Patent ID: 9413570
Filing Date: 2016-08-09
CPC Classification: H04L,H04W

Claim Text:
1. A mobile terminal test device comprising: frequency designation means for designating an uplink frequency and a downlink frequency which are used for communication based on an FDD system with a mobile terminal to be tested; a transmitting unit that outputs a downlink signal to be sent to the mobile terminal with the designated frequency; a coupler that sends the downlink signal output from the transmitting unit to the mobile terminal and inputs an uplink signal output from the mobile terminal; a receiving unit that mixes the uplink signal input through the coupler with a first local signal which has a predetermined frequency difference from the designated uplink frequency, performs a high-frequency cutoff process on the mixed signal, performs heterodyne conversion on the input uplink signal to convert a frequency of the input uplink signal into a frequency in an intermediate frequency band including the predetermined frequency, converts the heterodyne-converted signal into a digital signal string, and outputs the digital signal string; a quadrature demodulator that multiplies the output from the receiving unit by second and third local signals which have a frequency equal to the predetermined frequency and have a phase difference of 90 degrees therebetween and outputs baseband signals which are orthogonal to each other; a baseband processing unit that receives the baseband signals orthogonal to each other which are output from the quadrature demodulator as an in-phase component and a quadrature component of a baseband signal obtained by modulating the uplink radio-frequency signal and performs signal processing required for testing the mobile terminal; frequency comparison means for comparing the levels of the uplink and downlink frequencies designated by the frequency designation means; heterodyne switching means for setting a frequency of the first local signal to be lower than the uplink frequency by the predetermined frequency such that frequency conversion is performed by a lower-side heterodyne system when the frequency comparison means determines that the uplink frequency is lower than the downlink frequency; and for setting the frequency of the first local signal to be higher than the uplink frequency by the predetermined frequency such that frequency conversion is performed by an upper-side heterodyne system when the frequency comparison means determines that the uplink frequency is higher than the downlink frequency; and baseband switching means for outputting one baseband signal obtained by the multiplication of the second local signal by the quadrature demodulator and the other baseband signal obtained by the multiplication of the third local signal by the quadrature demodulator as an in-phase component and a quadrature component to the baseband processing unit, respectively, when the frequency comparison means determines that the uplink frequency is lower than the downlink frequency; and for outputting the one baseband signal and the other baseband signal obtained by the quadrature demodulator as the quadrature component and the in-phase component to the baseband processing unit, respectively, when the frequency comparison means determines that the uplink frequency is higher than the downlink frequency.