A display made up of seven segments.
The segments can be electromechanical components or LED bars.
AFNOR is a binary code-synchronising signal.
The complete time information is broadcast each second with a carrier frequency of 1 kHz.
American Wire Gauge
AWG 20 ... 0,813 mm / 0,519 mm2
AWG 21 ... 0,723 mm / 0,412 mm2
AWG 22 ... 0,644 mm / 0,325 mm2
AWG 23 ... 0,573 mm / 0,259 mm2
AWG 24 ... 0,511 mm / 0,205 mm2
AWG 25 ... 0,455 mm / 0,163 mm2
AWG 26 ... 0,404 mm / 0,128 mm2
AWG 24 ... 0,361 mm / 0,102 mm2
Mounting arm for affixing to ceilings of a one- or two-sided clock.
Wall bracket for double-faced outdoor clocks that are mounted hanging due to their weight.
Radio synchronisation from Germany. A 77 kHz longwave time signal is transmitted 24 hours a day, seven days a week from Mainflingen near Frankfurt from the Physikalisch-Technische Bundesanstalt (PTB). The signal includes information about the time as well as the date and daylight savings time.
The name DCF77 arose through international agreement. It consists of the letters ‘D’ for Deutschland (Germany), ‘C’ for longwave signal and ‘F’ for Frankfurt. The number 77 stands for the frequency. DCF77 is transmitted three times an hour as a Morse signal during the minutes 19, 39 and 59. Each transmitter that has a range over the country border must transmit this radio call sign.
The transmitter is situated in Mainflingen (50° 01' north, 09° 00' east, approx. 25 km southeast of Frankfurt) and is controlled by the national physics laboratory of the PTB in Braunschweig. Coded in second impulses, it transmits the current time, the date and the day of the week. Within each minute the complete time information is transmitted once.
The highly consistent carrier frequency of the time signal is 77.5 kHz. At the beginning of each second the carrier amplitude for 0.1s or 0.2s is reduced by approximately 25%. These second markers include binary-coded time information. Second markers with a duration of 0.1s equal one binary zero and those with 0.2s, a binary one. The information about time and date and also some parity and status bits are in the second markers 15 to 58 every minute. Should a leap second be added, the missing bit is inserted in the fifty-ninth second mark and becomes the sixtieth second.
In addition to the amplitude modulations the carrier of DCF77 is modulated with a phase noise. This noise is a pseudo-random sequence (PRS) of 512 bits, which are transmitted in the AM-second markers. The entire bit sequence has a symmetrical run so that each phase remains unchanged. This way, the carrier phase remains constant. The PRS signal can be received by broadband and can be correlated with a receiver-side reproduced PRS. This process, made possible by satellite technology, allows the determination of time with an accuracy of a few microseconds and thus far supersedes traditional AM receiver technology.
Dot matrix display
Display comprised of tiny dots. The dots can be electromechanical parts or LED dots.
The Global Positioning System is a satellite-supported system for radio positioning, navigation and time transmission. This system was installed by the US Department of Defense and works with two precision categories: the Standard Positioning Service (SPS) and the Precise Positioning Service (PPS). The structure of the transmitted SPS data is published, and reception for general use enabled while the time and navigation data of the more exact PPS are transmitted coded and thus only available for specific (mainly military) users.
The principle of position and time determination using a GPS receiver is based on the most exact measurement possible of the signal delay from the individual satellites to the receiver. Twenty-one active GPS satellites and three additional reserve satellites orbit the earth on six orbit paths at 20,000 km once in approximately 12 hours. This ensures that at any time at any point on the earth at least four satellites are visible. Four satellites must receive simultaneously for the receiver to calculate its position in space (x, y and z) and the deviation of its clock from the GPS system time.
Control stations on earth measure the path of the satellites and register the deviations of the GPS system time of the atomic clocks situated onboard. The data is transmitted to the satellites and is sent back to earth as navigation data. The highly precise path data of the satellites, called ephemeris, are needed for the receiver to calculate the exact position of the satellites in space at any time. A subframe with less accurate data is called an almanac. With approximate position and time using the almanac, the receiver calculates which of the satellites are visible from the location over the horizon. Each of the satellites transmits its own ephemeris and also the almanacs to all existing satellites.
The GPS system time is a linear time scale which, during the operation of satellite systems in 1980, was equated with the international time scale UTC. Since then, however, multiple leap seconds were added to the UTC time in order to adjust the UTC to the changes of the earth’s rotation. For this reason, today the GPS system time differs from the UTC by a whole number of seconds. However the number of the differential seconds is included in the data stream of the satellites so that the receiver can run internally synchronous with the international UTC time scale. The conversion of UTC time to local time and also the determining of the beginning and end of daylight savings are carried out by a microprocessor of the receiver because the necessary information is not contained in the data stream of the satellites.
Distance between the hand axis to the hand tip.
Electronic device for the tracking of slave clocks after power interruptions.
Housing according to protection class 54, that is, the protection against dust deposits. Complete protection against live or internally moving parts. Protection against damaging dust deposits. Dust penetration is not completely prevented, but dust penetration is not allowed to impair operation.
IRIG-B is an amplitude modulated 1kHz synchronising signal that transmits one frame per 100 elements per second. Seconds, minutes, hours, day and five other bits of information are transmitted per frame.
Light Emitting Diode.
Similar to a display element of a lamp, high efficiency and long service life.
Liquid crystal display that are polarised as translucent or opaque depending on current flow.
Line, slave clock line
Output module of a master clock for polarised slave clock impulses.
Controlled by a two-wire link between the master clock and the slave clocks.
Amplifier for slave clock impulses used in the expansion of central units and master clocks.
Type of battery preferred in analogue outdoor clocks with quartz or DCF clock networks.
The advantages of lithium batteries are:
Wide range of temperature: -55 °C - +85 °C
High cell voltage: 3.6 V
High energy density: nominal 16.5 Ah
Longer durability (approx. four years) and reliability
These batteries are not included in delivery due to high transport costs (dangerous goods category 9).
Central, highly accurate time base that controls slave clocks via impulses or data telegrams and has various options.
Some options are: access for external synchronisation, e.g. impulse, data telegrams, DCF, GPS output for data telegrams, e.g. RS232, RS485, W482, IRIG-B, etc., and programmeable relay-switch contacts.
Motor motion work
System with its own motor drive for 230VAC, controlled by a polarised minute impulse from a master clock.
Slave clock control impulse, which reverses the polarity of the output voltage (minutes, ½ minutes or second impulse) with every switching step.
A relay contact for which all three access lines can be used (change-over, open contact and normally-closed contact) without electrical connections to other relay contacts being identified.
Emergency power reserve with externally rechargeable batteries for master clocks and central units.
A port for the serial connection of two communication partners with asynchronous data rate over distances of up to 15m via non-twisted, non-shielded lines. Usually every PC has two RS232 ports (COM1, COM2).
Connected to and controlled by a master clock via impulses or data telegrams/signals.
Second hand that moves evenly via a synchronised motor, in contrast to a stepping second, where the second hand is moved by a clockwork mechanism in second movements.
Do You have Questions?
Ing. Erich Blaschka
+43 1 61055-216