LISNs - TEMPEST

TEMPEST LISNs — Security Emanations Testing

Com-Power TEMPEST Line Impedance Stabilization Networks (LISNs) are purpose-built for security emanations testing in classified and government environments. Standard commercial LISNs are designed for regulatory compliance testing up to 30 MHz and are not intended for the extended frequency coverage required by TEMPEST programs. The Com-Power TEMPEST series addresses this gap with continuous coverage from 5 kHz to 1 GHz—spanning the full frequency range needed to detect and characterize compromising emanations from modern high-speed digital equipment, encrypted communication systems, and classified information processing hardware.

The series consists of two complementary models that together provide uninterrupted frequency coverage across the entire TEMPEST-relevant spectrum: the LIP-120 for low-frequency evaluations (5 kHz–1 MHz) and the LIP-1000 for high-frequency assessments (1 MHz–1 GHz). Both models share a common electrical platform—50 Ω impedance, 10 A continuous current, and 270 VAC / 380 VDC voltage ratings—allowing test engineers to switch seamlessly between units without reconfiguring the power feed or EUT connections.

Model Comparison

LIP-120 — Low-Frequency TEMPEST LISN (5 kHz–1 MHz)

The LIP-120 is engineered for low-frequency TEMPEST conducted emissions testing across the 5 kHz to 1 MHz band. Its 1.37 mH inductance provides the high impedance necessary to capture compromising emanations that propagate on power lines at lower frequencies—a range where many digital clock harmonics, switching power supply signatures, and data bus leakage signals are most prominent. The LIP-120 features a dual-conductor design covering Line and Neutral, a 50 Ω N-type (female) RF measurement port for direct connection to an EMI receiver or spectrum analyzer, and a universal three-pin AC receptacle for the EUT power connection. Rated at 10 A continuous with 270 VAC / 380 VDC support, it accommodates the full range of equipment found in classified processing environments. Each unit ships with NIST-traceable calibration data, with ISO 17025 accredited calibration available upon request.

LIP-1000 — High-Frequency TEMPEST LISN (1 MHz–1 GHz)

The LIP-1000 extends TEMPEST conducted emissions testing to 1 GHz, covering the 1 MHz to 1 GHz high-frequency band where modern high-speed digital circuits, USB/HDMI interfaces, high-frequency clock oscillators, and encrypted communication buses generate their most significant compromising emanations. Its 23 µH inductance and 50 Ω impedance (+30/−20 Ω) are optimized for broadband performance across this extended range, while air-core inductors eliminate magnetic saturation to ensure stable impedance under all operating conditions. The LIP-1000 delivers > 40 dB isolation between mains and EUT ports and between Line and Line—critical for preventing ambient power line noise from masking low-level compromising signals. The RF measurement port uses a BNC (female) connector, and the EUT connection is via coaxial N-type connectors with an included adapter to a universal receptacle. With < 2.5 dB insertion loss across the full band, the LIP-1000 preserves signal integrity for accurate TEMPEST evaluations.

Key TEMPEST-Specific Features

TEMPEST Testing Applications

How the Two Models Work Together

TEMPEST evaluations typically require conducted emissions measurements across a wide frequency spectrum to ensure no compromising signals escape on the power lines at any frequency. The LIP-120 and LIP-1000 are designed as a complementary pair with a shared crossover point at 1 MHz. During a full TEMPEST assessment, the test engineer connects the LIP-120 first to sweep the 5 kHz–1 MHz band, then swaps to the LIP-1000 to cover 1 MHz–1 GHz. Because both models share the same 10 A / 270 VAC / 380 VDC electrical ratings and dual-conductor architecture, the transition requires no changes to the power feed or EUT wiring—only the LISN unit and the receiver frequency range are changed. Together, the pair provides uninterrupted 5 kHz to 1 GHz conducted emissions coverage in a compact, portable two-unit setup.

TEMPEST vs. Commercial LISNs

All Com-Power TEMPEST LISNs include individually calibrated data (impedance, insertion loss, and isolation), NIST-traceable calibration certificates, and a standard three-year manufacturer warranty. ISO 17025 accredited calibration is available upon request for laboratories requiring the highest level of compliance documentation.