DE4202435C2 - Radio-controlled clock - Google Patents

Description

The invention relates to a radio-controlled watch.

Radio-controlled clocks consist of a clockwork, a time display, an antenna, receiving means for receiving radio signals and means to correct the time display. The accuracy of the radio-based Clock is supported with radio signals emitted by a transmitter which time signals emit high accuracy. Such Radio-based clock is described in DE 38 22 412 C2.

DE 38 22 412 C2 also describes a method for automatic setting autonomous radio clocks known. Master clocks are used to Time signals broadcast, which is a time reference and the "coordinated World time "UTC included. By sending calendar information and other additional information about the signal origin of the respective master clocks, the radio clock can also go beyond the limits of Time zones are used.

A disadvantage of such clocks is the fact that the transmitter Time signals only in the range of the transmitter concerned can be received. That is about a radius of 1500 km. A worldwide use of such radio-controlled clocks therefore requires one large number of master clocks.  

Navigation systems are known (e.g. "Principle of Operation of NAVSTAR and System Characteristics, by R. J. Milliken and J. Zoller and "Performance Enhancements of GPS User Equipment "by N.B. Hemesath, both published in" Global Positioning System "by The Institute of Navigation, 1980), on radio signals based on satellites. One such system is the "GPS" (Global Positioning System). With such a system from the signals from four satellites from one Receivers on Earth are received a position information gained. The satellites each send one up accurate GPS time signal, a pseudo random code and one Time stamp (satellite clock) for sending this Random codes. The random code is a periodic repetitive, irregular sequence of impulses. This Random code becomes one in the receiver of one Receiver clock at a specific point in time with a similar, Correlated pseudo-random code generated in the receiver. For this purpose, the recipient's random code is over shifted back and forth over a certain period of time, in other words, phase-modulated. With a certain Phase occurs a correlation: the pseudo-random codes coincide. A correlation arises maximum. The location of this correlation maximum, i.e. the Time related to a reference mark at which the Correlation maximum occurs depends on the Runtime of the electromagnetic waves from the satellite to Receiver, or - in other words - the distance of the Satellites from the receiver, and also from one Time error of the receiver clock compared to the satellite clock. There are now the signals from four in the same way Receive and evaluate satellites. Are known then the positions of the satellites and the distance to the Receiver, the latter due to the time error is falsified. From the four obtained The position of the Receiver and the time error can be determined.  

It is still long-wave navigation systems such as the LORAN process or the OMEGA process known. These also serve exclusively for positions determination.

The invention has for its object a clock radio-supported by navigation radio networks to train so that they automatically on the different time zones in which they are currently is operated.

According to the invention, this task solved by a radio-controlled clock according to claim 1.

A is therefore not used to generate radio support signals separate transmitter related, which only in a limited Range can be received. Rather be Navigation radio networks used that are available worldwide are. Such navigation radio networks are usually used only for generating position information.  

It is known from the receivers of a navigation radio network too Get time information. According to the invention, however Time information that provides the same "GPS time" worldwide with the position also available from the navigation radio network automatic setting of the time zone dependent local time combined. In this way, a radio-supported watch will be obtained that is automatic worldwide displays the current local time without the user having to do any The watch would have to be manipulated.  

The receiving means for receiving and for processing GPS satellite signals set up.

An embodiment of the invention is as follows with reference to the accompanying drawing which explains a block diagram of an arrangement for radio support of a watch using a satellite Navigation system shows.

With 10 an antenna is designated, which receives signals from four GPS satellites 12 , 14 , 16 and 18 . The GPS satellites each send a highly precise time signal, their ephemeris data and a specific pseudo-random code as well as a time stamp (satellite clock) for the transmission of this pseudo-random code.

The antenna 10 is connected to a receiver 20 . The receiver 20 contains a preamplifier 22 , an RF part 24 and a quartz oscillator 26 . The quartz oscillator 26 represents the receiver clock. The quartz oscillator has a time error Δt _B. This is indicated by arrow 28 .

The HF part effects the generation and phase modulation of the pseudo-random code in the manner outlined above, which is known per se in GPS devices. The sequence of the pseudo-random code corresponds to the pseudo-random code sent out by the satellite. A correlation maximum occurs at a specific phase position. From the location of this correlation maximum, a measured value for the distance to the satellite 12 , 14 , 16 or 18 is obtained. If the receiver clock, namely the quartz oscillator 26 , were to operate exactly synchronously with the satellite clock, then the distance to the satellite could be determined directly from the position of the correlation maximum. Due to the "gait error" of the satellite clock, the output signal PR is only an apparent distance (pseudo range). However, the information from four satellites is available. From the four equations formed from this, the position of the receiver 20 on the earth's surface and the time error Δ t _{B of} the quartz oscillator can be determined by means of a processor 30 . The geographical longitude can be determined from the equations as further information.

An estimated value for the time error Δ t _B is obtained at an output 32 and switched to a time generator 34 . The geographic longitude which is obtained at an output 36 is applied to a memory 38 .

The memory 38 contains the time differences between local time (LMT) and Greenwich time (GMT) for the different time zones, which are determined by the geographical longitude (and possibly also by the geographical latitude). These time differences are also applied to the time generator 34 via an output 40 . Finally, the time generator receives the GPS time signal from the receiver 20 via an output 42 .

The Greenwich Mean Time GMT can be signaled using the GPS time signal and the transit times of the pseudo-random code signal from the satellite. B. 12 calculate to receiver 20 . The running time must be corrected by the measured error Δ t _{B of} the quartz oscillator 26 as the receiver clock. Furthermore, the Greenwich Mean Time GMT is corrected by the time difference of the relevant time zone output by the memory 38 for the measured position. From this, the time generator 34 outputs the exact local time (LMT). This is displayed by a display device 44 .

In this way, a clock can be realized that adjusts itself automatically to the local time and via Satellite signals is supported with high precision worldwide.

Claims (2)

1. Radio-controlled clock with a clockwork ( 26 ), a time display ( 44 ), an antenna ( 10 ), receiving means ( 20 ) for receiving radio signals from navigation radio networks, means ( 30 ) for determining position and time information from the radio signals , Means ( 38 ) for determining the time zone from the position information and means ( 34 ) for adapting the time display ( 44 ) to the time zone corresponding to the determined position. 2. Radio-controlled clock according to claim 1, characterized in that the receiving means ( 20 ) are set up to receive and process GPS satellite signals.