EP3001592B1 - Verification of time signals - Google Patents

Description

Technical field

The present invention relates to the wired or wireless transmission of time signals and more particularly to a method for verifying time information from time signals modulated on a continuous carrier signal, and to an apparatus for carrying out such a method.

State of the art

From the prior art, the automatic adjustment of free-running clocks by means of wired or wirelessly transmitted time information is well known. Time information which is modulated on a continuous carrier signal with definable assignment of the reference point are referred to hereinafter as time signals.

A well-known example of such a time signal are the time signals which have been transmitted over long-wave transmitters for several decades and which fill a fixed time interval with variable and typically amplitude-modulated symbols. The temporal reference point of the transmitted time information is accordingly given by the time grid. Details can be found in the article "Time and Frequency Distribution with the DCF77" in the issue 3/2009 of the PTB Mitteilungen, which is available online at [http://www.ptb.de/cms/fileadmin/internet/publikationen/mitteitungen/ 2009 / PTB-Mitteilungen_2009_Heft_3.pdf] is retrievable. In addition, a method for obtaining the time information from such a time signal in the document DE 10 2004 005 340 A1 disclosed.

Another known example of time signals are the packet-oriented transmitted time telegrams, which are used inter alia for the synchronization of receiving devices in ripple control technology in the operation of electricity networks. The ripple control technology allows the grid operator to control consumers and / or feed-in systems. For example, the grid operator can use the ripple control technology in Germany decentralized feed-in systems according to the law for the priority of renewable energies (EEG), so for example, solar systems, wind and hydroelectric power plants, selectively influence by ripple control telegrams for the purpose of load profile control. Ripple control telegrams can be transmitted by cable over the electricity network and wirelessly via radio. Wireless ripple control telegrams are called radio ripple control telegrams. Such a wireless transmission channel is provided by the European Radio-Rundsteuerung GmbH via a long-wave transmitter.

In addition to the radio ripple control telegrams, time telegrams for time synchronization of the receiving devices are broadcast via this transmitter. For more details, see the publication DE 102 14 146 C1 which discloses a radio ripple control system for controlling a plurality of remote customer terminals in response to customer-initiated send requests via central longwave transmitters.

Problem and brief description of the invention

With the known method for taking time information from time signals, however, there remains the problem that an unrecognized forgery is possible, in particular on wireless transmission links. For example, so-called. Replay attacks against the known methods appear promising feasible by already recorded time telegrams are collected and broadcast again in the vicinity of the attacking receiver with a relatively high local field strength.

One solution to this problem is provided by the present method for verifying time indications from time-signature signals modulated on a continuous carrier signal having the features specified in claim 1 and the device for providing a remotely synchronized verified time base having the features specified in claim 8. Advantageous embodiments and further developments are specified in the respective dependent subclaims.

A method for verifying time indications from time signals modulated on a continuous carrier signal with steps for receiving a first time signal with a first reference time, for receiving a second time signal with a second reference time following the first reference time, for calculating the between the Reference times lying desired time interval from the time information contained in the received time signal, for determining a time interval and determining a reference time interval using a count of periods of Continuous carrier signal within the time interval, for comparing the target time interval with the reference time interval and for outputting an error signal when the deviation determined by the comparison exceeds a predetermined tolerance value.

An advantage of this method can be seen in the fact that the verification of the received time data from the received signal out is possible and requires no additional time base. In addition, it is advantageous that the verification by the reference to the continuous carrier signal of fluctuations in the speed of transmission of the continuous carrier signal between the transmitter and receiver is independent. For example, a phase fluctuation caused by atmospheric fluctuations or movement of the receiver is disregarded.

In a first alternative of an embodiment of the basic method, the periods of the continuous carrier signal in the time interval between the reference times of the received time signals are counted to verify the time information from time signals transmitted in a fixed time grid for the determination of the reference time interval.

In a second alternative of an embodiment of the basic method, the periods of the continuous carrier signal in the time interval between the received time frames are counted and the reference time interval is obtained by adding a packet duration for verification of the time information from packet-oriented time frames transmitted in a time-lapse grid for determining the reference time interval.

