DSP Lock-In Amplifier model SR830 1290 D Reamwood Avenue Sunnyvale, CA 94089 USA Phone: (408) 744-9040 • Fax: (408) 744-9049 www.thinkSRS.com •e-mail: info@thinkSRS.com Copyright© 1999 All Rights Reserved Revision 1.
TABLE OF CONTENTS GENERAL INFORMATION Safety and Preparation for Use Specifications Abridged Command List 1-3 1-5 1-7 GETTING STARTED Your First Measurements The Basic Lock-in X, Y, R and θ Outputs, Offsets and Expands Storing and Recalling Setups Aux Outputs and Inputs 2-1 2-3 2-7 2-9 2-13 2-15 SR830 BASICS What is a Lock-in Amplifier? What Does a Lock-in Measure? The SR830 Functional Diagram Reference Channel Phase Sensitive Detectors Time Constants and DC Gain DC Outputs and Scaling Dynamic Reserve S
Table of Contents TESTING CIRCUITRY Introduction Preset Serial Number Firmware Revision Test Record If A Test Fails Necessary Equipment Front Panel Display Test Keypad Test 6-1 6-1 6-1 6-1 6-1 6-1 6-1 6-2 6-2 PERFORMANCE TESTS Self Tests DC Offset Common Mode Rejection Amplitude Accuracy and Flatness Amplitude Linearity Frequency Accuracy Phase Accuracy Sine Output Amplitude DC Outputs and Inputs Input Noise Performance Test Record 6-3 6-5 6-7 6-9 6-11 6-13 6-15 6-17 6-19 6-21 6-23 Circuit Boards CPU
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 LINE FUSE This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set for the wrong AC line voltage or if the wrong fuse is installed. Verify that the correct line fuse is installed before connecting the line cord.
1-4
SR830 DSP LOCK-IN AMPLIFIER SPECIFICATIONS SIGNAL CHANNEL Voltage Inputs Current Input Full Scale Sensitivity Input Impedance Gain Accuracy Input Noise Signal Filters CMRR Dynamic Reserve Harmonic Distortion REFERENCE CHANNEL Frequency Range Reference Input Phase Resolution Absolute Phase Error Relative Phase Error Orthogonality Phase Noise Phase Drift Harmonic Detect Acquisition Time DEMODULATOR Zero Stability Time Constants Harmonic Rejection INTERNAL OSCILLATOR Frequency Frequency Accuracy Frequency Res
SR830 DSP Lock-In Amplifier DISPLAYS Channel 1 Channel 2 Offset Expand Reference Data Buffer INPUTS AND OUTPUTS Channel 1 Output Channel 2 Output X and Y Outputs Aux. Outputs Aux. Inputs Trigger Input Monitor Output GENERAL Interfaces Preamp Power Power Dimensions Weight Warranty 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. 4 1/2 digit LED display with 40 segment LED bar graph.
SR830 DSP Lock-In Amplifier COMMAND LIST VARIABLES i,j,k,l,m f x,y,z s REFERENCE and PHASE PHAS (?) {x} FMOD (?) {i} FREQ (?) {f} RSLP (?) {i} HARM (?) {i} SLVL (?) {x} page 5-4 5-4 5-4 5-4 5-4 5-4 description Set (Query) the Phase Shift to x degrees. Set (Query) the Reference Source to External (0) or Internal (1). Set (Query) the Reference Frequency to f Hz.Set only in Internal reference mode. Set (Query) the External Reference Slope to Sine(0), TTL Rising (1), or TTL Falling (2).
SR830 DSP Lock-In Amplifier DATA STORAGE SRAT (?) {i} SEND (?) {i} TRIG TSTR (?) {i} STRT PAUS REST page 5-13 5-13 5-13 5-13 5-13 5-13 5-14 description Set (Query) the DataSample Rate to 62.5 mHz (0) through 512 Hz (13) or Trigger (14). Set (Query) the Data Scan Mode to 1 Shot (0) or Loop (1). Software trigger command. Same as trigger input. Set (Query) the Trigger Starts Scan modeto No (0) or Yes (1). Start or continue a scan. Pause a scan. Does not reset a paused or done scan. Reset the scan.
SR830 DSP Lock-In Amplifier STATUS BYTE DEFINITIONS SERIAL POLL STATUS BYTE (5-21) bit 0 1 2 3 4 5 6 7 name SCN IFC ERR LIA MAV ESB SRQ Unused LIA STATUS BYTE (5-23) usage No data is being acquired No command execution in progress Unmasked bit in error status byte set Unmasked bit in LIA status byte set The interface output buffer is non-empty Unmasked bit in standard status byte set SRQ (service request) has occurred bit 0 1 2 3 4 5 6 7 STANDARD EVENT STATUS BYTE (5-22) bit 0 1 2 3 4 5 6 7 name INP U
SR830 DSP Lock-In Amplifier 1-10
GETTING STARTED YOUR FIRST MEASUREMENTS The sample measurements described in this section are designed to acquaint the first time user with the SR830 DSP Lock-In Amplifier. Do not be concerned that your measurements do not exactly agree with these exercises. The focus of these measurement exercises is to learn how to use the instrument. It is highly recommended that the first time user step through some or all of these exercises before attempting to perform an actual experiment.
Getting Started 2-2
The Basic Lock-in THE BASIC LOCK-IN This measurement is designed to use the internal oscillator to explore some of the basic lock-in functions. You will need BNC cables. Specifically, you will measure the amplitude of the Sine Out at various frequencies, sensitivities, time constants and phase shifts. 1. Disconnect all cables from the lock-in. Turn the power on while holding down the [Setup] key. Wait until the power-on tests are completed.
The Basic Lock-in Use the knob to adjust the phase shift until Y is zero and X is equal to the positive amplitude. The knob is used to adjust parameters which are shown in the Reference display, such as phase, amplitude and frequency. The final phase value should be close to zero again. Press [Auto Phase] Use the Auto Phase function to return Y to zero and X to the amplitude. Show the internal oscillator frequency in the Reference display. 6.
The Basic Lock-in Parameters which have only a few values, such as filter slope, have only a single key which cycles through all available options. Press the corresponding key until the desired option is indicated by an led. 11. Press the [Slope/Oct] key until 6 dB/oct is selected. The X and Y outputs are somewhat noisy at this short time constant and only 1 pole of low pass filtering. The outputs are less noisy with 2 poles of filtering. Press [Slope/Oct] again to select 12 dB/oct.
The Basic Lock-in 2-6
X, Y, R and θ X, Y, R and θ This measurement is designed to use the internal oscillator and an external signal source to explore some of the display types. You will need a synthesized function generator capable of providing a 100 mVrms sine wave at 1.000 kHz (the DS335 from SRS will suffice), BNC cables and a terminator appropriate for the generator function output. Specifically, you will display the lock-in outputs when measuring a signal close to, but not equal to, the internal reference frequency.
X, Y, R and θ should now oscillate at about 0.2 Hz (the accuracy is determined by the crystals of the generator and the lock-in). 4. Press [Channel 1 Display] to select R. The default Channel 1 display is X. Change the display to show R. R is phase independent so it shows a steady value (close to 0.500 V). 5. Press [Channel 2 Display] to select θ. The default Channel 2 display is Y. Change the display to show θ. The phase between the reference and the signal changes by 360° approximately every 5 sec (0.
Outputs, Offsets and Expands OUTPUTS, OFFSETS and EXPANDS This measurement is designed to use the internal oscillator to explore some of the basic lock-in outputs. You will need BNC cables and a digital voltmeter (DVM). Specifically, you will measure the amplitude of the Sine Out and provide analog outputs proportional to the measurement. The effect of offsets and expands on the displayed values and the analog outputs will be explored. 1. Disconnect all cables from the lock-in.
Outputs, Offsets and Expands 5. Press [Channel 1 Auto Offset] X, Y and R may all be offset and expanded separately. Since Channel 1 is displaying X, the OFFSET and [Expand] keys below the Channel 1 display set the X offset and expand. The display determines which quantity (X or R) is offset and expanded. Auto Offset automatically adjusts the X offset (or Y or R) such that X (or Y or R) becomes zero. In this case, X is offset to zero. The offset should be about 50%.
Outputs, Offsets and Expands turn on the OVLD indicator in the Channel 1 display. With offset and expand, the output voltage gain and offset can be programmed to provide control of feedback signals with the proper bias and gain for a variety of situations. Offsets add and subtract from the displayed values while expand increases the resolution of the display. 6. Connect the DVM to the X output on the rear panel.
Outputs, Offsets and Expands 2-12
Storing and Recalling Setups STORING and RECALLING SETUPS The SR830 can store 9 complete instrument setups in non-volatile memory. 1. Turn the lock-in on while holding down the [Setup] key. Wait until the power-on tests are completed. Disconnect any cables from the lock-in. When the power is turned on with the [Setup] key pressed, the lock-in returns to its standard settings. See the Standard Settings list in the Operation section for a complete listing of the settings.
