GPS-disciplined OCXO maintains stability over loss of signal

October 28, 2014 // By Graham Prophet
IQD’s IQCM-110 is a series of GPS-disciplined OCXOs that incorporates an internal GPS receiver with a 1PPS output, housed in a 14-pin 60-mm square package.

When coupled to an external aerial via an SMA connector, in the event of the loss of the GPS signal the highly specified 10 MHz OCXO will switch-in with a holdover capability of 1.5 µsec for a 24-hour period thereby maintaining lock until restoration of the reference signal.

The standard operating temperature range of the module is -20 to 75C but other temperature ranges and holdover specifications can be considered upon request. The required power supply is 5V with the output being standard HCMOS. Current consumption is 2A maximum during warm-up with this reducing to 1A once the steady-state condition is reached.

The design incorporates an internal adaptive algorithm which enables the module to 'learn' the parameters of the GPS signal after a period of 2 days of lock so that the holdover function can start in the event of signal failure. An internal alarm is built-in to indicate lock failure and subsequent restoration of signal. In addition, the unit incorporates a serial connection for more detailed interrogation of the device’s performance.

Intended for a range of applications including land based telecommunications systems as well as marine based navigation systems the IQCM-110 forms part of a range of highly specified modules and Oven Controlled Crystal Oscillators.