HEIDENHAIN PWM 20 - Manual (Page 157)

160 HEIDENHAIN ATS Software User's Manual
Sig A; Sig B
These are the amplitudes of the sinusoidal incremental signals A and B. In the ATS software the
designations A and B are used for the sine and cosine signals of both interfaces. The up-to-date
voltage interface is 1 Vpp; the 11 µApp current interface is "older" (I1 and I2 in the diagram).
A / B
Amplitude ratio of signals A and B
Pha
Phase angle difference of signals A and B
TV A (I1); TV B (I2)
The on-to-off ratio (TV) is a measure of the offset of the signals A (I1) and B (I2).
It can alternatively also be indicated as asymmetry (SYM).
Note:
SYM is indicated in radian measure; multiply the value with 180

to

convert it into degrees.
Definition of TV and Pha
TV1/TV2
On-to-off ratio error of incremental signal 1 (A), incremental signal 2 (B)
Analog incremental signals are triggered at zero crossover, i.e. they are converted into square-
wave signals.
A period (= high time plus low time of the square-wave signal) is subdivided into 360°.
If high time and low time of the square-wave signal are the same (ideal case), i.e. 180° each
(180° + 180° = 360°), the on-to-off ratio is 0°.
If the high time of the square-wave signal is longer than its low time, one speaks of a positive
on-to-off ratio.
An on-to-off ratio error of e.g. + 10° means that the high time of the square-wave signal is 190°
(180° + 10°) and its low time 170° (180° - 10°).
Formula: A / B; Nominal value = 1
Formula: Pha = |

A +

B| / 2
Formula: Asymmetry = |P - N| / 2
 M
On-to-off ratio = 2
 180/

 sin (2  SYM)
Note
The on-to-off ratio error is also referred to as offset error.