Modem device and amplitude adjustment method

A modem device comprising:

• a modulation circuit configured to modulate a transmission signal and to generate a modulated signal;
• a frequency conversion circuit configured to convert a frequency of an external input signal and to generate an intermediate frequency signal, the external input signal being input from an external device;
• a demodulation circuit configured to demodulate the modulated signal or the intermediate frequency signal and to generate a reception signal;
• and
• an adjustment circuit configured to adjust amplitude of the transmission signal based on the reception signal, wherein
• in a communication mode for communicating with the external device,
• the modulation circuit is configured to output a first modulated signal to the external device, the first modulated signal being generated using the first frequency set at the time of output to the external device,
• the frequency conversion circuit is configured to convert a second frequency set to the external input signal into the intermediate frequency signal with a third frequency, and
• the demodulation circuit is configured to demodulate the intermediate frequency signal and to generate a first reception signal, and
• in an adjustment mode for adjusting the amplitude of the transmission signal,
• the modulation circuit is configured to output a second modulated signal generated using the third frequency to the demodulation circuit without passing the second modulated signal through the frequency conversion circuit,
• the demodulation circuit is configured to demodulate the second modulated signal and generates to generate a second reception signal, and
• the adjustment circuit is configured to adjust the amplitude of the transmission signal based on the second reception signal.