MODEL SR830 DSP Lock-In Amplifier 1290-D Reamwood Avenue Sunnyvale, California 94089 Phone: (408) 744-9040 • Fax: (408) 744-9049 email: [email protected] • www.thinkSRS.com Copyright © 1993, 2011 by SRS, Inc. All Rights Reserved. Revision 2.5 (10/2011) TABLE OF CONTENTS GENERAL INFORMATION REAR PANEL Safety and Preparation for Use 1-3 Power Entry Module 4-27 Specifications 1-5 IEEE-488 Connector 4-27 Abridged Command List 1-7 RS232 Connector 4-27 Aux Inputs (A/D Inputs) 4-27 Aux Outputs (D/A Outputs) 4-27 GETTING STARTED X and Y Outputs 4-27 Your First Measurements 2-1 Signal Monitor Output 4-28 The Basic Lock-in 2-3 Trigger Input 4-28 X, Y, R and q 2-7 TTL Sync Output 4-28 Outputs, Offsets and Expands 2-9 Preamp Connector 4-28 Storing and Recalling Setups 2-13 Using SRS Preamps 4-29 Aux Outputs and Inputs 2-15 PROGRAMMING SR830 BASICS GPIB Communications 5-1 What is a Lock-in Amplifier? 3-1 RS232 Communications 5-1 What Does a Lock-in Measure? 3-3 Status Indicators and Queues 5-1 The SR830 Functional Diagram 3-5 Command Syntax 5-1 Reference Channel 3-7 Interface Ready and Status 5-2 Phase Sensitive Detectors 3-9 GET (Group Execute Trigger) 5-2 Time Constants and DC Gain 3-11 DC Outputs and Scaling 3-13 DETAILED COMMAND LIST 5-3 Dynamic Reserve 3-15 Reference and Phase 5-4 Signal Input Amplifier and Filters 3-17 Input and Filter 5-5 Input Connections 3-19 Gain and Time Constant 5-6 Intrinsic (Random) Noise Sources 3-21 Display and Output 5-8 External Noise Sources 3-23 Aux Input and Output 5-9 Noise Measurements 3-25 Setup 5-10 Auto Functions 5-11 OPERATION Data Storage 5-12 Power On/Off and Power On Tests 4-1 Data Transfer 5-15 Reset 4-1 Interface 5-19 [Keys] 4-1 Status Reporting 5-20 Spin Knob 4-1 Front Panel BNC Connectors 4-2 STATUS BYTE DEFINITIONS Key Click On/Off 4-2 Serial Poll Status Byte 5-21 Front Panel Display Test 4-2 Service Requests 5-22 Display Off Operation 4-2 Standard Event Status Byte 5-22 Keypad Test 4-3 LIA Status Byte 5-23 Standard Settings 4-4 Error Status Byte 5-23 PROGRAM EXAMPLES FRONT PANEL Microsoft C, Nationall Instr GPIB 5-25 Signal Input and Filters 4-5 Sensitivity, Reserve, Time USING SR530 PROGRAMS 5-31 Constants 4-7 CH1 Display and Output 4-12 TESTING CH2 Display and Output 4-15 Introduction 6-1 Reference 4-18 Preset 6-1 Auto Functions 4-21 Serial Number 6-1 Setup 4-23 Firmware Revision 6-1 Interface 4-24 Test Record 6-1 Warning Messages 4-26 If A Test Fails 6-1 Necessary Equipment 6-1 1-1 TABLE OF CONTENTS Front Panel Display Test 6-2 Keypad Test 6-2 PERFORMANCE TESTS Self Tests 6-3 DC Offset 6-5 Common Mode Rejection 6-7 Amplitude Accuracy and Flatness 6-9 Amplitude Linearity 6-11 Frequency Accuracy 6-13 Phase Accuracy 6-15 Sine Output Amplitude 6-17 DC Outputs and Inputs 6-19 Input Noise 6-21 Performance Test Record 6-23 CIRCUITRY Circuit Boards 7-1 CPU and Power Supply Board 7-3 DSP Logic Board 7-5 Analog Input Board 7-7 PARTS LISTS DSP Logic Board 7-9 Analog Input Board 7-16 CPU and Power Supply Board 7-22 Front Panel Display Boards 7-26 Miscellaneous 7-33 SCHEMATIC DIAGRAMS CPU and Power Supply Board Display Board Keypad Board DSP Logic Board Analog Input Board 1-2 SAFETY AND PREPARATION FOR USE WARNING Dangerous voltages, capable of causing injury or death, are present in this instrument. Use extreme caution whenever the instrument covers are removed. Do not remove the