A pressure connection structure with coaxial cables, which can reduce the number of steps for terminal processing of ultra-thin coaxial cables or simplify the process. The device is placed in a swimming pool and submerged to a selected level. The focused beam of light is capable of penetrating several centimeters of tissue to deliver measurements and images associated with individual blood vessels and other discrete vascular components. The modem response signal is determined to be either an analog modem response signal or a digital modem response signal, and then the call is connected to either the analog modem or digital modem based on the modem response signal determination.