FR2512197A1 - METHOD FOR ACQUIRING AND PROCESSING OUTPUT SIGNALS OF DETECTORS DURING AN OPTOELECTRONIC FIELD LIFT AND DEVICE FOR IMPLEMENTING SUCH A METHOD - Google Patents

Abstract

DEVICE FOR ACQUIRING AND PROCESSING DETECTOR EXIT SIGNALS, DURING AN OPTO-ELECTRONIC FIELD SURVEY, WITH A ROTARY MIRROR 9 OPTICALLY EXPLORING ADJACENT GROUND STRIPS 7 SUCCESSING IN THE DIRECTION OF FLIGHT 8 AND PROJECTING THOSE -CI ON THE RECEIVING SURFACE OF A DETECTOR 11. DETECTOR 4 IS FOLLOWED BY AN ELECTRONIC GATE 21 AND BY A SAMPLING CIRCUIT 22. A CIRCUIT 17 IS PROVIDED FOR THE PREPARATION OF THE TRAJECTORY DATA, WITH A ROTARY MIRROR 9 DRIVED AT A CONSTANT ROTATIONAL SPEED, WHICH CONTROLS THE ELECTRONIC DOOR 21 THROUGH A CONTROL PULSE DURATION ELABORATOR 20 WITH OPENING CONTROL PULSES 49 WHOSE VARIABLE DURATION IS INVERSE PROPORTIONAL TO THE HEIGHT OVERVIEW H, AS WELL AS THE SAMPLING CONTROL CIRCUIT 22 BY MEANS OF A GENERATOR 19 OF THE SUCCESSION FREQUENCY OF THE SAMPLING CONTROL PULSES 28 WITH A FREQUENCY WHICH VARIES PROPORTIONALLY TO THE OVERVIEW HEIGHT H.

Description

12197

  The present invention relates to a method for the acquisition and processing of detector output signals, during an optoelectronic terrain survey, particularly by infrared, carried out from a missile taking into account the height of the overflight of

  and explore one by one, assimilating them

  lines, successive strips of land

  whose length extends perpendicular to the direction

  the flight and projecting them on a detector,

  that a device for the implementation of such methods.

  This kind of method and arrangement for their implementation are already known from the German patent DE-PS 17 98 311 To ensure that despite the speed of

  high flight and also in case of fluctuations in this

  speed and height of overflight there is no discontinuity between the strips of land explored one after the other along the trajectory followed and which extend from both sides, perpendicular to the direction of flight, the missile has a number of detectors aligned one behind the other in the direction of flight, and the rotation speed of the rotating mirror is adjusted by means of a signal which varies according to the height of overflight and the speed of the missile For the elaboration of this signal, one records twice in succession, using the detectors, a point of the

  field, singular from the point of view of the treatment of

  and by means of image processing methods on which we will not dwell here, we determine in which direction this point moves in the recorded terrain band. The direction and amplitude of a

  such displacement provide a measure of the speed of

  dragging, which may be too fast or too slow, the rotating mirror, with the flight conditions at the instant considered, for optical scanning of the strip of land

  and (in a way that is not represented), we transform

  me this moving into a correction signal to edit

the speed of rotation.

  The main disadvantage of these already known provisions is that the speed of

  rotation of the rotating mirror according to the characteristics

  the overflights at the moment considered and, in

  because of the inertia of the electro-mechanical training system

  This can lead to misinterpretation and operational problems. Another inconvenience is also a comparison of images to determine the direction and the amplitude of the displacement of a given point. not only requires the implementation

  important means, but also that such exploitation

  Comparative comparison of signals is only possible with reliable results for particularly well-characterized points in the field, in a very

  net, relative to their environment.

  That said, the object of the present invention is to ensure the possibility of surveying the terrain

  considered from a missile flying over it in ex-

  ploring a succession of strips of land all

  equal treatment of the image information thus collected.

  with a constant resolution and in particular of nu-

  to merit this information, this with circuits and

  relatively simple, feasible in any case by

  appearance of standardized subassemblies of the information processing technique and a functioning mode of the rotary mirror which is reliable and does not risk provoking

  incorrectness in the treatment.

