The typical assumption with these models is that all of the starlight incident on the image detector is detected. In reality, the measured intensity is less than the modeled star intensity, due to the effects of pixel saturation and star detection logic. Pixel saturation has the effect of masking image intensity, due to the bit depth of the analog-to-digital converters (ADCs) of the image detector. Star detection logic is used to detect candidate stars and separate the star image from the background image noise. Similar to the model described in the first row of Figure 1, the detection of a specific star is still defined by a minimum SNR. However, in this case, the SNR is based not only on the noise of the image detector and the size of the PSF, but on the length of the star smear.

These models are summarized by the second row of Figure 1.On the opposite end of the fidelity spectrum, we have various high fidelity models. These models produce more accurate results, but they rely on specific information about mission orbits and maneuvers. Availability is measured along the specific orientation track the sensor will follow on the celestial sphere. This track is defined by the dynamics of the spacecraft. Star detection is assessed by the exact detection routines employed on the star tracker. These models can include the effects of optical aberrations on the PSF, as well as the effects of bright bodies (Sun, Moon, other planets). Furthermore, these models would typically revise the definition of availability from having at least Nmin detectable stars in the FOV to having a detectable non-ambiguous star pattern in the FOV, which contains enough stars for star identification.

These models are summarized by the last row of Figure 1 and would typically be used to predict the availability performance of a spacecraft following launch.There is currently a gap in available performance models between those which yield high fidelity results and those which are not specific GSK-3 to a particular mission. This work attempts to bridge this gap and provide some intermediate models of availability. The aim is to increase the fidelity of the availability model while not limiting its applicability to any specific mission. We explicitly consid
Recently, there has been great interest in surface acoustic wave (SAW) rate sensors (so called gyroscopes) because of their many unique properties such as superior inherent shock robustness, a wide dynamic range, low cost, small size, and long working life compared to other current gyroscope types [1]. The Rayleigh wave can be generated at the surface of piezoelectric material by applying a voltage to interdigital transducers (IDTs) patterned on the substrate [2].