In one embodiment of the preceding second alternative, the packet duration is further determined by counting the periods of the continuous carrier signal during the transmission of a time message.

In an independent embodiment of the preceding second alternative, the counting of periods of a frequency-modulated continuous carrier signal, the counted periods are weighted by the varying by the frequency modulation period.

In one embodiment of the preceding method, the variation of the period of the frequency-modulated continuous carrier signal according to the derived therefrom by a demodulation data is determined.

An advantage of this embodiment can be seen in the fact that there is no additional effort for a direct measurement of the period or a direct detection of the modulation. The time course of the modulation and thus of the period is instead constructed from the already available data of the decoded time or data telegrams.

In one embodiment of the preceding method, the variation of the period duration of the frequency-modulated continuous carrier signal due to the frequency modulation according to a time telegram corresponding to the first reference time is determined in the determination of the packet duration. If the received signal is unadulterated, the thus determined variation of the period coincides with the actually present in the received signal, and the packet duration determined above is correct.

An advantage of this embodiment can be seen in the fact that a verification is still possible even if the transmission quality while the periods of the continuous carrier signal still recognize, a proper demodulation is no longer possible.

In one embodiment of the preceding method, a fixed predetermined value is added as the packet duration.

It is also fundamentally proposed to provide a remote synchronized verified time base, comprising receiving means for receiving a modulated time signal continuous carrier signal, decoding means for extracting the time signals from the continuous carrier signal and for marking a time interval by start and end mark signals, calculating means for calculating the time between reference times Target time interval from the time information contained in the received time signals, counting means for counting the periods of the continuous carrier signal in the time interval between the start and end mark signals, conversion means for converting the counted periods into a reference time interval and comparing means for comparing the target time interval with the reference time interval and for outputting an error signal to an error correction unit if the deviation determined by the comparison is one exceeds the given tolerance value. The error signal can also be output if the time signal could not be used, e.g. in case of a transmission fault.

In one embodiment of the basic device, the receiving devices are designed as direct receivers and in particular comprise a selective amplifier.

In one embodiment of the basic device, the decoding devices comprise a demodulator for demodulation of a frequency-modulated signal and a frame synchronization unit for frame synchronization of transmitted data packets.

In a further embodiment, a previously defined device is configured to be a billing unit in a charging station, a taximeter, a wind turbine, a solar system or other unit in which time-dependent actions are performed, the correctness of the existing time base must be present.

In a further refinement, a device defined above is designed as a time service computer, time server, trusted platform module (TPM) or hardware security module (HSM).

The term "continuous carrier signal" designates and in the following text an electromagnetic carrier signal which is continuously supplied to the transmission channel. The transmission channel may be a physical medium or a free radio link. As a physical medium, for example, an electrical conductor, a waveguide or a light guide can be used. A free radio link is assumed below when reference is made to the transmission of a radio carrier signal. The continuous supply of the carrier signal presupposes a suitable selection and definition of the modulation which is fundamentally required for the data transmission. As far as a frequency and / or phase modulation method is used, there are no further restrictions. When using an amplitude modulation method, the modulation index must be set such that the radio carrier signal can still be detected reliably enough on the transmission channel even during the reduced amplitude at the location of the intended receiving device.

The term "time signal" denotes a time transmitted by modulation of a continuous carrier signal. A time signal may in particular be a time signal or a time telegram.

The term "time signal" designates a data structure continuously transmitted in a fixed temporal raster with a time indication contained therein. Typically, the fixed temporal raster is uniform and the data structure is accordingly transmitted periodically recurring. The fixed time grid allows a particularly accurate determination of the so-called "reference time" of the time within the time signal. For a time signal, the reference time is the time within the transmission at which the time designated by the time signal is reached. A well-known time signal is the wirelessly transmitted DCF77, which from the Mainflingen transmitter via an amplitude-modulated continuous carrier signal with a frequency of 77.5 kHz and a fixed time lapse of one second. Every second a symbol is transmitted. The reference points of this time signal are at the end of a 60-second frame. As a special feature, in addition to the amplitude-modulated data aggregate with the time specification, the DCF77 also has a pseudo-random phase shift keying (PSK), which also repeats itself with the fixed time grid. This allows a very accurate determination of the reference points at the end of the 60-second frame by cross-correlation of the received signal against a generated in the receiver signal of the same frequency with identical pseudorandom phase shift keying. For further details, reference is made to the article referred to at the beginning in PTB Mitteilungen.

