Test Mode
The NetClock/2 includes a test mode feature to assist in troubleshooting reception problems. While in the test mode, the tens of hours digit displays the receiver WWVB time code bit every second. This feature is useful because it provides an instant indication of the received signal quality. To enter the IRIG Format Test Mode, place the IRIG Format switch into Position 9.
In the test mode, the left-most display digit shows valid time code characters as the numbers 0, 1, and 2. When a 0 is displayed, the receiver decoded a Binary 0 for that time code bit. A number 1 represents a Binary 1 was received. Every ten seconds, WWVB transmits a position identifier. This character is represented by the number 2. The pulse width of the demodulated time code determines which character was received.
If the received time code character does not meet the criteria for a Binary 0, Binary 1 or position identifier, it is considered invalid and is ruled a bit error. A bit error is represented by the number 4 on the display. Displaying frequent or constant bit errors is cause for concern, as the time required to synchronize is greatly extended. Bit errors may be caused by solar flares, poor atmospheric conditions, or local interference. Little can be done about the sun or weather, but local interference problems can be solved. Interference can be conducted over the power line and ground or radiated into open air. For more, see troubleshooting WWVB interference.