Patent ID: 7668234
Filing Date: 2010-02-23
Classification: H04B

Abstract:
1. A test signal generating apparatus for communications equipment, comprising: a pair of waveform memories in which I component waveform digital data (hereinafter, referred to as I waveform data) and Q component waveform digital data (hereinafter, referred to as Q waveform data) which configure a set of digital baseband quadrature signals I and Q in at least one or more types of unit data serving as sources of a test signal to be finally output, are respectively stored in advance at predetermined addresses; a read control unit to sequentially output the I waveform data and the Q waveform data from the pair of waveform memories; a pair of multipliers to set signal levels of the I waveform data and the Q waveform data which are sequentially output from the pair of waveform memories to desired signal levels, respectively; a pair of digital-to-analog converters which convert the I waveform data and the Q waveform data which are sequentially output from the pair of multipliers into an I waveform analog signal and a Q waveform analog signal, respectively; a frequency offset unit which sets offset frequencies for providing frequency offsets at a plurality of steps at predetermined intervals by using a predetermined carrier frequency provided to the test signal as a reference, with respect to the I waveform data and the Q waveform data between the pair of waveform memories and the pair of digital-to-analog converters; a sequence memory which stores in advance: (i) first sequence information including a reading order and read addresses of the unit data including the I waveform data and the Q waveform data stored in the pair of waveform memories, and the desired signal levels to be set in the unit data including the I waveform data and the Q waveform data read from the pair of waveform memories; and (ii) second sequence information including the offset frequencies set for providing frequency offsets at a plurality of steps at predetermined intervals by using the predetermined carrier frequency provided to the test signal as a reference, with respect to the unit data including the I waveform data and the Q waveform data read from the pair of waveform memories; a sequence control unit which (i) reads the first sequence information from the sequence memory, instructs the read control unit about the reading order and the read addresses included in the first sequence information, thereby causing the read control unit to sequentially output the I waveform data and the Q waveform data from the pair of waveform memories, and instructs the pair of multipliers about the desired signal levels included in the first sequence information in response to a timing at which the I waveform data and the Q waveform data are output from the pair of waveform memories, thereby causing the pair of multipliers to set signal levels of the I waveform data and the Q waveform data which are sequentially output from the pair of waveform memories respectively to the desired signal levels; and (ii) reads the second sequence information from the sequence memory, and instructs the frequency offset unit about the offset frequencies included in the second sequence information, thereby causing the frequency offset unit to set the offset frequencies for providing frequency offsets at a plurality of steps at predetermined intervals by using the predetermined carrier frequency provided to the test signal as a reference, with respect to the unit data including the I waveform data and the Q waveform data; and a test signal output unit which converts the I waveform analog signal and the Q waveform analog signal which are sequentially output from the pair of digital-to-analog converters into a high-frequency signal by using a carrier frequency signal after carrying out quadrature modulation to the signals, thereby causing the high-frequency signal to be output finally in the form of the modulating signal and as a test signal along with frequency offsets at a plurality of steps at predetermined intervals by using the predetermined frequency as a reference.