Abstract:
A portable antenna control unit that operates a radar antenna and simulatesarious control signals that are generated by a fire control radar. The antenna control unit can be interfaced to a standard commercial, portable computer, or it can be portable, stand-alone unit, manually controlled and easily transported to a test range. Both embodiments diagnose problems in an antenna radar system antenna without installing an entire radar system.

Description:
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without payment of any royalties thereon or therefor. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates specifically to the F/A 18 jet fighter aircraft fire control radar system APG65/73. This invention will be used to control and operate a APG65/73 radar set antenna, the AS3254 antenna and to simulate the various control signals that are generated by the APG65/73 fire control radar. 
     The AS3254/APG65/73 fire control radar antenna is an integral part of the APG65 radar system used for the search, track and destruction of enemy aircraft. The Navy uses the AS3254/APG65/73 fire control radar antenna to perform antenna testing and evaluation, There was a need in the Navy to control the APG3254/APG65/73 antenna without installing the entire radar system, therefore an antenna control and interface unit 1 was designed and built to interface the antenna measurements computer 2 to the AS3254/APG65/73 antenna 3 (See FIG. 1). This antenna control and interface has given the Navy the ability to do measurements utilizing the AS3254/APG65/73 antenna 3. 
     Prior to the design and construction of this device there was no &#34;stand-alone&#34;, portable AS3254/APG65/73 antenna control unit that could be interfaced to a standard commercial, portable computer or a portable unit manually controlled and easily transported to a test range. The present invention enables the Navy to troubleshoot and diagnose problems in the AS3254/APG65/73 antenna radar system antenna 3 without installing the entire radar system. The present invention, used with a commercial computer or in a stand alone embodiment, is lightweight and easily transported to a test range. 
     SUMMARY OF THE INVENTION 
     This invention will enable the use of the AS3254/APG65/73 antenna system without the APG65/73 radar system and enables automated testing of the AS3254 antenna using a portable commercial computer. 
     The antenna control unit 1 (ACIU) operates by simulating the signals sent to the AS3254/APG65/73 radar antenna by the APG65/73 fire control radar system. 
     The antenna has 4 modes of operation (TABLE 1), the receive mode, D/A mode, send mode and gap mode. The ACIU generates the &#34;ANT X&#34; and &#34;ANT R&#34; signals that are needed to put the antenna in receive mode and the D/A mode. When the antenna goes to receive mode, three 16 bit words are sent from the ACIU to the circuitry in the servo electronics unit in the antenna, this causes the antenna to drive to the proper angular position. The 3 digital control words are the &#34;D0&#34;, &#34;A01&#34;, and &#34;A02&#34;. See TABLE 2 for description of the contents of these control words. 
     The ACIU is comprised of three 16 bit shift registers connected in series 11, 12, 13 (See FIG. 2). The CLK signal 5 is created by the master 1 mhz clock 6. The &#34;ANT X&#34; signal 7 is created by counter &#34;B&#34; 8, the &#34;ANT R&#34; signal 9 is created by counter &#34;A&#34; 10. The control words D0, A01, and A02, are placed in the shift registers and are serially shifted out of each register and into the next register in the chain and serially out of the last shift register and out the &#34;DATA OUT&#34; 14 line of the ACIU. These four signals CLK 5, ANT R 9, ANT X 7, and DATA OUT 14, are then sent to 4 differential line drivers 18, 21, 22, 23 which are connected to the antenna inputs. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 Full Scale F-18 Test Range 
     FIG. 2 AS 3254 Antenna Control Block Diagram 
     FIG. 3 Timing Signals for the AS 3254 Antenna Control 
    
    
     DETAILED DESCRIPTION 
     The invention provides complete power control and overcurrent protection by means of switches and fuses of the 28 vdc, +-20 vdc, +10 vdc, +5 vdc, 115 vac 400 Hz and 115 vac 60 Hz and the invention provides the four logic signals necessary to control the AS3254/APG65/73 radar antenna. These signals are the 1 mhz clock signal (CLK) 5, the antenna receive signal (ANT R) 9, The antenna transmit signal (ANT X) 7, and the data serial output signal (DATA OUT) 14. (See FIG. 5). 
     In the preferred embodiment a 1 mhz clock signal is generated by a 2 mhz oscillator module that is divided by 2 using a &#34;D&#34; flip flop and then drives a synchronizing counter circuit which counts to 60 (ANT R) then resets the output from this counter which then is applied to an &#34;OR&#34; gate and combined with the 1 mhz clock signal to create a series of 60 1 mhz pulses. These pulses then clock another counter which counts to 20 and then resets creating the &#34;REC X&#34; signal (See FIG. 3). The &#34;ANT X&#34; signal 7 is created by applying &#34;REC X&#34; to an inverter. The &#34;SRCK&#34; 20 signal is generated by applying the &#34;REC X&#34; signal to on &#34;OR&#34; gate and combining with the 1 mhz clock which creates three 16 bit words with a 4 us gap between them. A timer circuit continuously triggers this process every 100 us. (See the TRIG. signal in FIG. 3) 
     The &#34;SRCK&#34; 20 is then used to clock 6 PISO (Parallel In Serial Out) shift registers connected in series. The input to these shift registers can be controlled by a computer or manually by six 8-bit dip switches which are fed into the parallel inputs of the shift registers. When a computer interface is wired into the circuit all dip switches to the off position when the computer is driving the circuit. After the shift registers are loaded, the &#34;SRCK&#34; signal 20 then shifts the data out of the shift registers to the differential line drivers circuits, then out to the antenna. 
     