covers while the unit is plugged into a live outlet. CAUTION SERVICE This instrument may be damaged if operated Do not attempt to service or adjust this instrument with the LINE VOLTAGE SELECTOR set for the unless another person, capable of providing first aid wrong AC line voltage or if the wrong fuse is or resuscitation, is present. installed. Do not install substitute parts or perform any LINE VOLTAGE SELECTION unauthorized modifications to this instrument. Contact the factory for instructions on how to return The SR830 operates from a 100V, 120V, 220V, the instrument for authorized service and or 240V nominal AC power source having a line adjustment. frequency of 50 or 60 Hz. Before connecting the power cord to a power source, verify that the FURNISHED Accessories LINE VOLTAGE SELECTOR card, located in the rear panel fuse holder, is set so that the correct - Power Cord AC input voltage value is visible. - Operating Manual Conversion to other AC input voltages requires a ENVIRONMENTAL CONDITIONS change in the fuse holder voltage card position and fuse value. Disconnect the power cord, open OPERATING the fuse holder cover door and rotate the fuse- Temperature: +10 °C to + 40 °C pull lever to remove the fuse. Remove the small (Specifications apply over + 18 °C to +28 °C) printed circuit board and select the operating Relative Humidity: <90 % Non-condensing voltage by orienting the printed circuit board so that the desired voltage is visible when pushed NON-OPERATING firmly into its slot. Rotate the fuse-pull lever back Temperature: -25 °C to 65 °C into its normal position and insert the correct Humidity: <95 % Non-condensing fuse into the fuse holder. WARNING REGARDING USE WITH LINE FUSE PHOTOMULTIPLIERS AND OTHER DETECTORS Verify that the correct line fuse is installed before The front end amplifier of this instrument is easily connecting the line cord. For 100V/120V, use a 1 damaged if a photomultiplier is used improperly with Amp fuse and for 220V/240V, use a 1/2 Amp the amplifier. When left completely unterminated, a fuse. cable connected to a PMT can charge to several hundred volts in a relatively short time. If this cable is LINE CORD connected to the inputs of the SR830 the stored charge may damage the front-end op amps. To The SR830 has a detachable, three-wire power avoid this problem, always discharge the cable and cord for connection to the power source and to a connect the PMT output to the SR830 input before protective ground. The exposed metal parts of turning the PMT on. the instrument are connected to the outlet ground to protect against electrical shock. Always use an outlet which has a properly connected protective ground. 1-3 Symbols you may Find on SRS Products Symbol Description Alternating current Caution - risk of electric shock Frame or chassis terminal Caution - refer to accompanying documents Earth (ground) terminal Battery Fuse On (supply) Off (supply) 1-4 SR830 DSP LOCK-IN AMPLIFIER SPECIFICATIONS SIGNAL CHANNEL Voltage Inputs Single-ended (A) or differential (A-B). Current Input 106 or 108 Volts/Amp. Full Scale Sensitivity 2 nV to 1 V in a 1-2-5-10 sequence (expand off). Input Impedance Voltage: 10 MW +25 pF, AC or DC coupled. Current: 1 kW to virtual ground. Gain Accuracy ±1% from 20°C to 30°C (notch filters off), ±0.2 % Typical. Input Noise 6 nV/(cid:214) Hz at 1 kHz (typical). Signal Filters 60 (50) Hz and 120(100) Hz notch filters (Q=4). CMRR 100 dB to10 kHz (DC Coupled), decreasing by 6db/octave above 10 kHz Dynamic Reserve Greater than 100 dB (with no signal filters). Harmonic Distortion -80 dB. REFERENCE CHANNEL Frequency Range 1 mHz to 102 kHz Reference Input TTL (rising or falling edge) or Sine. Sine input is1 MW , AC coupled (>1 Hz). 