Storing and Recalling Setups 2-14
Aux Outputs and Inputs AUX OUTPUTS and INPUTS This measurement is designed to illustrate the use of the Aux Outputs and Inputs on the rear panel. You will need BNC cables and a digital voltmeter (DVM). Specifically, you will set the Aux Output voltages and measure them with the DVM. These outputs will then be connected to the Aux Inputs to simulate external DC voltages which the lock-in can measure. 1. Disconnect all cables from the lock-in. Turn the power on while holding down the [Setup] key.
Aux Outputs and Inputs 6. Press [Channel 2 Display] to select AUX IN 3. Change the Channel 2 display to measure Aux Input 3. 7. Connect Aux Out 1 to Aux In 3 on the rear panel. Channel 2 should now display -5 V (Aux In 3). The Channel 1 and 2 displays may be ratio'ed to the Aux Input voltages. See the Basics section for more about output scaling. The displays may be stored in the internal data buffers at a programmable sampling rate.
SR830 BASICS WHAT IS A LOCK-IN AMPLIFIER? Lock-in amplifiers are used to detect and measure very small AC signals - all the way down to a few nanovolts! Accurate measurements may be made even when the small signal is obscured by noise sources many thousands of times larger. experiment at the reference frequency. In the diagram below, the reference signal is a square wave at frequency ωr. This might be the sync output from a function generator.
SR830 Basics This is a very nice signal - it is a DC signal proportional to the signal amplitude. sync) which is always phase-locked to the reference oscillator. Narrow band detection Magnitude and phase Now suppose the input is made up of signal plus noise. The PSD and low pass filter only detect signals whose frequencies are very close to the lockin reference frequency.
SR830 Basics WHAT DOES A LOCK-IN MEASURE? So what exactly does the SR830 measure? Fourier's theorem basically states that any input signal can be represented as the sum of many, many sine waves of differing amplitudes, frequencies and phases. This is generally considered as representing the signal in the "frequency domain". Normal oscilloscopes display the signal in the "time domain".
SR830 Basics 3-4
SR830 Basics THE FUNCTIONAL SR830 The functional block diagram of the SR830 DSP Lock-In Amplifier is shown below. The functions in the gray area are handled by the digital signal processor (DSP). We'll discuss the DSP aspects of the SR830 as they come up in each functional block description.
SR830 Basics 3-6
SR830 Basics REFERENCE CHANNEL A lock-in amplifier requires a reference oscillator phase-locked to the signal frequency. In general, this is accomplished by phase-locking an internal oscillator to an externally provided reference signal. This reference signal usually comes from the signal source which is providing the excitation to the experiment. When an external reference is used, this internal oscillator sine wave is phase-locked to the reference.
SR830 Basics jitter means that the average phase shift is zero but the instantaneous phase shift has a few millidegrees of noise. This shows up at the output as noise in phase or quadrature measurements. crystal oscillator and is very, very small). Harmonic Detection It is possible to compute the two PSD reference sine waves at a multiple of the internal oscillator frequency. In this case, the lock-in detects signals at Nxfref which are synchronous with the reference.
SR830 Basics THE PHASE SENSITIVE DETECTORS (PSD's) The SR830 multiplies the signal with the reference sine waves digitally. The amplified signal is converted to digital form using a 16 bit A/D converter sampling at 256 kHz. The A/D converter is preceded by a 102 kHz anti-aliasing filter to prevent higher frequency inputs from aliasing below 102 kHz. The signal amplifier and filters will be discussed later.
SR830 Basics 3-10
SR830 Basics TIME CONSTANTS and DC GAIN Remember, the output of the PSD contains many signals. Most of the output signals have frequencies which are either the sum or difference between an input signal frequency and the reference frequency. Only the component of the input signal whose frequency is exactly equal to the reference frequency will result in a DC output. stages of filtering with a maximum roll off of 12 dB/oct. This limitation is usually due to space and expense.
SR830 Basics increasingly useful the lower the reference frequency. Imagine what the time constant would need to be at 0.001 Hz! the dynamic reserve is increased to 80dB, then this offset needs to be 10 times smaller still. This is one of the reasons why analog lock-ins do not perform well at very high dynamic reserve. In the SR830, synchronous filters are available at detection frequencies below 200 Hz.
SR830 Basics DC OUTPUTS and SCALING The SR830 has X and Y outputs on the rear panel and Channel 1 and 2 (CH1 and CH2) outputs on the front panel. defined as X, Y or R, the output scale is also 10 V full scale. Lock-in amplifiers are designed to measure the RMS value of the AC input signal. All sensitivities and X, Y and R outputs and displays are RMS values.
SR830 Basics The analog output with offset and expand is where offset is a fraction of 1 (50%-0.5), expand is 1, 10 or 100, and the display can not exceed 100%. Output = (signal/sensitivity - offset) x Expand x10V where offset is a fraction of 1 (50%=0.5), expand is 1, 10 or 100, and the output can not exceed 10 V. In the above example, Output = (0.91mV/1mV - 0.9) x 10 x 10V = 1V For example, if the sensitivity is 1V and CH1 display is showing X/Aux 1. If X= 500 mV and Aux 1= 2.
SR830 Basics DYNAMIC RESERVE We've mentioned dynamic reserve quite a bit in the preceding discussions. It's time to clarify dynamic reserve a bit. because the DC output amplifier is running at very high gain and low frequency noise and offset drift at the PSD output or the DC amplifier input will be amplified and appear large at the output. The noise is more tolerable than the DC drift errors since increasing the time constant will attenuate the noise.
SR830 Basics signal input attenuates frequencies far outside the lock-in's operating range (fnoise>>100 kHz). In these cases, the reserve can be higher at these frequencies than within the operating range. While this may be a nice specification, removing noise at frequencies very far from the reference does not require a lock-in amplifier. Lock-ins are used when there is noise at frequencies near the signal. Thus, the dynamic reserve for noise within the operating range is more important.
SR830 Basics SIGNAL INPUT AMPLIFIER and FILTERS A lock-in can measure signals as small as a few nanovolts. A low noise signal amplifier is required to boost the signal to a level where the A/D converter can digitize the signal without degrading the signal to noise. The analog gain in the SR830 ranges from roughly 7 to 1000. As discussed previously, higher gains do not improve signal to noise and are not necessary. with a 100 ms time constant and 6 dB/oct of filter roll off.
SR830 Basics the measurement. Using either of these filters precludes making measurements in the vicinity of the notch frequencies. These filters have a finite range of attenuation, generally 10 Hz or so. Thus, if the lock-in is making measurements at 70 Hz, do not use the 60 Hz notch filter! The signal will be attenuated and the measurement will be in error. When measuring phase shifts, these filters can affect phase measurements up to an octave away.
SR830 Basics INPUT CONNECTIONS Differential Voltage Connection (A-B) In order to achieve the best accuracy for a given measurement, care must be taken to minimize the various noise sources which can be found in the laboratory. With intrinsic noise (Johnson noise, 1/f noise or input noise), the experiment or detector must be designed with these noise sources in mind. These noise sources are present regardless of the input connections.
SR830 Basics Current Input (I) AC vs DC Coupling The current input on the SR830 uses the A input BNC. The current input has a 1 kΩ input impedance and a current gain of either 106 or 108 Volts/Amp. Currents from 1 µA down to 2 fA full scale can be measured. The signal input can be either AC or DC coupled. The AC coupling high pass filter passes signals above 160 mHz (0.16 Hz) and attenuates signals at lower frequencies. AC coupling should be used at frequencies above 160 mHz whenever possible.
SR830 Basics INTRINSIC (RANDOM) NOISE SOURCES Random noise finds its way into experiments in a variety of ways. Good experimental design can reduce these noise sources and improve the measurement stability and accuracy. Slope 6 dB/oct 12 dB/oct 18 dB/oct 24 dB/oct There are a variety of intrinsic noise sources which are present in all electronic signals. These sources are physical in origin.
SR830 Basics quencies more difficult. Other sources of 1/f noise include noise found in vacuum tubes and semiconductors. Total noise All of these noise sources are incoherent. The total random noise is the square root of the sum of the squares of all the incoherent noise sources.
SR830 Basics EXTERNAL NOISE SOURCES In addition to the intrinsic noise sources discussed in the previously, there are a variety of external noise sources within the laboratory. For example, if the noise source is a power circuit, then f = 60 Hz and V noise = 120 V. Cstray can be estimated using a parallel plate equivalent capacitor. If the capacitance is roughly an area of 1 cm2 at a separated by 10 cm, then Cstray is 0.009 pF. The resulting noise current will be 400 pA (at 60 Hz).
