The downlead serves as the radiating element. This top hat is electrically isolated from the towers, and is electrically connected to a downlead suspended from the center of the top hat. A system of cables, often called a capacitance hat or top hat, is suspended between the four towers. Each antenna is a top loaded monopole consisting of four 122-m towers arranged in a diamond shape. The north antenna was originally built for the WWVL 20 kHz broadcast (discontinued in 1972), and the south antenna was built for the WWVB 60 kHz broadcast. WWVB uses two identical antennas that were originally constructed in 1962, and refurbished in 1999. Radio-controlled clocks that are based on synchronous AM demodulation (lock to the carrier), such as the Spectracom NetClock and receivers manufactured by True Time during the 1970s and 1980s, have also become obsolete. Note: disciplined oscillator products that track and lock to the 60 kHz WWVB carrier and were designed to work as frequency standards, will not work with the PM signal and have become obsolete.
#Leap office fort collins code
The data content, physical properties and scheduling features of this BPSK time code may be found here:Įnhanced WWVB Broadcast Format (revised ) The phase-modulated information may take several different forms, with the basic one having a frame duration of one minute, as in the legacy AM/PWM broadcast. This time code, also operating at a rate of 1 bit/sec, is delayed by 0.1 s with respect to the first time code described above, such that 180-degree transitions in the carrier phase can only occur 0.1 s after the 17 dB power reduction that is created by the pulse-width-modulation.
In the PM format, binary-phase-shift-keying (BPSK) modulation is used, wherein the carrier's phase is unaffected when conveying a "0" and is inverted (i.e.
Existing radio-controlled clocks and watches are not affected by this enhancement and continue to work as before. This enhancement to the broadcast provides significantly improved performance in new products that are designed to receive it. Since October 29, 2012, NIST Radio Station WWVB has been broadcasting a phase modulated (PM) time code that has been added to the legacy AM/pulse-width-modulation signal. The pulse-width modulated time code contains the year, day of year, hour, minute, UT1 time correction and flags that indicate the status of Daylight Saving Time, leap years, and leap seconds, as listed in the legacy WWVB time code format description and detailed in NIST Special Publication 432 (NIST Time and Frequency Services).
#Leap office fort collins full
In the first of the two formats, based on PWM, which has been in use for several decades, the carrier power is reduced by 17 dB at the start of each second and restored to full power 0.2 s later for a binary "0", 0.5 s later for a binary "1", or 0.8 s later to convey a position marker. The time codes are synchronized with the 60 kHz carrier and are broadcast continuously in two different formats at a rate of 1 bit per second using pulse width modulation (PWM) as well as phase modulation (PM). WWVB continuously broadcasts digital time codes on a 60 kHz carrier that may serve as a stable frequency reference traceable to the national standard at NIST. In addition, WWVB may be used in other consumer timekeeping applications, such as appliances, cameras, and irrigation controllers, as well as in high level applications such as accurate time synchronization. The WWVB broadcasts are used by millions of people throughout North America to synchronize consumer electronic products like wall clocks, clock radios and wristwatches. NIST radio station WWVB is located on the same site as NIST HF radio station WWV near Fort Collins, Colorado.
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