The term "time message" denotes a transmitted data packet with a time indication contained therein. The structure of the data packet corresponds to a specific or determinable scheme, whereby the time that is contained can be assigned to a specific reference time within or in the vicinity of the broadcasting time of the time telegram. For example, the reference time may correspond to the time of transmission of the first symbol in the data packet. In contrast to the above-defined time signal, the transmission of the time message does not have to take place in a fixed temporal grid, time telegrams can be transmitted in a loose time grid, which does not or only limited on the side of the receiver prediction of a way to receive. Occasionally, in practical applications, the continuous carrier signal used to transmit the time telegrams is simultaneously used for the transmission of other telegrams. Depending on the occurrence and prioritization of these other telegrams, the transmission of the time telegrams can thereby be displaced in the sense that the time interval between successive time telegrams increases. Accordingly, the possibilities for the especially predictable reception of the time information are reduced for a receiver of the time messages.

The term "time service" refers to the operation of a technical infrastructure for transmitting time signals. Typically, such a technical infrastructure includes a time standard that provides the binding basis for the time signals to be broadcast. Again, typically, the time standard is provided by an atomic clock. Furthermore, the technical infrastructure comprises a high-frequency transmitter for emitting a modulated continuous carrier signal, from which the time signals with the times can be derived by a suitable demodulation method. Long-wave transmitters with an operating frequency of 30-300 kHz appear particularly suitable for this purpose because the electromagnetic waves emitted with very short propagation times carry them over very large distances. In addition, the transmission of time signals requires very little bandwidth.

figure description

Fig. 1

einen schematischen Signalgang eines amplitudenmodulierten Dauerträgersignals mit einem festen zeitlichen Raster als Grundlage für ein erstes exemplarisches Verfahren;

Fig. 2

eine Veranschaulichung der zeitlichen Folge der Datenpakete in einem paketorientierten Übertragungsschema als Grundlage für ein zweites exemplarisches Verfahren; und

Fig. 3

eine exemplarische Vorrichtung zur Durchführung des zweiten exemplarischen Verfahrens für das Übertragungsschema gemäß Fig. 2.

Exemplary methods for verifying time indications from time signs modulated on a continuous carrier signal and an exemplary apparatus for carrying out such a method are illustrated in the attached drawings. Show:

Fig. 1

a schematic signal path of an amplitude-modulated continuous carrier signal with a fixed time grid as a basis for a first exemplary method;

Fig. 2

an illustration of the temporal sequence of the data packets in a packet-oriented transmission scheme as a basis for a second exemplary method; and

Fig. 3

an exemplary apparatus for performing the second exemplary method for the transmission scheme according to Fig. 2 ,

Detailed description

The schematic representation in Fig. 1 shows a typical timing signal 100 for the transmission of time signals 110, 120, 130 at the transmitter and receiver. The received signal is uninterrupted in uninterrupted reception available because the transmission uses a continuous carrier signal. Amplitude modulation is used to encode a plurality of directly successive time signals 110, 120, 130 on the continuous carrier signal. The time signals 110, 120, 130 are in a fixed temporal grid and each contain a time indication. In addition, the time signals mark the respective reference time 112, 122, 132 belonging to the time specification.

In the exemplary situation, the times and reference times 112, 122, 132 on the continuous carrier signal are coded by three different symbols transmitted in a temporal second grid. The logical values 0 and 1 are represented by a short or long reduction of the signal amplitude at the beginning of each second. The symbol for the reference time is realized by omitting the lowering. The subsequent falling edge in the signal strength can therefore be used to detect the reference time. The transmission is repeated in a 60-second frame. Accordingly, in each time signal 110, 120, 130, the symbol for the display of the reference time 59 is preceded by symbols with binary data in which the time associated with the reference time is suitably coded.

