CA1238399A - System for displaying solid radar and/or sonar targets on a television monitor or other raster scan display - Google Patents
System for displaying solid radar and/or sonar targets on a television monitor or other raster scan displayInfo
- Publication number
- CA1238399A CA1238399A CA000482343A CA482343A CA1238399A CA 1238399 A CA1238399 A CA 1238399A CA 000482343 A CA000482343 A CA 000482343A CA 482343 A CA482343 A CA 482343A CA 1238399 A CA1238399 A CA 1238399A
- Authority
- CA
- Canada
- Prior art keywords
- coupled
- output
- signal
- azimuth
- information
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Radar Systems Or Details Thereof (AREA)
Abstract
ABSTRACT
The invention of this disclosure is a system for filling in holes on a television monitor or other raster scan display which result when information is transformed from one coordinate system that represents a series of locations by at least a series of first and second numbers to another coordinate system that represents a series of locations by at least a series of third and fourth numbers. The apparatus of this invention accomplishes the foregoing by doing extra conversions for each first number at slightly different second numbered values, thereby producing slightly different third and fourth numbered values which will fill in the holes of the display.
The invention of this disclosure is a system for filling in holes on a television monitor or other raster scan display which result when information is transformed from one coordinate system that represents a series of locations by at least a series of first and second numbers to another coordinate system that represents a series of locations by at least a series of third and fourth numbers. The apparatus of this invention accomplishes the foregoing by doing extra conversions for each first number at slightly different second numbered values, thereby producing slightly different third and fourth numbered values which will fill in the holes of the display.
Description
1~:3~
_CKGROUN~ OF THE INVE TION
Field of the Invention This invention relates to electronic circuits, and more particularly to devices for electronically controlling television monitors or other raster scan displays to display radar and sonar information.
Descri~tion of the Prior Art The increased traffic in the air and on the sea has caused an increase in the number of air and marine collisions. In addltion to the loss of life and human hardships, property losses have been great. Reasons for such collisions are many and complex, but one of the most important of these is the lack of proper use of radar and sonar systems.
Radar and sonar systems produce signals which have the capability of penetrating fog, darkness, rain, ha~e, and locating objects which are a great distance from the source that generated the signals. Radar detection of an object is achieved by transmitting a beam of radio frequency (RF) energy and detecting the energy reflected by the object. A small part of the RF energy is reflected by the object back to a sensor located near the transmitter. Radar ranging is accomplished by timing the period required for the RF energy to make the round trip from the detected object to the transmitter. The distance to the detected object is equal to one half the time elapsed for the RF energy to make the round trip times the velocity of the RF energy. Sonar detection is similar to radar detection; however, acoustic radiation is the energy radiated rather than RF.
Prior art, radar and sonar system displayed radar and sonar information on CRT's that used a plan-position-indicator (PPI) format sweep. PPI systems were completely analogue systems with no digital storage capability. Thus, if you wanted to display the same radar or sonar information on more than one PPI display, you had to connect all of the outputs of the radar or sonar receiver to each PPI display that was going to display information. Another disadvantage of the PPI display was that the display was only clearly visible in a dark room or the operator 1~3~ 3 had to use a hood while looking at the display. The aforementioned type of display viewing caused operator fatigue.
As the prior art advanced the radar or sonar information was processed, stored in large memory integrated circuit arrays, and then displayed on television monitors. Many television monitors were able to display the same information with only one television cable being connected between each monitor. A television (TV) monitor also caused less operator fatigue since it could be used in a room that was illuminated by sunlight or other means of illumination.
The radar or sonar information was in polar coordinates (R, O) where R rho represented the range and Ç) theta represented the bearing. The TV monitor displayed information in a cartesian-coordinate-type format. Polar-coordinate radar or sonar information was converted into cartesian coordinates (X, Y) and then stored in large memory integrated circuit arrays. The expression for the conversion of the X position data is R Sin 0, and the expression for the conversion of the Y position data is R Cos 0. The aforementioned conversions must constantly take place as the antenna pointing vector moves around or sweeps the monitor. When the polar coordinate radar or sonar information was converted intocartesian coordinate information there were some X, Y locations in the memory array that did not have polar coordinates associated with them. Therefore those X, Y coordinates would never have any information in them. This tended to create the illusion of holes in the displayed television monitor picture. Thus one of the disadvantages of the prior art was that an operator looking at the television monitor would see some returns as multiple returns instead of one return. The reason for this is thst some of the X, Y coordinate information was missing and holes would appear in the return. The foregoing made it difficult for the operator to use the TV monitor.
Another disadvantage of the prior art was that when multiple radius offsets were displayed on a TV monitor, the lines radiating from the center of the monitor would be sufficiently far apart so that when they are displayed the return wouldappear as multiple returns. The reason for the foregoing is that as the range of the display increased, the lines radiating from the center of the monitor did not increase in number and they were now far enough apart that holes were present onthe return. This made it difficult for the r adar or sonar operator to use a television monitor in a multiple radius offset mode.
SI~MMARY OF TlIE INVENTION
This invention overcomes the disadvantages of the prior art by providing a system that fills in the holes caused by the rho-theta-to-X-Y conversion processand the gaps in inforiJ)ation caused by ~erforming multiple radius offsets of the television monitor. The foregoing is accomplished during the rho-thets-to-X-Y
conversion process by performing extra conversions for each rho at slightly different theta values, thereby producing slightly different X and Y values which will fill in the holes. This effectively simulates an increase of the number of azimuth data bits and the number of radar triggers. When the apparatus of this invention knows that an angle has been skipped due to an insufficient number of radar triggers, then the skipped angle may be filled in by extending the extra conversions to cover the skipped angle. Without departing from the spirit of this invention, otller missing information resulting from transformations from one coordinate system to another coordinate system may be accomplished, i.e., spherical coordinates to cartesian coordinates, elliptical coordinates to cartesian coordinates, and hyperbolic coordinates to cartesian coordinates. Since the circuitry for filling in the missing holes for the other transformations is the same as the circuitry for filling in the missing holes resulting from the rh~theta-to-X-Y
transformation, only the rho-theta-to-X-Y conversion will be discussed as this description continues.
Missing information is also created by a typical radar transmitter/receiver or display device, since the azimuth data theta is ordinarily digitized into 12 bits.
Therefore, there are 4,096 possible angles at which radar data may be displayed or stored. To store radar data at all of the 4,096 possible angles requires at least 4,096 radar triggers per antenna revolution. But, because of a radar system's antenna rotation speed and radar trigger pulse repetition frequency (PRF), many radar systems have fewer than 4,096 radar triggers per antenna revolution. This means that at several positions on the TV monitor, the angle will change twice between radar triggers and that an entire angle will contain no data on the TV
monitor. Therefore, the entire angle that was skipped will have holes in the displayed picture.
It is an object of this invention to provide a new and improved system for dispiaying radar and sonar information on a television monitor or other raster scan display. It is another object of this invention to provide a new and improved system for filling in the missing information that results when a transformation takes place from one coordinate system to another coordinate system.
It is a further object of this invention to provide a new and improved system that provides the missing information on a TV monitor or other raster scan display when multiple radius offsets are performed.
