CA1213017A - Method for transmitting digital signals - Google Patents
Method for transmitting digital signalsInfo
- Publication number
- CA1213017A CA1213017A CA000389926A CA389926A CA1213017A CA 1213017 A CA1213017 A CA 1213017A CA 000389926 A CA000389926 A CA 000389926A CA 389926 A CA389926 A CA 389926A CA 1213017 A CA1213017 A CA 1213017A
- Authority
- CA
- Canada
- Prior art keywords
- bit rate
- digital signal
- transmission
- signals
- transmission band
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/02—Channels characterised by the type of signal
- H04L5/06—Channels characterised by the type of signal the signals being represented by different frequencies
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
- H04L25/40—Transmitting circuits; Receiving circuits
- H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/14—Two-way operation using the same type of signal, i.e. duplex
- H04L5/1423—Two-way operation using the same type of signal, i.e. duplex for simultaneous baseband signals
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Dc Digital Transmission (AREA)
- Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
- Bidirectional Digital Transmission (AREA)
Abstract
Abstract of the Disclosure Digital signals are transmitted over a transmission path having a frequency transmission band whose upper limit frequency corresponds to the maximum bit rate of the signals to be transmitted by simultaneously transmitting digital signals having a high bit rate only in an upper part of the transmission band and digital signals having a low bit rate only in a lower part of the trans-mission band.
Description
?~
The present invention relates to a method ~or the trans-mission of digital signals over a p~th having a frequency transmis-sion range whose upper frequency limit corresponds to the maximum bit rate of the signals to be transmitted.
Such rnethods are known as direct current telegraphy or direct current data transmission, for example with low signal power level.
In direct current telegraphy it is known to provide for full duplex traffic by means of difference or bridge circuits. How-ever~ this traffic is limited to lower transmission bit rates thansimplex traffic allows. For high transmission bit rates, difference or bridge circuits become ver~ expensive and for very high bit rates ~ull duplex traLfic is practically impossible.
Therefore, traffic in the opposite direction generally requires an additional transmission path, for example by providing for four-wire operation.
It is therefore an object of the present invention to pro~
vide a transmission method of the above type which permits, while utilizing the maximum bit rate determined by the upper limit frequ-2n ency, the additional transmission of a further digital signal ata lower bit rate. A further object of ~he invention is to achieve the above-stated objective in an economical manner.
According to the present invention, there is provided in a method for transmitting digital signals over a transmission path having a frequency transmission band whose upper limit frequency corresponds to the maximum bit rate of the signals to be transmitted the digital signals including a digital signal having a high bit rate and having a substantial proportion of its energy spectrum ih.......................... -- 1 ` ' 3~7 located in the upper part of the transmission band, and a digital signal having a low bit rate, the improvement cornprising simultan-eously transmitting, over the transmission path, the digital signal havlng a high bit rate in an upper part of the transmission band and the digital signal having a low bit rate in a lower part of the transmission band, the digital signal with the high bit rate being coded in a code which has substantially no direct current component.
Brief Description of the Drawings:
Figure 1 shows a functional block diagram of a preferred embodiment of circuitry at the input and output ends of the trans-mission path for implementing the invention.
Figure 2 shows a diagram in which the energy spectrum of the signals are drawn versus frequency.
The solution according to the invention makes it possible, while utilizing the highest possible bit rate determined by the upper limit frequency of the transmission path, to effect an additional transmission of a digital signal w~th a lower bit rate.
The invention is based essentially on recognition of the fact that it is not absolutely necessary for the transmiss;on of digital signals to transmit all frequencies of the transmission range up to the upper limit frequency but rather that for a reliable detection of the transm~tted information it is suf~icient to make available only an upper portion of thetransmission range. Certain codes, e,g., the amicode, contain no d,c. component and the propor-tion of lower frequency components in the energy spectrum is very small~ The idea of the invention is therefore to transmit the high frequency components of a high bit rate digital signal so as to
The present invention relates to a method ~or the trans-mission of digital signals over a p~th having a frequency transmis-sion range whose upper frequency limit corresponds to the maximum bit rate of the signals to be transmitted.