The measures and devices for receiving the time signals 110, 120, 130, for taking the time information and for detecting the reference times 112, 122, 132 are known and are therefore not shown here. If a time specification is decoded on receipt of a time signal 110, 120, 130, it can be used for the respectively subsequently detected reference time 112, 122, 132 for the synchronization of a local clock of the receiver or for any other purpose.

In particular, if the carrier frequency of the continuous carrier signal is stabilized with the same time base from which the time data transmitted with the time signals 110, 120, 130 are derived, this allows a simple verification or consistency check of consecutively received time signals 110, 120, 130 by the first exemplary example explained below Method.

In the first exemplary method, for the purpose of verification, after the reception of a first time signal 110, in the present case upon detection of the reference point 112 at a decoded time, a count of the periods of the continuous carrier signal is started, which starts with the reception of a second, subsequent time signal 120 or 130 whose reference time 122 or 132 is stopped. The second time signal 130 does not have to follow directly the first time signal 110. Between the reception of the first and second time signals 110, 130, a longer period of time may also elapse with a number of further time signals 120, as long as an uninterrupted reception of the continuous carrier signal for the counting of the periods is guaranteed.

After the count has been completed, a desired time interval is calculated from the time specifications of the first and second received time signals 110, 120 and 110, 130. From the counted periods of the continuous carrier signal, a time interval 170, 180 is calculated over the known carrier frequency, which is referred to here as the reference time interval because of the reference to the continuous carrier signal of the time reference. If the deviations determined by the comparison between the desired time interval and the reference time interval exceed a predetermined tolerance value, an error signal is output.

An exemplary packet-oriented data transmission scheme 200 illustrates Fig. 2 , Such a data transmission scheme is realized, for example, in the known ripple control and in particular in the radio ripple control for power supply networks. Since this transmission scheme largely corresponds to the well-known approaches for packet-oriented transmission schemes, the further presentation will be limited to the aspects essential for the second exemplary verification method explained below.

Over time, from left to right, multiple data packets 210, 220, 230, 240, 250 are transmitted. In detail, these data packets are four time messages 210, 220, 240, 250 and a data telegram 230. The times of the respective transmission are not fixed rigidly but are determined on the transmitter side. However, the data packets 210, 220, 230, 240, 250 in the packet-wise transmission are temporally delimited from one another and in particular must not overlap in time. Within the data packets 210, 220, 230, 240, 250, the modulation also maintains a predetermined temporal grid. From this, the time position of a received data packet in the received signal can be determined by a measure called frame synchronization. Between the data packets 210, 220, 230, 240, 250 is typically at least a small time interval, which is not used for a transmission and therefore contains the continuous carrier signal without any modulation pattern.

On the basis of a signal with the temporal transmission scheme according to Fig. 2 The second exemplary method for verifying time information from time telegrams is obtained with the measures indicated below.

For this purpose, first a first time telegram 210 for a first reference time 212 is received. In particular, a data stream is generated by demodulation of the received continuous carrier signal from which the relevant first time specification is obtained by decoding. Furthermore, the reference point 212 of the first time telegram 210 is obtained by a frame synchronization of the received time telegram 210.

Connected to the frame synchronization of the first time frame 210, a start mark signal 214 is generated which coincides with the reference time 212 of the first time frame. Start mark signal 214 indicates the beginning of a time interval 216 during which periods of the steady state carrier signal are detected and counted. This count is terminated by a tail mark signal 224 derived from the frame synchronization of a second time frame 220 coinciding with the beginning of the second time frame 220. In addition, the second time telegram 220 is received in the same way as the first one. In particular, the time information contained therein is taken.

From the time information of the first and second time message 210, 220, the setpoint time interval 218 lying between the reference times 212 and 222 is furthermore determined. This target time interval 218 corresponds to the time elapsed at the transmitter end in the transmission between the reference times 212, 222 in the measurement in accordance with the time standard used by the transmitter.

