Telecommunications – Transmitter and receiver at separate stations – Frequency or phase modulation
Reexamination Certificate
1999-03-03
2001-03-06
Le, Thanh Cong (Department: 2745)
Telecommunications
Transmitter and receiver at separate stations
Frequency or phase modulation
C455S110000, C455S334000, C455S305000
Reexamination Certificate
active
06198908
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a system for transfer of a digital information carrying signal between an input of a transmitter and an output of a receiver, the transmitter including a modulator for modulating the information carrying signal, the modulator being connected to transmission means for transmission of the modulated signal via a transmission medium, the receiver including receiving means, for receiving the transmitted signal, connected to a demodulator for demodulating the received signal.
Further it relates to a method for transfer of a digital information carrying signal between an input of a transmitter and an output of a receiver, where the information carrying signal is modulated in a modulator included in the transmitter, the modulated signal is transmitted via a transmission medium by transmission means connected to the modulator, the transmitted signal is received by receiving means included in the receiver, and the received signal is demodulated in a demodulator.
BACKGROUND OF THE INVENTION
A system and a method of the kind mentioned above are disclosed in WO A1 96/37987. In this system and method a VCO generates an IF-signal with a frequency dependent on an input control voltage. The transfer function from voltage to frequency depends on the type of component, variations between different components, variations in temperature etc. This leads to deviation errors. In order to demodulate the information carrying signal satisfactorily the deviation errors, which are not known, must be corrected. Therefore the receiver includes means for correction of the deviation error.
Said document does not contain any information about how to achieve an efficient use of the available bandwidth, in a general situation.
The present invention however, aims at the problem of improving the efficient use of the bandwidth.
Further, in the present invention the information carrying signal is modulated with a known and selected modulation index. Therefore, no correcting device or measurement device are needed. The present invention therefore simplifies the efficient use of the available bandwidth.
Further, it is a general problem to use an assigned bandwidth efficiently for transmitting information carrying signals.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method and a system for transfer of a digital information carrying signal, employing a decreased bandwidth and still making it possible to use a simple or desired decision device (phase detector or demodulator).
It is also an object of the invention to provide a method and a system for transfer of a digital information carrying signal, employing an assigned bandwidth and still making it possible to use a simple or desired decision device.
It is also an object of the invention to provide a method and a system for transfer of a digital information carrying signal, in which the bandwidth can be adjusted or selected as desired, and still making it possible to use a simple or desired decision device.
It is also an object of the invention to provide a method and a system for transfer of a digital information carrying signal, in which the modulation index can be selected as desired and, still making it possible to use a simple or desired decision device.
It is also an object of the invention to provide a method and a system for transfer of a digital information carrying signal, in which the bit rate can be increased while maintaining the allowed bandwidth, and still making it possible to use a simple decision device.
It is also an object of the invention to provide a simple and cost effective method and system for transfer of a digital information carrying signal.
These and other objects are attained by the features of the characterizing portions of the independent claims.
It is also an object of the invention to provide a method and a system for transfer of a digital information carrying signal, in which the bit rate can be increased, more correcting code can be added, and the modulation index can be decreased, while maintaining the allowed bandwidth, and still making it possible to use a simple decision device and attain an improved transfer capacity.
REFERENCES:
patent: 4581749 (1986-04-01), Carney et al.
patent: 5832022 (1998-11-01), Scott
Allgon AB
Cong Le Thanh
Jacobson Price Holman & Stern PLLC
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