For an uncooled, `room temperature,' ambient temperature near 300 K, IR detector array for resolved ground targets such as vehicles, a bolometric array is superior to other types. Of the several bolometric types, the thermistor is probably the best. Large arrays (about 350 by 250 pixels) can be built using standard silicon lithographic technology. The time constant of a detector element is about 10 ms so that standard TV raster and display can be used. Though NEdT below 30 mK is attainable with detectors on 50 micrometers centers, inversely proportional to the spacing of the detectors, it is more likely that NEdT of only 40 mK will be available because of practical problems in the focal plane array design and operation. A comparison is made between MWIR photodiode and wide band bolometric detector arrays. A static noise model is developed including radiation noise both from the scene and from the detector itself (considering its heating by the bias power of the thermistor), the thermistor resistor, the bias current and the preamplifier. This model is modified to include low duty cycle pulsed bias.