Precision timing module for cellular networks

Paul Boughton

Machine-to-machine communications expert Alpha Micro Components has launched the LEA-M8F precision timing GNSS module from u-blox - a compact, surface-mount unising industrial data and communication systems such as small, femto and macro-cell mobile networks. High accuracy is achieved by disciplining a local oscillator or other clock source with timing signals received from satellite-hosted atomic clocks.

To ensure satellite availability, LEA-M8F is able to acquire and track all 50+ GPS, GLONASS and BeiDou satellites. High sensitivity and aided GNSS option enables quick autonomous start-up even inside structures with limited sky-view.

Measuring only 17 x 22mm, the LEA-M8F module includes a low-noise 30.72MHz VCTCXO (voltage and temperature controlled oscillator), meeting the master reference requirements for LTE Small Cells while providing 100 parts-per-billion autonomous hold-over accuracy. The module is also suitable for TD-LTE, LTE-Advanced and other applications requiring extended hold-over times when integrated with small cell platforms.

External sources of synchronisation are supported through time-pulse and frequency inputs and a message interface. This allows measurements from macro-sniff, Sync-E or packet timing to be combined with measurements from GNSS to extend the availability of accurate synchronisation and in doing so maximise cellular service availability.

LEA-M8F can track signals from satellites from any two constellations (eg, GPS and GLONASS, GPS and BeiDou, GLONASS and BeiDou) simultaneously. Compatibility with multiple GNSS systems gives the LEA-M8F access to a large number of satellites, allowing synchronization even in urban or indoor areas with limited sky view. For stationary applications, once a location is known, accurate timing can be maintained based on the signal from just a single satellite.