400 mV pk-pk minimum signal. Phase Resolution 0.01° Absolute Phase Error <1° Relative Phase Error <0.01° Orthogonality 90° ± 0.001° Phase Noise External synthesized reference: 0.005° rms at 1 kHz, 100 ms, 12 dB/oct. Internal reference: crystal synthesized, <0.0001° rms at 1 kHz. Phase Drift <0.01°/°C below 10 kHz <0.1°/°C to 100 kHz Harmonic Detect Detect at Nxf where N<19999 and Nxf<102 kHz. Acquisition Time (2 cycles + 5 ms) or 40 ms, whichever is greater. DEMODULATOR Zero Stability Digital displays have no zero drift on all dynamic reserves. Analog outputs: <5 ppm/°C for all dynamic reserves. Time Constants 10 µs to 30 s (reference > 200 Hz). 6, 12, 18, 24 dB/oct rolloff. up to 30000 s (reference < 200 Hz). 6, 12, 18, 24 dB/oct rolloff. Synchronous filtering available below 200 Hz. Harmonic Rejection -80 dB INTERNAL OSCILLATOR Frequency 1 mHz to 102 kHz. Frequency Accuracy 25 ppm + 30 µHz Frequency Resolution 4 1/2 digits or 0.1 mHz, whichever is greater. Distortion f<10 kHz, below -80 dBc. f>10 kHz, below -70 dBc.1 Vrms amplitude. Output Impedance 50 W Amplitude 4 mVrms to 5 Vrms (into a high impedance load) with 2 mV resolution. (2 mVrms to 2.5 Vrms into 50W load). Amplitude Accuracy 1% Amplitude Stability 50 ppm/°C Outputs Sine output on front panel. TTL sync output on rear panel. When using an external reference, both outputs are phase locked to the external reference. 1-5 SR830 DSP Lock-In Amplifier DISPLAYS Channel 1 4 1/2 digit LED display with 40 segment LED bar graph. X, R, X Noise, Aux Input 1 or 2. The display can also be any of these quantities divided by Aux Input 1 or 2. Channel 2 4 1/2 digit LED display with 40 segment LED bar graph. Y, q , Y Noise, Aux Input 3 or 4. The display can also be any of these quantities divided by Aux Input 3 or 4. Offset X, Y and R may be offset up to ±105% of full scale. Expand X, Y and R may be expanded by 10 or 100. Reference 4 1/2 digit LED display. Display and modify reference frequency or phase, sine output amplitude, harmonic detect, offset percentage (X, Y or R), or Aux Outputs 1-4. Data Buffer 16k points from both Channel 1 and Channel 2 display may be stored internally. The internal data sample rate ranges from 512 Hz down to 1 point every 16 seconds. Samples can also be externally triggered. The data buffer is accessible only over the computer interface. INPUTS AND OUTPUTS Channel 1 Output Output proportional to Channel 1 display, or X. Output Voltage: ±10 V full scale. 10 mA max output current. Channel 2 Output Output proportional to Channel 2 display, or Y. Output Voltage: ±10 V full scale. 10 mA max output current. X and Y Outputs Rear panel outputs of cosine (X) and sine (Y) components. Output Voltage: ±10 V full scale. 10 mA max output current. Aux. Outputs 4 BNC Digital to Analog outputs. ±10.5 V full scale, 1 mV resolution. 