The ANALOG:GEN_SCALE parameter is a single floating-point value that is used as a universal analog scaling factor.  It is applied in addition to the individual analog channel scaling factors and acts on all channels.  Common values for GEN_SCALE are:

·      0.0048828 – the value of a single bit of data from a 12-bit ADC that is measuring a ±10V input range.  An individual channel ANALOG:SCALE value would then be 1.00 to obtain the analog data scaled in Volts.

·      0.0024414 – the value of a single bit of data from a 12-bit ADC that is measuring a ±5V input range.  An individual channel ANALOG:SCALE value would then be 1.00 to obtain the analog data scaled in Volts.

·      1.00 – individual channel ANALOG:SCALE values must be set to 0.0048828 to obtain analog data scaled in Volts when sampled by a 12-bit ADC that is measuring a ±10V input range, or 0.0024414 when measuring with a ±5V ADC input range.

·      0.062500 – upgrading a 12-bit data collection system to use a 16-bit ADC requires only that the ANALOG:GEN_SCALE parameter change to reflect the new resolution while retaining the original .  If the system used a value of 1.00 with a 12-bit ADC then changing the ANALOG:GEN_SCALE parameter by a factor of 16 is all that is required when the ADC card is upgraded to continue using the original 12-bit ANALOG:SCALE values unchanged.

Since the value of the ANALOG:GEN_SCALE parameter is used with the individual ANALOG:SCALE values to calculate the correct value of each analog channel signal, it is critically important that the ANALOG:GEN_SCALE value is not changed without considering its effect on the individual ANALOG:GEN_SCALE values.

It is important to take into account the possible scaling ranges when selecting scaling values.  C3D files using an ANALOG:GEN_SCALE value of 1.000 will require individual ANALOG:SCALE values of 0.0048828 to scale the output data in Volts, an EMG application might require scaling in microvolts with corresponding ANALOG:SCALE value in the range of 0.0000048828 to 0.0000000048828, while the force plate, scaled in Newtons would use values of 100 – 300.