Technical Terms Glossary

 A   B   C   D   E   F   G   H   I   J   K   L   M 
 N   O   P   Q   R   S   T   U   V   W   X   Y   Z 

A

An atomic clock is a time counter, which is controlled by the oscillation frequency of certain atoms (e.g. caesium, rubidium), which are energized by an electromagnetic field or optical pumping.

Read more

AFNOR NFS 87-500 is a standarized french time code similar to IRIG-B but contains additional day, day-of-month and year information.

Read more

ACO (Access Control Override)
A button labelled "ACO" can be used if the access password has been forgotten. However, it only works if there is not a connection with a Meinberg monitoring software. If it is pressed briefly (please press and hold for about 4 seconds), the password will be reset for 30 seconds (to "nothing") and then put it back on the previous value. You can simply press RETURN in the password query.

This is true for both Telnet setup and mbgdevman connections. If a connection to the mbgdevman is established during the 30 seconds, the "empty" password for the duration of this connection will remain in any case (even if this lasts longer than 30 seconds). In this case, the old password will not be active until you stop the connection. This ACO mode should only be used to enter a new password when the old one has been lost.

Redundant Receiver Systems from Meinberg


Redundant GPS-synchronized Time and Frequency Reference in 1U Housing

Redundant GPS-synchronized Time and Frequency Reference in 1U Housing

Read More...

B

The Bureau International des Poids et Mesures (BIPM) has been founded by the "Meter Convention", signed by seventeen nations in Paris on 20 May 1875. It is located at Sèvres, near Paris, France. The International Prototype of the Kilogram, the sole remaining physical prototype of an SI unit, is kept at the bureau, as well the International Prototype of the Meter. Since 1985 the Bureau is responsible for the maintainance of the French atomic time.

A Bootstrap Loader (BSL) is a small program which can be activated immediately after a microcontroller has been powered up, in order to load and execute another program in a well defined manner. The bootstrap loader is hard coded into the microcontroller and is used by many Meinberg devices to upload a new firmware to the device.

Read more

C

The central European states have established the central European Summer time (CEST) which is applied from the last Sunday of March till the last Sunday of October, in each case at one o’clock UTC, which corresponds 2 o’clock CET, respectively 3 o’clock CEST. In order to be able to distinguish the in duplicate occurring time declarations from 2 to 3 o’clock at the end of the summertime, two new hours are being introduced: the hour before the time switch is called 2A o’clock, whereas the hour after was named 2B o’clock.

The Central European Time (CET) is the significant local time for Central Europe as Germany, Austria and Switzerland. It is commensurate to the central time of sun of the fifteenth degree of longitude eastside of Greenwich. Its difference to the UTC is plus one hour. In case of the Central European Summertime it is two hours ahead.

D

DCF77 is a longwave time signal broadcast station at Mainflingen, Germany, about 25 km south-east of Frankfurt (50°01' North, 09°00' East). The DCF77 radio signals are derived from an atomic clock, and broadcasted on 77.5 kHz. The signal can be received up to a distance of 2000 km and more. There are 2 transmitters installed, so in case of failure of the first one it is possible to use the reserve system.

Read more

Digital Video Broadcast (digital TV)
DVB-T is the abbreviation for Digital Video Broadcasting Terrestrial, that means the terristic transmitting of digital TV signals to the atmosphere. DVB-T is used in several european, african and asiatic states as a standard to transmit digital television via antenna.

Please have a look at our news article Time and Frequency Synchronization of DVB-T.

Digital Audio Broadcast (Terrestrial digital audio broadcast). The system for the digital transmission of radio signals was developed and standardized by the European Union research initiative EUREKA 147. The DAB specifications are free available from the european ETSI (Code "EN300401").

To synchronize DAB transmitters or base stations the telecom network synchronisation card LIU can be used together with a GPS receiver.

A DIN mounting rail (TS 35) is a mounting rail with a U-shaped respectively hatlike profile. These mounting rails are often used in substation installations.

