GPS3000C02

Ultrastable GPS based frequency standard with 10 MHz, 1 PPS, black-burst video sync, SD-SDI black digital video and SMPTE/EBU LTC and VITC time code outputs

The GPS3000C02 module is a highly stable time and frequency standard generator GPS-disciplined, designed for synchronization of telecommunications equipment in general and, in particular, for generation of all the synchronization signals needed for networks and production environments used in radio and television broadcasting.
The exceptional stability of the module is obtained by receiveing signal from the GPS network, which guarantees long-term stability and is equivalent to a cesium-based time standard. Short-term stability is provided by a thermostatic quartz crystal oscillator (OCXO). This oscillator is also responsible for maintaining operation of the module when synchronization to the GPS network is lost.
The GPS3000C02 module is basically a highly stable oscillator (OCXO) with GPS-based correction. All of the reference signals provided by the module are derived from this oscillator. In order to generate an exact OCXO frequency, this oscillator's frequency is continuously measured against the time standard of the signal received from the GPS system. The error obtained is then used to correct the frequency and phase of the master oscillator. In addition to this correction, the module tracks and learns the derivation of the OCXO frequency with respect to time and temperature and creates a precise behavioral model of the OCXO. This model is used to correct the small drift of the oscillator, in case of a loss of the GPS signal. In this way the module continues to deliver a good quality signal as long as the interruption to GPS reception is of a short duration. Operation using the OCXO without a reference from the GPS system is known in the industry as Holdover Mode.
If the characteristics of the high stability OCXO weren't sufficient in Holdover Mode and the user wished to improve them, the GPS3000C02 has an input for an external 10 MHz signal generator. This input can be used for higher quality 10 MHz references, for example a rubidium-based oscillator.
In addition to GPS-based correction, the GPS3000C02 module can admit external 1 PPS reference signals.
Given the importance of proper synchronization of any modern telecommunications system, the GPS3000C02 has been equipped with ample resources for redundant operation as well as supervision. Depending upon the type of installation, in some cases the user may want the sync signal generator to respond to a signal error by deactivating its output. Another operating mode is available designed especially for redundant installations and for simplification of the job of automated signal switches. This consists of a single control line cable, robust and easy to install, that allows the GPS3000C02 to report its operating mode to other modules. In this way, when a module detects an error in its operation it deactivates its own output unless it is the only active device is a group of redundant modules. In that case the module with the error keeps its outputs active, using the high quality internal oscillator in Holdover Mode . In this type of operation, the first device that recovers synchronization then activates its own output, deactivating the the output of the last device that lost synchronization.
The alarm management interface provides two relays with closed contacts to ground that indicate if the module's outputs are active or not as well as whether the module is in Holdover Mode or not.
Configuration of this module is simple and allows continuous use with or without external supervision. However, given that the links to GPS satellites are subject to loss of signal or interference, the front panel of the module contains LEDs to indicate the quality of the GPS signal: the intensity of the signal received, the number of visible satellites, etc. For more exhaustive analysis of the module's behavior there is also an RS232 serial port via which real-time data on the operating parameters of the GPS3000C02 can be obtained, and this data can be manipulated with ease with software applications. It is also possible to capture a large number of successive events in order to evaluate the operation of the module. Finally, the general monitoring and control system for the TL3000 family of modules can provide this and other diagnostic data.
The GPS3000C02 outputs timing signals in 1 PPS (one pulse per second), 10 MHz sinusoidal and variable frequency TTL at 1, 5 or 10 MHz. The 1 PPS output is synchronized with high precision to the GPS system, providing very little timing difference between two GPS3000 systems located in any part of the earth with GPS coverage. The sinusoidal 10 MHz output is phase locked to the 1 PPS signal and provides excellent short-term stability (phase noise) as well as Allan deviation and long-term drift. The adjustable frequency signal output provides the same quality as the 10 MHz sinusoid and it has TTL compatible levels when it is 50 ohms loaded.
The GPS3000C02 also generates video reference signals: Black Burst for analog, digital black, a TTL clock at 27 MHz and longitudinal time code (LTC). All of these signals are synchronized with high precision to the GPS signal.