US3886460A

US3886460A - Pulse position discriminator

Info

Publication number: US3886460A
Application number: US239548A
Authority: US
Inventors: Robert E Wilson
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1951-07-31
Filing date: 1951-07-31
Publication date: 1975-05-27
Anticipated expiration: 1992-05-27

Abstract

1. A pulse position discriminator comprising, connection means for a source of repetitive pulse signals, means for phase inverting said pulse signals to produce a positive-going pulse signal and a negative-going pulse signal, connection means for a source of repetitive sawtooth reference signals, means for phase inverting said sawtooth signals to produce a positive-going sawtooth signal and a negative-going sawtooth signal, a pair of electron discharge devices having similar grid-anode characteristics and each having cathode, anode, and at least two control electrodes, each of said control electrodes being biased for operation in the linear portions of said characteristics and the gains of said tubes being controllable by the instantaneous potential applied to one of the control electrodes of each of said electron devices the anode electrodes of said discharge devices being connected together, means for applying said positive-going sawtooth signal to a control electrode of one of said discharge devices and for applying said negative-going sawtooth signal to an electrode of the other said discharge device to program the gains of said discharge device in opposing senses, the gains of said discharge devices being equal at the midpoints of said positive and negative going signals, means for applying said positive-going pulse signal to a different control electrode of the discharge device to which said positive-going sawtooth signal is applied and for applying said negative-going pulse signal to a different control electrode of the discharge device to which said negative-going sawtooth signal is applied, and an output circuit connected to said discharge device anode electrodes responsive to application of said pulse and sawtooth signals to said discharge devices for producing output signals having their polarities and amplitudes determined by the timing of said pulse signals with respect to said sawtooth signals.

Description

D United States Patent 1 1 3,886,460

Wilson May 27, 1975 PULSE POSITION DISCRIMINATOR tive sawtooth reference signals, means for phase in- [75] Inventor Robert E wflsnn Momesmwn N J verting said sawtooth signals to produce a positivegoing sawtooth signal and a negative-going sawtooth Assigneei RCA Corporation. New York, NY. signal, a pair of electron discharge devices having similar grid-anode characteristics and each having cath- [22] Flled' July 1951 ode, anode, and at least two control electrodes, each [21] Appl- 239,543 of said control electrodes being biased for operation in the linear portions of said characteristics and the gains [52] US. CL 328/109; 328/225; 330/1; of said tubes being controllable by the instantaneous 332/9 343/73 potentlal applied to one of the control electrodes of 5| Int. Cl H03k 5/20; Hb3k 7/04 said amde electmdes [58] Field of Search 250/27 PD, 27 F, 27.1-35, dscha'ge P W9 i 250/20282' 36.19 27 BT; 178/68, 695; means for applylng sa1d posltlve-golng sawtooth signal 343/74, 73; 177/245 328/109. 146 147 to a control electrode of one of said dlscharge devices 5 330 332/9 and for applying sald negative-going sawtooth signal to an electrode of the other said discharge device to pro- [56] References Cited gram U1; gains offsaidl giscgarge ctiievice is opposing] senses, t e gains 0 sal lsc arge evlces elng equa UNITED STATES PATENTS at the midpoints of said positive and negative going Norgaard t t t r Signals means for said positive going pulse 1463335 3/1949 Fredendan gt 250/3619 signal to a different control electrode of the discharge 3:33 2? device to which said positive-going sawtooth signal is applied and for applying said negative-going pulse sig- FOREIGN PATENTS OR APPL CA IONS nal to a different control electrode of the discharge 124,653 6/1947 Australia 343/74 e ice to which said negative-going sawtooth signal is Primary Examiner-Malcolm F. Hubler Attorney, Agent, or Firm-Edward J. Norton EXEMPLARY CLAIM l. A pulse position discriminator comprising, connection means for a source of repetitive pulse signals, means for phase inverting said pulse signals to produce a positive-going pulse signal and a negative-going pulse signal, connection means for a source of repetiapplied, and an output circuit connected to said dis charge device anode electrodes responsive to application of said pulse and sawtooth signals to said discharge devices for producing output signals having their polarities and amplitudes determined by the timing of said pulse signals with respect to said sawtooth signals.

1 Claim, 2 Drawing Figures REIT/FENCE S 00176 E PULSE POSITION DISCRIMINATOR This invention relates generally to electronic circuits having discriminatory response characteristics and more particularly to a pulse position discriminator for producing output signals having an amplitude characteristic which is proportional to the relative timing of a plurality of input signals applied thereto.

in different types of electronic systems and particularly in pulse radar systems it is advantageous to analyze periodically the time relationship between two given signals. In automatic radar target tracking systems, for example, the comparison of repetitive radar target echo signals with signals produced by a reference source provides a correction signal which enables the radar system to track certain selected targets.

The pulse position discriminator hereinafter disclosed and claimed includes a push-pull signal combining circuit for producing a control signal in response to said comparison, said signal having an amplitude characteristic which is determined by the relative occurrences of the signals therein compared.

An object of the present invention is to provide an improved pulse position discriminator.

Another object of the invention is to provide a pulse position discriminator for translating the relative timing of a plurality of repetitive signals applied thereto into a signal amplitude analogue.

A further object of the invention is to provide a pulse position discriminator especially suited for use with a radar automatic target tracking system.

