Provided is a transmission system including: a signal processing apparatus 2 configured to transmit, via a signal cable 4, a delta-sigma modulated signal obtained by performing delta-sigma modulation on a transmission signal that is an RF signal; and a wireless apparatus 3 configured to transmit, via the signal cable 4, a reception signal that is an RF signal. The signal processing apparatus 2 transmits the delta-sigma modulated signal to the wireless apparatus 3, and the wireless apparatus 3 transmits the reception signal to the signal processing apparatus 2. In the delta-sigma modulated signal, quantization noise is suppressed at the frequency of the reception signal. The reception signal is transmitted to the signal processing apparatus 2 while the delta-sigma modulated signal is being transmitted to the wireless apparatus 3.