Mod 8 Unit 1

Apparent Solar Time

Based on the apparent location of the sun; the least accurate timing measure.

Quartz Oscillators

Resonating tuned voltage through a crystal; affected by temperature and age, requiring periodic calibration.

Atomic Oscillators

Use atom molecules to release radiation for timing; not impacted by age or temperature.

Cesium Standard

Atomic resonance at 9.192 GHz; highly stable with a drift of only 200 nanoseconds in 24 hours. Primary frequency standard, more accurate than rubidium

Rubidium Standard

Gas cell with resonance of 6.834 GHz; drifts approximately 1 microsecond every 24 hours. Second Frequency standard

Global Positioning System (GPS)

Provides timing standard by collecting data from satellites, offering timing more accurate with more satellites. Designed to provide FOUR satellite visiblity from anywhere in the world

Plesiochronous

Does not require synchronization between nodes; provides highly stable clocks at each station.

Mutual Synchronization

Requires all network nodes to have their own clocks; adjusts as nodes disconnect and connect.

Master Clock

One master station distributes timing to all others; a single point of failure.

Master-Slave

Most reliable technique; one master station distributes signals to subordinate nodes, expected to have backup clocks.