Such rnethods are known as direct current telegraphy or direct current data transmission, for example with low signal power level.
In direct current telegraphy it is known to provide for full duplex traffic by means of difference or bridge circuits. How-ever~ this traffic is limited to lower transmission bit rates thansimplex traffic allows. For high transmission bit rates, difference or bridge circuits become ver~ expensive and for very high bit rates ~ull duplex traLfic is practically impossible.
Therefore, traffic in the opposite direction generally requires an additional transmission path, for example by providing for four-wire operation.
It is therefore an object of the present invention to pro~
vide a transmission method of the above type which permits, while utilizing the maximum bit rate determined by the upper limit frequ-2n ency, the additional transmission of a further digital signal ata lower bit rate. A further object of ~he invention is to achieve the above-stated objective in an economical manner.
According to the present invention, there is provided in a method for transmitting digital signals over a transmission path having a frequency transmission band whose upper limit frequency corresponds to the maximum bit rate of the signals to be transmitted the digital signals including a digital signal having a high bit rate and having a substantial proportion of its energy spectrum ih.......................... -- 1 ` ' 3~7 located in the upper part of the transmission band, and a digital signal having a low bit rate, the improvement cornprising simultan-eously transmitting, over the transmission path, the digital signal havlng a high bit rate in an upper part of the transmission band and the digital signal having a low bit rate in a lower part of the transmission band, the digital signal with the high bit rate being coded in a code which has substantially no direct current component.
Brief Description of the Drawings:
Figure 1 shows a functional block diagram of a preferred embodiment of circuitry at the input and output ends of the trans-mission path for implementing the invention.
Figure 2 shows a diagram in which the energy spectrum of the signals are drawn versus frequency.
The solution according to the invention makes it possible, while utilizing the highest possible bit rate determined by the upper limit frequency of the transmission path, to effect an additional transmission of a digital signal w~th a lower bit rate.
The invention is based essentially on recognition of the fact that it is not absolutely necessary for the transmiss;on of digital signals to transmit all frequencies of the transmission range up to the upper limit frequency but rather that for a reliable detection of the transm~tted information it is suf~icient to make available only an upper portion of thetransmission range. Certain codes, e,g., the amicode, contain no d,c. component and the propor-tion of lower frequency components in the energy spectrum is very small~ The idea of the invention is therefore to transmit the high frequency components of a high bit rate digital signal so as to
-2~
~2~ 7 provide a frequency gap in the lower transmission range and to accommodate therein a digital signal having a low b~t rate.
According to one embodiment of the invention, the di~ital signals with the high and low bit rates, respectively, are each coupled into the transmission path via a corresponding bandpass filter.
The method according to the invention can be optionally employed in integrated broadband and narrowband distributing net-works, for example in video-telephone and television distributing networks in which, in a favourable manner, television programs can be selected or requested, respectively, by transmission -- -2a-~, .. , , ~ .
~2~ 7 provide a frequency gap in the lower transmission range and to accommodate therein a digital signal having a low b~t rate.
According to one embodiment of the invention, the di~ital signals with the high and low bit rates, respectively, are each coupled into the transmission path via a corresponding bandpass filter.
The method according to the invention can be optionally employed in integrated broadband and narrowband distributing net-works, for example in video-telephone and television distributing networks in which, in a favourable manner, television programs can be selected or requested, respectively, by transmission -- -2a-~, .. , , ~ .
3~
in the return direction of digital signals having a low bit rate.
In integrated broadband local networks employing optical fiber trans-mission paths, the method can be used to advantage in the low~r distribution plane where coaxial lines are provided between the subscribers and ~he terminal equipments of the optical transmission paths.
In Figure 1 is shown a line 1 as a transmission path with input/output ends 2~3, which each are connected to a high-pass- and a low-pass filter 4, 5 and 6, 7, respectively. The signal Sl with a high bit rate of about 300 Mbit/s is fed in the line end via the hp-filter 4 and the signal S2 with a low bit rate of about 80 kbi~/s is fed in the other line end 3 via the lp-filter 7 to be transmitted in the opposite direction. The signal with high bit rate received at the line end 3 via hp-filter 6 as signal Sl' and the signal with low bit rate is received at line end via lp-filter ~ as signal S2'.
