Classifications

• • 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
  • 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
  • H04L25/4902—Pulse width modulation; Pulse position modulation

Definitions

• This invention relates to communication between a transmitter and a receiver via a channel. It has application to telecommunications, recording, data storage, and control.
• a signal of any physical form corresponding to an information character of an encoding alphabet is transmitted as an analog waveform defining a symbol, the waveform being cyclical at the symbol rate, to a communication channel and then the signal when received by a receiver is converted to groups of pulses separated by silences, wherein each group of pulses maps to a count corresponding to a character of the encoding alphabet.
• the groups of pulses are separated by silences of arbitrary duration which are greater than the time between individual pulses.
• the pulses have a pulse rate greater than the frequency of the symbol.
• the invention is a baseband modulation and direct demodulation method and related system. It has advantages in that it does not require full characterization or extraction of the symbol by the receiver, so that simple detectors and decoders can be used. Furthermore, there is no need or concept of impressing information on a carrier or of carrier recovery. There is likewise no concept of frequency conversion nor detection in an intermediate frequency band.
• the invention is applicable not only to electromagnetic transmission and reception, it can be used with any energy form, whether or not coherent.
• Fig. 1 is a block diagram of a communication system according to the invention.
• Fig. 2 exemplifies an arbitrary analog waveform used to represent a symbol.
• Fig. 3 illustrates an example of the pulses corresponding to the portion of the waveform discussed in connection with Fig. 2.
• Fig. 4 is a simplified schematic of a receiver in accordance with the invention.
• FIG. 1 is a block diagram of a communication system 10 according to the invention.
• the system 10 comprises a transmitter 12 and a receiver 22 coupled via a channel 20.
• the transmitter 12 receives a data stream 14 and transmits, via an output 16 an analog output waveform 18, represented by x(t) in the form of a sequence of symbols.
• the channel 20 is representative of all impairments to the transmitted signal x(t), including noise, between the transmitter 12 and the receiver 22.
• the channel 20 yields a received signal y(t) to the receiver 22.
• the receiver 22 produces an output in the form of groups of pulses or P(t), as hereinafter explained, that are applied to a decision device 26.
• the decision device 26 recovers a representation of the data stream 14 as a data stream 14'. This is done for example by counting pulses in each group and mapping the pulse counts of each group of pulses to the character established by the system character set.
• the symbol 18 is an arbitrary analog waveform which may be a sinusoid, a ramp, a sawtooth, a square wave, an asymmetric waveform or a waveform having a shape selected to be optimized to the a priori characteristics of the channel 20, or any combination of such symbols.
• Each symbol is coded with information, for example by anything which affects the shape, including but not limited to amplitude, frequency, slope, phase and any combination thereof.
• the symbol 18 is encoded by the transmitter 12.
• the transmitter maps each information character of a character set or alphabet of values to at least one shape for the symbol or symbols to be applied to the channel 20.
• the simplest character set is the binary set "one” and “zero” or “true” and “false” but there is no limitation on the number of characters in the character set other than practical limitations imposed by natural laws about the number of bits per symbol.
• the symbol rate is typically relatively slow with respect to the pulse train extracted therefrom.
• Fig. 3 there is shown a representation of the groups 24 of pulses P(t) according to the invention.
• Each symbol maps to a single group of pulses 24.
• the rate of pulse generation must be greater than the symbol rate, and the duration of the silences between pulse groups must be greater than the expected rate of pulse generation.
• the duration of the silences plus the duration of the pulse train corresponds to duration 28 of a symbol.
• the silences are of arbitrary duration greater than the time between individual pulses.
• each set of pulses can start and terminate at any time within the duration of a symbol, assuming as contemplated, decoding is in real time.
• the number of pulses in each pulse group can thus readily correspond to the information character represented by the symbol to which the pulse train corresponds.
• the waveform 18 may have many different mappings to a specific pulse count. This provides further robustness through coding redundancy.
• a basic circuit for the receiver 22 comprises two elements Z 30 and ZD 32.
• a signal source 34 represents the received signal y(t), which is here represented by a voltage Vs.
• the output is P(t).
• the signal source 34 applies the waveform to a first generalized normalized impedance element Z 30, which in turn applies the output across a second generalized impedance Z D 32.
• the combination of the first and second generalized impedances Z 30 and Z D 32 produce the pulse train output P(t).
• Equations 4 and 5 are duals of Equations 2 and 3.
• the equations describe a direct conversion of a wave shape in current or voltage to a pulse train upon proper choice of ⁇ (.), where ⁇ (.) is the transfer characteristic of the impedance element Z D - ⁇ is a small perturbative parameter. This invention has been explained with reference to specific embodiments.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Dc Digital Transmission (AREA)
• Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
• Transmission Systems Not Characterized By The Medium Used For Transmission (AREA)

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• 1999
  • 1999-10-28 CA CA002387403A patent/CA2387403A1/en not_active Abandoned
  • 1999-10-28 AU AU63629/99A patent/AU6362999A/en not_active Abandoned
  • 1999-10-28 IL IL14924199A patent/IL149241A0/xx unknown
  • 1999-10-28 KR KR1020027005218A patent/KR20020060209A/ko not_active Application Discontinuation
  • 1999-10-28 JP JP2001533702A patent/JP2003513521A/ja active Pending
  • 1999-10-28 WO PCT/IB1999/001800 patent/WO2001031868A1/en not_active Application Discontinuation
  • 1999-10-28 CN CNB998169781A patent/CN1164060C/zh not_active Expired - Fee Related
  • 1999-10-28 EP EP99951057A patent/EP1228614A1/en not_active Withdrawn
• 2001
  • 2001-04-25 TW TW090109948A patent/TW552784B/zh not_active IP Right Cessation

Non-Patent Citations (1)

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