SOURCEFORGE » RALF » 2015 Evaluation and test of an optical / L-band tranceiver

h1. 3.2 Noise Figure

The purpose of this section is to assess the thermal noise degradation induced by the optical link. Related measurement parameter is the Noise Figure (measured with the FSV spectrum Analyzer).

The optical link output power is measured with an input termination (done with 50 Ohm termination instead of 75 Ohm as it wasn't available) at a temperature of 290 K.

Noise Factor :

F = No / kToBG (No : measured output power noise; k : Boltzman constant ;  To : ambiant temperature close to 290 K ; B : measurement bandwidth ; G : RF Gain)

Noise Figure :

NF=10*log10(Ftot)

The table below contains the Noise Figure measured on the optical link.

|_. Parameter |_. Unit |\5=.*Measurements* |

|_. Frequency |_. MHz |=. 700 |=. 1000 |=. 1500 |=. 2000 |=. 2300 |

|_. Optical Link Noise Figure |_. dB |=. 30.9 |=. 30.1 |=. 31.3 |=. 32.6 |=. 33.4 |

|_. Specified Noise Figure |_. dB |=. 31.0 |=. 31.0 |=. 31.0 |=. 31.0 |=. 31.0 |

Optical link meets its Noise Figure specification at lower frequencies.

For higher frequencies (2000 MHz & 2300 MHz), measured Noise Figure is higher than specifications. More work would be required to check if this could be related to our Noise Figure measurement set-up or an actual limitation from Optical Link.