A review of 9-year performance and operation of the MOPITT instrument

The MOPITT (Measurements of Pollution in the Troposphere) instrument has provided more than nine years of global carbon monoxide (CO) measurements on a continuous basis since its launch aboard the Terra Spacecraft on December 18th, 1999. This paper gives an overview of the core sub-system performance and major issues of the in-flight instrument over the mission period. Some of the instrument anomalies are also discussed. The major successes are: (1) the concept of using a combination of correlation systems such as Length Modulated Cells (LMCs) and Pressure Modulated Cells (PMCs) to retrieve CO profiles in the troposphere; (2) the redundant design in the instrumentation which was crucial for coping with unexpected in-flight anomalies and for continuing the mission in the case of component failure; (3) the thermal environment on orbit that is so stable that some calibration procedures are not necessary; and (4) the recent production of CO total column retrieved from the MOPITT 2.3 μm channel.     

Adaptive Arrays Can Be Used to Separate Communication Signals

Using eigentheory, it is shown how up to n unknown independent narrowband signals arriving from different directions at an array of n antenna elements can be separated into n channels where each channel contains primarily one signal. An expression for the signal-to-interference ratio (SIR) on eachoutput channel is determined analytically and evaluated for many illustrative cases. The results show that in most cases the SIR is + 10 dB or greater; only when two signals arrive within a few degrees of each other does the SIR fall substantially below 0 dB.