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: October 8, 2013
Saelig Co. Inc.
Tel: (585) 385-1750 Email:


Saelig Announces GPS-Guided TCXO Oscillator With or Without Built-in GPS Receiver

Low power OCXO-substitute locks to a satellite signal for a frequency accuracy of better than 5 x 10E10.

Fairport, NY, USA:   Saelig Company, Inc.  ( has introduced the RSGGO10T3G and RSGGO10T3P reference oscillators with the same form factor as standard ovenized crystal oscillators (OCXO - 1”x1”) but instead of a current-hungry oven they contain a temperature-compensated crystal oscillator with 100ppb stability locked to a 1 pulse per second (1pps) signal from an external (T3P) or integrated (T3G) GPS receiver.  A combination of novel circuits, special firmware algorithms, conformal-coating, and patented nanotechnology provide a low-current miniature unit with very high performance at an attractive price.

The RSGGO10T3x reaches its specified accuracy of better than 5 x 10E10 within two minutes after GPS lock - a much shorter time than an OCXO. The standard module frequency is 10MHz, but other frequencies are available on request.  The output is a filtered 3.3V square-wave with a low phase noise of -155 dBc/Hz typical @ 10kHz offset and -157 dBc typical noise floor. Under normal circumstances with average GPS jitter the accuracy will be 1x10E10. This is one of the biggest advantages of the RSGGO10T3x - it doesn't have to be powered 24/7 to be stable. Turning it on a few minutes before needed will provide better than double an OCXO’s stability.  Another big advantage of the RSGGO10T3x compared to OCXO's is that the crystal doesn't get stressed by heating and cooling which causes an oscillator to never really return to the original frequency. The RSGGO10T3x provides a 10 fold better accuracy than the best high end crystal oven controlled oscillators with the advantage that they will always be calibrated if a GPS signal is applied. RSGGO10T3x modules provide extremely low phase noise with none of the phase discontinuity or jumps of other solutions. In stark contrast to PLL based solutions, the RSGGO10T3x is highly immune to drops in GPS signal, missing 1pps pulses or pulse distortions caused by fading or other influences.  It uses a different locking mechanism using specially-developed algorithms which ensure that unavoidable, unpredictable jitter of the 1pps signal does not have a negative effect on the short- or long-term stability of the system.  Missing GPS pulses do not lead to an immediate loss of accuracy.   As the GPS signal is NIST traceable, these frequency references with GPS guidance are NIST traceable too and as such do not need calibration. As long as a GPS signal is applied they act as secondary standards.  The GPS signal “guides” the TCXO onto the correct frequency, which is why the name GPS Guided Oscillator (GGO) has been coined.    

Using a RSGGO10T3x module removes the need for a Rubidium standard to recalibrate references regularly.  Connecting the RSGGO10T3x to a GPS antenna produces a frequency source with the best possible accuracy and stability - short of a very expensive Rubidium standard.   Two of the unit’s pins can be used as an I2C interface for optional control or programming, or to drive a two-color LED to indicate internal status (red = no GPS; amber = locking; green = locked to spec.)   A test board with (RS-TBGGO) and without (RS-TBGGO-NG) GPS receiver is also available.

Swiss-made by RF Suisse AG, a leading-edge designer of RF sources, RSGGO10T3x modules are available now from their USA distributor Saelig Company. Inc.


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