The next four functions convert between analog-to-digital converter (ADC) units and physical units, using as a conversion factor the gain for the specified input signal. The first two (aduphys and physadu) are general-purpose functions that convert absolute levels (i.e., they account for non-zero baseline values); the last two (adumuv and muvadu) are for use with millivolt-dimensioned signals only, and convert potential differences (i.e., adumuv(s, 0) = muvadu(s, 0) = 0 for all s, irrespective of the baseline values specified in the header file). Normally, these functions should be invoked after isigopen or dbinit, either of which will determine the gain from the `header' file. If this is not done, or if the `header' file indicates that the gain is uncalibrated, or if the specified input signal is not currently open, a gain of DEFGAIN (defined in `<ecg/db.h>') ADC units per millivolt, and a baseline of zero, are assumed. If the physical units (see section Signal Information Structures) are not millivolts, adumuv and muvadu convert to and from thousandths of the defined physical units. Note that adumuv and muvadu deal exclusively with integers, but aduphys returns and physadu accepts double-precision floating point physical values.

aduphys

double aduphys(DB_Signal s, DB_Sample a)

Return:

(double)

physical value corresponding to a sample value of a ADC units

This function converts the sample value a from ADC units to physical units, based on the gain and baseline for input signal s. (aduphys was first introduced in DB library version 6.0.)

physadu

DB_Sample physadu(DB_Signal s, double v)

Return:

(DB_Sample)

sample value, in ADC units, corresponding to v, in physical units

This function converts the value v from physical units to ADC units, based on the gain and baseline for input signal s. (physadu was first introduced in DB library version 6.0.)

adumuv

int adumuv(DB_Signal s, DB_Sample a)

Return:

(int)

number of microvolts corresponding to a ADC units

This function converts the potential difference a from ADC units to microvolts, based on the gain for input signal s.

muvadu

DB_Sample muvadu(DB_Signal s, int v)

Return:

(int)

number of ADC units corresponding to v microvolts

This function converts the potential difference v from microvolts to ADC units, based on the gain for input signal s.

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