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US 6,563,891 B1Granted
Automatic gain control for slotted mode operation
AssigneeTelefonaktiebolaget L M Ericsson (publ)
InventorsHåkan Bengt Eriksson, Kjell Berthold Gustafsson, Paul Wilkinson Dent
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Abstract
A receiver having a digital automatic gain control (AGC) circuit is disclosed for use in a cellular communication system, including a Hierarchical Cellular System. The receiver includes a controller which switches between gain control values depending on system operational mode. In this way, the AGC can be optimized for different types of receive processing operations, e.g., traffic reception and measurement of other channels.
Claims29
A receiver, comprising:
- an amplifier for amplifying a received signal, the amplifier having gain control by an automatic gain control (AGC) system and producing an amplified signal;
- a state memory for storing a plurality of states, each state comprising a set of parameters stored in mutual association, the parameters including at least a receiver operating mode, a channel frequency, an AGC gain setting value, and an AGC time constant;
- an analog-to-digital converter for converting said amplified signal into a stream of digital values;
- and
- a processor configured to:
- receive said stream of digital values;
- and
- selectively retrieve a state from said state memory, thereby controlling a gain of said gain controlled amplifier using a first of said sets of parameters associated with a first receiver operating mode or alternatively using a second of said sets of parameters associated with a second receiver operating mode or at least a third of said sets of parameters associated with a third receiver operating mode.
5 more elements
A receiver, comprising:
- a gain controlled amplifier having a feedback control loop for amplifying a received signal;
- a mode selector for selecting one of a plurality of modes;
- an analog-to-digital converter for converting said amplified signal into a stream of digital values;
- and
- a processor configured to:
- receive said stream of digital values;
- and
- selectively control a gain of said gain controlled amplifier using a first set of parameter values when said receiver is operating in a first of said plurality of modes, a second set of parameter values when said receiver is operating in a second of said plurality of modes, and at least a third set of parameter values when said receiver is operating in a third of said plurality of modes;
- wherein said processor determines a mean signal level output by said analog-to-digital converter using a low-pass filter, said low-pass filter is a first order filter, said first set of parameter values includes a first filter time constant value and said second set of parameter values includes a second filter time constant value different from said first filter time constant value, and said first order filter includes a settable accumulator, which accumulator can be set by said processor using a value selected from said first, second and third set of parameter values depending upon whether said receiver is operating in said first, second, or third mode of operation, respectively.
6 more elements
A method for controlling a digital automatic gain control (AGC) circuit in a receiver, the method comprising the steps of:
- operating said receiver in a first mode to receive signals on a traffic frequency channel assigned thereto;
- switching to a second mode;
- operating said receiver in said second mode to measure signal strengths associated with frequency channels other than said traffic frequency channel;
- controlling a gain associated with an amplifier in said receiver by using a set of parameter values associated with said second mode of operation to process received signals after said receiver is switched to operate in said second mode, which set of parameter values is different for said first mode than said second mode;
- and
- switching to a third mode of operation of said receiver.
3 more elements
Dependencies are inferred from the claim text.