  With a device of the kind described in the preamble

  bule, this object is achieved, according to the present invention, essentially by the fact that the exploration of the strips of ground projected on the detector is done with a constant optical speed, that one quantifies and digitizes only a part of the signal of detector output, part of the shorter as the flyover is at a higher height, the quantization taking place with a frequency

  increasing in proportion to the

  overflight of the considered strip of land

  result is obtained according to the present invention in pre-

  for the exploration of the successive strips of land

  and their projection on the detector, a rotating mirror rotating at a constant speed; the output signal of the detector passes through an electronic gate and is then applied to a sampling control circuit; a device is provided for developing the data, height of overflight and speed, characterizing the trajectory, from these data other devices determine, on the one hand the duration of opening of the door, therefore the length of the band of field explored and the frequency of the control pulses of the sampling, so the resolution The duration of opening of the door varies inversely with the

  io overflight height, the frequency of sample pulses

  is proportional to this height.

  The basic idea of the solution is therefore, by renouncing the use of any intervention in the speed of rotation of the rotating mirror, which would be possible only with complicated and delicate equipment, to quantify

  to obtain the image of land strips of equal lengths

  only a part of the received signal, taken during a suitable time at the output of the detector by varying the duration of this sampling according to the height

  overflight, but at the same time

  time valb of the signal duration a number always equal to itself of digitizing pulses The height of overflight increasing and with a constant opening angle

  of the optical projection system, we will have an increase in

  the length of the strips of ground projected on the detector, during the exploration with the rotating mirror, but on the signal which appears at the output of the detector with an amplitude which fluctuates with time, for the subsequent processing only a short sample taken, centered on the total duration of this signal and corresponding to a specified length of the

  strip of land extending on either side of the

  As with a constant sampling frequency which would be used for the quantification and

  the digitization of this output signal of the detector, con-

  naked in time, with this shortening of the interval

  time it would be possible to collect only a certain number of

  their instantaneous amplitude amplitude reduces accordingly, the

  resolution of the information in the field, as well as

  would be subject to fluctuations, depending on the overflight height, the sampling frequency is adjusted so that it increases with the flyover height,

  so that even during the intervening times of treatment-

  of the detector output signal, maximum shortcuts, the same number of acquisitions of

instantaneous values.

  Thus, with purely electrical means, the quantization of the output signal of the detector is obtained an effect comparable to that of a "zoom" objective, namely the acquisition, independently of the distance, of a

  same domain of the object and this with a consistent resolution

  aunt, without the need for recourse to the use of an optical objective adjustable with mechanical means, with the complications and disadvantages

  which would result for implementation.

  So that the "sampling theorem" always remains satisfied, even in case of large fluctuations

  the flyover height and the large variations corresponding to

  of the sampling frequency it can be

  necessary to use additional low-pass filtering

  in addition to the characteristic low-pass characteristic of the

detector itself.

  In order to be able to carry out the opt-elec-

  tronic "without holes" of strips of land that succeed one another in the direction of the flight, while ensuring the conditions of validity of the "sampling theorem" and of being able to

  digitize the information collected for their

  later, it is properly installed in the detection

  in the manner already known from the publication analyzed in the preamble, several detector elements aligned one after the other in the direction of the flight, which is connected to a low-pass cell in number

  the larger the overflight height is

  It makes sense to connect in parallel

  two by two, the detector elements arranged symmetrically

  relative to a central detector element, a symmetrical variation of the

  reproduction in function of the overflight height at V'ins-

so much considered.

  The development of the variable quantities as a function of the overflight height, to act on the time interval during which the quantization of the output signal of the detector is carried out, with a number of snapshots of instantaneous values which remains constant, as well as only to switch the number of activated detector elements

  in the sense of theft, it is advantageous to resort to

  A signal proportional to the overflight height is obtained from the mutual correlations of sensor signals obtained with

  optical telescope systems oriented according to

  different gages in the direction of flight, weighted with a proportionality factor in which the instantaneous value of the speed of flight of the terrain and that of the angle between the respective orientations of the two telescopes intervene The speed, of its side, is obtained from the inverse value of the mutual correlative of the sensor output signals associated with optical systems having identical orientations, but offset

  relative to each other in the direction of the flight, multi-

  folded by a proportionality factor determined by the

  distance between said optical systems Such a treatment

  signal is much more reliable than the observation

  displacement of the image of a point of the field well

  determined but which can not be exercised

  because the acquisition covers the entire structure of

  the terrain overflown to obtain a result of

  correlation quite clearly, even with irregularities of

  little marked, it is advisable to provide, after the sensors of the differentiating stages, for a

  dynamic evidence, signal variations.

