As two types of optical terminals, digital optical terminals and analog optical terminals need to know their technical principles before they are used, so as to use them better. The following optical terminal series takes you to know about it.
1. Digital optical transceiver has obvious advantages in many aspects compared with traditional analog technology, so just as digital technology has replaced analog technology in many fields, the digitalization of optical transceiver is also an inevitable trend. At present, there are two main technical ways of digital image optical transceiver: one is MPEGII image compression digital optical transceiver, and the other is uncompressed digital image optical transceiver. Image compression digital optical terminals generally adopt MPEGII image compression technology, which can compress moving images into N×2Mbps data streams and transmit them through standard telecommunication interfaces or directly through optical fibers. Because of the image compression technology, it can greatly reduce the signal transmission bandwidth.
2. Analog optical terminal Analog optical terminal adopts PFM modulation technology to transmit image signals in real time, which is one of the most widely used ones at present. At the transmitter, the analog video signal is modulated by PFM (generally, there are frequency modulation, phase modulation and amplitude modulation, so that the analog optical transceiver can be divided into frequency modulation, phase modulation, amplitude modulation and other optical transceivers), and then the optical signal is converted to electricity, and then the optical signal is demodulated by PFM to recover the video signal. Due to the use of PFM modulation technology, its transmission distance can easily reach about 3Km, and the transmission distance of some products can reach 6Km or even hundreds of kilometers. Moreover, the image signal has little distortion after transmission, high signal-to-noise ratio and little nonlinear distortion. By using wavelength division multiplexing technology, two-way transmission of image and data signals can also be realized on one optical fiber.