10 mA max output current. Aux. Inputs 4 BNC Analog to Digital inputs. Differential inputs with1 MW input impedance on both shield and center conductor. ±10.5 V full scale, 1 mV resolution. Trigger Input TTL trigger input triggers stored data samples. Monitor Output Analog output of signal amplifiers (before the demodulator). GENERAL Interfaces IEEE-488 and RS232 interfaces standard. All instrument functions can be controlled through the IEEE-488 and RS232 interfaces. Preamp Power Power connector for SR550 and SR552 preamplifiers. Power 40 Watts, 100/120/220/240 VAC, 50/60 Hz. Dimensions 17"W x 5.25"H x 19.5"D Weight 30 lbs. Warranty One year parts and labor on materials and workmanship. 1-6 SR830 DSP Lock-In Amplifier COMMAND LIST VARIABLES i,j,k,l,m Integers f Frequency (real) x,y,z Real Numbers s String REFERENCE and PHASE page description PHAS (?) {x} 5-4 Set (Query) the Phase Shift to x degrees. FMOD (?) {i} 5-4 Set (Query) the Reference Source to External (0) or Internal (1). FREQ (?) {f} 5-4 Set (Query) the Reference Frequency to f Hz.Set only in Internal reference mode. RSLP (?) {i} 5-4 Set (Query) the External Reference Slope to Sine(0), TTL Rising (1), or TTL Falling (2). HARM (?) {i} 5-4 Set (Query) the Detection Harmonic to 1 £ i £ 19999 and i•f £ 102 kHz. SLVL (?) {x} 5-4 Set (Query) the Sine Output Amplitude to x Vrms. 0.004 £ x £ 5.000. INPUT and FILTER page description ISRC (?) {i} 5-5 Set (Query) the Input Configuration to A (0), A-B (1) , I (1 MW ) (2) or I (100 MW ) (3). IGND (?) {i} 5-5 Set (Query) the Input Shield Grounding to Float (0) or Ground (1). ICPL (?) {i} 5-5 Set (Query) the Input Coupling to AC (0) or DC (1). ILIN (?) {i} 5-5 Set (Query) the Line Notch Filters to Out (0), Line In (1) , 2xLine In (2), or Both In (3). GAIN and TIME CONSTANT page description SENS (?) {i} 5-6 Set (Query) the Sensitivity to 2 nV (0) through 1 V (26) rms full scale. RMOD (?) {i} 5-6 Set (Query) the Dynamic Reserve Mode to HighReserve (0), Normal (1), or Low Noise (2). OFLT (?) {i} 5-6 Set (Query) the Time Constant to 10 µs (0) through 30 ks (19). OFSL (?) {i} 5-6 Set (Query) the Low Pass Filter Slope to 6 (0), 12 (1), 18 (2) or 24 (3) dB/oct. SYNC (?) {i} 5-7 Set (Query) the Synchronous Filter to Off (0) or On below 200 Hz (1). DISPLAY and OUTPUT page description DDEF (?) i {, j, k} 5-8 Set (Query) the CH1 or CH2 (i=1,2) display to XY, Rq , XnYn, Aux 1,3 or Aux 2,4 (j=0..4) and ratio the display to None, Aux1,3 or Aux 2,4 (k=0,1,2). FPOP (?) i {, j} 5-8 Set (Query) the CH1 (i=1) or CH2 (i=2) Output Source to X or Y (j=1) or Display (j=0). OEXP (?) i {, x, j} 5-8 Set (Query) the X, Y, R (i=1,2,3) Offset to x percent ( -105.00 £ x £ 105.00) and Expand to 1, 10 or 100 (j=0,1,2). AOFF i 5-8 Auto Offset X, Y, R (i=1,2,3). AUX INPUT/OUTPUT page description OAUX ? i 5-9 Query the value of Aux Input i (1,2,3,4). AUXV (?) i {, x} 5-9 Set (Query) voltage of Aux Output i (1,2,3,4) to x Volts. -10.500 £ x £ 10.500. SETUP page description OUTX (?) {i} 5-10 Set (Query) the Output Interface to RS232 (0) or GPIB (1). OVRM (?) {i} 5-10 Set (Query) the GPIB Overide Remote state to Off (0) or On (1). KCLK (?) {i} 5-10 Set (Query) the Key Click to Off (0) or On (1). ALRM (?) {i} 5-10 Set (Query) the Alarms to Off (0) or On (1). SSET i 5-10 Save current setup to setting buffer i (1£ i£ 9). RSET i 5-10 Recall current setup from setting buffer i (1£ i£ 9). AUTO FUNCTIONS page description AGAN 5-11 Auto Gain function. Same as pressing the [AUTO GAIN] key. ARSV 5-11 Auto Reserve function. Same as pressing the [AUTO RESERVE] key. APHS 5-11 Auto Phase function. Same as pressing the [AUTO PHASE] key. AOFF i 5-11 Auto Offset X,Y or R (i=1,2,3). 