  The solution according to the invention can be used in a similar way, for example for the surveillance of terrestrial channels by radar scanning, or for the study of

  seabed by means of towed probes equipped with

  sonires and receivers sonar suitable Regarding the "missile" mentioned in the preamble, it must not necessarily be a projectile

  self-propelled or moving on a ballistic trajectory

  tick in the airspace, above the ground surface.

  Other features and advantages of the

  from the description below of an example

  a preferred embodiment of a device according to the invention.

  for the implementation of the method according to the invention, and which is shown in the drawing by limiting itself to

  the essential The different figures show respectively

is lying

  Figure 1, a simplified representation of the prin-

  optical system mounting system for the scanning of

  strips of land and the detector with the processing system

  following signal, in a missile above the area to be flown over, as seen

obliquely from the front.

  FIG. 2, an example of an output signal of the

  according to Figure 1, to explain the division,

  according to the height of overflight, an inter-

  suitable time in the duration of the signal, to work the analyzed strips of constant length independent of the overflight height, but without

  still take into account the constant resolution of the

  independent of the overflight height, and FIG. 3, in the form of a symbolic diagram, a circuit producing the flight data according to FIG.

  the mounting of the optical systems of the corresponding sensors

in the missile.

  The device sketched in FIG.

  you symbolically a missile 1, which flies over an area of land 2 by moving along it at a height

  instant flyover h and instant speed v.

  It is a question of ensuring aboard the missile I the acquisition of a

  digitized image point signals 3, supplied

  providing information on the peculiarities of the terrain zone 2 thus explored, for example on the two-dimensional distribution of terrain points 5 emitting more or less intense infrared radiation, which act one after the other on an infrared detector

  4 and which are transformed into electrical signals of

  of the detector 6 which succeed one another in time.

  For this, by means of a segmented rotary mirror 9 and through an optical condenser 10, on the receiving surface 11 of the detector 4 located in the focal plane of said condenser, projecting point by point, in form

  lines, strips of land 7 that extend

  specifically to the explored terrain zone 2, perpendicular

  cularily, therefore, to the direction of flight 8 followed

  missile 1 (actually slightly obliquely

  perpendicular to the direction of flight 8, because of the speed of flight v, but it was not taken into account in the drawing so as not to complicate it) In the path of the spokes, in front of the rotating mirror 9, one

  can insert in the manner known per se a deflect mirror

  correction unit 12, controlled by means of a

  compensation 13, stabilized for example by means of a gy-

  roscope, so as to tilt around its rotational axis

  14 parallel to the strips of land 7 to explore, so that in spite of possible tilting movements of the

  missile 1 on its trajectory, the rotating mirror 9 does not

  throws on the receiving surface II of the detector that the strips of land overflown at the instant considered and whose

it's about doing the survey.

  The rotating mirror 9 which deflects the acquisition radius 15 from the point of the ground along the strip of land 7 overflown at the instant in question, is driven by means of an electric motor device 16, with a speed of constant rotation It follows that for low flyover or survey heights h, the surface

  The receiver of the detector covers only a zone of

  rain 2 narrower, so 7 more land strips

  in a short time, while with large amounts of

  overflight h, we sweep in a longer time

  7 longer strips of land

  the simple formative nature of such reproducible field surveys, however, one must strive

  hover height h, as well as other criteria, if any,

  tiles, strips of land 7 of length always

  ticks converted with a constant resolution into a suc-

  assignment of digital image point 3 signals because

  above a rough terrain, the setting of this

  to a constant value can be made only in an approximate way and with the implementation of

additional important elements.

  In order to achieve this result, a cir-

  the development of trajectory 17 data (which will be described below in more detail), which, by means of a

  output signal 18 depending on the overflight height,

  requires a frequency generator 19, determining the rate

  of succession of control pulses of the sample-

  for example a frequency divider with a frequency

  high on its input, with a divisor ratio

  to be modified by electrical means and

  a gate-length pulse generator, for example a high frequency driven counter, whose

  output is activated between two different counting positions.

  symmetrical with respect to a counting position

median.

