Clock module provides holdover capability for GPS receivers

3rd March 2015

Nat Bowers

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Datasheet

The IQCM-300 precision clock module from IQD Frequency Products is designed to provide an easy to use holdover capability for GPS receivers. Housed in a 75mm square 28-pad metal surface mount package, the IQCM-300 provides ideal protection against deliberate GPS jamming and weather outages for applications including network base stations, clock sources, clock servers and IP backhaul.

Incorporating an internal high specification HCMOS OCXO as backup in case of failure of the GPS signal, the module achieves a holdover specification of 1.5µs over a 24-hour period by using an adaptive algorithm. This adaptive algorithm is normally built up over a period of 2 days operation when a good and constant GPS signal is present. In the case of failure of the 1PPS input from the GPS signal then an internal alarm will indicate its failure and consequent loss of lock and transfer to free-run using the OCXO.

The module also has transmit and receive serial gigabyte media independent interface ports to enable communication over the Ethernet for high speed data transfer so increasing its overall capability.

Operating from a 5V power supply which has the capability of providing a maximum current consumption of 2A during the warm up and stabilisation period but reduces to 1A once the steady state condition has been reached whilst tolerating relatively high levels of PSU ripple.

The module has a standard operating temperature range from -20 to +75°C although other temperature ranges and outputs may be available on request as well as alternative holdover specifications.