In addition, a reference time interval 270 is determined via the periods of the continuous carrier signal counted during the time interval 216 between the start mark signal 214 and the end mark signal 224. A first contribution to the reference time interval 270 is the packet duration 260, that is to say the time length of the second time telegram 220.

This packet duration 260 is assumed in the present case as a uniform and fixed value for all time frames. The further contribution 216 to the reference time interval 270 due to the time interval 216 is derived from the periods counted between the start mark signal 214 and the end mark signal 224. The derivative can be done solely on the basis of the counted value if the frequency of the continuous carrier signal during the counting is unchanged or the fluctuations of the period duration which may be present due to any frequency modulation compensate each other in the sum over the time interval 216.

In the exemplary data transmission according to Fig. 2 For example, in the gap between the first 210 and the second time telegram 220, it can be assumed that this condition exists in the sense of a first alternative. On the other hand, in the case of a second alternative, if the period duration of the continuous carrier signal undergoes a change due to frequency modulation during counting, as in the case of the data telegram 230, for example, this change should be adequately considered to improve the accuracy in determining the reference time interval 280 , In principle, several approaches come into consideration.

First, the modulation state of the continuous carrier signal could be detected continuously on a direct path. However, this detection is subject to blurring, because the temporal limits of the individual symbols of the modulation can no longer be exactly determined by the processing of the received signal. In addition, the detectability of these time limits can be degraded by disturbances on the transmission link.

These problems can be resolved, at least in part, by a modified approach. For this purpose, the data stream read by the continuous carrier signal by demodulation and decoding is used as the basis for a model of the transmitted continuous carrier signal. The received symbols are thus reconstructed quasi in the specified exact time grid. As far as the symbols are properly demodulated and decoded, this reconstruction results in the ideal frequency response at the transmitter. In addition, error correction measures on the data encoded with the symbols can further help to find this ideal frequency response. With this approach, for example, the content of the data telegram 230 is read and the frequency response ideally transmitted for its transmission is reconstructed on the basis of the given data and symbol layout.

A still further approach could provide for determining the frequency response and modulation pattern independently of the actual received sustainer signal. However, this is only possible if the data transmitted on the transmission path are predetermined in advance in that the contents of the subsequent ones can be determined based on a correctly recognized data packet. This This would be the case in particular if the continuous carrier signal is used exclusively for the transmission of the time messages and these time messages are transmitted exclusively at predetermined reference times. Then it could be concluded from the time of receipt of a data packet on its contents. However, this will probably not be the case in most practically relevant application scenarios.

In one possible embodiment of the exemplary method, provision could also be made for determining the package duration 260 by one of the approaches explained above. Such a modified method could deal with data packets of varying length.

Finally, in the second exemplary method, the target time interval 218 is compared to the reference time interval 270. For example, the difference between these two values is formed. If this difference exceeds a specified tolerance value, an error signal can be output.

The second exemplary method for verifying time data from time frames as set forth above may be used with the example apparatus 300 for providing a remote synchronized verified time base according to FIG Fig. 3 be performed. This includes along the processing path, so viewed in the direction of the signal and data flow, the modules or functional units explained below.

At the beginning of the processing path receiving means 310 are provided for receiving the continuous carrier signal with the frequency-modulated data structures. In particular, the receiving devices 310 comprise an antenna circuit 312 adapted to the frequency of the continuous carrier signal and connected to the input of a direct receiver 314. The direct receiver 314 is preferably a frequency-selective amplifier which can provide a particularly good suppression of interference signals and noise.

A direct receiver 314 has the advantage over the typical overlay receivers used in comparable situations that it does not suppress or attenuate the continuous carrier signal. Thereby, the continuous carrier signal can be used by counting the expiring periods as a time base. The amplified continuous carrier signal available at the output of the direct amplifier 314 is further suitably supplied via a filter 316 for subsequent processing.

