Description
■ A GPS disciplined OCXO incorporating a GPS receiver unit to
   give 1PPS and 10MHz output. With 1.5µs holdover stability
   achieved by using an adaptive algorithm. Standard NMEA0183
   data is available to the user via a serial port.
■ Model IQCM-110
■ Model Issue number 1
■ Working States (Reference Drawing):
   Run1: Fast track. Adjust the OCXO 10MHz output frequency
   quickly to track the GPS.
   Run2: Slow track. Adjust the OCXO 10MHz output frequency
   slowly when phase error is in the defined range.
   Holdover: No GPS input present; an algorithm enables
   adaptive modelling of the frequency stability of an OCXO with
   reference to the GPS timing signal.
   Free Run: Clock module powered up with no GPS input.
■ NMEA Data Words:
   The following standard GNSS data is available to the user via
   the interface on pin 6 and pin 7: GPRMC, GPVTG, GPGGA,
   GPGSA, GPGSV, GPGLL, GPZDA. These are broadcast every
   second in sync with the 1PPS output.
   Note 1: The IQCM-110 should be left powered and running for
   7 days minimum before operation to allow for the OCXOs
   internal drift to stabilise.
■ Note 2: The adaptive module algorithm can be built after two
   days operation with good GPS signal, however this data will be
   lost at power down.
   Note 3: When State Input (Pin 8) is set low the IQCM-110 will
   operate in Holdover mode regardless of the 1PPS signal
   condition.