What is the standard measurement speed for the R&S FSU series?

The FSU8, as an example from this series, is capable of up to 70 measurements per second, which includes the time required for trace data transfer via the GPIB interface.

Can the reference frequency stability be upgraded?

Yes. While the standard reference frequency aging rate is 1 x 10^-7 per year, option upgrades (such as Option FSU-B4) improve the aging rate. For example, it reduces aging to 2 x 10^-9 per year on the FSU46, FSU50, and FSU67, and to 1 x 10^-9 per day on the FSU26.

Are there differences in weight among these models?

Yes, weight varies depending on the frequency range and internal component configuration. The FSU8 weighs 14.6 kg, the FSU46 weighs 17.8 kg, the FSU3 weighs 18 kg, and the high-frequency FSU50 weighs 23 kg.

Rohde & Schwarz FSU Series Spectrum Analyzers

6 models with full specifications from Rohde & Schwarz.

The Rohde & Schwarz FSU Series of high-performance spectrum analyzers is engineered for demanding RF, microwave, and millimeter-wave measurements. Designed for both development and high-volume production environments, these analyzers serve engineers requiring high dynamic range, low phase noise, and precise level accuracy. Each model in the series shares a standard 20 Hz minimum frequency and identical physical dimensions, facilitating integration into rack systems and test benches. The primary differentiator within the family is the upper frequency limit, which spans from 3.6 GHz up to 67 GHz. This allows technical buyers to select the exact frequency range required for their application—whether it is mobile communications, microwave link testing, or millimeter-wave research—while utilizing a consistent interface and command set across the FSU3, FSU8, FSU26, FSU46, FSU50, and FSU67.

Frequency Range: 20 Hz to 67 GHz (model dependent)
Tuning Resolution: 0.01 Hz
Display Size: 8.4 inches (800 x 600 pixels)
Maximum Safe RF Input: +30 dBm (1 W)
Standard Reference Aging: 1 x 10^-7 per year

Models in this series

Model	Type	Dimensions (W×H×D)	Display	Frequency Range
FSU3	*misc	435 mm × 192 mm × 460 mm	8.4" color TFT LCD, SVGA (800 × 600 pixels)	20 Hz to 3.6 GHz
FSU8	*misc	435 × 192 × 460	8.4-inch color TFT SVGA (800 × 600)	20 Hz to 8 GHz
FSU26	*misc	435 × 192 × 460	8.4-inch color SVGA TFT LCD (800 × 600 pixels)	20 Hz to 26.5 GHz
FSU46	*misc	435 mm × 192 mm × 460 mm	8.4" color TFT LCD, SVGA (800 x 600 pixels)	20 Hz to 46 GHz
FSU50	*misc	435 mm x 192 mm x 460 mm	8.4-inch color TFT LCD (SVGA, 800 x 600 pixels)	20 Hz to 50 GHz
FSU67	*misc	435 mm × 192 mm × 460 mm	21 cm (8.4") TFT color SVGA LCD, 800 x 600 pixels	20 Hz to 67 GHz

Shared Physical and Electrical Characteristics

The FSU series models share a standardized mechanical and display architecture. Each instrument is housed in a chassis measuring 435 mm in width, 192 mm in height, and 460 mm in depth, and features an 8.4-inch color TFT SVGA display. Standard connectivity interfaces across the family include GPIB (IEEE 488.2), LAN (10/100 Base-T), USB, VGA output, RS-232-C, and PS/2.

From an electrical standpoint, all models share a starting frequency of 20 Hz and a high-resolution frequency tuning capability of 0.01 Hz. The input attenuation range spans from 0 dB to 75 dB, adjustable in 5 dB steps, ensuring flexible signal leveling. The maximum safe RF input power is rated at +30 dBm (1 W) across the series, safeguarding the sensitive front-end components.

Model Comparison and Frequency Coverage

Choosing the appropriate model within the R&S FSU series depends on the frequency requirements of the device under test:

RF and Low Microwave (FSU3 and FSU8): The FSU3 operates from 20 Hz to 3.6 GHz, while the FSU8 extends coverage to 8 GHz. Both models feature a typical third-order intercept (TOI) of +25 dBm and excellent phase noise characteristics (-123 dBc at 10 kHz offset).
Mid-Range Microwave (FSU26): Covering up to 26.5 GHz, the FSU26 is suitable for radar, satellite, and higher-frequency communication bands. It includes standard automated measurement routines such as TOI, channel power (MC ACP), occupied bandwidth (OBW), and complementary cumulative distribution function (CCDF).
High-Frequency Microwave (FSU46 and FSU50): The FSU46 covers 20 Hz to 46 GHz and features a typical 1 dB gain compression point of +13 dBm. The FSU50 operates up to 50 GHz and provides extensive resolution bandwidth options from 1 Hz to 50 MHz, with additional digital and channel filters.
Millimeter-Wave (FSU67): The FSU67 offers direct frequency coverage up to 67 GHz. By utilizing fundamental mixing across its entire range, it eliminates the need for external harmonic mixers, preserving signal integrity and dynamic range with a system displayed average noise level (DANL) of -152 dBm at 2 GHz.

Frequently asked questions

What is the standard measurement speed for the R&S FSU series?: The FSU8, as an example from this series, is capable of up to 70 measurements per second, which includes the time required for trace data transfer via the GPIB interface.
Can the reference frequency stability be upgraded?: Yes. While the standard reference frequency aging rate is 1 x 10^-7 per year, option upgrades (such as Option FSU-B4) improve the aging rate. For example, it reduces aging to 2 x 10^-9 per year on the FSU46, FSU50, and FSU67, and to 1 x 10^-9 per day on the FSU26.
Are there differences in weight among these models?: Yes, weight varies depending on the frequency range and internal component configuration. The FSU8 weighs 14.6 kg, the FSU46 weighs 17.8 kg, the FSU3 weighs 18 kg, and the high-frequency FSU50 weighs 23 kg.