AP-GTR20000 Linux Server based GPS NTP server Holdover Service Demonstration (고성능 서버기반 GPS NTP 시각동기서버 홀드오버 서비스 기능 데모)

 

GPS Card for PCIE 

Power Supply for Dual Hot-Swap Power

AP-GTR20000 GPS NTP server transmits GPS time information to network based application server which requires accurate time information using network time protocol.

AP-GTR20000 supports modular type dual power for power redundancy, 4port gigabit Ethernet interface and it has a built-in GPS hardware module to receive accurate time information from satellite GPS signals.

The AddPac GPS NTP time synchronization device supports a Holdover service feature to ensure continuous time information delivery to the NTP client in case the GPS signal is interrupted, disconnected, or affected by various other factors preventing the reception of GPS signals from satellites. This feature utilizes either an internal oscillator of GPS receiver chip or an externally mounted oscillator clock to generate time information independently, without receiving satellite time data.

The accuracy of the time information generated during Holdover depends on the precision of the oscillator clock. For applications requiring very high clock accuracy, such as those using GPS NTP time synchronization servers, high-precision oscillators like OCXO (Oven-Controlled Crystal Oscillator) are recommended. In other cases, a standard TCXO (Temperature-Compensated Crystal Oscillator) used in general GPS signal receiver chipsets can provide satisfactory accuracy for several hours, a day, or even a few days. It is crucial to resolve the underlying issues within this timeframe to restore normal GPS signal reception. This feature is supported in the new firmware.

Network Diagram

1.When receiving GPS time information normally

 

2.When failing to receive GPS time information normally

Demonstration

1.    Demonstration of the Holdover service feature using AP-GTR20000 unit