K = (C, - CJ 



' 2 D - ZC 



e 1 



where the expression is equal to — in Equation (2). 



D - ZC m. 



Equation (5) was used to reduce the buoy pitch data during basin tests and sea trials on 

 the BIAS system. 



DATA REDUCTION PROCEDURE 



In the process of data taking, a graphic or digital recording of the electrical-calibration 

 sequence is made before each datum point or group of data points. The frequency of record- 

 ing the electrical-calibration sequence is a function of the zero and sensitivity stability of the 

 transmitting and recording electronics used in the measurement system. Where a system is 

 highly stable the electrical-calibration sequence may require repeating only once per hour. In 

 fact the stability of the system can be monitored through repeated use of the electrical- 

 calibration sequence where the amount of zero drift or sensitivity drift can be determined. 

 For each electrical-calibration sequence, there will be four readings for each data channel: a 

 zero check, two electrical-calibration steps, and a datum point. The electrical zero-check read- 

 ing is equivalent to a physical zero at the sensor, and the datum point is a measure of the 

 parameter experienced by the sensor. 



Equation (5) is used to reduce the angle data from the buoy pitch and horizontal 

 stabilizer channels. These two parameters require a positive and negative readout with the 

 zero position in the center of the readout scale. Equation (5) is repeated here for 

 convenience: 



K (D - ZC) 



= 



C - c 



In the case of the buoy shallow and deep depth channels, the readout starts from a zero 

 position and increases positively as depth is increased from the water surface. A variation of 

 Equation (5) is used to reduce these data channels. 



K (D - ZC) 



DP = — ^^ (6) 



C, - ZC 



29 



