METHODS OF CONVERTING IMPEDANCE REPORTS APPLICABLE TO MEASURING DEVICES, IN PARTICULAR TO INDUSTRIAL PRESSURE TRANSMITTERS, AND THEIR IMPLEMENTING DEVICES.

摘要

P A digital / analog conversion method proceeds, according to the invention, by fractioning a duty cycle. BR/ Such a method finds an application in measuring the ratio of two impedances Z1, Z2 contained in a cell connected to a measuring apparatus and consists in generating square signals (Vh) by means of a clock (2) , of good, constant period, to apply during the first half-clock period, a voltage Vr at the input of the impedance Z1 and a zero voltage V0 at the input of the impedance Z2, then of applying during the second half-clock period a voltage Vm at the input of each of the two impedances Z1, Z2, to apply, the impedances Z1, Z2 having their outputs connected to an impedance output line (7) , the signal of said line (7) to the inverting input (10) of an operational amplifier (12) mounted in summed state looped on an impedance of the same nature as Z1, Z2 and to apply the output (14) of the operational amplifier (12) at the input (16) of a synchronous detector (18) controlled (20) by the clock (2), for ext error signal E. / P