The processing path further includes decoding means 320 for extracting the data from the continuous carrier signal and for determining the time frame of the data transmission. In particular, in the exemplary situation, the decoders 320 include a demodulator 322 for extracting the transmitted data packets, namely the time and data telegrams, by demodulation of the continuous carrier signal and for providing further devices for subsequent processing. Furthermore, in the exemplary situation, in particular, the decoding devices 320 include a frame synchronization unit 324 for determining the frame, ie the temporal position of the transmitted data packets.

In addition, in the exemplary embodiment, the frame synchronization unit 324 is configured to output start and end mark signals for displaying a time interval. These start and end mark signals are in particular derived from predetermined reference points in the context of the packet-wise transmission. In particular, in the exemplary embodiment, the frame synchronization unit 324 is configured to generate the start mark signal at the end of a preceding time frame and the end mark signal at the beginning of one of the subsequent time frames.

The processing path further includes calculation means 330 for calculating the target time interval 218, 228 between the reference times between the respective time frames of the respective received time frames 210, 220 and 220, 250. This target time interval 218, 228 is determined in particular by subtraction the time information and, if necessary, obtained by a subsequent conversion to a time-continuous representation. The latter is particularly necessary if the times are coded in the time telegrams divided into year, month, day, hour and second.

The processing section further includes counters 340 for counting the periods of the sustainer signal within the interval specified by the frame synchronization unit 324 by the start and end marker signals. In the present exemplary embodiment of the apparatus 300, the start mark signal generated by the frame synchronization unit 324 starts the counter 340, which counts the periods of the sustainer signal until the end mark signal arrives. The counter 340 is further configured to output the result of this count as a digitally coded count.

The processing section further includes conversion means 350 for converting the count value supplied from the counter 340 to a reference time interval. In the exemplary embodiment of the device 300, the conversion devices 350 are set up, in particular, to take into account, as described above, a frequency modulation pattern on the continuous carrier signal during the conversion. For this purpose, the conversion device 350 has the option of weighting parts of the counting result with different period lengths for the overall result.

The processing path further includes comparators 360 for comparing the target time intervals 218, 228 with the reference time interval 270. The comparators 360 are configured to output alternative signals to indicate whether the deviation determined by the comparison meets or exceeds a predetermined tolerance value. The signal output for indicating the compliance of the comparison devices 360 is fed to a control unit 380 which, on the basis of the incoming signal, processes the relevant time message as verified and, as an example, relays it to a time-dependent acting actuator 390. The actuator 390 is thus a remote-synchronized Verified time base available. On the other hand, the error signal possibly outputting the overshoot is fed to an error control unit 370 in the exemplary device and further processed there. The further processing may include the output of a signal to the control unit 380.

The above-explained device 300 can advantageously be used to make it difficult to manipulate the time information received via the time messages. It therefore lends itself as part of a billing unit for time-based billing, for example in a charging station, a taximeter, a wind turbine, a solar system or units in which time-dependent actions are performed, the correctness of the existing time base must be present.

Furthermore, the device 300 explained above may be expediently provided as part of a time service computer, time server, trusted platform module (TPM) or hardware security module (HSM).

LIST OF REFERENCE NUMBERS

100

signal transition

110

First time signal

112

Reference time first time signal

120

Second time signal

122

Reference time second time signal

130

Third time signal

132

Reference time third time signal

170

Reference interval

180

Reference interval

200

Data transmission scheme

210

First time telegram

212

Reference time of the first time telegram

214

Start mark signal

216

time interval

218

Set time interval

220

Second time telegram

222

Reference time of the second time telegram

214

Endmarkensignal

226

time interval

228

Soli interval

230

Data telegram

240

Third time telegram in case of disturbed transmission

250

Fourth time telegram

260

packet duration

270

Reference interval

280

Reference interval

300

Apparatus for providing a remote synchronized verified time base

310

receiving devices

312

Adapted antenna circuit

314

Selective amplifier

316

filter

320

Decoders

322

frequency demodulator

324

Frame synchronization unit

326

data decoder

330

calculators

340

counter

350

Calculator facilities

360

comparators

370

Error control unit

380

control unit

390

actuator

Claims (13)