  Via the electronic gate 21, the

  output signal 6 of the detector, the evolution of which

  time corresponds to the image information collected in the form of a sequence of land points 5 distributed along the strip of land 7 explored optically at

  considered, is applied to the entry of a cir-

  fired sampling control 22 At the rate of

  sampling drives, this transmits the instantaneous values 23 taken during the opening time Q of the electronic gate 21 (see Figure 2) to an analog-digital converter 24, which retransmits the image point signals 3 , coded in binary, to a system 25 for further processing, for example for storing this sequence of image points 3 and / or for comparison with pre-recorded data relating to the terrain, in order to deduce other functions

  of control in relation to the implementation of the missile 1.

  With a constant value 26 of the scanning angle

  optical geometry of the ground strips 7, symmetrical with respect to the vertical of the missile 1 on the terrain zone overflown 2, with consequently a constant duration of the intervals

  between the optical scans of the successive lines,

  the constant rotational speed of the rotating mirror 9, the circuit 22 would be influenced, as was

  already mentioned, by strips of land of 7

  depending on the hovering height, as well as

  represented it symbolically in Figure 2 by the evolution

  time dependence of the output signal 6 of the

  In the case of a radiation sensitive detector 4

  the amplitude of the amplitude represents the radiation intensities corresponding to the different points of the image, and therefore of the terrain, during the linear optical scanning, as a function of time, of the

  ground 7 flown over at the moment considered; the instant t L cor-

  responding to the acquisition of point 5 of the terrain which lies vertically below the missile I defines so

  the moment when the "scanning radius" coincides with the bis-

  Scanning angle sect 26 To process only image signals 3 corresponding to field strips

  7 of constant length independent of the height of

  v Ql (symmetrical with respect to the foot of the vertical of the missile 1), so only to perform the survey of a terrain zone overflown 2, of constant width, for low values of the overflight height h it is necessary to choose an opening time 27 of the electronic gate 21 longer than for the survey at hight overflight h,

  this is shown in Figure 2 with the arrow

parameter.

  With a constant succession frequency of

  sampling control pulses 28, for the purpose of

  tention, from the evolution of the amplitude of the signal

  6 of the detector, the sequence of values instan-

  23 to be quantified, depending on the value insur-

  of the flyover height h, we would obtain, for

  the strips of land 7 which have just been acquired

  tion, a variable number of digitized image points 3,

  which would correspond to a variable resolution of the in-

  sampled image formation and would therefore be detrimental to subsequent computer processing, for example for comparison with an information model

  This is why, in the context of the present

  the invention, by means of the circuit for generating the data of the trajectory 17, the frequency of succession is increased

  sample control pulses 28 proportional

  tionally at the height of hovering variable variable missile

  above the strip of land 7, in other words, because of

  its inverse of the opening time of the electronic door

  that 21; this means that for short periods of time

  the door (see Figure 2), corresponding to a large

  hovering height h, the circuit 22 transmits to the

  24 more instantaneous values 23 more dense

  that for long periods of opening 27 of the door cor-

  corresponding to lower flyover heights, so that, contrary to what is shown in Figure 2, during each time interval during which the

  door 21 is open and corresponding to the information

  tive to the strips of land 7, one always obtains the same

  number of digitized image signals 3 representing a number of

  equal number of samples of instantaneous values 23 (see below). To be certain of satisfying the theorem of

  sampling throughout the range of

  In addition to the low-pass behavior inherent in the detector 4, it is necessary to add a low-pass element to the output 29 of the detector, in accordance with the frequency of succession of the sampling control pulses.

additional.

  For the development of the signal 18 representative of the height h, is provided on the missile 1 (see Figure 3)

  two sensors 31, 32 corresponding to the detector 4,

  to Terrain Zone 2, overflown by Missile 1,

  in two directions forming between them an angle of

  35 and determined by means of two optical

  telescope respectively 33 and 34 suitably

  Preferably, one of the optical systems, the 33, is oriented vertically, so that the length of the path of its sensing radius corresponds to the value of the height h at the moment considered, while the other system optical 34 is oriented obliquely, preferably forward Due to these geometric characteristics

  of assembly, it can be shown that the instant value

  The height of overflight h is proportional to the flight time necessary to cover in the field the distance 36, which corresponds to the side of the triangle opposite the opening angle 35 (it being assumed that the irregularities of the terrain can not give rise to only an error

  negligible interpretation, or provoke in the evo-

  the acquisition of such value changes, which can be achieved without further trial and

  on plausibility considerations, eliminate the

  their corresponding as errors of measurement) The coefficient of proportionality which intervenes in this

  operation is given by the product of the instantaneous speed

  born from missile I by the cotangent of the opening angle

35.