SR830 Basics Microphonics Cures for inductively coupled noise include: Not all sources of noise are electrical in origin. Mechanical noise can be translated into electrical noise by microphonic effects. Physical changes in the experiment or cables (due to vibrations for example) can result in electrical noise over the entire frequency range of the lock-in. 1) Removing or turning off the interfering noise source.
SR830 Basics NOISE MEASUREMENTS Lock-in amplifiers can be used to measure noise. Noise measurements are generally used to characterize components and detectors. is computed. This is the mean value of X over some past history. The present mean value of X is subtracted from the present value of X to find the deviation of X from the mean. Finally, the moving average of the absolute value of the deviations is calculated. This calculation is called the mean average deviation or MAD.
SR830 Basics 3-26
FRONT PANEL CH1 Display Signal Inputs CH2 Display Analog Outputs Power Ref Display Ref Input Sine Output The power switch is on the rear panel. The SR830 is turned on by pushing the switch up. The serial number (5 digits) is shown in the CH1 and CH2 displays and the firmware version is shown in the Ref display at power on. A series of internal tests are performed at this point. DATA Performs a read/write test to the processor RAM. BATT The nonvolatile backup memory is tested.
Front Panel Knob The knob is used to adjust parameters in the Reference display. The parameters which may be adjusted are internal reference frequency, reference phase shift, sine output amplitude, harmonic detect number, offsets, Aux Output levels, and various Setup parameters. Local Lockout If the computer interface has placed the unit in the REMOTE state, indicated by the REMOTE led, then the keys and the knob are disabled.
Front Panel together to enter the front panel test mode. Press [Phase] to decrease the number of on LED's until all of the LED's are off. The SR830 is still operating, the output voltages are updated and the unit responds to interface commands. To change a setting, press any key other than [Phase] or [Freq] to return to normal operation, change the desired parameter, then press [Phase] and [Freq] together to return to the test mode. Turn the LED's all off with the [Phase] key.
Front Panel STANDARD SETTINGS If the [Setup] key is held down when the power is turned on, the lock-in settings will be set to the defaults shown below rather than the settings that were in effect when the power was last turned off. The default settings may also be recalled using the ❊RST command over the computer interface. In this case, the communications parameters and status registers are not changed.
Front Panel Signal Input and Filters [Input] The [Input] key selects the front end signal input configuration. The input amplifier can be either a single-ended (A) or differential (A-B) voltage or a current (I). The voltage inputs have a 10 MΩ, 25 pF input impedance. Their connector shields are isolated from the chassis by either 10 Ω (Ground) or 10 kΩ (Float). Do not apply more than 50 V to either input. The shields should never exceed 1 V. The current input uses the A connector.
Front Panel INPUT OVLD The OVLD led in this section indicates an INPUT overload. This occurs for voltage inputs greater than 1.4Vpk (unless removed by AC coupling) or current inputs greater than 10 µA DC or 1.4 µA AC (1MΩ gain) or 100 nA DC or 14 nA AC (100MΩ gain). Reduce the input signal level. [Couple] This key selects the input coupling. The signal input can be either AC or DC coupled. The current input is coupled after the current to voltage conversion.
Front Panel Sensitivity, Reserve and Time Constants [Sensitivity Up/Dn] The [Sensitivity Up] and [Sensitivity Down] keys select the full scale sensitivity. The sensitivity is indicated by 1-2-5 times 1, 10 or 100 with the appropriate units. The full scale sensitivity can range from 2 nV to 1 V (rms) or 2 fA to 1 µA (rms). The sensitivity indication is not changed by the X, Y, or R output expand. The expand functions increase the output scale as well as the display resolution.
Front Panel The actual dynamic reserves (in dB) for each sensitivity are listed below.
Front Panel the detection frequency is below 200 Hz and 100 s is the time constant and the frequency increases above 200 Hz, the time constant WILL change to 30 s. Decreasing the frequency back below 200 Hz will NOT change the time constant back to 100 s. The absolute minimum time constant is 10 µs. The actual minimum time constant depends upon the filter slope and the DC gain in the low pass filter (dynamic reserve plus expand).
Front Panel Read the minimum time constant for this entry. For example, if the slope is 12 dB/oct, the reserve is 64 dB, and the X expand is 10 (20 dB), then the DC gain is 84 dB and the min time constant is 100 µs. Time constant is a low priority parameter. If the sensitivity, dynamic reserve, filter slope, or expand is changed, and the present time constant is below the new minimum, the time constant WILL change to the new minimum.
Front Panel The poles which are set by the time constant are the ones closest to the PSD's. For example, if the time constant is 100 ms with 12 dB/oct slope and synchronous filtering is on, then the PSD's are followed by two poles of low pass filtering with 100 ms time constant, the synchronous filter, then two poles of minimum time constant. Synchronous filtering removes outputs at harmonics of the reference frequency, most commonly 2xf.
Front Panel CH1 Display and Output [Display] This key selects the Channel 1 display quantity. Channel 1 may display X, R, X Noise, Aux Input 1 or Aux Input 2. The numeric display has the units of the input signal. The bar graph is ±full scale sensitivity for X, R and X Noise, and ±10V for the Aux Inputs. Ratio displays are shown in % and the bar graph is scaled to ±100%. See the SR830 Basics section for a complete discussion of scaling.
Front Panel key. The Ratio indicator in the display is on to indicate a ratio measurement. Pressing this key until the AUX IN leds and the Ratio indicator are off returns the measurement to non-ratio mode. [Output] This key selects the CH1 OUTPUT source. The Channel 1 Output can provide an analog output proportional to the Display or X. The output proportional to X has a bandwidth of 100 kHz (the output is updated at 256 kHz). This output is the traditional X output of a lock-in.
Front Panel display key ([Phase], [Freq], [Ampl], [Harm #] or [Aux Out]). [Auto Offset] Pressing this key automatically sets the X or R offset percentage to offset the selected output quantity to zero. [Expand] Pressing this key selects the X and R Expand. Use the [Display] key to select either X or R. The expand can be 1 (no expand), 10 or 100. If the expand is 10 or 100, the Expand indicator below the display will turn on. The output can never exceed full scale when expanded.
Front Panel CH2 Display and Output [Display] This key selects the Channel 2 display quantity. Channel 2 may display Y, θ, Y Noise, Aux Input 3 or Aux Input 4. The numeric display has the units of the input signal. The bar graph is ±full scale sensitivity for Y and Y Noise, ±180 ° for θ, and ±10V for the Aux Inputs. Ratio displays are shown in % and the bar graph is scaled to ±100%. See the SR830 Basics section for a complete discussion of scaling.
Front Panel off returns the measurement to non-ratio mode. This key selects the CH2 OUTPUT source. The Channel 2 Output can provide an analog output proportional to the Display or Y. The output proportional to Y has a bandwidth of 100 kHz (the output is updated at 256 kHz). This output is the traditional Y output of a lock-in. Output proportional to the display (even if the display is simply Y) has a bandwidth of 200 Hz (updated at 512 Hz). [Output] Remember, The Y output has 100 kHz of bandwidth.
Front Panel [Expand] Pressing this key selects the Y Expand. The expand can be 1 (no expand), 10 or 100. If the expand is 10 or 100, the Expand indicator below the display will turn on. The output can never exceed full scale when expanded. For example, if an output is 10% of full scale, the largest expand (with no offset) which does not overload is 10. An output expanded beyond full scale will be overloaded.
Front Panel Reference [Phase] Pressing this key displays the reference phase shift in the Reference display. The knob may be used to adjust the phase. The phase shift ranges from -180° to +180° with 0.01° resolution. When using an external reference, the reference phase shift is the phase between the external reference and the digital sine wave which is multiplying the signal in the PSD.
Front Panel [+90°] and [-90°] The [+90°] and [-90°] keys add or subtract 90.000° from the reference phase shift. The phase does not need to be displayed to use these keys. Zero Phase Pressing the [+90°] and [-90°] keys together will set the reference phase shift to 0.00°. [Freq] Pressing this key displays the reference frequency in the Reference display. If the reference mode is external, then the measured reference frequency is displayed. The knob does nothing in this case.
Front Panel If the harmonic number is set to N, then the internal reference frequency is limited to 102 kHz/N. If an external reference is used and the reference frequency exceeds 102 kHz/N, then N is reset to 1. The SR830 will always track the external reference. Pressing this key displays the harmonic number in the Reference display. The harmonic number may be adjusted using the knob. Harmonics up to 19999 times the reference can be detected as long as the harmonic frequency does not exceed 102 kHz.
Front Panel Auto Functions Pressing an Auto Function key initiates an auto function which may take some time. The AUTO leds in the CH1 and CH2 displays will be on while the function is in progress. A multi-tone sound will indicate when the auto function is complete and the AUTO leds will turn off. [Auto Reserve] Pressing [AUTO RESERVE] will adjust the dynamic reserve to the minimum reserve required. To do this, the reserve is decreased until the analog input amplifier is overloaded.
