Application of nonlinear compensation to limit input dynamic range in analog optical fiber links

J. Rodriguez*¹, J. Velazquez², R. Garduno³, J. Montero⁴

^1,2,3,4 Instituto de Investigaciones Electricas, Control and Instrumentation Department, Reforma 113, Col. Palmira, 62490 Cuernavaca, Morelos, Mexico *E–mail: jrr@iie.org.mx

ABSTRACT

The dynamic range of a signal at the input of a measurement system during a short circuit test is increased several times by the nominal input voltage. Saturation of the measurement system may occur in a device under failure test. This paper introduces the application of a nonlinear compensation to limit the voltage range at the input of a voltage controlled oscillator which is used to produce the pulsed frequency modulation needed to transmit the analog signals over the optical fiber links. The proposed dynamic range compensation system is based on non–linear circuits to accommodate the input range of the voltage controlled oscillator. This approach increases the transient signal handling capabilities of the measuring system. This work demonstrates that the nonlinear compensated optical fiber approach yields a unique, electrically isolated, lightning–proof analog data transmission system for remote measuring systems in the highly aggressive EMI environment of high–power test laboratories.

Keywords: Nonlinear compensation, VCO dynamic input range, EMI, high power testing, optical fiber link.

RESUMEN

Cuando un dispositivo bajo prueba falla durante una prueba de corto circuito, la señal esperada se incrementa y la saturación de voltaje a la entrada del sistema de medición dificulta el análisis de la falla. Este artículo introduce la aplicación de una compensación no lineal para limitar el rango de voltaje en la entrada de un oscilador controlado por voltaje, el cual es usado para producir la modulación pulsada en frecuencia necesaria para transmitir las señales analógicas sobre las cadenas de fibra óptica. El sistema de compensación dinámica de rango propuesto está basado en circuitos no lineales para acomodar el rango de entrada del oscilador controlado por voltaje. Este enfoque incrementa la capacidad de manejo de señales del sistema de medición. Este trabajo demuestra que las cadenas de fibra óptica compensadas no linealmente proporciona un sistema de transmisión de datos analógicos único, eléctricamente aislado y a prueba de descargas eléctricas para sistemas de medición remotos en el ambiente altamente agresivo de un laboratorio de pruebas de alta potencia.

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