferred via diode gates to monostable multivibrators which are adjusted to provide pulse widths varying from one millisecond to eight milliseconds in sequence. Those multivibrators which are set, reset in order of their binary significance and pulses derived from the trailing edges of their outputs are used to trigger a monostable multivibrator having a time of one millisecond. The output from this is a serial mode binary number. The serial pulses are converted into a wave signal for wireless transmission to a central station by the transmitter 500. Central station.-The signal is received, demodulated and amplified to reproduce the binary number pulse train representing the bearing of the atmospherics signal. The pulses are gated under the control of eight differentially timed monostable multivibrators into eight storage triggers and thence in parallel into the stages of a binary counter. This counter is counted back to zero by pulses supplied at a rate 25.6 Kc/s. and the time taken, which is proportional to the direction angle # of the atmospherics, is sent to control a plotter. If three such atmospherics detecting outstations are positioned at spaced locations the actual position of the storm causing the atmospherics can be determined by the plotter at the central station and used for meteorological purposes.