The following products made by Meinberg are suitable for DIN rail mounting:

When is Daylight Savings Time?

Rules for daylight saving times:


There are two dates a year in Germany when the time is changed:

Summer Time
With time changing in the spring from winter time (CET) to summer time (CEST) the following rule applies:

The time change takes place on the last Sunday in March. At 2:00 AM the clocks are adjusted forward one hour to 3:00 AM.

Winter Time
With time changing in autumn from summer time (CEST) to normal time (CET) the following rule applies:

The time change takes place on the last Sunday in October. At 3:00 AM the clocks are adjusted backward one hour to 2:00 AM (end of daylight saving).

E

E1 (or E-1) is a European digital transmission format with a capacity of 2.048 Mbit/s from ITU-TS. It's like the North American T-carrier system format. Typically channelized into 30 D S0s channles, each capable of carrying a single voice conversation or data stream.

See Synchronization of Telecom Networks

Earth ellipsoids are used to approximate the mean surface of the earth by a set of parameters that is called "geodetic datum" which describe the form an location of that ellipsoid in space. The standard geodetic datum used with GPS is called WGS84, which approximates the surface of the globe reasonably all over the world.

see EIA-232

see RS-232

F

Fiber Optics are used widely in modern telecommunication and network technology. The Fiber Optics cable (a conductor, in which modulated light is transferred) is standardized and mentioned in the DIN 47002 and VDE 0888-2. The fiber-optic cable can consist of glass fiber or plastic and is characterised among other things by its extremely high data transmission rate, it is insensitively in relation to electromagnetic disturbances (important for power plants and industry applications), it is relatively tap-proof, and if it consists of glass fiber, it has an extremely small absorption value (long distances).

Meinberg devices can be equipped with a lot of different output signals (PPM, PPS, serial interface, DCF77 emulation, IRIG ...) via fiber optic.

G

The Global Positioning System is a satellite-based radio positioning, navigation, and time-transfer system. Theoretically three satellites are sufficient to find out an exact location and its height. Practically, however, most of the GPS-receivers have no source of time which is precise enough for correct runtime calculations. Therefore a fourth satellite that provides such a signal is strictly necessary.

Read more

Galileo is a planned European system for satellite navigation, which will represent the European version of the American GPS and therefore it could be the first step into the direction of technological independence on the division of satellite navigation. It is to be based on 30 satellites (27 + 3 spares) which are to be placed in an elevation of 15.000 miles surrounding the earth on so called Medium Earth Orbits (MEO) and a network of ground stations, which are to control the satellites.

Galileo will be capable of providing an optimal covering of the northern European regions and thereby could be a replacement for the GPS, which on his part is currently working with only 24 satellites. The first three Galileo satellites started in 2011. In 2020 the network with all 30 satellites shall be ready to operate.

Global System for Mobile Communications.

GMT ("Greenwich Mean Time") was the commonly used international time base and has been substituted by the term UTC (Coordinated Universal Time). Greenwich is located in England, directly on the zero longitudinal meridian.

GLONASS (Russian: ГЛОНАСС) - Global Navigation Satellite System, is a space-based satellite navigation system operated by the Russian Aerospace Defence Forces.

The signals used by our receivers are transmitted by GLONASS satellites over the L1 frequency band (1602 MHz).

I

The TeleCommunication Working Group (TCWG) of the American Inter Range Instrumentation Group (IRIG) was mandated in 1956 to standardize the different time codes. The different IRIG Formats are sorted alphabetically as:

  • IRIG-A
  • IRIG-B
  • IRIG-D
  • IRIG-E
  • IRIG-G
  • IRIG-H

For further information please refer to our IRIG info page.

The objective of IEEE 1588 is defined in the "Scope" section of the Project Authorization Request approved by the Standard Board of the IEEE as follows.

This standard defines a protocol enabling precise synchronization of clocks in measurement and control systems implemented with technologies such as network communication, local computing and distributed objects. The protocol will be applicable to systems communicating by local area networks supporting multicast messaging including but not limited to Ethernet. The protocol will enable heterogeneous systems that include clocks of various inherent precision, resolution and stability to synchronize.