Front Panel all possible input signals. In most cases, the following procedure should setup the SR830 to measure the input signal. 1.Press [AUTO GAIN] to set the sensitivity. 2.Press [AUTO RESERVE]. 3.Adjust the time constant and roll-off until there is no Time Constant overload. 4.Press [AUTO PHASE] if desired. 5.Repeat if necessary. At very low frequencies, the auto functions may not function properly.
Front Panel Setup [Save] Nine amplifier setups may be stored in non-volatile memory.To save a setup, press [Save] to display the buffer number (1..9) in the CH2 display. Use the knob to select the desired buffer number. Press [Save] again to store the setup in the buffer, or any other key to abort the save process. The message 'SAvE n donE' is displayed if the setup is successfully saved. The message 'SAve not donE' is displayed if the save process is aborted.
Front Panel Interface [Setup] Pressing the [Setup] key cycles through GPIB/RS232, ADDRESS, BAUD, PARITY and QUEUE. In each case, the appropriate parameter is displayed in the Reference display and the knob is used for adjustment. Press [Phase], [Freq], [Ampl], [Harm#] or [Aux Out] to return the display to normal and leave Setup. GPIB/RS232 The SR830 only outputs data to one interface at a time. Commands may be received over both interfaces but responses are directed only to the selected interface.
Front Panel Hex 2A 2B 2C 2D 2E 30 31 32 33 ASCII ❋ + , . 0 1 2 3 Hex 34 35 36 37 38 39 3B 3F ASCII 4 5 6 7 8 9 ; ? Hex 0A 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F ASCII linefeed A B C D E F G H I J K L M N O Hex 50 51 52 53 54 55 56 57 58 59 5A ASCII P Q R S T U V W X Y Z [Local] When a host computer places the unit in the REMOTE state, no keypad input or knob adjustment is allowed. The REMOTE indicator is on above the [Local] key. To return to front panel operation, press the [Local] key.
Front Panel WARNING MESSAGES The SR830 displays various warning messages whenever the operation of the instrument is not obvious. The two tone warning alarm sounds when these messages are displayed. Display Warning Message Meaning LOCL LOut LOCAL LOCKOUT If the computer interface has placed the unit in the REMOTE state, indicated by the REMOTE led, then the keys and the knob are disabled. Attempts to change the settings from the front panel will display this message.
REAR PANEL Power Entry Module The power entry module is used to fuse the AC line voltage input, select the line voltage, and block high frequency noise from entering or exiting the instrument. Refer to the first page of this manual for instructions on selecting the correct line voltage and fuse. IEEE-488 Connector The 24 pin IEEE-488 connector allows a computer to control the SR830 via the IEEE-488 (GPIB) instrument bus. The address of the instrument is set with the [Setup] key.
Rear Panel These outputs are affected by the X and Y offsets and expands. The actual outputs are X Output = (X/sensitivity - offset)xExpandx10V Y Output = (Y/sensitivity - offset)xExpandx10V where the offset is a percentage of full scale and the expand is an integer from 1, 10 or 100. The offsets and expand are set from the front panel. MONITOR OUT This BNC provides a buffered output from the signal amplifiers and prefilters. This is the signal just before the A/D converter and PSD.
Rear Panel Using SRS Preamps When using either the SR550 or SR552, connect the power cable (standard 9 pin D connectors) from the preamp to the rear panel preamp connector on the SR830. Use BNC cables to connect the A output from the preamp to the A input of the SR830. The B output from the preamp (preamp ground) may be connected to the B input of the SR830. In this case, use A-B as the input configuration.
Rear Panel 4-30
REMOTE PROGRAMMING INTRODUCTION completed. To help find program errors, the SR830 can display its receive buffer on the displays. Use the [Setup] key to access the QUEUE display. The last 256 characters received by the SR830 may be displayed in hexadecimal ASCII. See the OPERATION section for a complete description. The SR830 DSP Lock-in Amplifier may be remotely programmed via either the RS232 or GPIB (IEEE-488) interfaces. Any computer supporting one of these interfaces may be used to program the SR830.
Remote Programming be determined by querying the SR830 for its value. A query is formed by appending a question mark "?" to the command mnemonic and omitting the desired parameter(s) from the command. Values returned by the SR830 are sent as a string of ASCII characters terminated by a carriage return on RS232 and by a line-feed on GPIB. If multiple queries are sent on one command line (separated by semicolons, of course) the answers will be returned individually, each with a terminator.
Remote Programming DETAILED COMMAND LIST The four letter mnemonic in each command sequence specifies the command. The rest of the sequence consists of parameters. Multiple parameters are separated by commas. Parameters shown in { } are optional or may be queried while those not in { } are required. Commands that may be queried have a question mark in parentheses (?) after the mnemonic. Commands that may ONLY be queried have a ? after the mnemonic. Commands that MAY NOT be queried have no ?.
Remote Programming REFERENCE and PHASE COMMANDS PHAS (?) {x} The PHAS command sets or queries the reference phase shift. The parameter x is the phase (real number of degrees). The PHAS x command will set the phase shift to x. The value of x will be rounded to 0.01°. The phase may be programmed from -360.00 ≤ x ≤ 729.99 and will be wrapped around at ±180°. For example, the PHAS 541.0 command will set the phase to -179.00° (541-360=181=-179). The PHAS? queries the phase shift.
Remote Programming INPUT and FILTER COMMANDS ISRC (?) {i} The ISRC command sets or queries the input configuration. The parameter i selects A (i=0), A-B (i=1), I (1 MΩ) (i=2) or I (100 MΩ) (i=3). Changing the current gain does not change the instrument sensitivity. Sensitivities above 10 nA require a current gain of 1 MΩ. Sensitivities between 20 nA and 1 µA automatically select the 1 MΩ current gain. At sensitivities below 20 nA, changing the sensitivity does not change the current gain.
Remote Programming GAIN and TIME CONSTANT COMMANDS SENS (?) {i} The SENS command sets or queries the sensitivity. The parameter i selects a sensitivity below.
Remote Programming SYNC (?) {i} The SYNC command sets or queries the synchronous filter status. The parameter i selects Off (i=0) or synchronous filtering below 200 Hz (i=1). Synchronous filtering is turned on only if the detection frequency (reference x harmonic number) is less than 200 Hz.
Remote Programming DISPLAY and OUTPUT COMMANDS DDEF (?) i {, j, k} The DDEF command selects the CH1 and CH2 displays. The parameter i selects CH1 (i=1) or CH2 (i=2) and is required. The DDEF i, j, k command sets display i to parameter j with ratio k as listed below.
Remote Programming AUX INPUT and OUTPUT COMMANDS OAUX? i The OAUX? command queries the Aux Input values. The parameter i selects an Aux Input (1, 2, 3 or 4) and is required. The Aux Input voltages are returned as ASCII strings with units of Volts. The resolution is 1/3 mV. This command is a query only command. AUXV (?) i {, x} The AUXV command sets or queries the Aux Output voltage when the output. The parameter i selects an Aux Output (1, 2, 3 or 4) and is required.
Remote Programming SETUP COMMANDS OUTX (?) {i} The OUTX command sets the output interface to RS232 (i=0) or GPIB (i=1). The OUTX i command should be sent before any query commands to direct the responses to the interface in use. OVRM i In general, every GPIB interface command will put the SR830 into the REMOTE state with the front panel deactivated. To defeat this feature, use the OVRM 1 command to overide the GPIB remote.
Remote Programming AUTO FUNCTIONS AGAN The AGAN command performs the Auto Gain function. This command is the same as pressing the [Auto Gain] key. Auto Gain may take some time if the time constant is long. AGAN does nothing if the time constant is greater than 1 second. Check the command execution in progress bit in the Serial Poll Status Byte (bit 1) to determine when the function is finished. ARSV The ARSV command performs the Auto Reserve function.
Remote Programming DATA STORAGE COMMANDS Data Storage The SR830 can store up to 16383 points from both the Channel 1 and Channel 2 displays in an internal data buffer. The data buffer is NOT retained when the power is turned off. The data buffer is accessible only via the computer interface. Configure the displays to show the desired quantity (with appropriate ratio, offset and expand). The data buffer stores the quantities which are displayed.
Remote Programming Aliasing Effects In any sampled data stream, it is possible to sample a high frequency signal such that it will appear to be a much lower frequency. This is called aliasing. For example, suppose the lock-in is detecting a signal near 1 Hz with a relatively short time constant. The X output will have a DC component and a 2 Hz component (2xf). If the sample rate is 2 Hz, then the samples may be taken as illustrated below.
Remote Programming PAUS The PAUS command pauses data storage. If storage is already paused or reset then this command is ignored. REST The REST command resets the data buffers. The REST command can be sent at any time - any storage in progress, paused or not, will be reset. This command will erase the data buffer.