                                           TABLE 1__________________________________________________________________________ANT XANT R     MODE  DESCRIPTION__________________________________________________________________________0    1    RECEIVE           THREE SERIAL DIGITAL WORDS ARE RECEIVED FROM THE           RADAR MUX IN THE FOLLOWING SEQUENCE: D0 WORD, A01           WORD AND A02 WORD.0    0    D/A   THE 101, A02 AND NULL WORDS ARE CONVERTED FROM DIGITAL           TO ANALOG IN THAT ORDER. THE THREE CONVERSIONS ARE           CYCLIC UNTIL THE MODE CHANGES.1    0    SEND  THE AI WORDS ARE SEQUENTIALLY CONVERTED FROM ANALOG     (A/D) TO DIGITAL AND SENT ALONG WITH THE DI WORD TO THE RADAR           MUX. THE FIRST AND SECOND SERIAL WORDS TRANSMITTED           ARE THE DI WORD AND A &#34;DUMMY&#34; WORD. DURING THIS TIME,           THE FIRST AI WORD IS CONVERTED. IT IS THEN TRANSMITTED           AS THE THIRD SERIAL WORD AND SIMULTANEOUSLY THE           CONVERSION OF THE NEXT AI WORD BEGINS. THEREAFTER, ALL           VALID AI TRANSMISSIONS OCCUR DURING EVERY OTHER RADAR           MUX WORD TRANSMISSION. THE VALID WORDS ARE SEPARATED           BY MEANINGLESS &#34;DUMMY WORDS&#34; TO ALLOW THE 40 USEC           REQUIRED FOR THE CONVERSION OF THE NEXT AI WORD.1    1    GAP   THIS MODE IS REALLY A SUBSET OF THE RECEIVE AND AD           CONVERT AND SEND MODES WHICH ALLOWS FOR THE           INTERWORD GAP OF 4 BIT TIMES BETWEEN EACH RECEIVED OR           TRANSMITTED WORD.__________________________________________________________________________ 
    
     
                                           TABLE 2__________________________________________________________________________WORD BIT  SIGNAL TITLE FUNCTION__________________________________________________________________________1    0    MUX LOOP TEST   RDP R-MUX TEST BIT1,2       AZ GAIN ADJUST  0, 0   0&lt;|EG|&lt;31                     0, 1  31&lt;|EG|&lt;44                     1, 0  44&lt;&#34;EG|&lt;51                     1, 1  51&lt;|EG|                  ONE DEGREE OF EL GIMBAL                  ANGLE (EG) HYSTERESISD0   3,4  MEDIUM RATE     0, 0  LOW RATE     HIGH RATE       0, 1  MEDIUM RATE                     1, 0  INT HIGH RATE                     1, 1  HIGH RATE                  BOTH AZ AND EL GYRO TORQUER                  AMPLIFIERS5    28V ANTENNA MOTOR                  1 = 28V RELAY ENERGIZED     ENABLE6    AZ POSITION LOOP                  1 = AZ POSITION MODE     SELECT       0 = AZ RATE MODE7    EL POSITION LOOP                  1 = EL POSITION MODE     SELECT       0 = EL RATE MODE8    NULL HORN SELECT                  1 = NULL HORN ENABLED9    PENCIL SELECT                  1 = PENCIL BEAM                  0 = MAPPING BEAM2    0 -&gt; 11     AZ RATE/POSITION                  POSITION MODEA01       COMMAND      MSB = 72.0 DEGREES RIGHT                  POSITIVE = LEFT3    0 -&gt; 11     EL RATE/POSITION                  POSITION MODEA02       COMMAND      MSB = 72.0 DEGREES UP                  POSITIVE = DOWN__________________________________________________________________________