Other objects and advantages of this invention will become apparent as the following description proceeds, which description should be considered together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1 and 2 are block diagrams of the electrical system that comprises this invention.
DESCRIPTION OF THE PREFERRED EMBODI~1ENT
Referring now to the drawings in detail, the reference character 11 designates a radar antenna that receives return information. Antenna 11 is coupled to a radar transmitter/receiver 12. Characters 11 and 12 are included in Figure 1 for reference only and may be replaced by any suitable device, such as a sonar system. Transmitter/receiver 12 provides three basic output signals, line 13 azimuth data (theta), line 14 radar video, and line 15 radar trigger which are coupled to the radar video processing system 20. Line 13 transmits antenna azimuth information, theta, as either analogue synchro data that must be digitized, digit~l clock pulses (ACP/ARP) that must be counted or digital data that may be directly used, from transmitter/receiver 12 to the input of digitizer 16 of radar video processing system 20. The digitizer 16 either digitizes the synchro data, counts the ACP/APR clock pulses or passes through the digital data depending on the form of the received data. Line 14 transmits radar video information as either analogue video that must be digitized, or digital video and clock that may be directly used, from transmitter/receiver 12 to the input of A/D (analogue to digital) converter 17 - it is assumed in Figure 1 that the radar video information received by A/D converter 17 is in analogue form. Line 15 transmits radar timing information in the form of either a zero time radar trigger, or a pre-zero time trigger from the transmitter/receiver 12 to the radar video processing system 20.
Radar video processing system 20 is shown with a minimum of detail based on the following assumptions: the azimuth data 13 is svnchro data, the radar video 14 is :L~3~
analogue video, and the radar trigger 15 is a zero time trigger. The radar videoprocessing system comprises at least the following basic functions: an azimuth data digitizer 16, a radar video A/D converter 17, a range counter 18, and a range clock 19. The radar trigger signal (zero time trigger) is transmitted via line 1~ to range counter 18 and to one of the inputs of azimuth change detector and change counter 22. One of the three outputs of range clock 19 is coupled to the clock input of range counter 1~. The second output of clock 19 is coupled to the clockinput of A!D converter 17 and the third output of clock 19 is coupled to one of the inputs of AND gate 31. The output of the range counter 18 is coupled to the input of data holding register 28 and to the input of range window decoder 26. The output of range window decoder 26 (the range window is typically three bits) is coupled to the input of data holding register 29. The output of AiD converter 17 is coupled to the input of data holding register 27 and to the inputs of OR gate 30.
OR gate 30 "OR's" the digital video data and determines when video is present.
The output of OR gate 30 is cc~upled to one of the inputs of AND gate 31. The output of AND gate 31 is coupled to: the clock inputs of data holding registers 2~, 28 and 29; the start clock input of clock generator 32; and the trigger input of one-shot 60. The output of AND gate 31 is used to store the digital data in data holding registers 27, 28 and 29 and to start a R~-to-X-Y and hole fill-in conversion cycle for the current data. The azimuth data on line 13 is digitized by digitizer 16. The output of digitizer 16, line 21, is the digital azimuth data which will be hereinafter referred to as angle theta. Several of the least-significant-bits of angle thetatypically one to four bits are coupled to azimuth change detector and change co.lnter 22 and to azimuth rotation and direction detector 23. The output of:
register 29; counter 22; and the two least-significant-bits of angle theta are coupled to the input of ROM data look~up table 34. The input of one-shot 60 is coupled to the output of AND gate 31 and the output of one-shot 60 is coupled tothe reset input of number of cycles performed counter 33. Each time AND gate 31 produces an output pulse, one~hot 60 resets counter 33 and clock generator 32 istriggered to start generating clock pulses. ROM data look-up table 34 has three outputs. The first of which "the number of hole fill-in cycles to be performed" is coupled to one of the inputs of comparator 38, and the second output "the first value of delta theta" is coupled via line 40 to one input of multiplexer 39. Thethird output of ROM 34 is "the incremental value of delta theta" which is coupled via line 41 to one of the inputs of adder 42. The output of clock generator 32 is coupled to the clock input of counter 33, the clock input of register 44, the clock _ j _ 3~3~3 input of the R Ç)'-to-X-Y converter 45 and the store conversion input of raster scan converter memory system 37. The "number of cycles performed" output of counter 33 is coupled to comparator 38 and to count equal to one decoder 51 via line 50.T~le t'equal" output of comparator 38 is coupled to the stop clock input of clock generator 32. The output of the count equal to one decoder 51 is coupled to the select input of multiplexer 39. When the value of line 50 is equal to one the output of decoder 51 is coupled to the select input of multiplexer 39. When the value of line 50 is equal to one the output of decoder 51 causes multiplexer 39 to pass the data on line 40 to the input of register 44. Otherwise the output of sdder 42 isinput by multiplexer 39 and is passed to register 44. The output of register 44,delta theta, is coupled to one of the inputs of adder 42 and to the delt~ theta input of adder/subtracter 24. The angle theta is transmitted via line 21. Line 21 couples the output of digitizer 16 to the input of adder/subtracter 24. The output of azimuth rotation and direction detector 23 is coupled to the control input of adder/subtracter 24. The aforementioned signal determines if adder/subtracter 24should add or subtract delta theta to theta. The output of the adder/subtracter 24 is O' which is coupled to the O' input of the R~)'-to-X-Y converter 45. The range data from data holding register 28 is coupled via line 3~ to the R input of R~)'-to-X-Y converter 45. The outputs of the R~)'-to-X-Y converter 45 are the X and Y
data converted from the R and ~' data. The X and Y data from the R~)'-to-X-Y
converter 45 and the video data line 36 from the data holding register 27 are coupled to the inputs of the raster scan converter memory system 37. The output of system 37 is a television video signal which is connected to the input of television monitor 55.
Radar transmitter receiver 12 outputs antenna azimuth information, radar video in analogue format and radar triggers. Digitizer 16 digitizes the azimuth information to produce a digital azimuth, i.e., angle theta. Angle theta is N bits wide, and for purposes of this description N will be equal to 12 bits. I~etector 23 utilizes the least-significant-bit of the aforementioned 12 bits to determine the direction of rotation of antenna 11, i.e., clockwise or counterclockwise. Azimuth change detector and change counter 22 utilizes three of the aforementioned 12 bits and the radar trigger signal from receiver 12 to count the number of angle changes per radar trigger. Adder/subtracter 24 receives the entire 12 bits via line 21.
The analogue radar video signal produced by receiver 12 is digitized into a 4 bit digital video signal by A/D converter 17. When the aforementioned digital signal consists of anything other than aL zeros, gate 30 will be enabled. The digital video signal is also transmitted to the input of data holding register 27. The output of gate 30 is also one of the inputs to AND gate 31. The radar trigger signal ~3~
?roduced by receiver 12 resets range counter 18. Counter 18 is clocked by a continuously running range clock 19. Range clock 19 is related to the displayed range of the recei~ed radar signal, i.e., the range scale may be changed by changing the frequency of the range clock. The digital range data outputted by counter 18 is transmitted to the input of data holding register 28. The aforementioned range data is decoded by range window decoder 26 into a 3-bit word before being transmitted to the input of data holding register 29. Decoder 26 is essentially a ROM which contains information to specify in which of eight range windows each instantaneous range count falls. The range window boundaries are programmed into the ROM to determine when hole fill-in cycles are to be performed, because of the inadequacy of the rho-theta-to-X-Y conversion process.For each increment of the 3-bit output, one additional cycle will be performed.
