Learn how the ClassicSync 72MHz solution works and how the system devices provide synchronized time.
The ClassicSync 72MHz solution provides synchronized time using a 72MHz radio frequency to transmit a wireless signal to all system devices. The frequency allows the wireless signal to broadcast through common building materials and across longer distances with less potential for signal interference.
The system consists of a single Transmitter with an internal or external antenna, a GPS Receiver (optional), Repeater Transmitter (optional), and the system time and event devices in a single building, to a campus wide deployment.
Once a Transmitter has received its time from either a GPS Receiver or NTP time source or a main Transmitter, it sets its internal clock. It then wirelessly broadcasts its received time over a 72MHz radio frequency to the system clocks. As a result, time devices are precisely synchronized to each other and all time, schedules, and events are kept current.
Transmitter frequency and channel
Transmitters operate on channels with 20kHz bandwidths and 72MHz radio frequency and is preset to one of the channels licensed by the US: FCC/ Canada: ISED to minimize interference on these frequencies and channels.
Transmitter transmit (broadcast) schedule
1 Watt Transmitter with an internal antenna: Transmits (broadcasts) a time signal continuously, 24 hours a day.
1, 5, or 30 Watt Transmitters with an external antenna: Transmits (broadcasts) a time signal 24 hours a day ONLY between the 39th to the 6th minute of each hour, and changes to a standby mode and does NOT transmit a time signal during the 7th to the 38th minute of each hour.
Analog Clocks and Digital Clocks/Timers signal search
Analog Clock signal search frequency: at six pre-scheduled times a day, at 2:01 AM/PM, 6:01 AM/PM, and 10:01 AM/PM clock time (not the actual time of the day), a clock's receiver turns on to search for a Transmitter signal to receive a time update, starting with the previously stored channel number. If a signal is not received from the first channel, the clock scans all channels to search for a signal.
Digital Clock/Timer signal search frequency: every 10 minutes on the 5's (5, 15, 25, 35, 45, 55 minutes) of the hour, a clock's receiver turns on to search for a Transmitter signal to receive a time update.
When a clock has not received a valid signal/time update for three consecutive days, it displays a visual signal loss indicator; an analog clock's second hand advances and pauses continuously (stepping) and a digital clock/timer's colons flash. A clock may display the correct time, but it's not synchronized and its time may drift.
5 and 30 Watt Transmitters
A lightning arrester is housed inside the enclosure and helps protect the Transmitter and amplifier from lightning damage during severe weather. However, Primex cannot guarantee that all damage will be prevented even with the lightning arrester installed.
A high-power amplifier increases the output power of the base Transmitter. The amplifier is housed in the Transmitter's industrial style enclosure for safety reasons. Transmitter includes an externally mounted antenna and an RF power amplifier that increases the output power allowing it to transmit at a greater distance.
When the Transmitter is powered on, its front display lights up.
Green, yellow, and red LED lights turn on for 2 seconds as a test and then turn off.
Green LED illuminates to indicate the Transmitter is broadcasting.
Front display initially displays the time as 12:00:00 and its software version.
Transmitter checks the position of the switches on the back of the Transmitter, and stores the settings in its memory.
Transmitter completes an initialization sequence with its time source. Its time source may be either a GPS Receiver, NTP, or Repeater (Satellite) Transmitter.
During a power failure, the Transmitter continues to track time with the last valid time signal that it received. Once the power had been restored, the Transmitter begins to broadcast (even without a valid time signal) to the down-stream components. Once the Transmitter has been powered on for a few hours, it's capable of keeping track of time off its internal backup power for up to eight hours.
The system has a fail-safe design. If the failure of a system component or power loss to a component occurs, all down-stream components continue normal operations using their own internal time base.
If after a specified period of time communication has not been restored, a visual indicator of a loss of communication appears and remains until communication is restored. Loss of communication visual indicators: Transmitter front panel LED indicator, flashing colon on LED digital clocks/timers; and stepping of second hand on analog clocks.
Transmitter with an external antenna
In the event of a facility wide power outage, a Transmitter broadcasts continuously for 8 hours upon the restoration of power, synchronizing all Primex devices throughout the facility.
In the event power to a Transmitter is shut off and turned back on (power cycled), the Transmitter broadcasts continuously for 8 hours. Power-cycling the Transmitter can be used to set/reset system devices. It's not recommended to power-cycle a Transmitter when it is in an Error status.