GB1149970A - Improvements relating to measurement - Google Patents

Abstract

1,149,970. Selective signalling. WIRTH GALLO & CO. 10 Nov., 1966 [24 Nov., 1966], No. 50401/66. Heading G4H. In a measuring system employing a measuring instrument or transducer of the type that provides output signals that require processing before they can be used to control an indicator, the output signals are processed twice, once to determine a measured value and once to determine a comparison value, this processing taking place in measuring and comparison periods respectively, which may overlap (but not coincide) in time, and at the end of both periods the two results obtained are compared, agreement or lack of agreement determining the subsequent operation of the system. As described, the output signals from a string balance are processed during two non-coinciding periods and if the measured and comparison values obtained agree with each other it is assumed that the balance has reached an equilibrium condition and that measured value is an accurate measure of the load on the balance, while if the two values disagree it is assumed that the balance has not reached an equilibrium condition and that neither value is accurate. In the former case for the comparison values are derived and compared with the measured value-continual agreement indicating that the load on the balance has not changed, and in the latter case the whole process is repeated to determine new measured and comparison values. The string balance employed in the system described is of the type that produces two electric signals, which, when the balance is in equilibrium (i.e. when it has come to rest after the load has been applied) have constant frequencies # 1 and # 2 , and the Specification shows that a measure of the load on the balance can be obtained by counting cycles of f 1 until a predetermined number n of cycles of f 2 has occurred. In a first embodiment, measurement and comparison value counts of f 1 are started simultaneously, the measurement count is continued until n cycles of f 2 have been counted and the comparison count until ¢n cycles of f 2 have been counted. At the end of the measurement count, the measurement count and twice the comparison count are compared and if they agree to within Œ1, it is assumed that the measurement count accurately measures the load on the balance. Further comparison value counts are then made and compared with the measurement value, which is assumed to remain correct until a disagreement is detected. When a disagreement is detected the measurement value is redetermined by making a further count. In a second embodiment the comparison count is made after the measurement count using the same equipment, the measurement count having been transferred to a store. In both embodiments, once the accuracy of the measurement value has been ascertained, multiplication by a key-set price per unit weight is effected and the result is visually displayed.