1. A process to verify time information from time data (110, 120, 130; 210, 220) modulated on a continuous carrier signal, comprising:

   - Receiving first time data (110; 210) with a first reference time point (112; 212);

   - Receiving second time data (120; 220) with a second reference time point (122; 222), that follows the first reference time point (112; 212) in time;

   - Calculating the nominal time interval (218) between the reference time points (112, 122; 212, 222) from the time information contained in the received time data (110, 120; 210, 220);

   - determining a time interval (112-122; 216) and determining a reference time interval (170; 270) by counting periods of the continuous carrier signal within the time interval (112-122; 216);

   - Comparing the nominal time interval (218) with the reference time interval (170; 270) and outputting an error signal if the deviation determined by the comparison exceeds a specified tolerance value,

   the time data being time information conveyed by modulating a continuous carrier signal, it being possible for time data (110; 120; 210; 220) to be, in particular, a time signal or a time telegram, the time signal being a data structure that is continuously transferred in a fixed time-slot pattern and that contains time information, and a time telegram being a data packet that is transferred and that contains time information.
2. The process according to claim 1, wherein the time information from time signals (110, 120) transferred in a fixed time-slot pattern for determination of the reference time interval (170) is verified by counting the periods of the continuous carrier signal in the time interval (112-122) between the reference time points (112, 122) of the received time signals (110, 120).
3. The process according to claim 1, wherein the time information from time telegrams (210, 220) transferred in a packet-oriented manner in a loose time-slot pattern to determine the reference time interval (270) is verified by counting the periods of the continuous carrier signal in the time interval (216) between the received time telegrams (210, 220), and the reference time interval (270) is obtained by adding the packet duration (260).
4. The process according to claim 3, wherein furthermore the packet duration (260) is determined by counting the periods of the continuous carrier signal during the transfer of a time telegram (210, 220).
5. The process according to claim 3 or 4, wherein the counting of periods of a frequency-modulated continuous carrier signal involves weighting the counted periods with the period varying due to frequency modulation.
6. The process according to claim 5, wherein the period of the frequency-modulated continuous carrier signal is varied according to the data derived from it by demodulation.
7. The process according to claim 5, wherein the packet duration (260) is determined by varying the period of the frequency-modulated continuous carrier signal on the basis of frequency modulation according to a time telegram (210) corresponding to the first reference time point (212).
8. The process according to claim 3, wherein the packet duration (260) added is a fixed specified value.
9. A device (300) to provide a remotely synchronized, verified time base having:

   - Receiving devices (310) to receive a continuous carrier signal with modulated time signs;

   - Decoding devices (320) to extract the time signs from the continuous carrier signal and to mark a time interval by beginning and ending mark signals;

   - Calculation devices (330) to calculate the nominal time interval (218, 228) between the reference time points from the time information contained in the received time signs;

   - Counting devices (340) to count the periods of the continuous carrier signal in the time interval (216, 226) between the beginning and ending mark signals;

   - Conversion devices (350) to convert the counted periods into a reference time interval (270); and

   - Comparison devices (360) to compare the nominal time interval (228, 218) with the reference time interval (270) and output an error signal to an error control unit, if the deviation determined by the comparison exceeds a specified tolerance value.
10. The device (300) according to claim 9, wherein the receiving devices (102) are in the form of a tuned radio receiver, and in particular comprise a selective amplifier.
11. The device (300) according to one of claims 9 or 10, wherein the decoding devices (320) comprise a demodulator (322) for demodulation of a frequency-modulated signal and a frame synchronization unit (324) for frame synchronization of data aggregates transferred in a packet-oriented manner.
12. The device (300) according to any one of claims 9 through 11, that is in the form of a billing unit in an electric vehicle charging station, a taximeter, a wind power plant, a solar power system, or in the form of another unit in which time-dependent actions are carried out and the time base must be correct.
13. A device (300) according to any one of claims 9 through 12 that is in the form of a time service computer, time server, trusted platform module, or hardware security module.

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