1-7 SR830 DSP Lock-In Amplifier DATA STORAGE page description SRAT (?) {i} 5-13 Set (Query) the DataSample Rate to 62.5 mHz (0) through 512 Hz (13) or Trigger (14). SEND (?) {i} 5-13 Set (Query) the Data Scan Mode to 1 Shot (0) or Loop (1). TRIG 5-13 Software trigger command. Same as trigger input. q TSTR (?) {i} 5-13 Set (Query) the Trigger Starts Scan modeto No (0) or Yes (1). STRT 5-13 Start or continue a scan. PAUS 5-13 Pause a scan. Does not reset a paused or done scan. REST 5-14 Reset the scan. All stored data is lost. ‡ ‡ DATA TRANSFER page description ‡ ‡ OUTP? i 5-15 Query the value of X (1), Y (2), R (3) or (4). Returns ASCII floating point value. ‡ ‡ OUTR? i 5-15 Query the value of Display i (1,2). Returns ASCII floating point value. SNAP?i,j{,k,l,m,n} 5-15 Query the value of 2 thru 6 paramters at once. OAUX? i 5-16 Query the value of Aux Input i (1,2,3,4). Returns ASCII floating point value. SPTS? 5-16 Query the number of points stored in Display buffer. TRCA? i,j,k 5-16 Read k 1 points starting at bin j 0 from Display i (1,2) buffer in ASCII floating point. TRCB? i,j,k 5-16 Read k 1 points starting at bin j 0 from Display i (1,2) buffer in IEEE binary floating point. TRCL? i,j,k 5-17 Read k 1 points starting at bin j 0 from Display i (1,2) buffer in non-normalized binary floating k point. k FAST (?) {i} 5-17 Set (Query) Fast Data Transfer Mode On (1 or 2) or Off (0).On will transfer binary X and Y every sample during a scan over the GPIB interface. STRD 5-18 Start a scan after 0.5sec delay. Use with Fast Data Transfer Mode. INTERFACE page description RST 5-19 Reset the unit to its default configurations. k IDN? 5-19 Read the SR830 device identification string. k LOCL(?) {i} 5-19 Set (Query) the Local/Remote state to LOCAL (0), REMOTE (1), or LOCAL LOCKOUT (2). k k k OVRM (?) {i} 5-19 Set (Query) the GPIB Overide Remote state to Off (0) or On (1). k TRIG 5-19 Software trigger command. Same as trigger input. k k k k STATUS page description k CLS 5-20 Clear all status bytes. k ESE (?) {i} {,j} 5-20 Set (Query) the Standard Event Status Byte Enable Register to the decimal value i (0-255). ESE i,j sets bit i (0-7) to j (0 or 1). ESE? queries the byte. ESE?i queries only bit i. ESR? {i} 5-20 Query the Standard Event Status Byte. If i is included, only bit i is queried. SRE (?) {i} {,j} 5-20 Set (Query) the Serial Poll Enable Register to the decimal value i (0-255). SRE i,j sets bit i (0- 7) to j (0 or 1). SRE? queries the byte, SRE?i queries only bit i. STB? {i} 5-20 Query the Serial Poll Status Byte. If i is included, only bit i is queried. PSC (?) {i} 5-20 Set (Query) the Power On Status Clear bit to Set (1) or Clear (0). ERRE (?) {i} {,j} 5-20 Set (Query) the Error Status Enable Register to the decimal value i (0-255). ERRE i,j sets bit i (0-7) to j (0 or 1). ERRE? queries the byte, ERRE?i queries only bit i. ERRS? {i} 5-20 Query the Error Status Byte. If i is included, only bit i is queried. LIAE (?) {i} {,j} 5-20 Set (Query) the LIA Status Enable Register to the decimal value i (0-255). LIAE i,j sets bit i (0-7) to j (0 or 1). LIAE? queries the byte, LIAE?i queries only bit i. LIAS? {i} 5-20 Query the LIA Status Byte. If i is included, only bit i is queried. 1-8