The protocol will support system-wide synchronization accuracy in the sub-microsecond range with minimal network and local clock computing resources. The default behavior of the protocol will allow simple systems to be installed and operated without requiring the administrative attention of users.

M

A master clock is an electrically or electronically driven timepiece which adjusts slave clocks by sending them pulses in minute-by-minute intervals. Thereby you create a clock system.

N

The Network Time Protocol (NTP) is a protocol for synchronising the clocks of computer systems over packet-switched, variable-latency data networks. Although NTP is most commonly used in conjunction with the UDP/IP protocol, it can also be transported over other network protocols such as TCP/IP. It has been particularly designed to resist the effects of variable latency.

Read more

The NMEA 0183 GIS standard for Interfacing Marine Electronics Devices of the US American National Marine Electronics Association (NMEA) is an industry standard for a serial interface. It defines the electrical signal requirements and data communication protocol for the transmission of position and additional information from GPS receivers.

A NTP Server makes the current time available in a network using the Network Time Protocol - NTP (see also "time server").

A Network Time Server is an appliance that is synchronized by a high precision time source like GPS or other types of radio clocks. The Network Time Server then distributes the time information to a computer network. Reference clocks can also be cesium clocks or other high stable time references.

The time is then distributed via the Network Time Protocol (NTP). The NTP Package can be downloaded from our software site.

The National Institute of Standards and Technology (NIST) is an agency in the United States for technology, measurements and standards (similar to the German Physikalisch-Technische Bundesanstalt, PTB ). It was originally called the "National Bureau of Standards" (NBS).

The NIST is responsible for the dissemination of time signals via shortwave radio stations WWV and WWVH, and longwave WWVB.

O

An overview of the available oscillators for Meinberg products can be found on our Oscillator List.

P

The Physikalisch-Technische Bundesanstalt (PTB) (Federal Standards Laboratory), Braunschweig and Berlin, is the nature and engineer-scientific agency and technical upper authority of the Federal Republic of Germany for measurement and for physical safety engineering.

The PTB operates the long wave transmitter DCF77 for the synchronisation of radio clocks.

Pulse which is generated once per second (PPS).

Read more

Pulse which is generated once per minute (PPM).

Meinberg standard: rising edge at the beginning of minute, pulse length 200 ms. TTL or RS232 level available.

see pulse-per-second

The Precision Time Protocol (PTP) which is defined in the IEEE1588 – 2002 standard allows precise synchronization in networks like e.g. Ethernet. By using hardware generated time stamps in the data packets an accuracy within the nanosecond range can be achieved. Such precision is needed in measurement and control networks as well as in research environments.

Read more

In our opinion you need a dedicated time server for reliable and secure time synchronization in your company's network, but for single place computers or little networks public time servers may be sufficient. Here are a few links to public time server lists. You can use the Pool of NTP Servers to find time servers.

Here you find a list of public time servers

"PRP" stands for "Parallel Redundancy Protocol" and is defined in the standard "IEC 62439-3" since 2010. PRP is Layer-2 based and has been developed for computer networks which are in need of a reliable solution regarding high availability and operational functionality.

A PhotoMos signal is a digital signal controlled by a light-sensitive MOSFET (metal-oxide-semiconductor field-effect transistor). The PhotoMos device is a semiconductor relay that uses light to change the state of the transistor between an open and a closed circuit.

Read more

R

A radio clock is a clock which is synchronized by a broadcasted radio signal (for example, in Germany a longwave signal called DCF77 is available, worldwide the GPS signal can be used).

The Recommended Standard 232 (RS-232, today known as EIA-232-gateway) was formally introduced by the Electronic Industries Association (EIA) in 1969. At that time, text-terminals and mainframes used to be connected point to point via telephone circuit by using a modem. EIA-232 defines the connection between the terminal (DTE data terminal Equipment) and the modem (DCE data communication Equipment) concerning timing, level of voltage, protocol and plug.