Remote Programming DATA TRANSFER COMMANDS OUTP ? i The OUTP? i command reads the value of X, Y, R or θ. The parameter i selects X (i=1), Y (i=2), R (i=3) or θ (i=4). Values are returned as ASCII floating point numbers with units of Volts or degrees. For example, the response might be "-1.01026". This command is a query only command. OUTR ? i The OUTR? i command reads the value of the CH1 or CH2 display. The parameter i selects the display (i=1 or 2).
Remote Programming The SNAP? command is a query only command. The SNAP? command is used to record various parameters simultaneously, not to transfer data quickly. OAUX? i The OAUX? command reads the Aux Input values. The parameter i selects an Aux Input (1, 2, 3 or 4) and is required. The Aux Input voltages are returned as ASCII strings with units of Volts. The resolution is 1/3 mV. This command is a query only command. SPTS ? The SPTS? command queries the number of points stored in the buffer.
Remote Programming fers on the RS232 interface is not recommended. The parameter i selects the display buffer (i=1, 2) and is required. Points are read from the buffer starting at bin j (j≥0). A total of k bins are read (k≥1) for a total transfer of 4k bytes. To read a single point, set k=1. Both j and k are required. If j+k exceeds the number of stored points (as returned by the SPTS? query), then an error occurs.
Remote Programming always be ready to receive the next byte. In general, using binary transfers on the RS232 interface is not recommended. The parameter i selects the display buffer (i=1, 2) and is required. Points are read from the buffer starting at bin j (j≥0). A total of k bins are read (k≥1) for a total transfer of 4k bytes. To read a single point, set k=1. Both j and k are required. If j+k exceeds the number of stored points (as returned by the SPTS? query), then an error occurs.
Remote Programming INTERFACE COMMANDS ❊RST The ❊RST command resets the SR830 to its default configurations. The communications setup is not changed. All other modes and settings are set to their default conditions and values. This command takes some time to complete. This command resets any data scan in progress. Data stored in the buffers will be lost. ❊IDN? The ❊IDN? query returns the SR830's device identification string. This string is in the format "Stanford_Research_Systems,SR830,s/n00111,ver1.000".
Remote Programming STATUS REPORTING COMMANDS The Status Byte definitions follow this section. ❊CLS The ❊CLS command clears all status registers. The status enable registers are NOT cleared. ❊ESE (?) {i} {,j} The ❊ESE i command sets the standard event enable register to the decimal value i (0-255). The ❊ESE i,j command sets bit i (0-7) to j (0 or 1). The ❊ESE? command queries the value (0-255) of the status byte enable register. The ❊ESE? i command queries the value (0 or 1) of bit i.
Remote Programming STATUS BYTE DEFINITIONS The SR830 reports on its status by means of four status bytes: the Serial Poll Status byte, the Standard Event Status byte, the LIA Status byte, and the Error Status byte. The status bits are set to 1 when the event or state described in the tables below has occurred or is present. SERIAL POLL STATUS BYTE bit name usage 0 SCN No scan in progress (Stop or Done). A Paused scan is considered to be in progress. 1 IFC No command execution in progress.
Remote Programming SERVICE REQUESTS (SRQ) A GPIB service request (SRQ) will be generated whenever a bit in both the Serial Poll Status byte AND Serial Poll Enable register is set. Use ✳SRE to set bits in the Serial Poll Enable register. A service request is only generated when an enabled Serial Poll Status bit becomes set (changes from 0 to 1). An enabled status bit which becomes set and remains set will generate a single SRQ.
Remote Programming LIA STATUS BYTE bit name usage 0 INPUT/RESRV Set when an Input or Amplifier overload is detected. 1 FILTR Set when a Time Constant filter overload is detected. 2 OUTPT Set when an Output overload is detected. 3 UNLK Set when a reference unlock is detected. 4 RANGE Set when the detection frequency switches ranges (harmonic x ref. frequency decreases below 199.21 Hz or increases above 203.12 Hz).
Remote Programming 5-24
Remote Programming EXAMPLE PROGRAM 1 Using Microsoft C (v5.1) with the National Instruments GPIB card on the IBM PC. To successfully interface the SR830 to a PC via the GPIB interface, the instrument, interface card, and interface drivers must all be configured properly. To configure the SR830, the GPIB address must be set using the [Setup] key. The default GPIB address is 8; use this address unless a conflict occurs with other instruments in your system.
Remote Programming void void void void void void void main(int, char *[]); txLia(char *); initGpib(char *); setupLia(void); printOutBinaryResults(void); printOutIEEEResults(void); printOutLIAResults(void); /* National Instruments Interface Function Prototypes (488.1 Calls - see the National software manual). These are declared in "decl.
Remote Programming i=(int)ibcnt; txLia("PAUS"); printOutBinaryResults(); /* save total number of bytes read */ /* pause the data storage so no new points are taken */ /* format and print the results */ printf("\n%d bytes received.\nPress to continue.
Remote Programming void printOutIEEEResults(void) { /* prints the first 10 values of R transferred in IEEE floating point format by the SR830 */ int i; printf("\n\n"); for (i=0;i<10;i++) printf("%d %e\n",i,rfBuf[i]); /* this is simple since the values are already IEEE floats */ } void printOutLIAResults(void) { /* calculates the first 10 values of R transferred in LIA float format by the SR830 */ int i,mant,exp; int *ptr; float val; printf("\n\n"); ptr =(int *) rfBuf; /* ptr points to integers in rfBuf,
Remote Programming txLia("SRAT10; SEND0"); /* set 64 Hz sample rate, stop at end */ txLia("DDEF1,1,0; DDEF2,1,0"); /* set CH1=R, CH2=theta. Buffers store CH1 and CH2 */ printf("Scan is Initialized, Press to Begin Scan...
Remote Programming 5-30
Remote Programming USING SR530 PROGRAMS WITH THE SR830 The SR830 responds to most SR530 programming commands. This allows the SR830 to drop into an existing SR530 application with a minimum of program changes. Of course, some changes will be required and some features are unique to one instrument or the other. For example, SR530 commands can not put the SR830 into a configuration which is not allowed by the SR830.
Remote Programming H The SR830 does not sense the pre-amplifier. This command is emulated and always returns 0. I {n} Change the remote/local status. The SR830 Override Remote mode can override the I2 command. Use the OVRM command to change this. J Not implemented. Do not use. K Not implemented. Do not use. L m {,n} Change the line notch filter status. M {n} Change the reference mode to 2f. This command actually sets the harmonic detect number to n+1 in order to access harmonics higher than 2f.
Remote Programming If m=2: T2,0 changes the slope to 6 dB/oct, time constant not changed. T2,1 changes the time constant to 100 ms with 12 dB/oct slope. T2,2 changes the time constant to 1 s with 12 dB/oct slope. Use the T2,n command to change the filter slope, then use T1,n to select the time constant. U m {,n} Not implemented. Do not use. V {n} Change the value of the SRQ mask. This command changes the serial poll enable register of the SR830.
Remote Programming 5-34
PERFORMANCE TESTS Introduction The performance tests described in this section are designed to verify with a high degree of confidence that the unit is performing correctly. The results of each test may be recorded on the test sheet at the end of this section. Serial Number If you need to contact Stanford Research Systems, please have the serial number of your unit available. The 5-digit serial number is printed on a label affixed to the rear panel.
Performance Tests Spurious TTL SYNC ≤ -55 dBc available Recommended SRS DS335 2. AC Calibrator Freq Range 10 Hz to 100 kHz Amplitude 1 mV to 10 V Accuracy 0.1% External phase locking capability Recommended 3. DC Voltmeter Range Accuracy Recommended Fluke 5200A 19.999 V, 4 1/2 digits 0.005% Fluke 8840A 4. Feedthrough Terminations Impedance 50 Ω Front Panel Display Test To test the front panel displays, press the [Phase] and [Freq] keys together. All of the LED's will turn on.
Performance Tests 1. Self Tests The self tests check the lock-in hardware. These are functional tests and do not relate to the specifications. These tests should be checked before any of the performance tests. Setup No external setup is required for this test. Procedure 1) {PRESET} (Turn on the lock-in with the [Setup] key pressed) Check the results of the DATA, BATT, PROG and DSP tests. 2) This completes the functional hardware tests.
Performance Tests 6-4
Performance Tests 2. DC Offset This test measures the DC offset of the input. Setup Connect a 50Ω terminator to the A input. This shorts the input so the lock-in's own DC offset will be measured. Procedure 1) {PRESET} (Turn the lock-in off and on with the [Setup] key pressed) 2) Press the keys in the following sequence: [Freq] Use the knob to set the frequency to 1.00 Hz. [Sensitivity Down] Set the sensitivity to 1 mV. [CH1 Display] Set the Channel 1 display to R.
Performance Tests 6-6
Performance Tests 3. Common Mode Rejection This test measures the common mode rejection of the lock-in. Setup We will use the internal oscillator sine output to provide the signal. Connect the Sine Out to both the A and B inputs of the lock-in. Use equal length cables from A and B to a BNC TEE. Connect the cable from the Sine Out to the TEE. Do not use any termination.
Performance Tests 6-8
Performance Tests 4. Amplitude Accuracy and Flatness This test measures the amplitude accuracy and frequency response. Setup We will use the frequency synthesizer to provide an accurate frequency and the AC calibrator to provide a sine wave with an exact amplitude. Connect the output of the frequency synthesizer to the phase lock input of the calibrator. Connect the output of the AC calibrator to the A input of the lock-in. Be sure to use the appropriate terminations where required.
Performance Tests b) Press [Sensitivity Up/Dn] Select the sensitivity from the table. c) Wait for the R reading to stabilize. Record the value of R for each sensitivity. 4) Frequency response is checked at frequencies above 1 kHz. The test frequencies are listed below. Test Frequencies 24 kHz 48 kHz 72 kHz 96 kHz a) Set the AC calibrator to 1 kHz and an amplitude of 200.00 mVrms. b) Set the frequency synthesizer to 1 kHz. c) Press [Sensitivity Up/Dn] Set the sensitivity 200 mV.
Performance Tests 5. Amplitude Linearity This test measures the amplitude linearity. This tests how accurately the lock-in measures a signal smaller than full scale. Setup We will use the frequency synthesizer to provide an accurate frequency and the AC calibrator to provide a sine wave with an exact amplitude. Connect the output of the frequency synthesizer to the phase lock input of the calibrator. Connect the output of the AC calibrator to the A input of the lock-in.
Performance Tests 6-12
Performance Tests 6. Frequency Accuracy This test measures the frequency accuracy of the lock-in. This tests the accuracy of the frequency counter inside the unit. The counter is used only in external reference mode. The internal oscillator frequency is set by a crystal and has 25 ppm frequency accuracy. Setup We will use the frequency synthesizer to provide the reference signal. Connect the TTL SYNC output of the frequency synthesizer to the Reference input of the lock-in.
Performance Tests 6-14
Performance Tests 7. Phase Accuracy This test measures the phase accuracy of the lock-in. Due to the design of the lock-in, the phase accuracy can be determined by measuring the phase of the internal oscillator Sine Out. Setup Connect the Sine Out to the A input of the lock-in using a 1 meter BNC cable. Do not use any termination. Procedure 1) {PRESET} (Turn the lock-in off and on with the [Setup] key pressed) 2) Press the keys in the following sequence: [Slope /Oct] Select 24 dB/oct.
Performance Tests 6-16
Performance Tests 8. Sine Output Amplitude Accuracy and Flatness This test measures the amplitude accuracy and frequency response of the internal oscillator Sine Out. Setup We will use the lock-in to measure the Sine Out. Connect the Sine Out to the A input of the lock-in. Procedure 1) {PRESET} (Turn the lock-in off and on with the [Setup] key pressed) 2) Press the keys in the following sequence: [Channel 1 Display] Set the Channel 1 display to R.
Performance Tests d) Press [Freq] Use the knob to set the internal oscillator frequency to the value in the table. e) Wait for the R reading to stabilize. Record the value of R. f) Repeat steps 4d and 4e for all of the frequencies listed. 5) This completes the sine output amplitude accuracy and frequency response test. Enter the results of this test in the test record at the end of this section.
Performance Tests 9. DC Outputs and Inputs This test measures the DC accuracy of the DC outputs and inputs of the lock-in. Setup We will use the digital voltmeter (DVM) to measure the DC outputs of the lock-in. Then we will use one of the outputs to generate a voltage to measure on the DC inputs. Connect a 50Ω termination to the A input. Procedure 1) {PRESET} (Turn the lock-in off and on with the [Setup] key pressed) 2) For the CH1 and CH2 outputs, repeat steps 2a through 2e.
Performance Tests c) For each output voltage in the table below, repeat steps 3d and 3e. Output Voltages -10.000 -5.000 0.000 5.000 10.000 d) Use the knob to adjust the Aux Output level to the value from the table. e) Record the DVM reading. 4) Press [Aux Out] Display Aux Out 1 on the Reference display. 5) For Aux Inputs 1 and 2, repeat steps 5a through 5e. a) Connect Aux Out 1 to Aux Input 1 (or 2) with a BNC cable.
Performance Tests 10. Input Noise This test measures the lock-in input noise. Setup Connect a 50Ω termination to the A input. This grounds the input so the lock-in's own noise is measured. Procedure 1) {PRESET} (Turn the lock-in off and on with the [Setup] key pressed) 2) Press the keys in the following sequence: [Sensitivity Down] Set the sensitivity to 100 nV. [Channel 1 Display] Set the Channel 1 display to X Noise. 3) Wait until the reading of Channel 1 stabilizes. Record the value of Channel 1.
Performance Tests 6-22
Page 1 of 4 SR830 Performance Test Record Serial Number Firmware Revision Tested By Date Equipment Used 1. Self Tests Test DATA BATT PROG DSP Pass ____ ____ ____ ____ Fail ____ ____ ____ ____ 2. DC Offset Input Coupling AC DC Reading _______ _______ Upper Limit 0.500 mV 0.500 mV Reading _______ Upper Limit 30 µV 3. Common Mode Rejection Frequency 100 Hz 4. Amplitude Accuracy and Flatness Sensitivity 1V 200 mV 100 mV 20 mV 10 mV Calibrator Ampl. 1.0000 Vrms 200.00 mVrms 100.000 mVrms 20.
Page 2 of 4 SR830 Performance Test Record 5. Amplitude Linearity Sensitivity 1V Calibrator Ampl. 1.0000 Vrms 100.00 mVrms 10.000 mVrms Lower Limit 0.9900 V 0.0990 V 0.0098 V Reading _______ _______ _______ Upper Limit 1.0100 V 0.1010 V 0.0102 V 6. Frequency Accuracy Input Frequency 10 kHz Lower Limit 9.990 kHz Reading _______ Upper Limit 10.010 kHz Lower Limit -1.0 deg -1.0 deg -1.0 deg -1.0 deg Reading _______ _______ _______ _______ Upper Limit +1.0 deg +1.0 deg +1.0 deg +1.0 deg 7.
Page 3 of 4 SR830 Performance Test Record 9. DC Outputs and Inputs (continued) Output CH2 Offset -100.00 -50.00 0.00 50.00 100.00 Lower Limit 9.980 V 4.980 V -0.010 V -5.020 V -10.020 V Reading _______ _______ _______ _______ _______ Upper Limit 10.020 V 5.020 V 0.010 V -4.980 V -9.980 V Output AUX OUT 1 Voltage -10.000 -5.000 0.000 5.000 10.000 Lower Limit -10.020 V -5.020 V -0.010 V 4.980 V 9.980 V Reading _______ _______ _______ _______ _______ Upper Limit -9.980 V -4.980 V 0.010 V 5.020 V 10.
Page 4 of 4 SR830 Performance Test Record 9. DC Outputs and Inputs (continued) Input AUX IN 1 Voltage -10.000 -5.000 0.000 5.000 10.000 Lower Limit -10.040 V -5.030 V -0.020 V 4.970 V 9.960 V Reading _______ _______ _______ _______ _______ Upper Limit -9.960 V -4.970 V 0.020 V 5.030 V 10.040 V Input AUX IN 2 Voltage -10.000 -5.000 0.000 5.000 10.000 Lower Limit -10.040 V -5.030 V -0.020 V 4.970 V 9.960 V Reading _______ _______ _______ _______ _______ Upper Limit -9.960 V -4.970 V 0.020 V 5.
CIRCUIT DESCRIPTION CPU and Power Supply Board DSP Logic Board Analog Input Board Display Board Keypad Board CAUTION CIRCUIT BOARDS Always disconnect the power cord and wait at least one minute before opening the unit. Dangerous power supply voltages may be present even after the unit has been unplugged. The SR830 has five main printed circuit boards. The five boards shown contain most of the active circuitry of the unit.
Circuit Description 7-2
Circuit Description CPU and POWER SUPPLY BOARD The CPU board contains the microprocessor system. All display, front panel, disk, and computer interfaces are on this board. SPIN KNOB The knob is an optical encoder buffered by U612. Each transition of its outputs is clocked into U610 or U611 and generates an interrupt at the output of U602A. The processor keeps track of the knob's position continuously.
Circuit Description POWER SUPPLY The 24 VDC brushless fan cools the heat sink and power supply rectifiers. CAUTION: Dangerous voltages are present on this circuit board whenever the instrument is attached to an AC power source and the rear panel power switch is "on". Always disconnect the power cord and wait at least one minute before opening the unit. Check the LED at the front edge of the power supply board. The unit is safe only if the LED is OFF.
