The Model 875 from Berkeley Nucleonics is a vector signal generator designed for electronic warfare (EW), radar, avionics, and receiver testing. Covering frequencies from 10 MHz to 40 GHz, it combines real-time Pulse Descriptor Word (PDW) playback, phase-coherent multi-channel operation, nanosecond-level timing control, and advanced waveform generation to support the simulation of modern RF threat scenarios.
Modern EW and radar systems must operate in environments where multiple signals are active simultaneously, often changing frequency, power, phase, timing, and waveform characteristics. The Model 875 is designed to help engineers evaluate these systems under conditions that closely reflect real-world operation.
Illustration of dynamic waveform and frequency changes used to represent agile RF emitters during real-time threat simulation.
Real-Time Pulse-by-Pulse Threat Simulation
At the core of the instrument is a real-time PDW engine that directly controls RF output on a pulse-by-pulse basis. Each pulse can be individually defined by its frequency, power level, phase, timing, width, and waveform segment. Instead of relying on pre-generated waveforms, the instrument applies these changes directly at the RF output in real time, enabling the simulation of agile radar and EW emitters.
The PDW engine supports both List Mode and Stream Mode operation. List Mode can store up to 65 million PDWs and uses a 1,024-PDW buffer to support uninterrupted playback of complex threat libraries. Stream Mode uses the Fast Control Port (FCP) to accept live PDW updates from an external computer, allowing scenarios to be modified while testing is underway. The instrument offers 8 ns timing resolution and, with the Ultra-Fast Switching (UFS) option, pulse widths down to 8 ns. Pulse rise and fall times are as fast as 5 ns, while frequency and phase can be adjusted for every pulse with approximately 0.002 Hz frequency resolution and 0.0055° phase resolution.
Real-time PDW playback across multiple RF channels while maintaining phase continuity during frequency switching.
Phase-Coherent Multi-Emitter Signal Generation
The Model 875 supports up to four RF channels within a single chassis, with each channel capable of running its own independent PDW simulation. Through the Phase-Coherent Switching (PHS) option, channels maintain deterministic and repeatable phase relationships, ensuring the same relative phase is restored whenever a given frequency and power combination is used, even after a power cycle.
The instrument also supports phase memory, allowing a channel that switches away from a frequency and later returns to behave as though transmission had continued uninterrupted. This capability helps accurately represent continuous emitters and coordinated RF sources. For larger test scenarios, the SYNC option allows multiple Model 875 systems to operate together while maintaining phase coherence across all units. Channel-to-channel isolation exceeds 90 dB, while channel-to-channel jitter is typically within ±10 ps.
High-Fidelity Signal Generation and Test Flexibility
The Model 875 delivers single-sideband phase noise of -145 dBc/Hz at 1 GHz with a 20 kHz offset and better than -150 dBc/Hz at a 100 kHz offset, helping ensure that test results are limited by the device under test rather than the signal source.
Beyond PDW-based simulation, the Model 875 functions as a full vector signal generator with 400 MHz RF modulation bandwidth. Its integrated I/Q modulator supports arbitrary waveform generation with up to 512 megasamples of onboard memory and sample rates from 10 Hz to 500 MHz at 16-bit resolution, enabling the creation of complex radar, communication, and custom modulation waveforms.
Optional features expand the platform’s versatility even more. The AVIO option adds built-in avionics modulation formats, the AWGN option introduces additive white Gaussian noise for more realistic signal conditions, and the AIQ option enables external analog I/Q inputs for integrating external baseband sources. The generator supports Ethernet, USB 2.0, and optional GPIB interfaces for remote control and test automation. An internal OCXO reference provides frequency stability, while an external reference input allows synchronization with laboratory standards and larger test systems.
Available in 4 GHz, 6 GHz, 12 GHz, 20 GHz, and 40 GHz variants, the Model 875 is suited for radar threat simulation, EW receiver testing, avionics evaluation, high-speed antenna testing, and other applications requiring precise, synchronized, and dynamically controlled RF signal generation.
Click here to learn more about the Model 875 Multi-Channel Signal Generator.