The second input to AND gate 31 is the output of clock 19. Thus, gate 31 will beenabled when video data is present on one of gate 31's inputs and h clock pulse is present on the second input to gate 31. When gate 31 is enabled the digital video information will be clocked into register 27, the digital range data will be clocked into register 28, the digital range window data will be clocked into register 29, clock generator will start and one-shot 60 will be fired to reset counter 33 to a c~unt of one. Once generator 32 starts, it outputs a stream of clock pulses until it is told to stop by the stop clock signal which is the output of comparator 38. Each of the aforementioned clock pulses advances the count of counter 33, loads register 44, does a conversion cycle on rho-theta-to-X-Y converter 45 and signals raster scan converter memory system 37 to store the results of the conversion performedby converter 45. Additional azimuth resolution is created to fill in the holes caused by having insufficient azimuth resolution by taking the least-significant-bit from the output of digitizer 16, the output of detector 22, ~nd the output of register 29, and coupling them to the three inputs of ROM data look-up table 34.The information contained within table 34 generates a number representing how many hole fill-in cycles must be performed, a first value of delta theta, and anincremental value of delta theta from the input data consisting of the number ofazimuth changes per radar trigger pulse, range window count, and two least-significant-bits of the antenna azimuth angle. ROM 34 has three outputs, the first of which represents the number of hole fill-in cycles to be performed. The aforementioned output is coupled to the input of comparator 38. The second output of ROM 34 is the first value of delta theta which is transmitted via line 40 to one of the inputs of multiplexer 39, and the third output of RO.~ 34 is line 41 lZ;38;~
which transmits the incremental value of the delta theta signal to the in?ut of adder 42. ROM 34 performs two functions; it fills in the holes, and it fi11s in the skipped angles due to there not being a sweep for every angle that digitizer 16 can digitize. ROM 34 uses the decoded range from decoder 26 and register 29 to fiU in the missing holes. The output of counter 22, i.e., the number of azimuth changesper radar trigger, and the output of digitizer 16 are used to fill in the skipped angles. Skipped angles will occur when there are fewer radar triggers then the number of angles that azimuth digitizer 16 can digitize. In this example the azimuth angle is digitized to 12 bits and the binary number 212 is equal to 4,096.
Thus, if there were fewer than 4,096 radar triggers per antennh 11 rotation there will be some skipped angles. The skipped angles will create extra holes which are slightly different in nature from the basic holes this system was trying to fill in.
However, the apparatus of this invention will fill in both of the foregoing tvpes of holes in the same manner.
For purposes of illustration we will assun e that the apparatus of this invention is operating within a range window where the table contained within ROM 34 states that only one cycle needs to be performed. Hence, in that case theinput to comparator 38 would be equal to one. Once counter 33 was reset to one by the output of one-shot 60, counter 33 will have an output signal that is equa] to one which will be transmitted to the input of comparator 38 and the input of count-equal-to-one decoder 51 via line 50. Comparator 38 will now have the same valuedsignal on both its inputs causing the output of comparator 38 to output a signal that will stop clock 32 from outputting clock pulses. The output of decoder 51 will cause multiplexer 39 to select the signal appearing on line 40, i.e., the first value of delta theta. This signal will pass through register 44 and become the delta theta signai. The delta theta signal is coupled to one of the three inputs of adder/subtracter 24. The aforementioned signal will be added to or subtracted from the original delta theta signal appearing on line 21 to produce a theta prime signal on the output of adder/subtracter 24. It will be added if detector 23 transmits a signal via line 25 to one of the inputs of adder/subtracter 24 indicating that antenna ll is turning counterclockwise and it will be subtracted if detector 23 transmits a signal via line 25 indicating that antenna 11 is turning clockwise.
rIence, the fill-ins will always occur behind the sweep. The theta prime signal will be coupled to one of the inputs of ~'-to-X-Y converter 45, and the digital rangesignal will be transmitted to one of the inputs of converter 45 via line 35.
Converter 45 contains look-up tables and digital multiplier circuits. The look-up ~383~
tables provide sines and cosines of the various values of theta prime. The multipliers generate the product of the range and the sine of theta prirne, which is X, and the product of the range and the cosine of theta prime, which is Y.
Converter 45 will do a R~)'-to-X-Y conversion when it receives a clock signal from generator 32. The digital video signal being transmitted on line 36, the X signal, and the Y signal will be stored in raster scan converter memory system 37 when system 37 receives a clock signal from generator 32. ~lemory system 37 now stores a TV video signal that filled in the holes for one cycle. The above reference television video signal will be transmitted to television monitor ~5 when system 37 reaches that particular X, Y location that contains new X, Y data.
In the foregoing example the number of hole fill-in cycles to be performed was equal to one. Counter 33 was advanced to one and comparator 3~ compared one against one and said that they were equal, thereby stopping clock generator 32 and causing only one cycle to be performed. For some greater value of range a different range window would be decoded by decoder 26 and for sake of discussionwe will say that decoder 26 said to perform two hole fill-in cycles. Henee, counter 33 and comparator 38 would allow two clock pulses to occur before clock generator 32 was stopped. The first clock pulse from generator 32 would advance counter 33to the state of one, which would then be decoded by the count-equal-to-one decoder 51. Decoder 51 would select the first value of delta theta from ROM 34 and that value would pass through multiplexer 39 and be stored in register 44.
r~elta theta will now be added or subtracted to theta to create theta prime. A
conversion cycle would now occur at theta plus delta theta, where delta theta was typically equal to zero. That is typically the first value of delta theta. When the second clock pulse occurred, counter 33 will be advanced from a count equal to one to a count equal to two. Decoder 51 will no longer have an active output.
Multiplexer 39 will now select the output of adder 42. Adder 42 adds the previous delta theta to the increment~l value of the delta theta signal appearing on line 41.
The incremental value of delta theta may only be zero, one, two, three, or four.The aforementioned system does a first cycle followed by a second conversion cycle. In the first cycle performed, delta theta was equal to zero and ~) was equal to theta. In the second cycle performed, delta theta will be equal to two and Q~iLl be equal to the value of old theta plus or minus two. However, the foregoing number represents ne-w bits ~hat are lower in significance then any other bits OI the original angle theta. Hence, the foregoing created a half, a quarter, an eighth least-significant-bit type of step changes to theta prime. Each time a cycle is 9~
performed, a rho-theta-to-X-Y conversion occurs. This conversion is then stored in memory system 37, and on the next time that memory system 37 reaches that particular X-Y location, a new value of X and Y will be displayed on television monitor 55. The foregoing will tend to fill in the missing holes. In essence, the apparatus of this invention fills in missing holes created by the rho-theta-to-X-Y
conversion process. The above is accomplished by doing a conversion at the givenrho-theta conversion position, and then doing one or more extra conversions at aslightly different angle determined by the delta theta signal~ which usually adds or subtracts fractions of a least-significant-bit to the given theta for the particular rho-theta conversion. Then an extra conversion is done. The foregoing makes thisinvention think it has a greater number of azimuth resolution bits and a greaternumber of input sweeps then it really does, thereby causing the location of the holes to be at a distance greater than what is displayed on television monitor 55.