S

The stratum value is calculated from the number of computers in the NTP hierarchy to the time reference. The time reference has a fixed stratum value n (usually stratum 0) and each subsequent computer in the NTP chain has a stratum value n+1.

Read more

SNTP (Simple Network Time Protocol) desribes a simplified form of NTP. While they both use the same network package format, a SNTP software does not reach the level of accuracy compared to a full implementation of NTP and does not include a very good protection against wrong/bad time information (hardly any protection at all in almost all cases).

Read more

In the SI-system of units the second is defined by an atomic time normal, due to the fact that compared to astronomic time standards (e.g. "sun or ephemeris second) a higher accuracy and long-term consistency can be assured. Due to definition, a second is based on the period of a Microwave which is in resonance with the transition of a caesium atom, multiplied by 9.192.631.770. A second can therefore be described as 9.192.631.770 times the duration of a period of a transition between two special levels of the ground state of the Nuclides of a 133 Caesium atom's radiation.

This determination has been introduced to ensure the average duration of one day of sun, which has to conform to the position of the sun being at the same location after one full turn. Because of some irregularities due to the slowing down of the earth rotation leap seconds have been introduced.

A server is a program, which waits for the commencement of contact of a Client program. After the approach the two programs are able to interact and transfer information. The actual hardware on which the programs are able to communicate is called Host. The communication itself follows the principle of the Client-Server-System which is considered as the opposite of the Peer-to-Peer principle in the Info Technology. The directives elucidating the format and the explicit determinations between the server and its client are titled Protocols. File-servers implement file transfers for which protocols like FTP, NFS or SMB/CIFS are in use.

Time Servers are capable of controlling Process clocks and offer opportunities of synchronisation.

A supporting rail is a structural shape made of out metal which is generally used in electrical engineering in order to adjust components in distribution cabinets, control cubicles, connection cabinets and other similar products. Several electronic operating funds such as relays, impulse switches, time-switch clocks or automatic cutouts can be shelved on sideways or mounted and arrested from the font. These mounting possibilities enable simple wiring within a row or between several rows.

Steel, copper and aluminium are used to produce them. In addition to their holding function, supporting rails made out of copper or aluminium can be applied as protective earth conductors. Steel is due to its characteristics a bad conductor and inapplicable for this function.

DIN-mounting rails are supporting rails with a U-shaped respectively hatlike profile.

A slave clock is an unusual timepiece, since it has no own clock pulse generator from which it could count its impulse, it merely comprises a step-by-step switch, which is being controlled and adjusted by a central clock in certain intervals. By using such a system all clocks are dependent on the same source of time signals and therefore will show the same result. A divergency due to differences concerning the precision of the clockworks is consequently preventable. Corrections like clock shifts (e.g.normal time to summer time) can easily be carried out, because they are made centrally.

The Simple Network Management Protocol (SNMP) is part of the internet protocols which where defined by the IETF.

Read more

In most of the cases a SNTP Server is just a NTP Server that can answer SNTP requests as well. Due to the fact that SNTP (Simple Network Time Protocol) is just a subset of NTP (Network Time Protocol) every NTP Server should be able to synchronize SNTP clients too.

Read more

A sine signal, also known as a sinusoidal signal or sine wave, is a periodic signal that oscillates with a smooth, repeating waveform. The waveform of a sine signal is a mathematical function representing a single frequency, with each point of the waveform determined by the value of a sine function at a particular point in time.

Read more

SSL is a cryptographic protocol designed to provide secure communication over a computer network, most commonly the Internet. SSL has been widely used to secure various types of online communication.

The primary target of SSL is to ensure the confidentiality and integrity of data transmitted between a client (such as a web browser) and a server (host of a website or web application). SSL uses encryption algorithms to protect the data from eavesdropping and tampering during transit.

T

A time server consists of a computer networking device that reads the actual time from a reference clock and distributes this information to its clients using a computer network.

