Time code ambiguity

Last updated

In telecommunication, time code ambiguity is the shortest interval between successive repetitions of the same time code value.

For example, in a time code in which year-of-century (the '72' in 10/04/72) is the most slowly changing field, the time code ambiguity would be 100 years; it is ambiguous whether this value refers to a date in 1872, 1972 or some other century. For a digital clock in which hours and minutes up to a maximum of 11:59 are displayed, the time code ambiguity would be 12 hours.

The Year 2000 problem is an example of the pitfalls of time code ambiguity. Very often dates are now recorded with 4 digit years (10/04/1972). Assuming that the use of a 4-digit year field would continue, even in the far future, this would change the time code ambiguity from 100 years to 10 000 years.

Related Research Articles

Binary-coded decimal System of digitally encoding numbers

In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for a sign or other indications.

Chinese numerals are words and characters used to denote numbers in Chinese.

A calendar date is a reference to a particular day represented within a calendar system. The calendar date allows the specific day to be identified. The number of days between two dates may be calculated. For example, "25 October 2021" is ten days after "15 October 2021". The date of a particular event depends on the observed time zone. For example, the air attack on Pearl Harbor that began at 7:48 a.m. Hawaiian time on 7 December 1941 took place at 3:18 a.m. Japan Standard Time, 8 December in Japan.

In mathematics and computing, the hexadecimal numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the common way of representing numbers using 10 symbols, hexadecimal uses 16 distinct symbols, most often the symbols "0"–"9" to represent values 0 to 9, and "A"–"F" to represent values from 10 to 15.

ISO 8601 is an international standard covering the worldwide exchange and communication of date- and time-related data. It is maintained by the Geneva-based International Organization for Standardization (ISO) and was first published in 1988, with updates in 1991, 2000, 2004, and 2019. The standard aims to provide a well-defined, unambiguous method of representing calendar dates and times in worldwide communications, especially to avoid misinterpreting numeric dates and times when such data is transferred between countries with different conventions for writing numeric dates and times.

ISO 4217 Standard that defines codes for the representation of currencies

ISO 4217 is a standard published by International Organization for Standardization (ISO) that defines alpha codes and numeric codes for the representation of currencies and provides information about the relationships between individual currencies and their minor units. This data is published in three tables:

Numeral system Notation for expressing numbers

A numeral system is a writing system for expressing numbers; that is, a mathematical notation for representing numbers of a given set, using digits or other symbols in a consistent manner.

The octal numeral system, or oct for short, is the base-8 number system, and uses the digits 0 to 7, that is to say 10 represents 8 in decimal and 100 represents 64 in decimal. However, English uses a base-10 number language system and so a true octal system might use different language to avoid confusion with the decimal system.

Resistor Passive electrical component providing electrical resistance

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistors that can dissipate many watts of electrical power as heat, may be used as part of motor controls, in power distribution systems, or as test loads for generators. Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements, or as sensing devices for heat, light, humidity, force, or chemical activity.

The reflected binary code (RBC), also known just as reflected binary (RB) or Gray code after Frank Gray, is an ordering of the binary numeral system such that two successive values differ in only one bit.

Vehicle identification number System for identifying vehicles

A vehicle identification number (VIN) is a unique code, including a serial number, used by the automotive industry to identify individual motor vehicles, towed vehicles, motorcycles, scooters and mopeds, as defined in ISO 3779 and ISO 4030.

Mixed radix numeral systems are non-standard positional numeral systems in which the numerical base varies from position to position. Such numerical representation applies when a quantity is expressed using a sequence of units that are each a multiple of the next smaller one, but not by the same factor. Such units are common for instance in measuring time; a time of 32 weeks, 5 days, 7 hours, 45 minutes, 15 seconds, and 500 milliseconds might be expressed as a number of minutes in mixed-radix notation as:

... 32, 5, 7, 45; 15, 500 ... ∞, 7, 24, 60; 60, 1000
WWV (radio station) Shortwave radio station broadcasting time signals

WWV is a shortwave radio station, located near Fort Collins, Colorado. It is best known for its continuous time signal broadcasts begun in 1945, and is also used to establish official United States government frequency standards, with transmitters operating on 2.5, 5, 10, 15, and 20 MHz, as well as an "experimental mode" transmission on 25 MHz. WWV is operated by the U.S. National Institute of Standards and Technology (NIST), under the oversight of its Time and Frequency Division, which is part of NIST's Physical Measurement Laboratory based in Gaithersburg, Maryland.

WWVB Time signal radio station in the United States

WWVB is a time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology (NIST). Most radio-controlled clocks in North America use WWVB's transmissions to set the correct time. The 70 kW ERP signal transmitted from WWVB is a continuous 60 kHz carrier wave, the frequency of which is derived from a set of atomic clocks located at the transmitter site, yielding a frequency uncertainty of less than 1 part in 1012. A one-bit-per-second time code, which is based on the IRIG "H" time code format and derived from the same set of atomic clocks, is then modulated onto the carrier wave using pulse-width modulation and amplitude-shift keying. A single complete frame of time code begins at the start of each minute, lasts one minute, and conveys the year, day of year, hour, minute, and other information as of the beginning of the minute.

Inter-range instrumentation group timecodes, commonly known as IRIG timecode, are standard formats for transferring timing information. Atomic frequency standards and GPS receivers designed for precision timing are often equipped with an IRIG output. The standards were created by the Tele Communications Working Group of the U.S. military's Inter-Range Instrumentation Group (IRIG), the standards body of the Range Commanders Council. Work on these standards started in October 1956, and the original standards were accepted in 1960.

Unix time System for identifying instants in time for computers

Unix time is a system for describing a point in time. It is the number of seconds that have elapsed since the Unix epoch, excluding leap seconds. The Unix epoch is 00:00:00 UTC on 1 January 1970. Unix time is nonlinear with a leap second having the same Unix time as the second before it, so that every day is treated as if it contains exactly 86400 seconds, with no seconds added to or subtracted from the day as a result of positive or negative leap seconds. Due to this treatment of leap seconds, Unix time is not a true representation of UTC.

Keystroke programming describes a specific way of programming by which each keystroke on a device or application is recorded in some way and then played back so that the recorded key-presses can be repeated multiple times. Keystroke programming is most commonly but not exclusively found in programmable calculators, but there are keystroke-programmable software applications, too, for example Vim

Year 2000 problem Class of computer bugs related to dates beginning in the year 2000

The Year 2000 problem, also known as the Y2K problem, Millennium bug, Y2K bug, Y2K glitch or Y2K error, refers to potential computer errors related to the formatting and storage of calendar data for dates in and after the year 2000. Many programs represented four-digit years with only the final two digits, making the year 2000 indistinguishable from 1900. Computer systems' inability to distinguish dates correctly could potentially bring down worldwide infrastructures for industries ranging from banking to air travel.

Date windowing is a method by which dates with two-digit years are converted to and from dates with four-digit years. The year at which the century changes is called the pivot year of the date window. Date windowing was one of several techniques used to resolve the year 2000 problem in legacy computer systems.

​JN53dv is the Maidenhead grid square of an experimental shortwave time signal station in Italy. It is located in the town of Corsanico-Bargecchia near Massarosa and operated by Italcable