When an extra bit of resolution is added to this invention the holes are still there but they cannot be seen on monitor 55. Thus, they are filled in. The increased resolution enables the apparatus of this invention to generate more of the X, Y
locations that were missing, permitting this invention to fi~l in the skipped angles.
Only now instead of adding a fraction of a least significant bit, this invention adds wholly significant bits. The missing holes are still filled in at the same time by adding a fraction of a least-significant-bit and then a wholly significant bit and then fractions again of a least-significant-bit until as many of the skipped angles as desired are filled in.
The above specification has described a new and improved system for displaying radar andlor sonar information on a television monitor. It is realized that the above description may indicate to those skilled in the art addition~l ways in which the principles of this invention may be used without departing from itsspirit. It is, therefore, intended that this invention be limited only by the scope of the appended claims.
_CKGROUN~ OF THE INVE TION
Field of the Invention This invention relates to electronic circuits, and more particularly to devices for electronically controlling television monitors or other raster scan displays to display radar and sonar information.
Descri~tion of the Prior Art The increased traffic in the air and on the sea has caused an increase in the number of air and marine collisions. In addltion to the loss of life and human hardships, property losses have been great. Reasons for such collisions are many and complex, but one of the most important of these is the lack of proper use of radar and sonar systems.
Radar and sonar systems produce signals which have the capability of penetrating fog, darkness, rain, ha~e, and locating objects which are a great distance from the source that generated the signals. Radar detection of an object is achieved by transmitting a beam of radio frequency (RF) energy and detecting the energy reflected by the object. A small part of the RF energy is reflected by the object back to a sensor located near the transmitter. Radar ranging is accomplished by timing the period required for the RF energy to make the round trip from the detected object to the transmitter. The distance to the detected object is equal to one half the time elapsed for the RF energy to make the round trip times the velocity of the RF energy. Sonar detection is similar to radar detection; however, acoustic radiation is the energy radiated rather than RF.
Prior art, radar and sonar system displayed radar and sonar information on CRT's that used a plan-position-indicator (PPI) format sweep. PPI systems were completely analogue systems with no digital storage capability. Thus, if you wanted to display the same radar or sonar information on more than one PPI display, you had to connect all of the outputs of the radar or sonar receiver to each PPI display that was going to display information. Another disadvantage of the PPI display was that the display was only clearly visible in a dark room or the operator 1~3~ 3 had to use a hood while looking at the display. The aforementioned type of display viewing caused operator fatigue.
As the prior art advanced the radar or sonar information was processed, stored in large memory integrated circuit arrays, and then displayed on television monitors. Many television monitors were able to display the same information with only one television cable being connected between each monitor. A television (TV) monitor also caused less operator fatigue since it could be used in a room that was illuminated by sunlight or other means of illumination.
The radar or sonar information was in polar coordinates (R, O) where R rho represented the range and Ç) theta represented the bearing. The TV monitor displayed information in a cartesian-coordinate-type format. Polar-coordinate radar or sonar information was converted into cartesian coordinates (X, Y) and then stored in large memory integrated circuit arrays. The expression for the conversion of the X position data is R Sin 0, and the expression for the conversion of the Y position data is R Cos 0. The aforementioned conversions must constantly take place as the antenna pointing vector moves around or sweeps the monitor. When the polar coordinate radar or sonar information was converted intocartesian coordinate information there were some X, Y locations in the memory array that did not have polar coordinates associated with them. Therefore those X, Y coordinates would never have any information in them. This tended to create the illusion of holes in the displayed television monitor picture. Thus one of the disadvantages of the prior art was that an operator looking at the television monitor would see some returns as multiple returns instead of one return. The reason for this is thst some of the X, Y coordinate information was missing and holes would appear in the return. The foregoing made it difficult for the operator to use the TV monitor.
Another disadvantage of the prior art was that when multiple radius offsets were displayed on a TV monitor, the lines radiating from the center of the monitor would be sufficiently far apart so that when they are displayed the return wouldappear as multiple returns. The reason for the foregoing is that as the range of the display increased, the lines radiating from the center of the monitor did not increase in number and they were now far enough apart that holes were present onthe return. This made it difficult for the r adar or sonar operator to use a television monitor in a multiple radius offset mode.
SI~MMARY OF TlIE INVENTION
This invention overcomes the disadvantages of the prior art by providing a system that fills in the holes caused by the rho-theta-to-X-Y conversion processand the gaps in inforiJ)ation caused by ~erforming multiple radius offsets of the television monitor. The foregoing is accomplished during the rho-thets-to-X-Y
conversion process by performing extra conversions for each rho at slightly different theta values, thereby producing slightly different X and Y values which will fill in the holes. This effectively simulates an increase of the number of azimuth data bits and the number of radar triggers. When the apparatus of this invention knows that an angle has been skipped due to an insufficient number of radar triggers, then the skipped angle may be filled in by extending the extra conversions to cover the skipped angle. Without departing from the spirit of this invention, otller missing information resulting from transformations from one coordinate system to another coordinate system may be accomplished, i.e., spherical coordinates to cartesian coordinates, elliptical coordinates to cartesian coordinates, and hyperbolic coordinates to cartesian coordinates. Since the circuitry for filling in the missing holes for the other transformations is the same as the circuitry for filling in the missing holes resulting from the rh~theta-to-X-Y
transformation, only the rho-theta-to-X-Y conversion will be discussed as this description continues.
Missing information is also created by a typical radar transmitter/receiver or display device, since the azimuth data theta is ordinarily digitized into 12 bits.
Therefore, there are 4,096 possible angles at which radar data may be displayed or stored. To store radar data at all of the 4,096 possible angles requires at least 4,096 radar triggers per antenna revolution. But, because of a radar system's antenna rotation speed and radar trigger pulse repetition frequency (PRF), many radar systems have fewer than 4,096 radar triggers per antenna revolution. This means that at several positions on the TV monitor, the angle will change twice between radar triggers and that an entire angle will contain no data on the TV
monitor. Therefore, the entire angle that was skipped will have holes in the displayed picture.
It is an object of this invention to provide a new and improved system for dispiaying radar and sonar information on a television monitor or other raster scan display. It is another object of this invention to provide a new and improved system for filling in the missing information that results when a transformation takes place from one coordinate system to another coordinate system.
It is a further object of this invention to provide a new and improved system that provides the missing information on a TV monitor or other raster scan display when multiple radius offsets are performed.
Other objects and advantages of this invention will become apparent as the following description proceeds, which description should be considered together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1 and 2 are block diagrams of the electrical system that comprises this invention.