Read more

Synchronisation of computers, networks or industrial applications, using the DCF77 longwave transmitter as a time source in Germany, or with GPS receivers worldwide.

see Time-Synchronisation

The North American T1-1.544M is similar to E1 but it has only 24 64kHz channels, because of this only 1.544 Mbit/s.

See Synchronization of Telecom Networks

The time signal emissions listed down below follow the UTC system, in accordance with the recommendation 460-4 of the Radio communication Bureau (RB) of the International Telecommunication Union (ITU) unless otherwise stated. Their maximum deviation from the Universal Time UT1 is thus 0.9 seconds. A quick overview about the general types of signals and their area of application:

  • ATA: New Delhi, India;
  • BPM: Pucheng, China;
  • BSF: Taiwan, Rep of China;
  • CHU: Ottawa, Canada;
  • DCF77: Frankfurt, Germany;
  • EBC: San Fernando, Spain;
  • HBG: Prangins, Switzerland;
  • HLA: Taedok, Rep. of Korea;
  • IAM: Roma, Italy;
  • JJY: Miyakoji, Fukushima, Japan;
  • LOL: Buenos Aires, Argentina;
  • MSF: Rugby, United Kingdom;
  • RAB-99: Khabarovsk, Russia;
  • RBU: Moscow, Russia;
  • RJH-63: Krasnodar, Russia;
  • RJH-69: Molodechno Belarus;
  • RJH-77: Arkhangelsk, Russia;
  • RJH-86: Bishkek, Kirgizstan;
  • RJH-90: Nizhni Novgorod, Russia;
  • RTZ: Irkutsk, Russia;
  • RWM: Moscow, Russia;
  • TDF: Allouis, France;
  • VNG: Llandilo, New South, Wales, Australia;
  • WWV: Fort-Collins, CO, USA;
  • WWVB: Fort-Collins, CO, USA;
  • WWVH: Kauai HI, USA;
  • YVTO: Caracas, Venezuela.

A timeserver is a network server that disseminates time information via the network. It can be either a dedicated time server or another server, that is synchronized by a radio clock and is used as a time reference.

The exact time is then propagated on the network with a time synchronisation protocol. Mostly the Network Time Protocol (NTP is used, but tody more often the Precision Time Protocol (IEEE-1588 Time Server) is used.

List of Time Signal Transmitters

Read more

TTL stands for transistor-transistor logic, a digital circuit that uses transistors to switch between two voltage levels representing logic 0 and 1. A TTL signal is a digital signal that meets the specifications of TTL logic.

Read more

Transport Layer Security (TLS) is a cryptographic protocol that ensures data privacy and integrity when communicating over a computer network. It provides a secure communication channel between two devices, usually a client (e.g. a web browser) and an NTP server (hosting a website), or between two servers.

Read more

U

The Universal Mobile Telecommunications System is a mobile communication standard that next to multimedia Services also implies satellite- and ground based transmitters. Unified messaging, interpersonal and video supported communication are the main divisions of application of this technology. Europe has installed its UMTS network in 2002. Two years later Germany adapted this invention for its own purpose.

In the FDD-Mode (Frequency Division Duplex ) the mobile station and the base station send signals in two different frequency ranges: the mobile part sends throughout the Uplink Channel while the Downlink Channel is being occupied by the base station. The rate of data throughput of the FDD-Mode, which is currently being built up in Germany, measures 384 Kbit/s for the Downlink. In the TDD-Mode (Time Division Duplex) the mobile station and the base station use the same frequency band, which means they are sending at different times.

This procedure is technically much more intricate and the rate of complexity intensifies with distance or the movement of a transmitter. However, there is an achievable rate of transfer of 2 Mbit/s for the Downlink using the W-CDMA in the TDD-Mode.

Meinberg Time and Frequency products are often used for synchronizing UMTS networks and base stations.

UTC (Coordinated Universal Time) is the name of the international time standard and is identical to GMT (Greenwich Mean Time), which was commonly used as a world wide time base.

Read more

X

Former name of the NTP daemon on Linux systems.

Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact Meinberg Mail Contact