Rohde & Schwarz FMU36 36MHz – 500MHz Spectrum Analyzer

The Rohde & Schwarz FMU36 is a baseband signal analyzer that delivers FFT-based spectrum analysis with simultaneous time-domain measurement capabilities. Operating from DC to 36 MHz, it accepts dual I/Q analog inputs with 36 MHz bandwidth per branch (72 MHz total for complex signals) and achieves exceptional sensitivity through its FFT architecture. The instrument measures pulsed signals, pulse duration, and rise/fall times - functionality equivalent to zero span operation in traditional spectrum analyzers.

The FMU36 provides a noise floor typically below 4 nV [1 Hz] and signal-to-noise ratio exceeding 143 dB [1 Hz], with level uncertainty under 0.25 dB and I/Q imbalance below 0.1 dB. Resolution bandwidth spans 0.5 Hz to 20 MHz in 1-2-3-5-10 steps, supporting Flattop, Gaussian, Rectangular, Hamming, Hanning, and Chebyshev windowing functions.

Technical Specifications

• Frequency Range: DC to 36 MHz (baseband)


• I/Q Bandwidth: 36 MHz per branch; 72 MHz total (complex signals)


• Noise Floor: 143 dB [1 Hz]


• Level Uncertainty: < 0.25 dB


• I/Q Imbalance: < 0.1 dB


• Resolution Bandwidth: 0.5 Hz to 20 MHz (1-2-3-5-10 steps)


• I/Q Memory: 16 Msample standard; extendable to 705 Msample


• Analog Inputs: Dual I/Q channels, balanced/unbalanced, 50 Ω or 1 MΩ impedance

Key Features

• Five detector modes: RMS, Average, Sample, Positive Peak, Negative Peak


• Frequency-selective time-domain analysis with pulse characterization


• Trace operations: Average, Maximum Hold, Minimum Hold


• Marker functions: standard, delta, noise, and phase noise markers


• Adjacent channel power, carrier-to-noise ratio, occupied bandwidth, modulation depth measurements


• Amplifier distortion and third-order intercept analysis

Vector Signal Analysis With optional R&S®FSQ-K70 firmware, the FMU36 enables vector signal analysis including modulation accuracy, carrier leakage, I/Q imbalance measurements, and demodulation to bit-stream level with symbol rates to 25 MHz and 3GPP standard compliance.

Typical Applications Mechanical vibration analysis, audio signal evaluation, ADSL modem characterization, RFID reader testing, and pulsed signal measurement.