DESCRIPTION OF THE PREFERRED EMBODI~1ENT
Referring now to the drawings in detail, the reference character 11 designates a radar antenna that receives return information. Antenna 11 is coupled to a radar transmitter/receiver 12. Characters 11 and 12 are included in Figure 1 for reference only and may be replaced by any suitable device, such as a sonar system. Transmitter/receiver 12 provides three basic output signals, line 13 azimuth data (theta), line 14 radar video, and line 15 radar trigger which are coupled to the radar video processing system 20. Line 13 transmits antenna azimuth information, theta, as either analogue synchro data that must be digitized, digit~l clock pulses (ACP/ARP) that must be counted or digital data that may be directly used, from transmitter/receiver 12 to the input of digitizer 16 of radar video processing system 20. The digitizer 16 either digitizes the synchro data, counts the ACP/APR clock pulses or passes through the digital data depending on the form of the received data. Line 14 transmits radar video information as either analogue video that must be digitized, or digital video and clock that may be directly used, from transmitter/receiver 12 to the input of A/D (analogue to digital) converter 17 - it is assumed in Figure 1 that the radar video information received by A/D converter 17 is in analogue form. Line 15 transmits radar timing information in the form of either a zero time radar trigger, or a pre-zero time trigger from the transmitter/receiver 12 to the radar video processing system 20.
Radar video processing system 20 is shown with a minimum of detail based on the following assumptions: the azimuth data 13 is svnchro data, the radar video 14 is :L~3~
analogue video, and the radar trigger 15 is a zero time trigger. The radar videoprocessing system comprises at least the following basic functions: an azimuth data digitizer 16, a radar video A/D converter 17, a range counter 18, and a range clock 19. The radar trigger signal (zero time trigger) is transmitted via line 1~ to range counter 18 and to one of the inputs of azimuth change detector and change counter 22. One of the three outputs of range clock 19 is coupled to the clock input of range counter 1~. The second output of clock 19 is coupled to the clockinput of A!D converter 17 and the third output of clock 19 is coupled to one of the inputs of AND gate 31. The output of the range counter 18 is coupled to the input of data holding register 28 and to the input of range window decoder 26. The output of range window decoder 26 (the range window is typically three bits) is coupled to the input of data holding register 29. The output of AiD converter 17 is coupled to the input of data holding register 27 and to the inputs of OR gate 30.
OR gate 30 "OR's" the digital video data and determines when video is present.
The output of OR gate 30 is cc~upled to one of the inputs of AND gate 31. The output of AND gate 31 is coupled to: the clock inputs of data holding registers 2~, 28 and 29; the start clock input of clock generator 32; and the trigger input of one-shot 60. The output of AND gate 31 is used to store the digital data in data holding registers 27, 28 and 29 and to start a R~-to-X-Y and hole fill-in conversion cycle for the current data. The azimuth data on line 13 is digitized by digitizer 16. The output of digitizer 16, line 21, is the digital azimuth data which will be hereinafter referred to as angle theta. Several of the least-significant-bits of angle thetatypically one to four bits are coupled to azimuth change detector and change co.lnter 22 and to azimuth rotation and direction detector 23. The output of:
register 29; counter 22; and the two least-significant-bits of angle theta are coupled to the input of ROM data look~up table 34. The input of one-shot 60 is coupled to the output of AND gate 31 and the output of one-shot 60 is coupled tothe reset input of number of cycles performed counter 33. Each time AND gate 31 produces an output pulse, one~hot 60 resets counter 33 and clock generator 32 istriggered to start generating clock pulses. ROM data look-up table 34 has three outputs. The first of which "the number of hole fill-in cycles to be performed" is coupled to one of the inputs of comparator 38, and the second output "the first value of delta theta" is coupled via line 40 to one input of multiplexer 39. Thethird output of ROM 34 is "the incremental value of delta theta" which is coupled via line 41 to one of the inputs of adder 42. The output of clock generator 32 is coupled to the clock input of counter 33, the clock input of register 44, the clock _ j _ 3~3~3 input of the R Ç)'-to-X-Y converter 45 and the store conversion input of raster scan converter memory system 37. The "number of cycles performed" output of counter 33 is coupled to comparator 38 and to count equal to one decoder 51 via line 50.T~le t'equal" output of comparator 38 is coupled to the stop clock input of clock generator 32. The output of the count equal to one decoder 51 is coupled to the select input of multiplexer 39. When the value of line 50 is equal to one the output of decoder 51 is coupled to the select input of multiplexer 39. When the value of line 50 is equal to one the output of decoder 51 causes multiplexer 39 to pass the data on line 40 to the input of register 44. Otherwise the output of sdder 42 isinput by multiplexer 39 and is passed to register 44. The output of register 44,delta theta, is coupled to one of the inputs of adder 42 and to the delt~ theta input of adder/subtracter 24. The angle theta is transmitted via line 21. Line 21 couples the output of digitizer 16 to the input of adder/subtracter 24. The output of azimuth rotation and direction detector 23 is coupled to the control input of adder/subtracter 24. The aforementioned signal determines if adder/subtracter 24should add or subtract delta theta to theta. The output of the adder/subtracter 24 is O' which is coupled to the O' input of the R~)'-to-X-Y converter 45. The range data from data holding register 28 is coupled via line 3~ to the R input of R~)'-to-X-Y converter 45. The outputs of the R~)'-to-X-Y converter 45 are the X and Y
data converted from the R and ~' data. The X and Y data from the R~)'-to-X-Y
converter 45 and the video data line 36 from the data holding register 27 are coupled to the inputs of the raster scan converter memory system 37. The output of system 37 is a television video signal which is connected to the input of television monitor 55.
Radar transmitter receiver 12 outputs antenna azimuth information, radar video in analogue format and radar triggers. Digitizer 16 digitizes the azimuth information to produce a digital azimuth, i.e., angle theta. Angle theta is N bits wide, and for purposes of this description N will be equal to 12 bits. I~etector 23 utilizes the least-significant-bit of the aforementioned 12 bits to determine the direction of rotation of antenna 11, i.e., clockwise or counterclockwise. Azimuth change detector and change counter 22 utilizes three of the aforementioned 12 bits and the radar trigger signal from receiver 12 to count the number of angle changes per radar trigger. Adder/subtracter 24 receives the entire 12 bits via line 21.
The analogue radar video signal produced by receiver 12 is digitized into a 4 bit digital video signal by A/D converter 17. When the aforementioned digital signal consists of anything other than aL zeros, gate 30 will be enabled. The digital video signal is also transmitted to the input of data holding register 27. The output of gate 30 is also one of the inputs to AND gate 31. The radar trigger signal ~3~
?roduced by receiver 12 resets range counter 18. Counter 18 is clocked by a continuously running range clock 19. Range clock 19 is related to the displayed range of the recei~ed radar signal, i.e., the range scale may be changed by changing the frequency of the range clock. The digital range data outputted by counter 18 is transmitted to the input of data holding register 28. The aforementioned range data is decoded by range window decoder 26 into a 3-bit word before being transmitted to the input of data holding register 29. Decoder 26 is essentially a ROM which contains information to specify in which of eight range windows each instantaneous range count falls. The range window boundaries are programmed into the ROM to determine when hole fill-in cycles are to be performed, because of the inadequacy of the rho-theta-to-X-Y conversion process.For each increment of the 3-bit output, one additional cycle will be performed.
