Transmitter device having a modulation closed loop
First Claim
1. Transmitter device, in particular for a base transceiver station in a mobile radio system, comprisinga digital modulator for making available a baseband signal which contains a phase information and a modulation closed loop having a digital phase comparator whose first input is connected to the output of the digital modulator, a controllable oscillator for generating an RF transmission signal with a controllable transmission frequency, a device which is assigned to the controllable oscillator and has the purpose of converting the RF transmission signal into a baseband signal which contains a phase information, the output of the converter device being connected to a second input of the digital phase comparator, wherein the converter device has an analog/digital converter which is connected to an input of a complex digital multiplier, a controllable digital complex oscillator being connected to the other input of the complex digital multiplier.
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Abstract
The invention relates, inter alia, to a transmitter device, in particular for a base transceiver station in a mobile radio system, which has a digital modulator for making available a signal containing a phase information, and a modulation closed loop having a digital phase comparator operating at baseband whose first input is connected to the output of the digital modulator. In addition, a controllable oscillator is provided for generating an RF transmission signal at a controllable transmission frequency, a device which is assigned to the controllable oscillator and has the purpose of converting the RF transmission signal into a baseband signal containing a phase information. The output of the converter device is connected to a second input of the digital phase comparator.
A GSM transmitter which has such a modulation closed loop exhibits, in terms of its out-band noise and interference characteristics, significantly improved properties in comparison with a GSM transmitter which does not include a modulation loop.
51 Citations
14 Claims
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1. Transmitter device, in particular for a base transceiver station in a mobile radio system, comprising
a digital modulator for making available a baseband signal which contains a phase information and a modulation closed loop having a digital phase comparator whose first input is connected to the output of the digital modulator, a controllable oscillator for generating an RF transmission signal with a controllable transmission frequency, a device which is assigned to the controllable oscillator and has the purpose of converting the RF transmission signal into a baseband signal which contains a phase information, the output of the converter device being connected to a second input of the digital phase comparator, wherein the converter device has an analog/digital converter which is connected to an input of a complex digital multiplier, a controllable digital complex oscillator being connected to the other input of the complex digital multiplier.
Specification