  The determination of the proportional time interval

  at the flyover height h, which separates the detections of any point of terrain 5 'by the ray paths corresponding to the two optical systems 33 and

  34 inclined relative to each other, is carried out pre-

  by means of a mutual correlation device 37 known per se, which receives the two output signals of the

  two sensors 31 and 32 It is known that the maximum of

  latives mutuelles, determined by means of a filter of values

* maximum 38, provides a measure of the time that elapses

  the two respective output signals of the detectors

  31 and 32 corresponding, if we neglect the angles of inci-

  dence, on receipt of the two rays emitted by

  the ground point 5 ', therefore a measure of the proportional time

  at the height h that was needed to fly over

the distance 36.

  To determine the instant flight speed v

  missile 1, which is included in the said proportion coefficient

  tionality, it is preferable also to use a

  correlation signals because the signal processing circuits that are then required are less complicated than for effect-based

  Doppler, which could have been used with a

  It is provided in the missile 1 another sensor 39, with an optical system 40 arranged parallel to one of the other two

  optical systems 33 or 34, in preference to the optical system

  that is oriented vertically As it is possible

  to demonstrate that the instantaneous speed v is inverse-

  proportional to the time taken by missile 1 to

  run the distance 41 physically separating the two systems

  For this purpose, the output signals of the two sensors 31 and 39, used for the determination of the speed of rotation, are applied to the optical correlations.

  theft, at the entrance of another correlation device

  42, to elaborate by means of another filter of maximum values 43, from the maximum of the function

  mutual correlation thus obtained, a measure of the in-

  time considered, so for the value v of the

instant flight speed.

  The output signal 18 representative of the height

  h and variable over time according to the characteristics

  of the land overflown, is then obtained as a

  of the two output signals of the manual value

  ximals 38 and 43 applied to the inputs of a multiplier 44, taking into account the information provided by two sources of constant values 45 and 46 attacking respectively a multiplier 47, as a representative value of

  the opening angle 35, and a divider 48 as dividing

  representative of the actual distance 41

31 and 39 -

  It is wise to provide sensors

  31, 32 and 39 of the differentiating stages 55 in order to

  kill, thanks to the high-pass behavior of these,

  variations in the area of the land, and to obtain

  if for mutual correlations, sensor signals with significant variations over time, even with terrain whose surface

is only slightly uneven.

  As one can be satisfied with precisions of comma of moderate, as for the electronic door 21 according to the height,

  whereas for the circuit 22, in the interest of the economy, it is sufficient to provide for both the generator of the sampling frequency 19 and for the developer 20 of the duration of the opening of the electronic door (see FIG. 1), information stored in tabular form which, according to the relations stored in memory, does not control a switching of the frequency of the sampling pulses 28 and, if appropriate, of the

  duration of the impulse 49 of activation of the door according to

  the instantaneous value of the overflight height v,

  in case of exceeding certain tolerance limits.

  Such arrays stored in ROMs can be judiciously incorporated into an information processing device designed to perform also the other steps of data processing, which is shown for simplicity, as part of the

  present description, in the form of a compound schema

  discrete blocks; particularly with regard to the circuitry of the trajectory data and the subsequent information processing circuit 25 which follows the digital analog converter 24, since this analogy-to-digital conversion is not already realized as that component

  periphery of the microcomputer, in accordance with the

  modern information processing devices.

  In particular, for carrying out the functions that have been described (and yet to be described) by means of a calculator adapted accordingly, it is advisable to replace the function of the electronic gate 21 and that of the developer 20 of the the pulse of variable duration that activates this gate 21 for a time which is a function of the flying height so that for the band of

  swept ground 7, that is for each scan cycle

  optical geometry by the radius of acquisition of the points of the ter-

  However, this is, as already explained above, with the variable frequency of the pulses 28, which results in a predetermined number of quantizations of the output signal 6 of the detector. control the sampling according to the overflight height and the time interval fluctuating in the opposite direction during which the quantification during

  optical scanning cycle (active segment of the mirror

  9), to obtain for the swept 7 strips

  one after the other, an always identical number of

  discrete instantaneous values of the amplitude.

  However, this corresponds for each acquisition cycle to a

  constant number of pulses 28, which control the functions

  sampling and analogue-digital conversion

  than; that is, instead of the function blocks represented

  in dotted lines in Figure 1, provision can be made for

  counter 56, adjustable if necessary, which determines the

  The number of active pulses 28 in each acquisition cycle (whose succession frequency is controlled according to the overflight height) for the implementation of the circuit 22 and the analog-digital converter 24, corresponds to the length of the strip of land 7 which is thus explored, to the width by

  consequently, of the zone of ground 2 which is surveyed.

  For this purpose, it is possible to have the sampling frequency generator 19 set directly in accordance with the

  height, the counter 56 determining the duration of ac-

  tivation of the door and which is released periodically by a control device provided on the rotating mirror 9; it is also possible to connect following this counter 56, as has been shown for the sake of clarity in the drawing, an "AND" gate 57 so that it passes each time z sample control pulses 28. this number z is reached, the counter 56 resets to zero and remains there until it is again started (released) by the rotating mirror 9 to recount again up to z the control pulses. provided by the generator 19 In order to avoid, in case of

  fluctuation of the height h, a reciprocal offset

  between the strips of land 7 explored after

  the others, we can thus symbolically represent

  In the drawing, since the rotating mirror 9 rotates at a constant speed, provide the triggering mechanism 58 mounted on the rotating mirror 9, with a suitable predetermination device of the triggering time of the counter 56, so that the number z of active pulses

  during a cycle is equally divided between

  from the moment of the overflight of the ground point 5 which

  located vertically, under the missile, at the instant

  when the active sector of the rotating mirror 9 is parallel to the receiving surface 11, that is to say where

  excites the central sensor element 50 ').

  The discontinuity of the processing of the output signal

  of the detector, which results from the fact that the latter

  the analog-to-digital converter 24 through the circuit 22 is not critical (from the point of view of compliance with the sampling theorem), as regards the succession of information along the strip of land 7 which is explored optically at the instant considered because, as already mentioned, the detector 4, used for the conversion of the input signal (infrared, for example)

  in an electrical output signal 6, has a

  low-pass that can be further strengthened in the case

  To the extent necessary, without any other form of trial, adding to the output a low-pass cell which is critical for the discrete signal processing, however, is that at the end of the optical exploration of a field strip 7, when passing to the ground strip 7 which succeeds the previous one, in the direction 8 of the flight, instead of a continuous evolution of the output signal 6 of the detector there occurs a " leap of information "The absence

  the effect of limiting the bandwidth by detecting

  4, which does not exist for this direction of scanning,

  limits the possibility of satisfying the "exchange theorem"

  therefore, non-continuous signal processing. In order to eliminate this limitation, it is

  ride on Missile 1, in the sense of Flight 8, to the

  detector 4, a number of detection

  50 and connect a larger or smaller number to the output 29 of the detector in inverse ratio

-12,197

  the instantaneous hovering height h of the ground, with insertion of a low-pass element 51 It is thus possible to vary according to the overflight height, the width

  taken in the direction of the flight of the strips of land 7 explo-

  one after the other with the optical scanning rotating mirror 9, in order to ensure proper reciprocal encroachments and, consequently, continuity

  the output signal 6 of the detector.

  In FIG. 1, provision is made for and the possibility of activating the different detector elements symmetrically with respect to a sensor element 50 'which is in the center and which is permanently connected to

  the low-pass element 51 through an amplifier

  neur 52 When the flyover height h decreases, the signal

  -15 18 representative of the height acts on a circuit of com-

  53 of the switches 54, which causes first of all

  activating the two closest detector elements-50

  Then, if the height h decreases further, that of the two detector elements 50 located outside In order to use a number of switches 54 as small as possible, the detector elements 50 which must be activated at the same time are connected directly in

  parallel, so that they do not require interrup-

  individual consumers connecting them to

  summation of the additional amplifier

neur 52.

Claims (8)

  1 Process for acquisition and treatment   of detector output signals during a survey of   Opto-electric rain, especially in infrared, made from a missile taking into account the height of overflight of the ground and consisting of exploring one by one, assimilating them to lines, successive strips of land the length of which extends perpendicularly to the direction of the flight and projecting them onto a detector, characterized in that with a constant optical scanning speed of the projected land strip on the detector, one does not quantify and digitizes only a part of the output signal of the detector, part all the more   shorter than the overflight height is larger, the amount   by sampling with a frequency of   this sampling that grows proportionally to the   height of overflight in relation to the strip of land considered   SOE. Process according to Claim 1, characterized   by the fact that low-pass filtering of the   detector output, before performing a sample   the instantaneous values of the amplitude of this signal.   3 Method for the acquisition and the processing of detector output signals during an optoelectronic field survey, in particular in infrared,   from a missile, taking into account the   overflight device according to one of the claims   I or 2, characterized by the fact that the length, taken in the direction of flight, of the strip of land explored   optically and projected on the detector, decreases proportionally   tionally at flyover height.   4 Process according to Claim 3, characterized in that the addition of the   out of several detecting elements that can be activated   individually in a greater or lesser number depending on the overflight height, the signal thus obtained being subject then to low pass filtering.   Method according to claim 4, characterized   by the fact that the switching of activation or deactivation   sensing elements, controlled according to the flying height, are symmetrically   other than a central detector element.   6. Process according to one of the preceding claims.   characterized in that a signal derived from the overflight height is generated from the mutual correlation of the signals provided by two sensors having a different optical orientation in the overflight direction,   multiplied by the inverse of the mutual correlative of   provided by two sensors with the same orientation   optically but offset from each other in the direc-   flight. 7 Device for acquiring and processing detector output signals during a survey   optoelectronics, for example in the field of infrared   from a missile (1) and taking into account the   overflight, in particular for the implementation of one   processes according to the above claims, with a   rotary mirror (9) optically exploring   adjacent grooves (7) succeeding one another in the direction of the flight (8)   and projecting them onto the receiving surface of a detection   tor (11) characterized in that the detector (4) is   followed by an electronic gate (21) and an exchange circuit.   (22) and that a circuit (17) for   trajectory data, with a rotating mirror   (9) driven at a constant speed of rotation, which   sends the electronic gate (21) through a processor of the duration of the control pulse (20) with pulses   opening command (49 ') whose variable duration is invert-   proportionally to the overflight height (h) as well as the sampling control circuit (22) by means of a generator (19) of the frequency of succession of the sampling control pulses (28) with a frequency who   varies proportionally with the overflight height (h).   8 Device according to claim 7, characterized   because the detector (4) has several   detecting elements (50) arranged one after the other   very in the direction (8) of the flight and which can be activated by the circuit producing the data of the trajectory (17) which connects them to the output (29) of the detector in number   inversely proportional to the overflight height (h).   9 Device according to claim 8, characterized   in that the sensor elements (50) connected to the output of the detector (29) are followed by a cell low pass (51).   Device according to any one of the   8 and 9, characterized in that the sensor elements (50) arranged symmetrically with respect to a   central detector element (50 ') are united together, electrically triply, two by two.   Apparatus according to any of the claims   8 to 10, characterized in that the circuit for   development (17) of the trajectory data comprises a mutual correlation device (37) actuated by two sensors (31, 32), whose optical systems (33, 34) have different orientations with respect to the direction of rotation.   (8), and a device for mutual correlation (42)   by two sensors (31, 39) provided with optical systems (33, 40) having the same orientation, but shifted relative to each other in the flight direction (8), the outputs of these correlation devices being connected to the entrances   of an output multiplier (44) via,   respectively, of maximum value filters (38, 43), a   multiplier by a constant value (47) and a division   by a constant value (48) for producing an output signal (18) representative of the overflight height (h).   Apparatus according to claim 11, characterized   rised by the fact that the sensors (31, 32, 39) are monitored differentiating stages (55).   13 Apparatus according to any one of the   7 to 12, characterized by the fact that the door   electronics (21) controlled by the device (20) for   the duration of the control pulse of the door, is replaced by a counter (56) for measuring the duration of the opening of the door, which is periodically triggered by the rotating mirror (9) and which allows the passage a number (z) of sampling control pulses (28)   whose value can be predetermined.