What is the meaning of DAC-card acronym?

Answer 1

It means (MAYBE!) "Digital to Analog Converter". This is a hardware device that is used to turn a digital signal into an analog signal. A digital signal can send information encoded on a carrier value of either "1" or "0". For example, on a 5 milliwatt carrier current, the signal can be 5 milliwatts for "0" or 10 milliwatts for "1". The sender and receiver of the signal must agree on the frequency that the values can change; typically this is expressed in Hertz, or cycles per second. So, with a 30Hz frequency, as I measure the power coming from my sender, the first 30th of a second, the signal is 5mw (that's a "0"). The second 30th is 10mw (that's a "1"). It continues on as 5,5,10,5,5,10,... so the signal I am getting is a series of two 0's and one 1, repeated. An analog signal can range from whatever the lowest value to the highest value, agreed upon by the sender and receiver. Each of the discreet voltages can carry a different meaning, or no meaning at all. So, if I send a predefined digital signal to the DAC, I can send out from it discreet voltages that would be used by whatever device needed an analog signal.