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 100 Hz to 1 GHz—spanning the full frequency range needed to detect and characterize compromising emanations from DC-powered equipment, modern high-speed digital systems, encrypted communication hardware, and classified information processing equipment.

The series consists of three complementary models that together provide uninterrupted frequency coverage across the entire TEMPEST-relevant spectrum: the LIP-0010 for DC power line evaluations (100 Hz–10 kHz), the LIP-120 for low-frequency AC evaluations (5 kHz–1 MHz), and the LIP-1000 for high-frequency assessments (1 MHz–1 GHz). All three models share a common electrical platform—50 Ω impedance, 10 A continuous current, and 380 VDC voltage ratings—allowing test engineers to switch seamlessly between units without reconfiguring the EUT connections.

Model Comparison

LIP-0010 — DC Power TEMPEST LISN (100 Hz–10 kHz)

The LIP-0010 is engineered specifically for TEMPEST conducted emissions testing of DC-powered devices over the 100 Hz to 10 kHz frequency range. As classified and government installations increasingly rely on DC-powered equipment—battery-backed systems, DC bus architectures, uninterruptible power supplies, and portable secure devices—the need for a dedicated DC LISN covering sub-10 kHz frequencies has grown significantly. The LIP-0010 fills this gap, providing the measurement platform required to capture low-frequency compromising emanations that propagate on DC power lines below the range of conventional LISNs.

The LIP-0010 uses 2.8 mH air-core inductors to present a stable, well-defined 50 Ω (±10%) impedance across its full operating range. Air-core construction prevents magnetic saturation and permeability variation under DC load conditions—a critical design requirement when operating with up to 10 A DC continuous at up to 380 VDC. The dual-conductor network covers both power lines simultaneously, with each line providing an independent N-type (female) RF measurement port for direct connection to a spectrum analyzer or EMI receiver. The EUT power port is fitted with a universal multi-configuration receptacle to accommodate the widest range of DC-powered equipment, while the power input port uses a standard IEC C13 receptacle. The mounting plate is left unpainted to facilitate direct connection to earth ground, which is essential given the high leakage current characteristics of the design. Each unit ships with full NIST-traceable calibration data (impedance, insertion loss, and isolation), with ISO 17025 accredited calibration available upon request.

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 Three Models Work Together

TEMPEST evaluations require conducted emissions measurements across a wide frequency spectrum to ensure no compromising signals escape on the power lines at any frequency. The LIP-0010, LIP-120, and LIP-1000 are designed as a complementary set providing coverage from 100 Hz to 1 GHz. For equipment with DC power supplies, the LIP-0010 addresses the sub-10 kHz range that standard AC LISNs cannot reach. When AC power line testing is required, the LIP-120 sweeps 5 kHz–1 MHz, and the LIP-1000 extends coverage to 1 GHz. All three models share the same 10 A / 380 VDC electrical ratings and dual-conductor architecture, so transitions between units require no changes to EUT wiring—only the LISN and receiver frequency range are changed. Together, the three units deliver uninterrupted 100 Hz to 1 GHz conducted emissions coverage for the most comprehensive TEMPEST power line assessment possible.

TEMPEST vs. Commercial LISNs

All Com-Power TEMPEST LISNs—LIP-0010, LIP-120, and LIP-1000—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.