SA636 circuit funtion - What is the purpose of the cap?

[robismyname]

application note sa636

On page 11 of the SA636 datasheet pin #9 is labeled "DATA". There is a capacitor C8 with a value of 1uF. My question is what would be the actual value of Xc?

What is the purpose of this cap?

 

[E-design]

SA636 circuit funtion

To AC couple the data signal

 

[robismyname]

Re: SA636 circuit funtion

To AC couple the data signal

So this is behaving as a high pass filter. Why would I want to strip away the low frequency content of the signal? What is the benefit?

 

[E-design]

Re: SA636 circuit funtion

This signal needs to be coupled to outside circuits which may have different DC conditions. That is why the application note shows a DC blocking cap. The data will be pulses that pass easy through this cap.