IBM 7220 - Manual

i v TABLE OF CONTENTS 6.3 RS232 and GPIB Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2 6.3.01 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....

v TABLE OF CONTENTS Appendix B, Pinouts B.1 RS232 Connector Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1 B.2 Preamplifier Power Connector Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....

Introduction Chapter 1 1-1 1.1 How to Use This Manual This manual gives detailed instructions for setting up and operating the EG&GInstruments Model 7220 Digital Signal Processing (DSP) dual phase lock-inamplifier. It is split into the following chapters:- Chapter 1 - IntroductionProvides an int...

1-3 Chapter 1, INTRODUCTION 1.3 Key Specifications and Benefits The EG&G Instruments Model 7220 represents the latest in DSP Lock-in Amplifiertechnology at an affordable price, and offers:- n Frequency range: 0.001 Hz to 120 kHz n Voltage sensitivity: 20 nV to 1 V full-scale n Current input mode...

Installation &Initial Checks Chapter 2 2-1 2.1 Installation 2.1.01 Introduction Installation of the model 7220 in the laboratory or on the production line is verysimple. Because of its low power consumption, the model 7220 does not incorporateforced-air ventilation. It can be operated on almost ...

Technical Description Chapter 3 3-1 3.1 Introduction The model 7220 lock-in amplifier is capable of outstandingly good signal recoveryperformance, provided that it is operated correctly. This chapter describes the designof the instrument, enabling the best use to be made of its facilities. Of partic...

3-9 Chapter 3, TECHNICAL DESCRIPTION 3.3.02 Relative Accuracy The majority of lock-in amplifier measurements are concerned with the variation ofthe input signal with time, temperature, etc. or with the comparison of two differentspecimens. In these cases the absolute accuracy is of less importance t...

3-10 Chapter 3, TECHNICAL DESCRIPTION reserve is often expressed in decibels, for which DR( in dB) = 20 log(DR( as a ratio)) Applying this formula to the model 7220 we may put in the maximum value ofINPUT LIMIT (3 V) and the smallest available value of FULL-SCALESENSITIVITY (20 nV) to reach a value ...

3-11 Chapter 3, TECHNICAL DESCRIPTION The circuits connected to the REF IN socket actually detect a positive-going crossingof the mean value of the applied reference voltage. Therefore when the reference inputis not sinusoidal, its effective phase is the phase of a sinusoid with positive-going zeroc...

3-12 Chapter 3, TECHNICAL DESCRIPTION The 6 dB/octave filters are not satisfactory for most purposes because they do notgive good rejection of periodic components in the demodulator output, including theinevitable component at double the reference frequency. However, the 6 dB/octavefilter finds use ...

3-14 Chapter 3, TECHNICAL DESCRIPTION 3.10 Noise Measurements The noise measurement facility is available only in the baseband mode (i.e. atreference frequencies less than 60 kHz) and uses the output processor to perform anoise computation on the Y output where it is assumed that the waveform isGaus...

Front and Rear Panels Chapter 4 4-1 4.1 Front Panel Figure 4-1, Model 7220 Front Panel Layout As shown in figure 4-1 there are four BNC connectors with associated LEDindicators, two LCD display panels, an edge-indicating analog meter, eight doubleand three single keys mounted on the model 7220’s fro...

Front Panel Operation Chapter 5 5-1 5.1 Introduction This chapter describes how to operate the model 7220 using the front panel controls,and describes its capabilities when used in this way. Chapter 6 provides similarinformation in the situation where the unit is operated remotely using one of theco...

5-2 Chapter 5, FRONT PANEL OPERATION the right-hand display. The setup menu description is shown on the left-hand side ofthe left-hand display. Figure 5-1 makes this clear. One further press of the MENU key causes the instrument to leave the setup menumode and return to the main display mode. On lea...

5-3 Chapter 5, FRONT PANEL OPERATION the front panel BNC connector marked “B/I ”, and uses a low-noise (LN) currentto voltage converter. Input This control has four settings:- Flt/DC The shells of the “A” and “B/I ” connectors are connected to chassis ground via a1 k Ω resistor and the signal channe...

5-4 Chapter 5, FRONT PANEL OPERATION 5.2.02 Reference Setup Menu Figure 5-3, Reference Setup Menu In this menu, shown in figure 5-3, there are three controls affecting the referencechannel of the instrument. They are:- Ref Source This control allows selection of the source of reference signal used t...

5-5 Chapter 5, FRONT PANEL OPERATION ON When the Demodulator Monitor is switched ON and the instrument is operatingin External Reference mode, the signal at the OSC OUT connector changes fromthat of the internal oscillator to an analog representation of the drive from thereference channel to the X o...

5-6 Chapter 5, FRONT PANEL OPERATION OFF Output expansion is turned off. X ONLY A ×10 output expansion is applied to the X output only. Y ONLY A ×10 output expansion is applied to the Y output only. X & Y A ×10 output expansion is applied to both the X and Y outputs. CH1 OUTPUTS CH2 This control...

