The Advantest U3751 is a portable spectrum analyzer engineered for signal analysis across production, field maintenance, and service environments. Operating from 9 kHz to 8 GHz, it delivers processing speeds twice that of previous models, reducing test time and cost per measurement. The instrument achieves overall amplitude accuracy of ±0.8 dB (10 MHz to 3.1 GHz) and ±1.0 dB (3.1 GHz to 8 GHz) through a digital IF section and advanced circuit design. A built-in standard preamplifier covering 10 MHz to 8 GHz provides typical noise performance of −135 dBm at 5 GHz, enabling detection of weak signals. The frequency counter resolves signals from 1 Hz to 1 kHz under specified conditions, while residual FM stability remains below 60 Hz p-p / 100 ms in zero-span mode. Resolution bandwidth spans 300 Hz to 3 MHz with ±12% accuracy; video bandwidth ranges 10 Hz to 3 MHz. The input attenuator offers 0 to 50 dB in 10 dB steps. Amplitude range extends from noise floor to +30 dBm with reference level setting from −140 to +40 dBm. Five detector types—Normal, Posi, Nega, Sample, and RMS—support accurate power measurement of broadband modulation and CW signals. Measurement capabilities include PASS/FAIL judgment via limit lines, harmonics analysis for radio device testing, and channel configuration using calculation and table methods. Frequency span accuracy maintains ±1% of span setting. The frequency reference exhibits aging of 2 × 10⁻⁶ / year and temperature stability of 2.5 × 10⁻⁶ (0 to 50°C). USB 1.1, LAN, and GPIB interfaces enable remote operation and data transfer.
Technical Specifications
• Frequency Range: 9 kHz to 8 GHz (Band 0: 9 kHz to 3.1 GHz; Band 1: 3.0 GHz to 8 GHz)
• Preamplifier: Built-in standard, 10 MHz to 8 GHz; Noise −135 dBm @ 5 GHz (Pre-Amp ON)
• Amplitude Accuracy: ±0.8 dB (10 MHz to 3.1 GHz); ±1.0 dB (3.1 GHz to 8 GHz)
• Amplitude Range: Noise level to +30 dBm
• Reference Level Setting: −140 to +40 dBm
• Input Attenuator: 0 to 50 dB (10 dB steps)
• Resolution Bandwidth: 300 Hz to 3 MHz (±12% accuracy)
• Video Bandwidth: 10 Hz to 3 MHz
• Frequency Span: 0, 10 kHz to Full (±1% accuracy)
• Residual FM (zero span): < 60 Hz p-p / 100 ms
• Frequency Counter Resolution: 1 Hz to 1 kHz (RBW −50 dBm)
• Frequency Reference Aging: 2 × 10⁻⁶ / year
• Temperature Stability: 2.5 × 10⁻⁶ (0 to 50°C)
• Detectors: Normal, Posi, Nega, Sample, RMS
– Key Features
• Processing speed 2× faster than previous generation models
• PASS/FAIL judgment via limit line configuration
• Harmonics measurement capability for radio device analysis
• Channel setting function supporting calculation and table methods
• Display range options: 100/50/20/10/5 dB linear
• Scale units: dBm, dBmV, dBµV, dBµVemf, dBpW, W, V
• High repeatability in power measurement via digital interface
– Typical Applications
• Production line signal verification and testing
• Field maintenance and troubleshooting
• Harmonics and spectral content analysis
• Communication channel characterization
• Weak signal detection and measurement
– Compatibility & Integration
• USB 1.1, LAN, and GPIB connectivity
• Remote operation and automated data transfer
• Portable form factor for on-site deployment