In Figure 2 energy spectrum of the digital signals are shown ~, frequency f. It is obvious that the signals with the high bit rate ~l,J ~
have no energy proportions for frequencies lower than the cut-off frequency fg of the low pass and the high pass, respectively. The above described signals have frequency ranges of 0,8 to 80 kHz and 3 to 300 MHz for S2, S2' and Sl, Sl', respectively. Cut-off frequency fg has therefore an optimal value of about 1 M~lz.
If cut-off frequencies of high and low pass arechosen nearly to 3 MHz and 80 k~z, respectively, the frequency range gap may be used for transmission of further digital or modulated signals.
The digital signals are optimally encoded in AMI-code ~alternate mark inversion), which is also named "bipolarsignal") wherein the binary value O corresponds with the voltage level O and the binary value 1 is alternating a positive and a negative voltage level. Other codes with similar energy spectrum ' 1 ,. , :
~ t7 like HDB 3 (high density bipolar of order 3) may be used advantageously.
In another modification the ~ method can be advantag.eou~I.y implemen~ed by combining with the burst mode (ping-pong-system) also referred to~time compression multiplexed (TCM) system, wherein transmission in each direction occurs in alternating, disjoint time intervals, detailed described by Bosik, Bell Labor., in "NTG (Nachrichtentechnishe Gesellschaft)-Fachbericht"
volume 73, pp~ 26 f.
It will be understood that the above descrip~ion of the present inven-tion is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.
in the return direction of digital signals having a low bit rate.
In integrated broadband local networks employing optical fiber trans-mission paths, the method can be used to advantage in the low~r distribution plane where coaxial lines are provided between the subscribers and ~he terminal equipments of the optical transmission paths.
In Figure 1 is shown a line 1 as a transmission path with input/output ends 2~3, which each are connected to a high-pass- and a low-pass filter 4, 5 and 6, 7, respectively. The signal Sl with a high bit rate of about 300 Mbit/s is fed in the line end via the hp-filter 4 and the signal S2 with a low bit rate of about 80 kbi~/s is fed in the other line end 3 via the lp-filter 7 to be transmitted in the opposite direction. The signal with high bit rate received at the line end 3 via hp-filter 6 as signal Sl' and the signal with low bit rate is received at line end via lp-filter ~ as signal S2'.
In Figure 2 energy spectrum of the digital signals are shown ~, frequency f. It is obvious that the signals with the high bit rate ~l,J ~
have no energy proportions for frequencies lower than the cut-off frequency fg of the low pass and the high pass, respectively. The above described signals have frequency ranges of 0,8 to 80 kHz and 3 to 300 MHz for S2, S2' and Sl, Sl', respectively. Cut-off frequency fg has therefore an optimal value of about 1 M~lz.
If cut-off frequencies of high and low pass arechosen nearly to 3 MHz and 80 k~z, respectively, the frequency range gap may be used for transmission of further digital or modulated signals.
The digital signals are optimally encoded in AMI-code ~alternate mark inversion), which is also named "bipolarsignal") wherein the binary value O corresponds with the voltage level O and the binary value 1 is alternating a positive and a negative voltage level. Other codes with similar energy spectrum ' 1 ,. , :
~ t7 like HDB 3 (high density bipolar of order 3) may be used advantageously.
In another modification the ~ method can be advantag.eou~I.y implemen~ed by combining with the burst mode (ping-pong-system) also referred to~time compression multiplexed (TCM) system, wherein transmission in each direction occurs in alternating, disjoint time intervals, detailed described by Bosik, Bell Labor., in "NTG (Nachrichtentechnishe Gesellschaft)-Fachbericht"
volume 73, pp~ 26 f.
It will be understood that the above descrip~ion of the present inven-tion is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.
- 4 -. ~
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method for transmitting digital signals over a trans-mission path having a frequency transmission band whose upper limit frequency corresponds to the maximum bit rate of the signals to be transmitted, the digital signals including a digital signal having a high bit rate and having a substantial proportion of its energy spectrum located in the upper part of the transmission band, and a digital signal having a low bit rate, the improvement comprising simultaneously transmitting, over the transmission path, the digital signal having a high bit rate in an upper part of the transmission band and the digital signal having a low bit rate in a lower part of the transmission band, the digital signal with the high bit rate being coded in a code which has substantially no direct current component.