5-7 Chapter 5, FRONT PANEL OPERATION MAG %fs CH1/2 Voltage+120 12.0 V +100 10.0 V 0 0.0 V -100 -10.0 V -120 -12.0 V PHASE1 When set to PHASE1 the corresponding rear panel CH1/CH2 connector willoutput a voltage related to the PHA deg front panel display as follows:- PHA deg CH1/2 Voltage +180 9.0 V +...

5-8 Chapter 5, FRONT PANEL OPERATION 5.2.04 Control Options Menu Figure 5-5, Control Options Setup Menu This menu, shown in figure 5-5, has three controls affecting the line frequencyrejection filter, AC Gain control and output time constants, as follows:- Linefilt This control sets the mode of oper...

5-9 Chapter 5, FRONT PANEL OPERATION MANUAL In this setting the AC Gain may be manually adjusted from the main display. AUTOMATIC In this setting the AC Gain value is automatically selected by the instrument,depending on the full-scale sensitivity. TC’s This control affects the output time constants...

5-10 Chapter 5, FRONT PANEL OPERATION 5.2.05 Miscellaneous Options Menu Figure 5-6, Miscellaneous Options Setup Menu This menu, shown in figure 5-6, has three controls affecting the auxiliary ADCtrigger rate and the front panel display as follows:- Trigger This control selects the trigger which is u...

5-11 Chapter 5, FRONT PANEL OPERATION 5.2.06 RS232 Setup 1 Menu Figure 5-7, RS232 Setup 1 Menu This menu, shown in figure 5-7, has three controls affecting the RS232 computerinterface, as follows:- BaudRate Thirteen values of Baud Rate are available in the range 75 to 19200 bits per second. Format T...

5-13 Chapter 5, FRONT PANEL OPERATION MP command (report Magnitude and Phase). Hence it is necessary for the controllingprogram to be able to determine when all of the first value has been sent. Thedelimiter is a separator character sent between each response which may be used forthis purpose. The c...

5-15 Chapter 5, FRONT PANEL OPERATION 5.2.10 GPIB Setup 2 Menu Figure 5-11, GPIB Setup 2 Menu This menu, shown in figure 5-11, has two controls affecting the GPIB computerinterface, as follows:- SRQ Mask The instrument includes the ability to generate a Service Request on the GPIBinterface, to signa...

5-16 Chapter 5, FRONT PANEL OPERATION 5.2.11 Digital Outputs Setup Menu Figure 5-12, Digital Outputs Setup Menu This menu, shown in figure 5-12, is used to control the 8 TTL lines of the rear paneldigital output port, used for controlling external equipment. Decimal The bit pattern appearing at the ...

5-17 Chapter 5, FRONT PANEL OPERATION 5.2.12 Control Setup Menu Figure 5-13, Control Setup Menu The final setup menu, shown in figure 5-13, is used to set the instrument to a knownstate and to adjust the sampling rate of the main analog to digital converter. Default Setting Pressing a key adjacent t...

5-18 Chapter 5, FRONT PANEL OPERATION 5.3 Auto Functions Menu When in the Main Display mode, one press of the MENU key accesses the AUTOMENU showing four auto functions that are built into the instrument. The left-handLCD changes to that shown in figure 5-14. Figure 5-14, Auto Functions Menu - Left-...

5-19 Chapter 5, FRONT PANEL OPERATION are steady, implying the signal phase is stable, when the procedure is called. If a zero error is present on the outputs, such as may be caused by unwanted couplingbetween the reference and signal channel inputs, then the following procedure shouldbe adopted:- 1...

Computer Operation Chapter 6 6-1 6.1 Introduction The model 7220 includes both RS232 and IEEE-488 (also known as GPIB forGeneral Purpose Interface Bus) interface ports, designed to allow the lock-inamplifier to be completely controlled from a remote computer. All the instrument’scontrols may be oper...

6-2 Chapter 6, COMPUTER OPERATION 6.2.04 Internal Oscillator Frequency Sweep Generator The instrument’s internal oscillator may be swept in frequency both linearly andlogarithmically over a specified range. This facility allows the instrument to functionas a simple swept-frequency oscillator, or, in...

6-10 Chapter 6, COMPUTER OPERATION 6.4 Command Descriptions This section lists the commands in logical groups, so that, for example, all commandsassociated with setting controls affecting the signal channel are shown together.Appendix E gives the same list of commands but in alphabetical order. 6.4....

6-30 Chapter 6, COMPUTER OPERATION 6.4.12 Front Panel LTS [n] Lights on/off control The value of n controls the front panel LEDs and LCD backlights according to thefollowing table: n Selection 0 All lights off 1 Normal operation 6.4.13 Default Setting ADF Default Setting command This command will au...

6-32 Chapter 6, COMPUTER OPERATION 6.5.04 X and Y Output Curve Storage Measurement In this example, the lock-in amplifier is measuring a current input signal applied tothe B input connector and the measured X output and Y output are recorded for 10seconds at a 100 Hz sampling rate. The acquired curv...

6-33 Chapter 6, COMPUTER OPERATION NC Clear and reset curve buffer LEN 20000 500 ms recording time at 40 kHz = 20,000 points TADC 6 Set ADC1 sampling to burst mode, fixed rate ( ≈ 40 kHz), external trigger, and arm trigger As soon as a trigger occurs, the acquisition starts. Once it completes the ac...

Specifications Appendix A A-1 Measurement Modes X In-phase  Y Quadrature  The unit can simultaneously present any R Magnitude  two of these as outputs θ Phase Angle  Noise  Harmonic 2F or 3F Noise Measures noise in a given bandwidth centeredon frequency F Displays Two LED backlit, two-line, 16-...

A-2 Appendix A, SPECIFICATIONS Current Input Mode Low Noise or Wide Bandwidth Full-scale Sensitivity Low Noise 20 fA to 10 nA in a 1-2-5 sequence Wide Bandwidth 20 fA to 1 µA in a 1-2-5 sequence Dynamic Reserve > 100 dB (with no signal filters) Frequency Response Low Noise -3 dB at 500 Hz Wide Ba...

A-3 Appendix A, SPECIFICATIONS Orthogonality 90º ±0.0001º Drift < 0.01º/ºC below 10 kHz < 0.1º/ºC above 10 kHz Acquisition Time Internal Reference instantaneous acquisition External Reference 2 cycles + 50 ms Reference Frequency Meter Accuracy 120 kHz > F > 40 kHz ±4 Hz 40 kHz > F >...

A-4 Appendix A, SPECIFICATIONS Amplitude Range 1 mV to 5 V Setting Resolution 1 mV to 500 mV 1 mV 501 mV to 2 V 4 mV 2.001 V to 5 V 10 mV Accuracy 0.001 Hz to 60 kHz ±0.3 % 60 kHz to 120 kHz ±0.5 % Stability 50 ppm/ºC Output Impedance 50 Ω Auxiliary Inputs ADC 1 and 2 Maximum Input ±10 V Resolution ...

A-5 Appendix A, SPECIFICATIONS Signal Monitor Amplitude ±10 V FS Impedance 1 k Ω Aux D/A Output 1, 2 Maximum Output ±10 V Resolution 1 mV Accuracy ±0.1 % Output Impedance 1 k Ω 8-bit Digital Output 8 TTL compatible lines that can beindependently set high or low to activateexternal equipment Referenc...

A-6 Appendix A, SPECIFICATIONS General Dimensions Width 432 mm (17 ") Depth 415 mm (16.4 ") Height With feet 74 mm (2.9 ") Without feet 60 mm (2.4 ") Weight 7.4 kg (16.3 lb)

Pinouts Appendix B B-1 B.1 RS232 Connector Pinout 1 2 3 4 6 7 8 5 9 Figure B-1, RS232 and AUX RS232 Connector (Female) PIN FUNCTION COMMENT 2 RXD Data In 3 TXD Data Out 5 GND Signal Ground 7 RTS (Always at +12 V) All other pins are not connected. B.2 Preamplifier Power Connector Pinout Figure B-2, P...

B-2 Appendix B, PINOUTS B.3 Digital Output Port Connector Figure B-3, Digital Output Port Connector 8-bit TTL-compatible output set from the front panel or via the computer interfaces;each line can drive 3 LSTTL loads. This connector mates with a 20-pin IDC HeaderPlug. The pinout is as follows. PIN ...

DemonstrationPrograms Appendix C C-1 C.1 Simple Terminal Emulator This is a short terminal emulator with minimal facilities, which will run on a PC-compatible computerin a Microsoft GW-BASIC or QuickBASIC environment, or can be compiled with a suitable compiler. 10 'MINITERM 9-Feb-9620 CLS: PRINT &#...

C-3 Appendix C, DEMONSTRATION PROGRAMS C.3 GPIB User Interface Program GPCOM.BAS is a user interface program which illustrates the principles of the use of the serial pollstatus byte to coordinate the command and data transfer. The program runs under Microsoft GW-BASIC or QuickBASIC on a PC-compatib...

Cable Diagrams Appendix D D-1 D.1 RS232 Cable Diagrams Users who choose to use the RS232 interface to connect the model 7220 lock-inamplifier to a standard serial port on a computer, will need to use one of two types ofcable. The only difference between them is the number of pins used on the connect...

Default Settings Appendix F F-1 Default Setting Function The default setting function sets the model 7220’s controls and output displays asfollows:- Left-hand LCDDisplays the AC Gain control on the upper line and the full-scale sensitivity controlon the lower line. Right-hand LCDDisplays the magnitu...

Index Index Index-1 * command 6-18, E-16 \N n command 6-28, E-12 2F reference mode 3-7, 5-4 8-bit programmable output port 3-8 90° Key 4-5 Absolute accuracy 3-8 AC Gain and full-scale sensitivity 3-9and input overload 3-4control 5-8, 5-22description of 3-4 AC GAIN [n] command 6-12, E-1 AC/DC input c...

WARRANTY EG&G Instruments Corporation warrants each instrument of its own manufacture to be free of defects in material andworkmanship for a period of ONE year from the date of delivery to the original purchaser. Obligations under this Warrantyshall be limited to replacing, repairing or giving c...