Circuit Description DSP LOGIC BOARD OVERVIEW also sets accuracy. The DSP LOGIC BOARD takes a digital input from the A/D Converter on the Analog Input Board and performs all of the computations related to the measurement before it is displayed on the screen. This includes generating the digital reference sine wave, demodulating the signal, low-pass filtering the results, and offset and expanding the outputs. The internal oscillator sine output and Aux D/A outputs are generated on this board as well.
Circuit Description transmit port each cycle. The transmit port operates at twice the frequency of the receive port. The DSP writes to the other channel of each DAC via a pair of parallel-to-serial registers (U504 and U505). ±22V from the power supply is used to generate ±15V for the op amps. ±5.6V for analog switches and op amps is generated from the ±15V supplies. The reference and sine discriminators use separate ±5V supplies regulated from the ±15V supplies as well.
Circuit Description ANALOG INPUT BOARD OVERVIEW and frequency adjustment. (60 Hz - depth:P222 and freq:P221 120 Hz - depth:P202 and freq:P201). The 120 Hz notch filter has a configurable gain of either 1 or 3.17. The Analog Input Board provides the very important link between the user's input signal and the DSP processor. From the front panel BNC, the user's signal passes through a low distortion frontend amplifier, gain stages, notch filters, antialiasing filter, and finally an A/D Converter.
Circuit Description a rate of 256 kHz. One channel is dedicated to the input signal. The other channel reads one of the Aux A/D inputs. The Aux inputs are multiplexed so that each input is read every four cycles. The two digital output streams are buffered by U406 and sent to the DSP board. I/O INTERFACE The Analog Input Board communicates with the CPU Board via its I/O Interface. U504 and U506 are simple latches which hold configuration data for the analog board.
Parts List PARTS LIST DSP Logic Board Parts List Ref No. SRS Part No. Value Component Description C 101 C 114 C 117 C 119 C 120 C 121 C 130 C 135 C 136 C 137 C 140 C 141 C 142 C 143 C 144 C 150 C 151 C 152 C 153 C 154 C 155 C 156 C 157 C 171 C 173 C 180 C 181 C 182 C 183 C 202 C 203 C 204 C 205 C 206 C 207 C 210 C 211 C 235 C 236 C 237 C 238 C 254 C 255 C 260 C 261 C 264 C 265 C 280 C 281 C 282 1.0U 2.2U 2.2U .002U 1P .1U .1U 100P 100P 47P .033U .033U .015U .0047U .1U .1U .1U .1U .1U .1U .1U .1U .
Parts List C 283 C 290 C 301 C 302 C 303 C 305 C 307 C 308 C 309 C 310 C 350 C 351 C 352 C 353 C 381 C 382 C 383 C 384 C 385 C 386 C 387 C 388 C 389 C 390 C 401 C 402 C 403 C 404 C 406 C 407 C 408 C 409 C 410 C 420 C 421 C 422 C 423 C 424 C 425 C 426 C 427 C 428 C 429 C 430 C 431 C 432 C 433 C 434 C 435 C 450 C 453 C 456 C 459 C 470 C 471 C 601 C 602 5-00100-517 5-00023-529 5-00002-501 5-00002-501 5-00002-501 5-00002-501 5-00002-501 5-00002-501 5-00002-501 5-00002-501 5-00023-529 5-00023-529 5-00023-529 5-
Parts List C 603 C 604 C 610 C 611 C 630 C 631 C 650 C 651 C 652 C 653 C 654 C 655 C 656 C 657 C 658 C 659 C 660 C 661 C 662 C 663 C 664 C 665 C 666 C 667 C 668 C 669 C 670 C 671 CX623 D 103 D 104 D 105 D 180 D 181 D 280 D 281 JP301 JP501 JP502 K 101 K 201 L 101 L 601 N 101 N 102 N 201 N 202 N 301 N 302 N 303 N 304 N 305 N 306 N 420 N 421 N 501 N 502 5-00038-509 5-00239-562 5-00002-501 5-00002-501 5-00033-520 5-00033-520 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-
Parts List N 503 N 601 N 602 N 603 N 604 PC1 Q 101 Q 102 Q 201 R 102 R 103 R 114 R 115 R 116 R 117 R 118 R 119 R 120 R 121 R 130 R 131 R 132 R 133 R 140 R 141 R 142 R 143 R 156 R 157 R 170 R 171 R 172 R 173 R 174 R 175 R 176 R 177 R 178 R 180 R 181 R 201 R 202 R 203 R 204 R 205 R 206 R 207 R 208 R 209 R 210 R 211 R 212 R 213 R 214 R 215 R 216 R 217 4-00333-421 4-00767-420 4-00334-425 4-00463-421 4-00463-421 7-00356-701 3-00021-325 3-00022-325 3-00021-325 4-00022-401 4-00130-407 4-00056-401 4-00142-407 4-00
Parts List R 220 R 221 R 222 R 226 R 227 R 228 R 231 R 232 R 237 R 238 R 239 R 240 R 250 R 251 R 280 R 281 R 290 R 301 R 302 R 303 R 304 R 381 R 382 R 383 R 384 R 385 R 386 R 387 R 388 R 389 R 390 R 401 R 402 R 450 R 451 R 452 R 453 R 470 R 471 R 503 R 601 R 602 R 603 R 604 R 611 RX623 T 201 TP101 TP102 TP103 TP104 TP105 TP106 TP107 TP108 TP201 TP202 4-00139-407 4-00130-407 4-00188-407 4-00782-448 4-00193-407 4-00704-407 4-00519-407 4-00467-407 4-00787-407 4-00031-401 4-00062-401 4-00022-401 4-00772-402 4-
Parts List TP203 TP204 TP301 TP302 TP303 TP304 TP401 TP402 TP403 TP404 TP501 TP502 U 101 U 102 U 103 U 104 U 105 U 106 U 107 U 110 U 111 U 120 U 121 U 122 U 180 U 181 U 201 U 202 U 203 U 205 U 206 U 207 U 208 U 209 U 210 U 280 U 281 U 301 U 302 U 303 U 380 U 381 U 382 U 383 U 401 U 402 U 403 U 404 U 501 U 502 U 503 U 504 U 505 U 601 U 602 U 603 U 604 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 3-00461-340 3-
Parts List U 606 U 608 U 609 U 610 U 611 U 612 U 613 U 614 U 621 U 622 U 623 U 630 Z0 Z0 Z0 Z0 Z0 3-00499-343 3-00411-340 3-00411-340 3-00387-340 3-00440-340 3-00440-340 3-00440-340 3-00038-340 3-00441-340 3-00491-340 3-00036-340 3-00049-340 0-00012-007 0-00043-011 0-00373-000 0-00388-000 0-00438-021 SR850 U606 74HC273 74HC273 74HC245 74HC573 74HC573 74HC573 74HC139 74HC113 UPD71054C 74HC00 74HC74 TO-220 4-40 KEP CARD EJECTOR RCA PHONO 4-40X5/16PP GAL/PAL, I.C.
