Digital radio communication apparatus and method of controlling the same

A method of controlling a digital radio communication apparatus, comprising the steps of:

• a) supplying a test RF signal to an RF signal terminal of a radio wave reception unit having an analog filter and a digital filter coupled to said analog filter;
• b) detecting an error occurring in a digital demodulated signal derived from the test RF signal;
• c) temporarily setting a tap factor of said digital filter that reduces a level of the error;
• d) repeating steps a)-c) so as to determine a target tap factor that minimizes the error, and setting the target tap factor in said digital filter to thereby perform equalization adjustment of said digital filter to compensate for a characteristic of said analog filter.

In a combination of a digital radio communication apparatus and a control unit for compensating distortion characteristics in the apparatus;

• said apparatus comprising:
• a radio wave transmission unit for transmitting a radio wave;
• and
• a radio wave reception unit for receiving a radio wave and demodulating the same, said reception unit comprising:
• an analog filter provided in a first stage of said reception unit, and
• a digital filter provided in a second stage of said reception unit so as to compensate a characteristic of said analog filter by having a fiter characteristic of said digital filter varied by varying a tap factor;
• said control unit being aranged externally of said apparatus and being coupled to said reception unit said control unit comprising:
• a test signal generation unit for supplying a test signal to said reception unit;
• an error state detection unit for detecting an error based on a digital demodulated signal derived from the test signal;
• and
• a tap factor setting unit for temporarily setting a tap factor of said digital filter that reduces a level of the error;
• wherein
• supplying of the test signal and detecting of the error are repeated until a target tap factor that minimizes the error is determined, whereupon the target tap factor is set in said digital filter.

A digital radio communication apparatus comprising:

• a transmission unit for transmitting a radio wave;
• and
• a reception unit for receiving a radio wave and demodulating the same, said reception unit comprising:
• an analog filter provided in a first stage of said reception unit;
• a digital filter provided in a second stage of said reception unit so as to compensate a characteristic of said analog filter by having a filter characteristic of said digital filter varied by varying a tap factor;
• and
• a control unit which comprises:
• an error state detection unit for detecting an error based on a digital demodulated signal from said reception unit;
• and
• a tap factor setting unit for temporarily setting a tap factor of said digital filter that reduces a level of the error;
• said control unit being built in said apparatus to perform equalization adjustment of said digital filter to compensate for a characteristic of said analog filter when said apparatus is not in use, wherein setting of the tap factor and detecting of the error are repeated until a target tap factor that minimizes the error is determined, whereupon the target tap factor is set in said digital filter.

A digital mobile radio communication apparatus for performing communication via a base station of a digital mobile communication system, said digital mobile radio communication apparatus comprising:

• a radio wave transmission unit for transmitting a radio wave;
• and
• a radio wave reception unit for receiving a radio wave and demodulating the same, said reception unit comprising:
• an analog filter provided in a first stage of said reception unit;
• a digital filter provided in a second stage of said reception unit so as to compensate a characteristic of said analog filter by having a filter characteristic of said digital filter varied by varying a tap factor;
• and
• a variable tap count control unit for variably controlling the number of effective taps of said digital filter depending on conditions that occur in communication, wherein said variable tap count control unit temporarily reduces attenuation provided by said digital filter with respect to an adjacent channel so as to detect a current reception state, and updates the number of effective taps of said digital filter depending on a result of the detection.

A digital mobile radio communication apparatus for performing communication via a base station of a digital mobile communication system, said digital mobile radio communication apparatus comprising:

• a transmission unit for transmitting a radio wave;
• and
• a reception unit for receiving a radio wave and demodulating the same, said reception unit comprising:
• an analog filter provided in a first stage of said reception unit:
• a digital filter provided in a second stage of said reception unit so as to compensate a characteristic of said analog filter by having a filter characteristic of said digital filter varied by varying a tap factor:
• a variable tap count control unit for variably controlling the number of effective taps of said digital filter depending on conditions that occur in communication;
• a monitoring control unit for monitoring a usage of a bandwidth for an adjacent channel, using unoccupied time in communication, wherein
• said variable tap count control unit updates the number of effective taps of said digital filter depending on a result of the monitoring by said monitoring control unit.