EP0367897A2 - Méthode pour la transmission simultanée de données numériques sur des canaux de transmission à bande réduite - Google Patents

Méthode pour la transmission simultanée de données numériques sur des canaux de transmission à bande réduite Download PDF

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Publication number
EP0367897A2
EP0367897A2 EP89108348A EP89108348A EP0367897A2 EP 0367897 A2 EP0367897 A2 EP 0367897A2 EP 89108348 A EP89108348 A EP 89108348A EP 89108348 A EP89108348 A EP 89108348A EP 0367897 A2 EP0367897 A2 EP 0367897A2
Authority
EP
European Patent Office
Prior art keywords
data signals
rounded
data
digital data
curve shape
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP89108348A
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German (de)
English (en)
Other versions
EP0367897A3 (fr
Inventor
Dietmar Prof. Dr. Rudolph
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telefunken Sendertechnik GmbH
Original Assignee
Telefunken Sendertechnik GmbH
Licentia Patent Verwaltungs GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telefunken Sendertechnik GmbH, Licentia Patent Verwaltungs GmbH filed Critical Telefunken Sendertechnik GmbH
Publication of EP0367897A2 publication Critical patent/EP0367897A2/fr
Publication of EP0367897A3 publication Critical patent/EP0367897A3/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/28—Arrangements for simultaneous broadcast of plural pieces of information
    • H04H20/36—Arrangements for simultaneous broadcast of plural pieces of information for AM broadcasts

Definitions

  • the invention relates to a method according to the preamble of claim 1.
  • Methods of this type are used for the additional transmission of digital data signals via an already existing band-limited transmission channel, which is mainly used for the transmission of other signals.
  • the data signals must be rounded in such a way that they meet this condition. In most cases, this is done by severely limiting the spectrum of the data signals, e.g. with the FM radio broadcast radio data system (“FM-RDS”) or with data transmission via a narrowband data channel, for example the sound channel from the studio (in the broadcasting house) to the transmitter. In other cases, the rounding must take place in such a way that the first time derivative of the rounded curve shape has a minimum of vibrations (extrema), e.g. with the AM radio broadcast radio data system (“AM-RDS").
  • FM-RDS FM radio broadcast radio data system
  • AM-RDS AM radio broadcast radio data system
  • EBU European Broadcasting Union
  • the EBU waveform designed as a biphase signal in FIG. 1a is symmetrical of origin and for T ⁇ ⁇ ⁇ oscillator very quickly approaches zero, where T is the width (duration) of the unrounded data signal (single bit). With this curve shape, amplitudes that differ substantially from zero can only be found in the range of ⁇ 2T.
  • the associated spectral distribution in FIG. 1b is also symmetrical of origin and has spectral components that differ substantially from zero only within a range defined by the cut-off frequencies + Fg and -Fg, which represents the bandwidth of this EBU curve shape and which according to the above-mentioned.
  • EBU regulation depends on the data or band rate. For biphase waveforms e.g. there is a range of ⁇ 2 ⁇ band rate. With a band rate of 1.2 kBd for FM RDS, for example, the bandwidth ⁇ Fg is thus ⁇ 2.4 kHz. In the case of AM applications, on the other hand, the band rate is ⁇ 200 Bd, which results in a cut-off frequency Fg ⁇ 400 Hz for biphase signal shapes in accordance with this EBU regulation.
  • FIG. 2a shows a typical chronological sequence of unrounded digital data signals in the NRZ (No Return to Zero) format.
  • the digital data signals in the AM area that is to say in the AM-RDS, are transmitted as phase modulation (PM) of the carrier.
  • PM phase modulation
  • phase modulation (PM) for the data and the amplitude modulation (AM) for the message are orthogonal to one another, the two modulations in principle do not interfere with one another and can therefore be separated again at the receiving end.
  • phase shift influences the immunity to interference of the data transmission.
  • a phase shift of approx. ⁇ 15 degrees is required. (This value depends on the interference phase shift of the transmitter and the receiver and is therefore subject to technical change.)
  • the shape of the rounded data has a direct effect on the data speed (due to the compatibility) that can be achieved.
  • the program interferes with the data due to a conversion of the PM into an AM.
  • the frequency modulation (FM) that is always associated with the PM is converted into an AM.
  • This conversion of the FM into AM takes place in particular on asymmetrical edges of the intermediate frequency (IF) filter.
  • FIG. 3 shows the transmission curve U (f) of a typical IF filter as a function of the frequency f and which has an asymmetrical flank towards higher frequencies.
  • This edge makes it symmetrical about a center frequency f frequency modulation with a frequency deviation ⁇ f into asymmetrical fluctuations ⁇ U of the amplitude of the IF signal U around the center frequency f belonging amplitude value U implemented what can interfere with the reception of the main program.
  • the selected phase deviation ⁇ and thus also the associated frequency deviation ⁇ f and the shape of the rounded data signal are included in the magnitude of this disturbance.
  • Phase and frequency modulation are linked as follows: If phase modulation includes a (data) signal s (t), frequency modulation includes a signal ds (t) / dt, i.e. the time derivative of the (data) signal s (t).
  • FIG. 5a is again the one shown in FIG. 2b already shown and formed according to the above EBU regulation F (t) together with their first time derivative F '(t). Due to the sags S in F (t), the derivative F '(t) has a comparatively high number of vibrations or extremes, which, as practical tests have shown, a given certain propagation ranges conditions above the tolerance limit and thus audible "data hum" can result.
  • the object of the invention is to provide a method of the type mentioned, in which the additional data signals to be transmitted are rounded so that they also under extreme propagation conditions in data transmission systems that have a minimum of vibrations or extremes in the first derivative of the time function f (t) require the data signal sequence to be transmitted, such as AM-RDS, can be used in compliance with the specified minimum signal-to-noise ratio.
  • the solution according to the invention provides temporal waveforms for rounded data signals, in which the minima of the time function f (t) of the sequence of the rounded data signals are only in the lower part of the permissible total amplitude range and the maxima accordingly only in the upper part, both of which the lower and the upper sub-area each make up about 25% of the total amplitude range. Furthermore, in the curve shapes according to the invention, the number of extremes (minima and maxima) of this time function f (t), on the one hand, and their first time derivative f '(t), on the other hand, is each less than or at most equal to the number of extremes (minima and maxima) the basis of the EBU waveform (see FIG.
  • this inner partial area ⁇ Ti is advantageously approximately 60-90%, preferably approximately 70-80%, in particular approximately 75%, of twice the bit width ⁇ T, the temporal curve shape advantageously consisting of three sections, each with a sinusoidal transition between directly adjacent sections consists.
  • the method according to the invention can be used particularly advantageously in data transmission systems which require a minimum of vibrations as extremes in the first time derivative of the time function of the rounded data signal sequence, such as e.g. the AM-RDS.
  • FIG. 4 shows, on the same scale as FIG. 1, the time function (a) and the spectral distribution (b) of a particularly advantageous waveform according to the invention (type C) for a single rounded data signal (single bit) in biphase format, which in the time domain (FIG. 4a) consists of three Parts with a sinusoidal transition between directly adjacent parts is composed.
  • the type C waveform according to the invention is also symmetrical of origin both in the time domain and in the spectral distribution.
  • the amplitude of the curve shape C according to the invention assumes values other than zero in the time domain only in the inner partial region ⁇ Ti (with the exception of the origin lying in the middle of ⁇ Ti) and is otherwise zero (also in the two outer partial regions ⁇ Ta).
  • the inner partial region ⁇ Ti is approximately 75% of twice the bit width (duration) ⁇ T of a rounded data signal.
  • the bandwidth of the type C waveforms according to the invention is larger than that of the EBU waveform (FIG. 1) (which is why the waveform C according to the invention cannot be used for VHF RDS).
  • the corresponding eye pattern for curve shape C is shown in FIG. 6b.
  • time function f (t) of the data signal sequence rounded according to the invention no longer has sags in the area of the extrema (in contrast to the time function F (t) of the data signal sequence rounded according to the EBU regulation).
  • the rounding according to the invention means that additional data signals can be transmitted even under extreme propagation conditions without " Data humming "is now possible.
  • the invention is not limited to the biphase format, but can also be used directly in the NRZ format (ie without converting the unrounded NRZ data sequence into a rounded biphase data sequence). This is particularly important for AM-RDS.
  • the application of the invention is not limited to AM-RDS, but also extends to similar data transmission systems in which the requirement for hard band limitation takes a back seat to the requirement for a minimum number of overshoots in the first time derivative f '(t ) the time function f (t) for rounded data signal sequences.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Dc Digital Transmission (AREA)
EP19890108348 1988-11-11 1989-05-10 Méthode pour la transmission simultanée de données numériques sur des canaux de transmission à bande réduite Withdrawn EP0367897A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19883838226 DE3838226A1 (de) 1988-11-11 1988-11-11 Verfahren zur zusaetzlichen uebertragung von digitalen daten in bandbegrenzten uebertragungskanaelen
DE3838226 1988-11-11

