Different designs of analog fiber-optic lines (FOCL) for transmitting information at different distances in different frequency ranges are considered. The peculiarities of optical analog signals transmission, which will influence its registration in the FOCL photodetector module, are noted. The format of analog signals to be transmitted over a FOCL over a distance of more than 500 km without the use of optical amplifiers was determined. A photodetector module of the type PDA 400 Thorlabs with a peak response of 0.95 A/W at 1550 nm is considered. The bandwidth of which is from DC to 10 Mhz. Response: from 800 to 1750 nm. Based on the calculation of various parameters of the FOCL and its energy balance, the requirements to the design and characteristics of the photodetector module were determined. A laboratory mockup of the photodetector module was assembled. The results of its operation as a part of the analog FOCL with different ranges of information transmission are presented.