The second input to AND gate 31 is the output of clock 19. Thus, gate 31 will beenabled when video data is present on one of gate 31's inputs and h clock pulse is present on the second input to gate 31. When gate 31 is enabled the digital video information will be clocked into register 27, the digital range data will be clocked into register 28, the digital range window data will be clocked into register 29, clock generator will start and one-shot 60 will be fired to reset counter 33 to a c~unt of one. Once generator 32 starts, it outputs a stream of clock pulses until it is told to stop by the stop clock signal which is the output of comparator 38. Each of the aforementioned clock pulses advances the count of counter 33, loads register 44, does a conversion cycle on rho-theta-to-X-Y converter 45 and signals raster scan converter memory system 37 to store the results of the conversion performedby converter 45. Additional azimuth resolution is created to fill in the holes caused by having insufficient azimuth resolution by taking the least-significant-bit from the output of digitizer 16, the output of detector 22, ~nd the output of register 29, and coupling them to the three inputs of ROM data look-up table 34.The information contained within table 34 generates a number representing how many hole fill-in cycles must be performed, a first value of delta theta, and anincremental value of delta theta from the input data consisting of the number ofazimuth changes per radar trigger pulse, range window count, and two least-significant-bits of the antenna azimuth angle. ROM 34 has three outputs, the first of which represents the number of hole fill-in cycles to be performed. The aforementioned output is coupled to the input of comparator 38. The second output of ROM 34 is the first value of delta theta which is transmitted via line 40 to one of the inputs of multiplexer 39, and the third output of RO.~ 34 is line 41 lZ;38;~
which transmits the incremental value of the delta theta signal to the in?ut of adder 42. ROM 34 performs two functions; it fills in the holes, and it fi11s in the skipped angles due to there not being a sweep for every angle that digitizer 16 can digitize. ROM 34 uses the decoded range from decoder 26 and register 29 to fiU in the missing holes. The output of counter 22, i.e., the number of azimuth changesper radar trigger, and the output of digitizer 16 are used to fill in the skipped angles. Skipped angles will occur when there are fewer radar triggers then the number of angles that azimuth digitizer 16 can digitize. In this example the azimuth angle is digitized to 12 bits and the binary number 212 is equal to 4,096.
Thus, if there were fewer than 4,096 radar triggers per antennh 11 rotation there will be some skipped angles. The skipped angles will create extra holes which are slightly different in nature from the basic holes this system was trying to fill in.
However, the apparatus of this invention will fill in both of the foregoing tvpes of holes in the same manner.
For purposes of illustration we will assun e that the apparatus of this invention is operating within a range window where the table contained within ROM 34 states that only one cycle needs to be performed. Hence, in that case theinput to comparator 38 would be equal to one. Once counter 33 was reset to one by the output of one-shot 60, counter 33 will have an output signal that is equa] to one which will be transmitted to the input of comparator 38 and the input of count-equal-to-one decoder 51 via line 50. Comparator 38 will now have the same valuedsignal on both its inputs causing the output of comparator 38 to output a signal that will stop clock 32 from outputting clock pulses. The output of decoder 51 will cause multiplexer 39 to select the signal appearing on line 40, i.e., the first value of delta theta. This signal will pass through register 44 and become the delta theta signai. The delta theta signal is coupled to one of the three inputs of adder/subtracter 24. The aforementioned signal will be added to or subtracted from the original delta theta signal appearing on line 21 to produce a theta prime signal on the output of adder/subtracter 24. It will be added if detector 23 transmits a signal via line 25 to one of the inputs of adder/subtracter 24 indicating that antenna ll is turning counterclockwise and it will be subtracted if detector 23 transmits a signal via line 25 indicating that antenna 11 is turning clockwise.
rIence, the fill-ins will always occur behind the sweep. The theta prime signal will be coupled to one of the inputs of ~'-to-X-Y converter 45, and the digital rangesignal will be transmitted to one of the inputs of converter 45 via line 35.
Converter 45 contains look-up tables and digital multiplier circuits. The look-up ~383~
tables provide sines and cosines of the various values of theta prime. The multipliers generate the product of the range and the sine of theta prirne, which is X, and the product of the range and the cosine of theta prime, which is Y.
Converter 45 will do a R~)'-to-X-Y conversion when it receives a clock signal from generator 32. The digital video signal being transmitted on line 36, the X signal, and the Y signal will be stored in raster scan converter memory system 37 when system 37 receives a clock signal from generator 32. ~lemory system 37 now stores a TV video signal that filled in the holes for one cycle. The above reference television video signal will be transmitted to television monitor ~5 when system 37 reaches that particular X, Y location that contains new X, Y data.
In the foregoing example the number of hole fill-in cycles to be performed was equal to one. Counter 33 was advanced to one and comparator 3~ compared one against one and said that they were equal, thereby stopping clock generator 32 and causing only one cycle to be performed. For some greater value of range a different range window would be decoded by decoder 26 and for sake of discussionwe will say that decoder 26 said to perform two hole fill-in cycles. Henee, counter 33 and comparator 38 would allow two clock pulses to occur before clock generator 32 was stopped. The first clock pulse from generator 32 would advance counter 33to the state of one, which would then be decoded by the count-equal-to-one decoder 51. Decoder 51 would select the first value of delta theta from ROM 34 and that value would pass through multiplexer 39 and be stored in register 44.
r~elta theta will now be added or subtracted to theta to create theta prime. A
conversion cycle would now occur at theta plus delta theta, where delta theta was typically equal to zero. That is typically the first value of delta theta. When the second clock pulse occurred, counter 33 will be advanced from a count equal to one to a count equal to two. Decoder 51 will no longer have an active output.
Multiplexer 39 will now select the output of adder 42. Adder 42 adds the previous delta theta to the increment~l value of the delta theta signal appearing on line 41.
The incremental value of delta theta may only be zero, one, two, three, or four.The aforementioned system does a first cycle followed by a second conversion cycle. In the first cycle performed, delta theta was equal to zero and ~) was equal to theta. In the second cycle performed, delta theta will be equal to two and Q~iLl be equal to the value of old theta plus or minus two. However, the foregoing number represents ne-w bits ~hat are lower in significance then any other bits OI the original angle theta. Hence, the foregoing created a half, a quarter, an eighth least-significant-bit type of step changes to theta prime. Each time a cycle is 9~
performed, a rho-theta-to-X-Y conversion occurs. This conversion is then stored in memory system 37, and on the next time that memory system 37 reaches that particular X-Y location, a new value of X and Y will be displayed on television monitor 55. The foregoing will tend to fill in the missing holes. In essence, the apparatus of this invention fills in missing holes created by the rho-theta-to-X-Y
conversion process. The above is accomplished by doing a conversion at the givenrho-theta conversion position, and then doing one or more extra conversions at aslightly different angle determined by the delta theta signal~ which usually adds or subtracts fractions of a least-significant-bit to the given theta for the particular rho-theta conversion. Then an extra conversion is done. The foregoing makes thisinvention think it has a greater number of azimuth resolution bits and a greaternumber of input sweeps then it really does, thereby causing the location of the holes to be at a distance greater than what is displayed on television monitor 55.
When an extra bit of resolution is added to this invention the holes are still there but they cannot be seen on monitor 55. Thus, they are filled in. The increased resolution enables the apparatus of this invention to generate more of the X, Y
locations that were missing, permitting this invention to fi~l in the skipped angles.
