The HAA-1203W 12 Inch Atomic wall clock, By Hewes Time and Weather Instruments (HTAWI) maintains split second accuracy by receiving WWVB radio time transmissions. HTAWI clocks have proven to have exceptional sensitivity, often capturing the WWVB signal faster and in more difficult conditions than other clocks we have tested. These clocks are ideal for anyone wanting to know the correct time, and are especially popular for environments such as schools and businesses where many clocks must remain in synchronization (*see limitations below).

The HAA-1203W has a white rim, a white face, and highly readable numeric hour and minute/second markers. Its 12-inch diameter is perfect for home or business applications.

HTAWI atomic clocks are easy to set up.  Simply set the time zone switch to the correct time zone, enable or disable DST compliance (disable only if you are in an area that does not switch to DST), and hang the clock.  The clock will receive the WWVB signal and set itself*.  In good conditions, this will occur within the hour.  In non-ideal conditions, it could take longer, possibly overnight.  It is possible to manually set the clock, in which case the manual setting will be overridden when the signal is received.   

Features:

• High quality construction with a scratch resistant glass face to endure many years of cleanings
• Accurate to 1 second per million years
• Sets automatically to WWVB radio signal
• Switch selection for all four U.S. mainland time zones
• Automatically adjusts for daylight savings time (may be optionally disabled)
• White face with white rim for an exceptionally clean, contemporary look
• Powered by one AA alkaline battery (not included), with normal life of over 1 year

Dimensions:

• Diameter:
  12 inches overall, 9.25 inch face
• Depth:
  1.75 inches

The NIST (National Institute of Standards and Technology, Time and Frequency Division) maintains a highly accurate master clock based on the resonance of a Cesium-133 atom (hence the name, atomic clock).  Timing information from this master atomic source is broadcasted by the WWVB radio station in Ft. Collins, Colorado.  

Hewes Time and Weather Instruments (HTAWI) "Atomic" clocks maintain exceptional accuracy by tuning into the WWVB radio signal. The built-in receiver achieves reliable signal reception up to 2000 miles from the WWVB transmitter in Ft. Collins, Colorado. As a result, HTAWI atomic clocks will calibrate themselves to the atomic clock throughout the continental U.S., and also in much of Canada. Just set the time zone switch, insert the battery, and wait until the signal is received.

*Although HTAWI clocks have proven to have excellent signal reception capabilities, like any radio receiver, they cannot receive a signal that doesn't reach the clock, or is overwhelmed by interference.  Building construction with a large steel content (like many modern high rises) may block the transmissions, making clock setting problematic, unless the clock is placed with a view out a window facing Colorado.  Interference from lamp dimmers, computer monitors, or other electrically noisy devices which are in close proximity to the clock can also cause problems.  If the clock does not set itself within 24 hours, you may wish to try placing the clock in a window facing Colorado to receive it's first setting, and then relocating it to your desired location.  

Instructions for setup