Pulse or digital communications – Multilevel
Reexamination Certificate
1999-04-05
2001-09-11
Pham, Chi (Department: 2631)
Pulse or digital communications
Multilevel
C326S060000, C370S537000
Reexamination Certificate
active
06289055
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method for transmission of digital signals between a transmitter unit and at least one receiver unit.
In circuit technology, it is frequently necessary to transmit several digital transmission signals simultaneously from a transmitter unit to a receiver unit. Usually in such a case, one signal lead is needed a transmission medium for each digital transmission signal. In particular, in the case of signal transmission between integrated circuits, this results in expensive wiring and hence leads to high production costs.
SUMMARY OF THE INVENTION
The object of the invention is to provide a method of the type originally mentioned above that can be realized with simple circuit means and which allows transmission of digital signals via a small number of signal leads.
The above object generally is achieve according to the present invention by a method for the transmission of digital transmission signals between a transmitter unit and at least one receiver unit, wherein: in the transmitter unit, at least two digital transmission signals are totaled or combined to form a multilevel signal: the multilevel signal is transmitted through a signal lead from the transmitter unit to the receiver unit; and, in the receiver unit, digital received signals corresponding to the digital transmission signals are from the multilevel signal by amplitude filtering. Advantageous variation and further developments are disclosed.
The essential idea behind the invention is that, from the digital transmission signals to be transmitted, a multilevel signal can be generated with several equidistantly spaced logical signal levels that is transmitted via a signal lead from the transmitter unit to the receiver unit, and is there broken down by amplitude filtration into the digital received signals corresponding to the digital transmission signals. The multilevel signal in the receiver unit is therefore compared With compare thresholds positioned between the possible logical signal levels, the digital received signals being formed as compare result. Owing to the equidistantly spaced signal levels of the multilevel signal, optimal utilization of the dynamic range and a favorable noise behavior is ensured.
In an advantageous development of the method, the digital transmission signals are derived from a clock signal and a serial data signal in synchronism with it, ie. from a signal containing bit information in bit cells in synchronism with the clock signal and, possibly, from a data enable signal that marks the validity of the data signal. Logic operations ensure that, before summation of the digital transmission signals, partial areas of the data signal are blanked out by the clock signal and possibly partial areas of the data enable signal by the clock signal or partial areas of the clock signal by the data enable signal. Consequently, with the exception of one of the transmission signals, each of the remaining transmission signals can assume its active transmission level only when one of the other transmission signals has an active signal level, where each of the transmission signals can have either a high level or a low level as active signal level. If one of the transmission signals is a low-active signal, i.e. has a low level as active signal level, then this transmission signal is added with negative sign to the other transmission signals to form the multilevel signal in the transmitter unit. On the receiving side, the clock signal, the data signal and possibly the data enable signal are regenerated from the digital received signals after the signal transmission. In order to avoid disturbances resulting from the clock signal, the latter is advantageously made available only at the time of data transmission.
A preferred application of the method is the signal transmission through flexible leads between a transmitter unit and receiver unit that can be moved relative to the transmitter unit. An application of this kind is, for example, the control of a laser diode driver in a drive system for rewritable optical storage disks, which driver can be moved over the storage disk. In this application, the data signal, the clock signal and the data enable signal are used to set various parameters of the laser diode driver, e.g. the laser power for various modes of operation, and a write signal, a read signal and an erase signal for controlling the laser power in the various modes of operation, in particular in the “write”, “Read” and “Delete” modes. On the receiver side, received signals are formed corresponding to the write, read and erase signals, weighted in each case with a weighting factor and totaled after weighting into a control signal for a laser diode. The method thus allows both transmission of amplitude information, i.e., the laser power for the various modes of operation, and the transmission of any desired time information contained in the pulse widths of the write, read or erase signal.
Advantageously, a multilevel signal is made up of the write signal, the erase signal and the read signal, or two multilevel signals are made up of the write signal, the read signal, the erase signal, the clock signal, the data signal and the data enable signal, where these two signals are transmitted through two signal leads from a control unit, i.e., from the transmitter unit, to the laser diode driver, i.e., to the receiver unit. Preferably, transmission takes place in amplitude and time multiplex, i.e., in a first time window the clock signal, the data signal and the data enable signal are grouped together and transmitted simultaneously in a multilevel signal. In a subsequent time window, the write and erase signal are also transmitted simultaneously through the same signal lead grouped together. Furthermore, the read signal and the write enable signal are in turn transmitted simultaneously and grouped together in another multilevel signal preferably through another signal lead, with the write enable signal marking the time window by transmitting the write and erase signal at the same time to the receiver unit through the other signal lead.
REFERENCES:
patent: 4280221 (1981-07-01), Chun et al.
patent: 4339818 (1982-07-01), Gruenberg
patent: 5510919 (1996-04-01), Wedding
patent: 2330263 (1975-01-01), None
patent: 4035996A1 (1992-05-01), None
Corrielus Jean
Kunitz Norman N.
Pham Chi
Temic Semiconductor GmbH
Venable
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