WWVB Signal Strength Measurement
The NetClock/2 may be used to measure the relative field strength of the 60-kHz WWVB signal. This measurement is used to optimize reception by indicating the best location and orientation of the antenna. This is especially useful for the Model 8219 Loop Antenna, due to its directional reception pattern.
The NetClock/2 employs synchronous AGC which responds to the 60-kHz signal only, and is not affected by noise. The AGC level, therefore, provides an excellent indication of field strength.
The AGC voltage increases in strong signal locations, rising to a limiting value of approximately 3.6 VDC. The AGC voltage is approximately 2.3 VDC at a field strength of 100 µV/meter using a properly-oriented Model 8219 Loop Antenna and Model 8207 Preamplifier. The AGC voltage increases in strong signal locations, rising to a limiting value of approximately 3. 6 VDC.
If the maximum obtainable AGC voltage is less than 1.8 VDC, the antenna or preamplifier gain or tuning (if a preamp is used) could be a problem. The preamplifier may also be installed backwards.
As the signal strength decreases to the receiver phase lock minimum threshold of about 0.2 µV, the AGC voltage decreases to about +1.0 VDC. The SIGNAL lamp changes from green to red below this level. The AGC voltage will decrease to a varying level around zero if the input signal is removed completely. As the signal is reapplied and increased, the receiver will again lock at an AGC level of approximately 1.0 volt. To measure the AGC voltage, select your style of NetClock/2: