Actuators linearization of a large volume environmental simulation chamber via pulse code modulation

Ultra-stable room-sized environmental chambers may involve significant powervariations leading to hysteresis and nonlinearities of the stabilization system.This paper describes utilization of a pulse code modulation control efficientlymitigating significant nonlinearity of the chamber actuation system. Stabilityof environmental conditions for temperature ΔT = ±25 mK (15-35oC dynamicrange), relative humidity ΔRh = ±0.1% (3-95% dynamic range), and pressureΔP = ±12 Pa (±500 Pa dynamic range) was achieved within 27 m3 chambervolume, which is two orders of magnitude better if compared with the stabilizationachievable using a standard linear proportional-integral-derivative (PID)controller. Utilizing the chamber we have demonstrated two orders of magnitudeimprovement of the operational relative frequency stability of ultrastablequartz oscillators, reaching 2 × 10−13 at 1 s-105 s averaging time.