Time Interval and Frequency Counter

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8 Front Panel OperationSample mean value graph. Each point corresponds to the mean value from onemeasurement. The vertical scale is 10 Hz/div. The measurements are relative to a RELof 10.022176 kHz. The REL is at the center of the graph. The cursor (dotted line) showsthat measurement number 67 was 1.635 kHz below the REL.Sample jitter stripchart. This graph shows the jitter associated with each measurementabove. The vertical scale is 10 Hz/div. The cursor is at measurement number 165 andthe jitter value there is 32.6 Hz.SR620 Universal Time Interval Counter
Front Panel Operation 9SETTING THE INPUTSSETTING TRIGGER LEVELSThe trigger levels are set by rotating the triggerlevel adjust knobs. These knobs may have a fullscale range of ±5.00V, ±2.50V, or ±1.25V. Thefull scale range is set in the CONFIGURATIONmenu (see that section of the manual for details).In all cases the trigger level resolution is 10mVand the actual level may be displayed on the frontpanel. The trigger inputs have about 40mV ofhysteresis and the trigger levels are corrected forthis hysteresis so that the inputs will trigger at theselected voltage independent of the selectedtrigger slope.The LED's above the trigger knobs will flash whenthe input comparator triggers. The A and B inputsmay also be set to autolevel by rotating the knobscompletely counter-clockwise. The "AUTO" LEDunder the knob will come on and the triggerthreshold will automatically be set to the midpointof the signal. Autolevel will work for a signal fasterthan about 10Hz and a duty cycle greater thanabout 0.0001%. The autolevel circuit will notchange the trigger level until the input stopstriggering for more than 1/2 second. Then it willtry to reset the trigger level to a new value. Thered LEDs behind the words "START" and "STOP"will flash each time the autolevel circuit tries toadjust the trigger threshold.NOTE: in width and rise/fall time modes, whichuse only one input, the A trigger knob sets thestart trigger voltage and the B trigger knob sets thestop trigger voltage.SETTING TRIGGER SLOPESThe A and B inputs can be set to trigger on eithera rising or falling edge by pressing the "SLOPE"buttons. The EXT input can be set to rising edgeor falling edge by pressing the "LOGIC" button. Ifthe EXT input is being used to supply a gate pulsethe SR620 will use the time above threshold asthe gate if POSitive logic is selected and the timebelow threshold as the gate if NEGative logic isselected.INPUT TERMINATIONThe EXT, A, and B input may all be terminated ineither 1MOhm or 50 Ohms by pressing the"INPUT" or "TERM" buttons. If the inputs areterminated in 50 ohms and the input signalexceeds ±6V peak the 50 Ohm terminator willautomatically be removed to prevent damage tothe terminator. When this overload conditionoccurs the 50 ohm LED will flash.UHF PRESCALERSIn frequency and period modes the input signalmay be fed to the SR620's UHF prescalers tomeasure signals between 40MHz and 1.3GHz. Toengage the prescalers press the "INPUT" buttonfor the desired channel repeatedly until the UHFLED comes on. The sensitivity of the prescalersmay be adjusted by adjusting the channel A and Btrigger knobs. Setting the knobs for 0V or toautolevel will set the sensitivity to maximum.Setting the knobs to 5V will reduce the sensitivitySR620 Universal Time Interval Counter
Page 1 and 2: MODEL SR620Universal Time Interval
Page 3 and 4: Table of ContentsiTable of Contents
Page 5 and 6: Table of ContentsiiiTimebase 79Fron
Page 7 and 8: Safety and Preparation for UsevSafe
Page 9 and 10: SpecificationsviiSpecificationsFunc
Page 11 and 12: SpecificationsixGraphicsScopeDispla
Page 13 and 14: Abridged Command ListxiAbridged Com
Page 15 and 16: Abridged Command ListxiiiGENA(?) jG
Page 17 and 18: Quick Start Instructions 1Quick Sta
Page 19 and 20: Front Panel Operation 3FRONT PANEL
Page 21 and 22: Front Panel Operation 5CHOOSING THE
Page 23: Front Panel Operation 7HARDCOPY OUT
Page 27 and 28: Sample Arming 11SAMPLE ARMINGThe SR
Page 29 and 30: Sample Arming 13Time interval sampl
Page 31 and 32: Sample Arming 15the period of the A
Page 33 and 34: Configuration Menus 17CONFIGURATION
Page 35 and 36: Configuration Menus 19the PRINT key
Page 37 and 38: Configuration Menus 21Scan Configur
Page 39 and 40: Specification Guide 23SR620 SPECIFI
Page 41 and 42: Specification Guide 25accuracy of t
Page 43 and 44: Specification Guide 27FREQUENCY MOD
Page 45 and 46: Programming Commands 29PROGRAMMING
Page 47 and 48: Programming Commands 31MTRG jThe MT
Page 49 and 50: Programming Commands 33returned is
Page 51 and 52: Programming Commands 35SCEN (?) jTh
Page 53 and 54: Programming Commands 37DISP (?) jTh
Page 55 and 56: Programming Commands 39LOCL jThe LO
Page 57 and 58: Programming Commands 41byte enable
Page 59 and 60: Programming Examples 43PROGRAMMING
Page 61 and 62: Programming Examples 45Program Exam
Page 63 and 64: Programming Examples 47490 CALL ENT
Page 65 and 66: Programming Examples 49call DMA2 (s
Page 67 and 68: Programming Examples 51tstring(22:2
Page 69 and 70: Programming Examples 53if ( !strlen
Page 71 and 72: Programming Examples 55/* *********
Page 73 and 74: Troubleshooting Tips 57TROUBLESHOOT
Page 75 and 76:
Troubleshooting Tips 59Be certain t
Page 77 and 78:
Performance Test 61PERFORMANCE TEST
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Performance Test 63PERFORMANCE TEST
Page 81 and 82:
Performance Test 655) Set D/A outpu
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Performance Test 67SR620 PERFORMANC
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Calibration Procedure 69CALIBRATION
Page 87 and 88:
Calibration Procedure 714) Set the
Page 89 and 90:
Calibration Procedure 731) Attach t
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Circuit Description 75SR620 CIRCUIT
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Circuit Description 77high bit from
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Circuit Description 79front panel E
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Circuit Description 81Gate_Ctrl set
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Circuit Description 83There are thr
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Circuit Description 85temperature c
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Parts List 87SR620 Parts ListFront
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Parts List 89REF. SRS PART VALUE DE
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Page 117 and 118:
Parts List 101REF. SRS PART VALUE D
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Time Interval and Frequency Counter

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