Only now instead of adding a fraction of a least significant bit, this invention adds wholly significant bits. The missing holes are still filled in at the same time by adding a fraction of a least-significant-bit and then a wholly significant bit and then fractions again of a least-significant-bit until as many of the skipped angles as desired are filled in.
The above specification has described a new and improved system for displaying radar andlor sonar information on a television monitor. It is realized that the above description may indicate to those skilled in the art addition~l ways in which the principles of this invention may be used without departing from itsspirit. It is, therefore, intended that this invention be limited only by the scope of the appended claims.
Claims (14)
PRIVILEGE IS CLAIMED IS DEFINED AS FOLLOWS:
1) A system for filling in holes on a raster scan display which results when information is transformed from one coordinate system that represents a series of locations by at least a series of first and second numbers to another coordinatesystem that represents a series of locations by at least a series of third and fourth numbers, said system comprising:
a) means coupled to said information for transforming every first and second number in one coordinate system to a third and fourth number in another coordinate system;
b) means coupled to said information and said means for transforming and for performing extra transformations for each first number at slightly different second numbered values, thereby producing slightly different third and fourth numbered values which will fill in the holes; and c) a raster scan converter memory coupled to the output of said means for transforming said memory stores each of said transformed third and fourth numbers and said extra transformations, whereby the information stored in said memory may be coupled to and displayed on a television monitor so that an observer of the television monitor will see a solid displayed picture since all the holes have been filled in.
a) means coupled to said information for transforming every first and second number in one coordinate system to a third and fourth number in another coordinate system;
b) means coupled to said information and said means for transforming and for performing extra transformations for each first number at slightly different second numbered values, thereby producing slightly different third and fourth numbered values which will fill in the holes; and c) a raster scan converter memory coupled to the output of said means for transforming said memory stores each of said transformed third and fourth numbers and said extra transformations, whereby the information stored in said memory may be coupled to and displayed on a television monitor so that an observer of the television monitor will see a solid displayed picture since all the holes have been filled in.
2) The system claimed in claim I wherein said one coordinate system represents locations in polar coordinates and said other coordinate system represents location in cartesian coordinates.
3) The system claimed in claim 1 wherein said one coordinate system represents locations in spherical coordinates and said other coordinate system represents locations in cartesian coordinates.
4) The system claimed in claim 1 wherein said one coordinate system represents locations in elliptical coordinates and said other coordinate system represents locations in cartesian coordinates.
5) The system claimed in claim 1 wherein said one coordinate system represents locations in hyperbolic coordinates and said other coordinate system represents locations in cartesian coordinates.
6) The system claimed in claim 1 wherein said transforming means is rho-theta-to-X-Y converter.
7) The system claimed in claim 2 wherein said means for performing extra transformations comprises:
a) a read only memory that contains information regarding the first value to transform said first number at slightly different second numbered values, the incremental value for transforming said first number at slightly different second numbered values and the number of hole fill in cycles to be performed;
b) means coupled to said read only memory and said means for transforming and for controlling the number of hole fill in cycles to be performed;
c) a first adder coupled to said read only memory for adding the incremental value for transforming said first number to the first value of said first number; and d) a second adder whose inputs are coupled to the output of said first adder and said information for adding the output of said first adder with the original values of a series said second numbers, the output of said second adder being coupled to the input of said means for transforming.
a) a read only memory that contains information regarding the first value to transform said first number at slightly different second numbered values, the incremental value for transforming said first number at slightly different second numbered values and the number of hole fill in cycles to be performed;
b) means coupled to said read only memory and said means for transforming and for controlling the number of hole fill in cycles to be performed;
c) a first adder coupled to said read only memory for adding the incremental value for transforming said first number to the first value of said first number; and d) a second adder whose inputs are coupled to the output of said first adder and said information for adding the output of said first adder with the original values of a series said second numbers, the output of said second adder being coupled to the input of said means for transforming.
8) A method for filling in holes on a television monitor which results when information is transformed from one coordinate system that represents a series of locations by at least a series of first and second numbers to another coordinatesystem that represents a series of locations by at least a third and a fourth number, said method comprising the steps of:
a) converting every first and second number in one coordinate system to a third and fourth number in another coordinate system;
b) doing extra conversions for each first number at slightly different second numbered values, thereby producing slightly different third and fourth numbered values which will fill in the holes;
c) storing each of said converted third and fourth numbers and said extra conversions in a raster scan memory converter; and d) displaying the information stored in said memory on a television monitor.
a) converting every first and second number in one coordinate system to a third and fourth number in another coordinate system;
b) doing extra conversions for each first number at slightly different second numbered values, thereby producing slightly different third and fourth numbered values which will fill in the holes;
c) storing each of said converted third and fourth numbers and said extra conversions in a raster scan memory converter; and d) displaying the information stored in said memory on a television monitor.
9) A system for displaying in cartesian coordinates (X, Y) on a television monitor continuous radar and/or sonar return information that is received from aradar and/or sonar transmitter/receiver in polar coordinates (R, ?), said systemcomprising:
a) means for processing the output of said receiver, said processing means is coupled to the output of said receiver in order to produce digital azimuth, digital video and digital range information signals.
b) means for detecting the number of azimuth (?) changes per radar trigger and the direction of rotation of the antenna of said receiver, said detecting means is coupled to said digital azimuth signal and said receiver;
c) means for storing said digital video signal, said storing means is coupled to said video signal, d) means for determining the range (R) of said receiver, said determining means is coupled to said digital range signal;
e) a memory look-up table that contains information, the inputs of said table are coupled to the outputs of said detecting means, said range means and said azimuth signal to cause said table to select the information in said table that determines the incremental value of the change in azimuth, the first value of the change in azimuth and the number of hole fill in cycles to be performed;
f) timing means coupled to said storing means and said table for maintaining said system in synchronization;
g) means for performing extra transformations for each azimuth location received by said receiver at slightly different range locations, said performing means inputs are coupled to the incremental value of the change in said azimuth and the first value of the change in azimuth signals outputted by said table;
h) an adder/subtracter whose inputs are coupled to said digital azimuth signal, the outputs of said detecting and performing means, said adder/subtracter adds the output of said performing means to the digital azimuth signal if the antenna of said receiver is rotating counterclockwise and subtracts the output of said performing means from said digital azimuth signal if the antenna of said receiver is rotating clockwise;
i) a R-?-to-X-Y converter whose inputs are coupled to the output of said adder and said means for determining the range, said converter transforms its R,? inputs into X, Y outputs when a signal is received from said timing means; and j) a raster scan converter memory coupled to the X, Y outputs of said convertor, the output of said timing means and said storing means, said raster memory stores the return information in X, Y
coordinates, whereby said raster memory causes said radar and/or sonar target information to be displayed on a television monitor.
a) means for processing the output of said receiver, said processing means is coupled to the output of said receiver in order to produce digital azimuth, digital video and digital range information signals.