2. Method as defined in claim 1 wherein the digital signal having a high bit rate is constituted, prior to transmission, by a coded signal whose energy spectrum has a major portion disposed in the upper part of the frequency transmission band.
3. Method as defined in claim 1 wherein said step of trans-mitting comprises coupling the high and low bit rate signals to the transmission path via bandpath filters having respective pass bands in the upper and lower parts of the transmission band.
4. Method as defined in claim 1 wherein the high and low bit rate digital signals are transmitted over the path in respect-ively opposite directions.
5. Method as defined in claim 1 used in an integrated broadband and narrowband distributing network.
6. Method as defined in claim 1 wherein the transmission path has two transmission directions and the digital signals are transmitted in both directions along the path according to the burst mode.
7. Method as defined in claim 1 wherein said step of simul-taneously transmitting comprises separating the high bit rate digital signal from the low bit rate digital signal at at least one end of the transmission path,
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3042612.1 | 1980-11-12 | ||
| DE19803042612 DE3042612A1 (en) | 1980-11-12 | 1980-11-12 | TRANSMISSION PROCEDURE FOR DIGITAL SIGNALS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1213017A true CA1213017A (en) | 1986-10-21 |
Family
ID=6116563
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000389926A Expired CA1213017A (en) | 1980-11-12 | 1981-11-12 | Method for transmitting digital signals |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0051725A1 (en) |
| JP (1) | JPS57111151A (en) |
| CA (1) | CA1213017A (en) |
| DE (1) | DE3042612A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3044657A1 (en) * | 1980-11-27 | 1982-07-08 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | "SERVICE-INTEGRATED DIGITAL TRANSMISSION SYSTEM" |
| DE3232599A1 (en) * | 1982-09-02 | 1984-03-08 | ANT Nachrichtentechnik GmbH, 7150 Backnang | System for transmission of digital signals |
| JPH0644775B2 (en) * | 1985-08-14 | 1994-06-08 | 株式会社ザナヴィ・インフォマティクス | Transmitter / receiver using batteries |
| DE3802088C2 (en) * | 1987-01-26 | 1996-12-12 | Dirr Josef | Method for coding and decoding information in terminal stations of switching devices and transmission via connection paths / lines to and from the switching devices |
| JPH0817339B2 (en) * | 1993-01-14 | 1996-02-21 | 日本電気株式会社 | Error correction transmitter |
| US5459607A (en) * | 1993-04-19 | 1995-10-17 | C-Cor/Comlux, Inc. | Synchronous optical digital transmission system and method |
| KR100765492B1 (en) * | 2006-08-28 | 2007-10-10 | 마츠시다 덴코 가부시키가이샤 | Electrostatic spraying device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1166249B (en) * | 1960-06-24 | 1964-03-26 | Int Standard Electric Corp | Duplex data transmission arrangement |
| US3601544A (en) * | 1969-04-16 | 1971-08-24 | Sperry Rand Corp | Baseband frequency multiplexing scheme |
| FR2446570A1 (en) * | 1979-01-09 | 1980-08-08 | Telecommunications Sa | METHOD AND DEVICE ALLOWING THE SIMULTANEOUS TRANSMISSION OF A DIGITAL SIGNAL AND A LOW FREQUENCY WAVE |
| US4273955A (en) * | 1979-03-02 | 1981-06-16 | Paradyne Corporation | System for in-service quantitative performance analysis of data communications system |
-
1980
- 1980-11-12 DE DE19803042612 patent/DE3042612A1/en not_active Withdrawn
-
1981
- 1981-09-18 EP EP81107387A patent/EP0051725A1/en not_active Ceased
- 1981-11-11 JP JP17985881A patent/JPS57111151A/en active Pending
- 1981-11-12 CA CA000389926A patent/CA1213017A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3042612A1 (en) | 1982-06-16 |
| EP0051725A1 (en) | 1982-05-19 |
| JPS57111151A (en) | 1982-07-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |