The Stanford Research Systems SR780 is a high-performance, two-channel dynamic signal analyzer (FFT analyzer) covering the frequency range of DC to 102.4 kHz with a 90 dB dynamic range. It is designed for demanding applications in acoustics, vibration, electronic design, and control systems, offering real-time dual-channel octave analysis, swept-sine measurements, order tracking, and a low-distortion signal source.
Specifications
General
| Parameter | Value |
|---|---|
| Interfaces | GPIB (IEEE-488.2), RS-232, Parallel (Printer), 3.5" MS-DOS floppy drive |
| Display | 7-inch monochrome CRT (640 × 480 resolution) |
| Standard Memory Size | 8 MSamples |
| Memory Expansion Option | 32 MSamples (with Option 01) |
| Built-in Floppy Drive | 3.5-inch, 1.44 MB MS-DOS compatible format |
Physical
| Parameter | Value |
|---|---|
| Power Supply | 100 / 120 / 220 / 240 VAC (±10%), 50/60 Hz, 150 W |
| Operating Temperature | 0 °C to 50 °C |
| Dimensions (W×H×D) | 432 × 210 × 565 mm (17" × 8.25" × 22.25") |
| Weight | 25.4 kg |
Frequency Specifications
| Parameter | Value |
|---|---|
| Frequency Range | 488 μHz to 102.4 kHz (both channels) |
| Frequency Resolution | 100, 200, 400, 800 lines |
| Frequency Accuracy | ±25 ppm (0 °C to 50 °C) |
| Real-Time Bandwidth | 102.4 kHz (single channel) |
| Frequency Span | 195.3 mHz to 102.4 kHz |
| Phase Accuracy | ±0.5° (DC to 51.2 kHz), ±1.0° (DC to 102.4 kHz) |
| Amplitude Accuracy | ±0.15 dB (excluding window effects) |
Performance
| Parameter | Value |
|---|---|
| Dynamic Range | 90 dB typical, 80 dB guaranteed |
| A/D Converter | 16-bit, 262 kHz delta-sigma |
| Crosstalk | <-145 dB (DC to 102.4 kHz, 50 Ω source) |
| Noise Floor | <-160 dBVrms/rtHz typical (>1 kHz, -50 dBV range) |
| Spurious Response | <-80 dBc |
| Harmonic Distortion | <-90 dBc (<15 kHz), <-80 dBc (<102.4 kHz) |
| Intermodulation Distortion | <-90 dBc (two tones at -6.02 dBV) |
| Two-Channel Real-Time Bandwidth | 51.2 kHz |
| Swept-Sine Dynamic Range | 145 dB (with auto-ranging) |
| Warm-Up Time | 30 minutes |
Signal Input Channels
| Parameter | Value |
|---|---|
| Number of Channels | 2 |
| Input Configuration | Single-ended or differential |
| Input Coupling | AC, DC, or ICP (4 mA / 24 V source) |
| Input Impedance | 1 MΩ + 50 pF |
| Maximum Input Level | 50 Vp |
| Input Sensitivity Range | -50 dBV (3.16 mVrms) to +34 dBV (50.1 Vrms) |
| CMRR | 90 dB at 60 Hz, 80 dB at 1 kHz |
Signal Source Output
| Parameter | Value |
|---|---|
| Source Types | Sine, Two-Tone, Swept-Sine, White Noise, Pink Noise, Chirp, Arbitrary |
| Source Frequency Range | DC to 102.4 kHz |
| Source Amplitude Range | 0.1 mVp to 5 Vp |
| Source Amplitude Accuracy | ±1 dB (0.1 mVp to 5 Vp) |
| Source Output Impedance | < 5 ̤ |
| Source Distortion | <-80 dBc (f < 10 kHz, 1 Vp) |
| DC Offset Range | ±5 V |
Measurement Modes and Analysis
| Parameter | Value |
|---|---|
| Measurement Modes | FFT, Octave, Swept-Sine, Order Tracking, Time Capture |
| Window Functions | Uniform, Flattop, Hanning, Kaiser, Force/Exponential, User-defined |
| Averaging Types | RMS, Vector, Peak Hold |
| Octave Analysis Bandwidth | 1/1, 1/3, 1/12 octave bands |
| Octave Real-Time Bandwidth | Up to 40 kHz (1/1, 1/3, 1/12 octave) |
| Time Capture Buffer Size | 8 MB (expandable to 32 MB) |
| Waterfall Depth | Up to 2048 traces |
| Swept-Sine Frequency Range | 1 mHz to 102.4 kHz |
| Swept-Sine Sweep Type | Linear or Logarithmic |
| Order Tracking Maximum Order | Up to 64 orders |
Triggering
| Parameter | Value |
|---|---|
| Trigger Source | Free Run, Internal, External (Analog or TTL), Source |
| External Trigger Level Range | ±5 V in 40 mV steps (Analog) or TTL level |
| Trigger Delay | Pre-trigger up to 8192 samples, Post-trigger up to 100,000 samples |
Display and User Interface
| Parameter | Value |
|---|---|
| Trace Configurations | Single, Dual, Horizontal, Vertical, Waterfall |
| Y-Axis Units | V, V², V²/Hz, V/rtHz, dBV, dBp, dBV/rtHz, user-defined engineering units |
| X-Axis Units | Hz, s, Degrees, Rad, Orders |
| Marker Functions | Dual, Track, Band, Sideband, Harmonic, Peak Search |
Connectivity and Storage
| Parameter | Value |
|---|---|
| File Formats Supported | SDF (Standard Data Format), ASCII, binary |
Power and Physical Specifications
| Parameter | Value |
|---|---|
| Storage Temperature | -20 °C to 60 °C |
| Relative Humidity Range | 95% non-condensing (maximum) |
Compliance and Standards
| Parameter | Value |
|---|---|
| Calibration Interval | 1 year |
Inputs & Outputs
| Parameter | Value |
|---|---|
| Transducer (ICP) Power Source | 4.8 mA current source, 24 V compliance |
| Preamplifier Power Port | ±15 V, 100 mA maximum, 7-pin DIN connector |
| External Sampling Input | TTL level, up to 262.144 kHz |
| Preamplifier Power Outputs | ±15 V at up to 100 mA |
| ICP Transducer Output | 4.8 mA @ 24 VDC |
Source
| Parameter | Value |
|---|---|
| Arbitrary Source Resolution | 16-bit |
Power
| Parameter | Value |
|---|---|
| Line Frequency Range | 47 Hz to 63 Hz |
| Power Consumption | 150 W |
Signal Source
| Parameter | Value |
|---|---|
| Source D/A Converter Resolution | 16-bit |
| Arbitrary Source Memory Length | 2 MSamples (standard), up to 8 MSamples (memory option dependent) |
Trigger
| Parameter | Value |
|---|---|
| Maximum Pre-trigger Delay | 8192 samples |
| Maximum Post-trigger Delay | 150,000 samples |
| Trigger Delay Resolution | 1 sample |
Standards & Compliance
| Parameter | Value |
|---|---|
| Octave Analysis Standards Compliance | ANSI S1.11-1986 (Order 3, Type 1-D), IEC 225-1966 |
Interfaces
| Parameter | Value |
|---|---|
| GPIB Interface Capabilities | SH1, AH1, T6, L4, SR1, RL1, PP0, DC1, DT1, C0, E2 |
| RS-232 Maximum Baud Rate | 115.2 kbps |
| Hardcopy Output Formats | PostScript, HP-GL, PCX, GIF |
Technology
FFT Analyzer
Applications
Acoustics, vibration, noise analysis, electronic testing, and control systems