A wireless communications apparatus, comprising: a local oscillator circuit, configured to output local oscillator signals; a digital frequency converter, configured to perform a digital frequency conversion operation on a to-be-transmitted signal, to obtain a digital frequency conversion signal, and output the digital frequency conversion signal, wherein the digital frequency conversion signal comprises a first digital frequency conversion signal in a first time period and a second digital frequency conversion signal in a second time period, wherein the digital frequency converter is adjusted in an intermediate time period between the first time period and the second time period, wherein the first digital frequency conversion signal corresponds to a first sounding reference signal, SRS, to be transmitted on a first carrier, and the second digital frequency conversion signal corresponds to a second SRS to be transmitted on a second carrier; and a frequency mixer respectively coupled to the local oscillator circuit and the digital frequency converter, configured to sequentially receive the first digital frequency conversion signal and the second digital frequency conversion signal, and respectively perform analog frequency conversion operations on the first digital frequency conversion signal and the second digital frequency conversion signal based on local oscillator signals at a same frequency that are provided by the local oscillator circuit, to transmit the first SRS on the first carrier in the first time period, and transmit the second SRS on the second carrier in the second time period, where the second time period is later than the first time period. a local oscillator circuit, configured to output local oscillator signals; a digital frequency converter, configured to perform a digital frequency conversion operation on a to-be-transmitted signal, to obtain a digital frequency conversion signal, and output the digital frequency conversion signal, wherein the digital frequency conversion signal comprises a first digital frequency conversion signal in a first time period and a second digital frequency conversion signal in a second time period, wherein the digital frequency converter is adjusted in an intermediate time period between the first time period and the second time period, wherein the first digital frequency conversion signal corresponds to a first sounding reference signal, SRS, to be transmitted on a first carrier, and the second digital frequency conversion signal corresponds to a second SRS to be transmitted on a second carrier; and a frequency mixer respectively coupled to the local oscillator circuit and the digital frequency converter, configured to sequentially receive the first digital frequency conversion signal and the second digital frequency conversion signal, and respectively perform analog frequency conversion operations on the first digital frequency conversion signal and the second digital frequency conversion signal based on local oscillator signals at a same frequency that are provided by the local oscillator circuit, to transmit the first SRS on the first carrier in the first time period, and transmit the second SRS on the second carrier in the second time period, where the second time period is later than the first time period.