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Unformatted text preview: Name Real Time Computing Systems EE 4770 Final Examination 15 May 1998, 17:30-19:30 CDT Alias Problem 1 (30 pts) Problem 2 (30 pts) Problem 3 (20 pts) Problem 4 (20 pts) Exam Total (100 pts) Good Luck! Problem 1: Precise temperature measurements over a 3 ◦ C range are to be made using a thermis- tor. Though the range is 3 ◦ C, it can fall within 250K to 350K, that is, it might be [250K , 253K] for one set of measurements and [302K , 305K] for another. Design a circuit to convert the temper- ature, x ∈ [250K , 350K], into floating point number H ( x ) = x/ K to be written to variable tee so that two consecutive measurements that fall within a 3 ◦ C range are made precisely, as described below. To achieve the high precision over a narrow range the circuit will use an instrumentation amplifier with an adjustable gain and a digital-to-analog converter (DAC) as a bias source, as shown below. The gain of the amplifier is set to i × a 1 from the interface routine by calling setGain(i) , where i ∈ [1 , 256] and a 1 is a chosen value for the amplifier. The voltage is set to j × v 2 by calling setVolt(j) , where j ∈ [0 , 2 16- 1] and v 2 is another chosen value. See the sample code below. The thermistor has model function H t2 ( T ) = R e β/T , where β = 3000K and R = 0 . 059Ω. The circuit uses a 16-bit, 10-volt ADC. Resistor R = 9289Ω and voltage source...
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This note was uploaded on 12/11/2011 for the course EE 4770 taught by Professor Staff during the Fall '99 term at LSU.
- Fall '99