s an embedded design, the Lassen iQ GPS module provides direct CMOS compatible TTL level serial I/O. The RX and TX signals on the J2 I/O connector are driven directly by the DUART on the Lassen iQ GPS receiver. Interfacing these signals directly to a UART in your application circuitry provides direct serial communication without the complication of RS-232 or RS-422 line drivers.
If we want to connect the GPS receiver to any RS232 serial port you need a converter. MAX3232 is an serial driver IC which can operate from 3v to 5v.
Serial Port Interface for GPS Receiver
How to interface a GPS receiver with microcontroller