Crystal Instruments GRS Ground Recorder System

The Ground Recorder System (GRS) is a rugged, lightweight, battery-powered dynamic data recorder and real-time signal analyzer developed by Crystal Instruments in collaboration with NASA, engineered for autonomous remote deployment. It combines precision acoustic and vibration measurement, GNSS timing, aircraft tracking, intelligent triggering, on-board processing and cellular or satellite communications.

The GRS enclosure measures 54.5 x 35 x 21 cm (21.5 x 14 x 8.3 in) and is ruggedized and weatherproof, with all connectors rated IP67 and LEMO connectors chosen for stability in high winds and harsh environments. It operates from -20 C to 55 C and can power on fully after cold soaking at 0 F for 24 hours. Two removable 94 Wh Li-ion batteries (188 Wh total) provide up to 12 hours of full-operation runtime; solar charging and low-power modes support extended unattended operation, with hibernate drawing only 55 mW.

Acquisition uses four analog input channels, each with dual 24-bit ADCs and a DSP implementing US Patent 7,302,354 to achieve better than 150 dBFS dynamic range with automatic range selection. The SD card records four channels of both ADCs at up to 102.4 kHz for months of storage, and data can be encrypted per FIPS PUB 140-2. Triggered recording provides up to 150 seconds of pre-trigger ring-buffer data (the page also cites up to 300 seconds of pre-trigger buffering), with events defined from input channels or peripherals; six internal and two external digital inputs can generate events such as starting or stopping a recording.

Timing and communications are central: a multi-constellation GNSS provides location accuracy better than 2.5 m and hardware-level ADC time stamps accurate to 100 ns, so multiple GRS units spread over hundreds of miles can be aligned on one time base in EDM-PA without any hardware link. Integrated LTE and Inmarsat satellite links enable remote monitoring, control and data transfer, preferring low-power LTE where available and switching to satellite when isolated. An onboard ADS-B module (Aerobits TT-MC1b) acquires aircraft broadcasts within a 200-mile radius. The GRS passed IEC 60068-2-27 shock and IEC 60068-2-64 vibration testing, and a dedicated battery-powered real-time clock (about 10-year life) enables failure recovery.