b) means for detecting the number of azimuth (?) changes per radar trigger and the direction of rotation of the antenna of said receiver, said detecting means is coupled to said digital azimuth signal and said receiver;
c) means for storing said digital video signal, said storing means is coupled to said video signal, d) means for determining the range (R) of said receiver, said determining means is coupled to said digital range signal;
e) a memory look-up table that contains information, the inputs of said table are coupled to the outputs of said detecting means, said range means and said azimuth signal to cause said table to select the information in said table that determines the incremental value of the change in azimuth, the first value of the change in azimuth and the number of hole fill in cycles to be performed;
f) timing means coupled to said storing means and said table for maintaining said system in synchronization;
g) means for performing extra transformations for each azimuth location received by said receiver at slightly different range locations, said performing means inputs are coupled to the incremental value of the change in said azimuth and the first value of the change in azimuth signals outputted by said table;
h) an adder/subtracter whose inputs are coupled to said digital azimuth signal, the outputs of said detecting and performing means, said adder/subtracter adds the output of said performing means to the digital azimuth signal if the antenna of said receiver is rotating counterclockwise and subtracts the output of said performing means from said digital azimuth signal if the antenna of said receiver is rotating clockwise;
i) a R-?-to-X-Y converter whose inputs are coupled to the output of said adder and said means for determining the range, said converter transforms its R,? inputs into X, Y outputs when a signal is received from said timing means; and j) a raster scan converter memory coupled to the X, Y outputs of said convertor, the output of said timing means and said storing means, said raster memory stores the return information in X, Y
coordinates, whereby said raster memory causes said radar and/or sonar target information to be displayed on a television monitor.
10) The system claimed in claim 9 wherein said detecting means comprises:
a) a first azimuth detector that is coupled to said digital azimuth signal and said receiver in order to detect the number of azimuth changes per receiver trigger; and b) a second azimuth detector that is coupled to said digital azimuth signal to detect the direction of rotation of the antenna of said receiver.
a) a first azimuth detector that is coupled to said digital azimuth signal and said receiver in order to detect the number of azimuth changes per receiver trigger; and b) a second azimuth detector that is coupled to said digital azimuth signal to detect the direction of rotation of the antenna of said receiver.
11) The system claimed in claim 9 wherein said storing means comprises:
b) an AND gate whose inputs are coupled to said processing means and the output of said OR gate; and c) a register for holding video data, the inputs of said register are coupled to said digital video signal and the output of said and gate.
b) an AND gate whose inputs are coupled to said processing means and the output of said OR gate; and c) a register for holding video data, the inputs of said register are coupled to said digital video signal and the output of said and gate.
12) The system claimed in claim 9 wherein said determining means comprises:
a) a range decoder whose input is coupled to said digital range signal to decode the range of said receiver;
b) a first register for holding range information, the input of said first register is coupled to said digital range signal; and c) a second register for holding the decoded range, the inputs of said second register are coupled to the outputs of said range decoder and said AND gate.
a) a range decoder whose input is coupled to said digital range signal to decode the range of said receiver;
b) a first register for holding range information, the input of said first register is coupled to said digital range signal; and c) a second register for holding the decoded range, the inputs of said second register are coupled to the outputs of said range decoder and said AND gate.
13) The system claimed in claim 10 wherein said timing means comprises:
a) a clock generator that begins outputting a series of clock pulses when it receives the output signal of said AND gate;
b) a counter that begins counting when it receives the output signal of said AND gate;
c) a count equal to one decoder whose input is coupled to the output of said counter, said decoder determines when said counter has reached a count equal to one; and d) a comparator whose inputs are coupled to the number of hole fill in cycles to be performed, signal produced by said table and the output of said counter, said comparator compares its two input signals and if they are equal said comparator sends said clock a signal to stop outputting clock pulses.
a) a clock generator that begins outputting a series of clock pulses when it receives the output signal of said AND gate;
b) a counter that begins counting when it receives the output signal of said AND gate;
c) a count equal to one decoder whose input is coupled to the output of said counter, said decoder determines when said counter has reached a count equal to one; and d) a comparator whose inputs are coupled to the number of hole fill in cycles to be performed, signal produced by said table and the output of said counter, said comparator compares its two input signals and if they are equal said comparator sends said clock a signal to stop outputting clock pulses.
14) The system claimed in claim 13 wherein said performing means comprises:
a) a adder that adds said incremental value of the change in azimuth signal to a first signal;
b) a multiplexer that is coupled to the output of said count-equal-to-one decoder that multiplexes said first value of the change in azimuth signal with the output of said adder; and c) a register that stores the output of said multiplexer when it receives a signal from said timing means, the output of said register is said first signal which is coupled to said adder and said adder/subtracter.
a) a adder that adds said incremental value of the change in azimuth signal to a first signal;
b) a multiplexer that is coupled to the output of said count-equal-to-one decoder that multiplexes said first value of the change in azimuth signal with the output of said adder; and c) a register that stores the output of said multiplexer when it receives a signal from said timing means, the output of said register is said first signal which is coupled to said adder and said adder/subtracter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000482343A CA1238399A (en) | 1985-05-24 | 1985-05-24 | System for displaying solid radar and/or sonar targets on a television monitor or other raster scan display |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000482343A CA1238399A (en) | 1985-05-24 | 1985-05-24 | System for displaying solid radar and/or sonar targets on a television monitor or other raster scan display |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1238399A true CA1238399A (en) | 1988-06-21 |
Family
ID=4130546
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000482343A Expired CA1238399A (en) | 1985-05-24 | 1985-05-24 | System for displaying solid radar and/or sonar targets on a television monitor or other raster scan display |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1238399A (en) |
-
1985
- 1985-05-24 CA CA000482343A patent/CA1238399A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3765018A (en) | Digital scan converter | |
| US5339085A (en) | Three-dimensional radar display | |
| US4084158A (en) | Method of operating synthetic aperture radar | |
| US4829308A (en) | Raster display system | |
| CA2116713A1 (en) | Three Dimensional Imaging Radar | |
| US4729029A (en) | Process and apparatus for the insertion of insets into the image supplied by a digital scan converter | |
| CA1210117A (en) | Algorithm for radar coordinate conversion in digital scan converters | |
| US5418535A (en) | Mixed radar/graphics indicator | |
| KR930000138B1 (en) | Sar signal azimuth ambiguity cancellation | |
| US4443797A (en) | Radar display apparatus | |
| US4068233A (en) | Radar system having interference rejection | |
| CN111707992B (en) | Radar data processing system and method | |
| US4660043A (en) | Method for processing video signals in a digital image transformer | |
| CA2075409A1 (en) | Radar apparatus | |
| US4644356A (en) | Bistatic coherent radar receiving system | |
| CA1177563A (en) | Digital scan converter | |
| US4149252A (en) | Digital ρ-θ to XY scan converter for use with limited access or random access reiteration memory | |
| US4383258A (en) | Time encoded spatial display | |
| US4348693A (en) | Television weather radar system | |
| US3501762A (en) | Multisensor correlation apparatus | |
| CA1238399A (en) | System for displaying solid radar and/or sonar targets on a television monitor or other raster scan display | |
| US4208721A (en) | Fast-ρ θ random access memory device | |
| US3697986A (en) | Collision avoidance system | |
| US4757317A (en) | Method and a device for extending the range of radar recurrence frequencies acceptable by a digital image converter | |
| US3789403A (en) | Digital line graphics control on range scalable radar crt display |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |