Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/40—Means for monitoring or calibrating
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/28—Details of pulse systems
  • G01S7/285—Receivers
  • G01S7/295—Means for transforming co-ordinates or for evaluating data, e.g. using computers
  • G01S7/298—Scan converters

Definitions

• the subject of the present invention is a method for testing the operation of a device for displaying radar information, such as a digital image transformer, as well as its means of implementation.
• the present invention relates to a test method
• the equipment is then broken down into a few functions essential, at which comparisons are made between input signals and output signals of the function considered. It is then a question of verifying that, for a set of values given at the input of the function, the output result is indeed the expected result, the latter being obtained by calculating moreover, logically for example, the result which must be obtained by applying the function to the same set of input values.
• the input data of the function to be tested is useful data, which crosses the entire equipment processing chain; these data are then recorded at the input and output of the function under test; in deferred time, the function considered is subjected to the input recording in order to obtain theoretical output values which are compared to the recording of the actual output signals, and the result of the comparison then gives the indication of good or bad operation; "the data at the input of the function to be tested can be interrupted, either because they are a priori known, or because they are momentarily insignificant; a test sequence is then introduced at the input of the function considered; at the output of this function, the data corresponding to this sequence are on the one hand recorded and, on the other hand, obscured so that they are not transmitted to the rest of the processing chain; then the sequence of enter the function under test and verify, as before, the identity with the actual output sequence recorded.
• the advantage of the second method lies in the possibility of choosing the test sequence, which can then be more particularly adapted to the function to be tested and therefore of better efficiency. Its disadvantage is that it is necessary to have a free range where. the data is only not significant or have a particular known value, which can be restored at a point further down the processing chain.
• an area is determined during a given antenna turn. 'there is no radar echo; knowing the speed of the objects viewed (planes for example), we determine a second zone, located inside the first, where there will certainly be no echo during the next antenna turn, and we operate substantially according to the second method described above, by inserting then occulting test sequences.
• the method according to the invention is a method of testing in operation a device for displaying radar information, the latter being obtained by successive scans of a predefined area;
• the device comprises a processing chain in which a first determined function, at least, is executed;
• the process mainly comprises the following steps:
• Figure 1 is therefore a block diagram of a digital image transformer used for viewing radar information.
• a digital image transformer also called TDI, allows the visualization in television mode of information supplied by a radar receiver in polar coordinates.
• TDI is described in the request for French patent 85,05013 in the name of THOMSON- CSF. Such a TDI can be broken down into a few subsets, each performing an independently testable operational function:
• sub-assembly 1 forming an input interface and connected to the radar receiver;
• a memory subset 3 in which the radar information is recorded in the format in which it will be viewed in television mode by a device 4 (Cartesian coordinates).
• the main function of the interface 1 is the acquisition of the radar video signal, namely its sampling, its digitization and its storage, as well as, where appropriate, certain brief processing operations on this video signal.
• the coordinate conversion subset 2 allows the calculation of the address in memory (3) of each of the points of the radar video signal.
• the memory sub-assembly 3 also includes remanence circuits, ensuring an artificial aging of the information stored as the radar antenna rotates, thus simulating the remanent screens.
• the processing chain described above can also include a sub-assembly for inserting a synthetic video, consisting of cards, tracks and pads, which is sent to the device display 4 in synchronism with the television scan, this sub-assembly being arranged between the memory 3 and the display 4.
• FIG. 2 represents a method of carrying out the method according to the invention for testing a function provided by one of the subsets of the previous figure.
• the radar video signal is obtained by successive scans of a predefined area; it may, for example, be scans by rotation of an antenna over 360 °; it is for example in the latter case that we place our for the following description.
• the first step, identified 21, consists in analyzing the incident video signal,. that is to say the one which arrives at the input of the function to be tested, denoted F, in order to determine an area, or. window, called Z Q , in which there is no radar echo, that is to say where the video signal is substantially zero or less than a predefined detection threshold, and this for a determined antenna turn , noted T.
• the next step, marked 22, consists in determining a second zone Z- in which, for sure, there will be no echo on the next antenna turn (denoted T + 1).
• zone Z .. is then defined as a zone located inside zone Z -. at a distance at least equal to the maximum speed of the mobiles multiplied by the time which separates two scans, that is to say the period of rotation of the antenna.
• the zones Z n and Z .. are illustrated in FIGS. 5 to 7.
• the next step, marked 23, consists in transmitting at the input of the function F a series of signals forming a test sequence; this emission is carried out in turn T + l, during at least part of the video corresponding to the zone z r
• test sequence is processed by the function F under test, then recorded at its output during the next step, marked 25.
• test sequence is concealed at the output of the function F during a step 26, of so as not to be passed on to the rest of the processing chain.
• theoretical value of the test sequence is calculated (step 24) when the function F is applied to it.
• step 27 this theoretical value is compared (step 27) to the real value previously stored (step 25), the result of the comparison providing error or correct operation information of the function F.
• FIG. 3 represents an embodiment of the method according to the invention for testing the various functions of a digital image transformer, such as that described in FIG. 1.
• the three sub-assemblies 1, 2 and 3 of FIG. 1 are therefore independently tested, the functions fulfilled by these sub-assemblies being designated respectively by F .., F "and F ,, all s 'performing under the command and control of the processor 5 of Figure 1, not shown here.
• the incident radar signal is supplied to a circuit Z for determining the zone Z ⁇ , then an insertion circuit I .. before arriving at the interface 1 (function F.,).
• the function of circuit Z is to detect an area without echo such as Z ⁇ , allowing the processor to deduce Z 1 therefrom.
• the function of the insertion circuit is to transmit, at the next turn, at the input of interface 1 a predefined test sequence, more particularly adapted to the test of this interface.
• the interface 1 is followed by an acquisition circuit A .., allowing the storage of the test sequence after its exit from the interface 1, then by a concealment circuit O 1 of this test sequence, so that it is not passed on to the rest of the processing chain.
• FIGS. 4a to 4d each represent an embodiment of the circuits used in FIG. 3.
• FIG. 4a represents the circuit Z for determining the zone Z Q.
• the circuit Z is placed in parallel on the arrival of the radar signal on the insertion circuit L,. It comprises :
• a circuit 40 receiving the incident radar signal and a reference signal REF Q , which is a threshold below which the incident signal is considered to be zero; this circuit thus permanently detects areas where there is no radar echo;
• a comparator 42 which. receives, on the one hand, the pair of the current values (p, ⁇ ) and, on the other hand, the couples (p Q , ⁇ Q ) m and (p 0 , ⁇ Q ) M of these values defining the window Z 0 (illustrated in FIG. 5) which are supplied to it by the radar processor 5 when the values (P, ⁇ ) are included in the window Z_, the comparator 42 emits a validation signal, denoted VALID;
• a logic circuit 41 such as a flip-flop, receiving the VALID signal and the result of the zero test; flip-flop 41 supplies the radar processor (5) with a detection signal of Z n when it effectively detects a zero video in the window Z 0 which is supplied to it.
• FIG. 4b represents an insertion circuit I, such as I- j , I Crowor L , placed upstream of a function F to be tested.
• Circuit I includes:
• comparator 45 analogous to comparator 42 of circuit 7 (FIG. 4a), which receives the pair of values
• a switch 43 interposed on the path of the incident signal to the function F, controlled by the generator 44 and ensuring the switching between the incident signal and the test sequence.
• FIG. 4c represents an acquisition circuit A, such as A.,, A "or A", placed in parallel on the output of a function F to be tested.
• This circuit A also includes a comparator, analogous to comparator 42 or 45, making it possible to control the writing in a memory 45 of the test sequence at the output of the function F, in the reception window (p, ⁇ ) m (by
• memory 47 stores the test sequence to transmit it to processor 5.
• FIG. 4d represents a concealment circuit O, such as O., OBOOKor O 3 , placed in the processing chain at the output of the function F under test.
• circuit O includes: - a comparator 48, emitting a validation signal (VALID) when it identifies the occultation window (for example Z-, FIG. 6) which is supplied to it by processor 5; a logic circuit 49, of the AND type, interposed on the path of the output signal of the function F and inhibiting the transmission of this signal under the control of the signal VALID.
• FIG. 5 represents another embodiment of the method according to the invention, also in a digital image transformer such as that shown diagrammatically in FIG. 1, but in which a certain number of the circuits 5 described in FIG. 3 are eliminated, in order to '' lighten the realization of the device.
• the circuit Z for determining the zone Z fl no longer appears in FIG. 5.
• This function is only fulfilled at the level of the acquisition circuit A., knowing that a non-zero video signal, in a given range, at the output of interface 1 can mean either that the video is not zero at the input of the TDI, or a malfunction of the subset 1.
• _ decrease the size of the window (Z 0 ) in which a zero video signal is sought and vary the detection thresholds from zero. If it is then not possible to find a zero video zone, it is probably a defect in the subset 1.
• the concealment circuit O has also been removed.
• the memory function (F_) includes a remanence function which is exerted on several turns of
• the acquisition circuit A. (or A n in the case of FIG. 3) must take account of this persistence, that is to say detecting a zone Z_ sufficiently large so that it can - be determined a zone Z 1 which, after several turns antenna, or of still sufficient size (see Figure 8).
• the remanence function in the zone considered is accelerated or completely eliminated.
• the acceleration of the afterglow can, in another alternative embodiment, be made a function of the proximity of detected echoes of the zones concerned.
• the insertion circuit I, of FIG. 3 has also been deleted from the embodiment of FIG. 5, the test sequence used for the function F ⁇ being generated by the circuit I_ for example, it being understood that the the Oluiconcealment circuit is not permanent.
• the insertion circuit I- is deleted, the test sequence of the function F drapethen being generated by the circuit I ...
• test video must be hidden (circuit O before viewing 4.
• FIG. 6 is a diagram illustrating the different zones in which the tests are carried out with regard to the interface function F.
• zone Z which is, as we recall, an echo-free zone (with substantially zero video) detected during a given antenna turn T.
• the zone Z ′ is for example limited by two radials R and
• test sequence is therefore emitted in place of the incident video signal at the time corresponding to the scanning of this zone Z .., for example in a zone Z-.
• the video signal is obscured using for example the window Z .. and the test signal is memorized by the circuit
• FIG. 7 represents a diagram similar to that of FIG. 6, but for the test of the function F hinderof coordinate conversion.
• the video signal is expressed in polar coordinates upstream of the coordinate conversion subset 2, but in Cartesian coordinates downstream of this subset, in accordance with the organization of the memory 3.
• a window Z has also been represented corresponding to window Z., that is to say a window without echo at the antenna turn T + 1, but expressed in Cartesian coordinates, that is to say a rectangular window strictly included in window Z .. and which is used as occultation window for the circuit Odium, since at the output of the conversion sub-assembly 2, the data are expressed in Cartesian coordinates.
• FIG. 8 is a diagram similar to the previous two, but which relates to the test of the memory subset 3.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Radar Systems Or Details Thereof (AREA)

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• 1987
  • 1987-05-15 FR FR8706846A patent/FR2615291B1/fr not_active Expired
• 1988
  • 1988-05-10 JP JP63504108A patent/JPH02503471A/ja active Pending
  • 1988-05-10 WO PCT/FR1988/000228 patent/WO1988008987A1/fr not_active Application Discontinuation
  • 1988-05-10 EP EP88904241A patent/EP0362236A1/de not_active Withdrawn
  • 1988-05-10 US US07/455,439 patent/US5014065A/en not_active Expired - Fee Related

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