Parts List C 371 C 372 C 381 C 382 C 386 C 390 C 391 C 392 C 393 C 394 C 395 C 396 C 397 C 398 C 410 C 411 C 414 C 430 C 431 C 456 C 460 C 461 C 462 C 463 C 480 C 481 C 482 C 483 C 511 C 512 C 513 C 514 C 515 C 516 C 517 C 520 C 521 C 523 C 524 C 530 C 531 C 540 C 560 C 561 C 562 D 101 D 180 D 181 D 480 D 481 J 101 J 102 JP201 JP221 JP401 K 101 K 102 5-00148-545 5-00148-545 5-00148-545 5-00148-545 5-00013-501 5-00148-545 5-00023-529 5-00023-529 5-00023-529 5-00023-529 5-00023-529 5-00023-529 5-00023-529 5-
Parts List K 103 K 104 K 105 L 501 N 101 N 102 N 103 N 261 N 401 N 402 N 403 N 404 N 405 N 406 N 501 P 101 P 102 P 103 P 201 P 202 P 221 P 222 PC1 R 101 R 102 R 103 R 104 R 106 R 107 R 108 R 109 R 110 R 111 R 114 R 115 R 119 R 120 R 123 R 124 R 125 R 126 R 127 R 129 R 130 R 131 R 132 R 133 R 140 R 141 R 150 R 151 R 180 R 181 R 201 R 202 R 203 R 204 3-00444-335 3-00196-335 3-00444-335 6-00006-602 4-00560-421 4-00244-421 4-00497-421 4-00560-421 4-00756-421 4-00757-421 4-00756-421 4-00757-421 4-00694-421 4-00
Parts List R 205 R 207 R 208 R 221 R 222 R 223 R 224 R 225 R 226 R 227 R 228 R 241 R 242 R 244 R 245 R 246 R 247 R 249 R 252 R 261 R 262 R 299 R 301 R 302 R 303 R 304 R 305 R 306 R 307 R 308 R 309 R 311 R 312 R 313 R 314 R 315 R 321 R 322 R 323 R 324 R 325 R 331 R 332 R 333 R 334 R 335 R 341 R 342 R 343 R 344 R 345 R 351 R 361 R 363 R 364 R 365 R 371 4-00321-407 4-00380-407 4-00556-407 4-00595-407 4-00663-407 4-00322-407 4-00732-407 4-00321-407 4-00158-407 4-00158-407 4-00158-407 4-00380-407 4-00556-407 4-
Parts List R 372 R 373 R 374 R 375 R 379 R 381 R 382 R 383 R 384 R 385 R 386 R 387 R 388 R 389 R 391 R 392 R 393 R 394 R 395 R 396 R 397 R 398 R 430 R 431 R 452 R 460 R 461 R 462 R 463 R 480 R 481 R 511 R 512 R 513 R 514 R 515 R 516 R 517 R 518 R 519 R 520 R 540 R 560 SO101 SO102 SO108 SO361 TP101 TP102 TP103 TP104 TP201 TP301 TP302 TP303 TP405 TP406 4-00700-407 4-00763-407 4-00158-407 4-00158-407 4-00303-407 4-00156-407 4-00202-407 4-00595-407 4-00158-407 4-00158-407 4-00185-407 4-00141-407 4-00021-401 4-
Parts List TP407 TP408 TP501 TP502 TP503 TP504 TP505 TP506 TP507 U 101 U 102 U 103 U 104 U 105 U 106 U 108 U 109 U 180 U 181 U 201 U 202 U 203 U 204 U 241 U 242 U 243 U 244 U 261 U 301 U 302 U 303 U 304 U 305 U 311 U 321 U 331 U 341 U 361 U 362 U 371 U 381 U 386 U 391 U 401 U 402 U 403 U 406 U 407 U 480 U 481 U 504 U 506 U 508 U 509 U 510 U 511 U 530 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 1-00143-101 3-00494-340 3-00246-340 3-00423-340 3-00143-340 3-
Parts List Z0 Z0 Z0 Z0 Z0 0-00043-011 0-00187-021 0-00243-003 0-00373-000 1-00087-131 4-40 KEP 4-40X1/4PP TO-220 CARD EJECTOR 2 PIN JUMPER Nut, Kep Screw, Panhead Phillips Insulators Hardware, Misc. Connector, Female CPU and Power Supply Parts List Ref No. SRS Part No.
Parts List C 1017 C 1018 C 1019 C 1021 C 1022 C 1023 C 1024 C 1026 C 1030 C 1031 C 1035 C 1036 C 1037 C 1040 C 1041 C 1042 C 1043 C 1044 D2 D3 D4 D5 D6 D7 D8 D9 D 15 D 16 D 18 D 19 D 20 D 30 D 31 D 32 D 33 D 34 D 35 D 36 D 37 D 38 D 401 D 701 DS1 JP4 JP302 JP303 JP305 JP602 JP603 JP604 JP902 JP903 JP1000 L1 LS701 N 101 N 102 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-00100-517 5-00225-548 5-00100-517 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-00225-548 5-00
Parts List PC1 Q3 Q4 Q 401 Q 701 Q 702 Q 705 R3 R4 R5 R6 R7 R 30 R 32 R 33 R 34 R 35 R 36 R 37 R 38 R 39 R 40 R 401 R 402 R 601 R 701 R 702 R 703 R 704 R 712 R 713 R 901 R 911 R 912 R 913 SO101 SO303 SO304 SW1 T1 U1 U3 U4 U5 U6 U8 U9 U 10 U 101 U 201 U 202 U 203 U 204 U 205 U 206 U 207 U 208 7-00512-701 3-00021-325 3-00021-325 3-00026-325 3-00022-325 3-00021-325 3-00022-325 4-00034-401 4-00032-401 4-00034-401 4-00046-401 4-00065-401 4-00360-401 4-00360-401 4-00027-401 4-00027-401 4-00185-407 4-00185-407 4-
Parts List U 401 U 402 U 501 U 502 U 503 U 601 U 602 U 608 U 610 U 611 U 612 U 614 U 615 U 701 U 705 U 901 U 902 U 903 U 904 U 905 U 906 X 101 X 902 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 3-00551-341 3-00551-341 3-00342-340 3-00342-340 3-00342-340 3-00467-340 3-00348-340 3-00401-340 3-00467-340 3-00467-340 3-00039-340 3-00539-340 3-00539-340 3-00051-340 3-00110-340 3-00350-340 3-00645-340 3-00078-340 3-00079-340 3-00247-340 3-00109-340 6-00068-620 6-00037-620 0-00158-000 0-00186-021 0-00187-021 0-00231-043 0-00246-
Parts List C 10 C 11 C 12 C 13 C 14 C 15 C 16 C 17 C 18 C 2001 C 2003 C 2005 C 2007 C 2009 C 2010 C 2011 C 2012 C 2013 C 2014 C 2015 C 2020 C 2021 CX30 CX31 CX32 CX34 CX35 D1 D2 D3 D4 D5 D6 D7 D8 D9 D 10 D 11 D 12 D 13 D 14 D 15 D 16 D 17 D 18 D 19 D 20 D 21 D 22 D 23 D 24 D 25 D 26 D 27 D 28 D 29 D 30 5-00219-529 5-00219-529 5-00219-529 5-00219-529 5-00219-529 5-00219-529 5-00219-529 5-00041-509 5-00225-548 5-00219-529 5-00219-529 5-00219-529 5-00219-529 5-00219-529 5-00219-529 5-00219-529 5-00219-529 5-0
Parts List D 31 D 32 D 33 D 34 D 35 D 36 D 37 D 38 D 39 D 40 D 41 D 42 D 43 D 44 D 45 D 46 D 47 D 48 D 49 D 50 D 51 D 52 D 53 D 54 D 55 D 56 D 57 D 58 D 59 D 60 D 61 D 62 D 63 D 64 D 65 D 66 D 67 D 68 D 69 D 70 D 71 D 72 D 73 D 74 D 75 D 76 D 77 D 78 D 79 D 80 D 81 D 82 D 83 D 84 D 85 D 86 D 87 3-00547-310 3-00547-310 3-00547-310 3-00547-310 3-00547-310 3-00547-310 3-00885-306 3-00885-306 3-00885-306 3-00885-306 3-00885-306 3-00885-306 3-00885-306 3-00885-306 3-00547-310 3-00547-310 3-00547-310 3-00547-310
Parts List D 88 D 89 D 90 D 91 D 92 D 93 D 94 D 95 D 96 D 97 D 98 D 99 D 100 D 101 D 102 D 103 D 104 D 105 D 106 D 107 D 108 D 109 D 110 D 111 D 112 D 113 D 114 D 115 D 116 D 117 D 118 D 119 D 120 D 121 D 122 D 123 D 124 D 125 D 126 D 127 D 128 D 129 D 130 D 131 D 132 J1 J2 J3 J4 J5 J6 J7 J8 J9 J 10 J 2001 J 2002 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00575-311 3-00
Parts List J 2003 JP4 JP5 N1 N2 N3 N4 N5 N6 N7 N8 N9 N 10 N 11 N 12 N 13 PC1 PC2 PC3 PC4 PC5 Q1 Q2 R1 U1 U2 U3 U4 U5 U6 U7 U8 U9 U 10 U 11 U 12 U 13 U 14 U 15 U 16 U 17 U 18 U 19 U 20 U 21 U 22 U 23 U 24 U 25 U 26 U 27 U 28 Z0 Z0 Z0 Z0 Z0 1-00181-165 1-00171-130 1-00138-130 4-00468-420 4-00468-420 4-00468-420 4-00835-420 4-00468-420 4-00468-420 4-00468-420 4-00468-420 4-00805-420 4-00246-421 4-00421-420 4-00494-421 4-00263-425 7-00492-701 7-00493-701 7-00437-701 7-00513-701 7-00514-701 3-00264-340 3-00264-
Parts List Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 0-00089-033 0-00097-040 0-00100-040 0-00104-043 0-00108-054 0-00122-053 0-00125-050 0-00126-053 0-00127-050 0-00130-050 0-00149-020 0-00187-021 0-00195-020 0-00209-021 0-00212-021 0-00241-021 0-00256-043 0-00257-000 0-00259-021 0-00310-010 0-00351-029 0-00372-000 0-00377-004 0-00378-004 0-00382-000 0-00389-000 0-00390-024 0-003
Parts List Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z1 6-00212-630 6-00214-630 7-00124-720 7-00406-720 7-00497-740 7-00499-735 7-00500-709 7-00502-721 7-00505-720 7-00506-720 7-00507-709 7-00510-720 7-00511-720 7-00515-720 7-00532-720 7-00582-720 9-00267-917 9-00552-924 1-00141-171 1”X.25”CYL Ferrite Beads .5”X.
Parts List 7-31