Publications (2)

Publication Number Publication Date
EP0367897A2 true EP0367897A2 (fr) 1990-05-16
EP0367897A3 EP0367897A3 (fr) 1991-10-02

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890108348 Withdrawn EP0367897A3 (fr) 1988-11-11 1989-05-10 Méthode pour la transmission simultanée de données numériques sur des canaux de transmission à bande réduite

Country Status (3)

Country Link
EP (1) EP0367897A3 (fr)
DE (1) DE3838226A1 (fr)
DK (1) DK324289A (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4239509A1 (de) * 1992-11-25 1994-05-26 Daimler Benz Ag Verfahren und Empfänger für die terrestrische digitale Rundfunkübertragung

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2096424A (en) * 1981-04-01 1982-10-13 Philips Nv Transmitter for angel-modulated signals
DE3616864A1 (de) * 1985-09-25 1987-04-02 Verkehrswesen Hochschule Modifiziertes am-hoerrundfunksystem

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2096424A (en) * 1981-04-01 1982-10-13 Philips Nv Transmitter for angel-modulated signals
DE3616864A1 (de) * 1985-09-25 1987-04-02 Verkehrswesen Hochschule Modifiziertes am-hoerrundfunksystem

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
IEEE TRANS. ON. COMM., Band COM-28, Nr. 6, Juni 1980, Seiten 889-897, IEEE, New York, US; H. YAZDANI et al.: "Constant envelope bandlimited BPSK signal" *
TELECOMMUNICATIONS AND RADIO ENGINEERING, Band 24, Nr. 7, Juni 1970, Seiten 30-32, Scripta Publishing Co., Washington, DC, US; G.B. SELEZNEV et al.: "Automatic stepped carrier adjustment" *

Also Published As

Publication number Publication date
DK324289A (da) 1990-05-12
DK324289D0 (da) 1989-06-29
DE3838226A1 (de) 1990-05-17
EP0367897A3 (fr) 1991-10-02

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