Service Improvement Plans
WWVB's Colorado location makes the signal weakest on the U.S. east coast, where urban density also produces considerable interference. In 2009, NIST raised the possibility of adding a second time code transmitter, on the east coast, to improve signal reception there and provide a certain amount of robustness to the overall system should weather or other causes render one transmitter site inoperative. Such a transmitter would use the same time code, but a different frequency.
Use of 40 kHz would permit use of dual-frequency time code receivers already produced for the Japanese JJY transmitters. With the decommissioning of the Swiss longwave time station HBG at 75 kHz, that frequency is potentially also available.
Plans were made to install the transmitter on the grounds of the Redstone Arsenal in Huntsville, Alabama, but the Marshall Space Flight Center objected to having such a high power transmitter so near to their operations. Funding, which was allocated as part of the 2009 ARRA "stimulus bill", expired before the impasse could be resolved, and it is now unlikely to be built.
As of 2011, two other possibilities are being explored. One is to add a second transmission frequency at the current transmitter site. While it would not help signal strength, it would reduce the incidence of interference and (frequency-dependent) multipath fading. A second possibility is to add phase modulation to the WWVB carrier, broadly similar to the current DCF77 signal. This would allow receivers with greater processing gain to decode the signal at a lower signal-to-noise ratio than the current AM time code.
Read more about this topic: WWVB
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