According to a typical embodiment of the invention a plurality of sawtooth type wave signals are utilized as reference signals for comparison with different repetitive signals derived from some signal source which, by way of example, may be a pulse radar receiver. The sawtooth signals and the radar signals are applied to a signal combining circuit such that the signals are effectively superimposed. The duration of the reference signals is selected to be substantially greater than the duration of the radar pulse signals. Coincidently, these radar and reference signals are phase inverted and are applied to the same combining circuit such that the input circuit of said combining circuit operates in pushpull. When a given repetitive signal to be examined appears at the center of the linear portion of the sawtooth signal, the push-pull operation of the circuit causes sensing in the output and no signal is produced therefrom. In the event that the signal to be inspected is displaced in one sense from the center of the reference signal, an output signal of one polarity is produced having an amplitude proportional to said displacement, and if the signal is displaced in the opposite sense the amplitude characteristic is again proportional to the signal displacement but the polarity of the output signal is reversed.

The invention will be described in greater detail with reference to the accompanying drawing in which,

FIG. I is a schematic circuit diagram of a first embodiment of the pulse position discriminator of the invention; and

FIG. 2 is a schematic circuit diagram of a pulse position discriminator, according to a second embodiment of the invention, for use in an automatic radar target tracking system.

Similar reference characters are applied to similar elements throughout the drawings.

Referring to FIG. 1, signals produced by a source 1 of repetitive pulse signals are applied to a phase splitter device 3. Corresponding oppositely phased signals are therein obtained which are preferably capacitively coupled to the suppressor grids of different remote cut-off pentode tubes 5 and 7 having commonly connected cathode and anode circuits. These tubes 5 and 7 may be of the 6AS6 type which exhibits a sharp suppressor grid control characteristic. Substantially linear sawtooth wave signals are produced by a reference source 9 preferably at the repetition rate of the source of repetitive signals which are to be investigated. The reference sawtooth signals are then applied by some phase inverting means such as a transformer 11 to each of the 6AS6 tubes 5 and 7 simultaneously but in phase opposition.

By operating the 6AS6s so that the tubes operate in the linear region of their grid-anode characteristic curves, displacement of the pulse signals produced by the source 1 relative to the reference sawtooth signals is emphasized. It is apparent that if the pulse signals applied to each tube 5 and 7 effectively appear at the midpoint of their respective sawtooth signals, the gains of the tubes are equal, there is sensing in the commonly connected anode circuit, and no output signal is produced. If pulse signals occur earlier or later than the midpoints of the sawtooth wave signals, the gain of one of said tubes, for example 7, is greater than the gain of the remaining tube 5 and output signals are produced having amplitudes which are proportional to the relative displacement of these signals. Similarly, the occurrence of pulse signals later than the midpoints of the reference signals produces output signals having a similar amplitude characteristic but in this case the output signals are of the opposite polarity. An advantage of the push-pull input and parallel output connections herein disclosed is that the reference signals are eliminated from the final output of the discriminator.

In FIG. 2, a pair of pulse position discriminators are shown, according to the invention, which are adapted for use with an automatic radar target tracking while scanning system. In some target tracking systems different selected targets displayed on an electrical storage tube are periodically inspected one at a time by a small scanning raster. Deviation of a particular target from a prescribed portion of the raster causes an error signal to be generated which is fed to an error prediction circuit such as the presently disclosed discriminator. The output of the error prediction circuit is stored and subsequently utilized for positioning of the aforementioned raster for the next inspection of the previously mentioned selected target.

The first pulse position discriminator which includes tubes 5 and 7 parallel connected and operating in pushpull may be responsive to an X coordinate variation of a given radar target while a second discriminator having similar circuitry, designated by primes, is responsive to Y coordinate deviations. The sawtooth reference signal source 9 in this adaptation of the invention provides different frequency output signals for each coordinate error channel, the frequency of the reference signals depending upon the circuitry (not shown) for generating the inspection raster. Separate X and Y correction signals may then be obtained at terminals 13 and 15, respectively, in the output circuits of each of the pulse position discriminators.

What is claimed is:

l. A pulse position discriminator comprising, connection means for a source of repetitive pulse signals, means for phase inverting said pulse signals to produce a positive-going pulse signal and a negative-going pulse signal, connection means for a source of repetitive sawtooth reference signals, means for phase inverting said sawtooth signals to produce a positive-going sawtooth signal and a negative-going sawtooth signal, a pair of electron discharge devices having similar grid-anode characteristics and each having cathode, anode, and at least two control electrodes, each of said control electrodes being biased for operation in the linear portions of said characteristics and the gains of said tubes being controllable by the instantaneous potential applied to one of the control electrodes of each of said electron devices the anode electrodes of said discharge devices being connected together, means for applying said positive-going sawtooth signal to a control electrode of one of said discharge devices and for applying said negative-going sawtooth signal to an electrode of the other said discharge device to program the gains of said discharge device in opposing senses, the gains of said discharge devices being equal at the midpoints of said positive and negative going signals, means for applying said positive-going pulse signal to a different control electrode of the discharge device to which said positive-going sawtooth signal is applied and for applying said negative-going pulse signal to a different control electrode of the discharge device to which said negative-going sawtooth signal is applied, and an output circuit connected to said discharge device anode electrodes responsive to application of said pulse and sawtooth signals to said discharge devices for producing output signals having their polarities and amplitudes determined by the timing of said pulse signals with respect to said sawtooth signals.