The first thing that catches your eye is a huge circuit board, the reason why it is huge, is completely compared with the fiber optic host in the previous life, the host in the previous life is very small, and someone's face is so big, and now this is probably so big with countless faces. Pen | fun | pavilion www. ｂｉｑｕｇｅ。 ｉｎｆｏ

The sound source of the host is a cassette tape, and those who have listened to the cassette know that its noise background is very large, especially in the gap between syllables, especially obvious, and it does not reflect the various subtle layers of a song at all.

The optical fiber processing circuit of the switch used does not pay attention to the details of the music, because their requirements are fundamentally different, it only needs to be able to make the person answering the phone hear what the other party is saying.

With so many flaws coming together, it's no wonder that the sound quality is so good. Such an alternative structure of the wonderful optical fiber system, it is really an eye-opener for Ye Kai, no wonder in the previous life until long after the advent of plastic optical fiber, optical fiber was officially applied to in-car entertainment. It's not that no one thought of applying optical fiber in this way, but because the optical fiber at this time really has no practical application value in it!

Ye Kai remembers very well that in the previous life, optical fibers passed through glass optical fibers, stone fiber optical fibers, and finally plastic optical fibers were finalized and began to be promoted and applied worldwide.

That's because plastic optical fibers have the advantages of high bandwidth, no crosstalk, low price, and no radio waves and electromagnetic interference, so plastic optical fibers can be used in vehicle communication and audio-visual systems. The communication network and control system of the on-board machine form a network, and the peripherals such as microcomputers, satellite navigation equipment, mobile phones, and faxes are incorporated into the overall design of the locomotive. Passengers can also enjoy music, movies, video games, shopping, Internet and other services from their seats through a plastic fibre optic network.

The reason why the optical fiber system used in the car in the previous life is called MOST is actually because there are multiple devices in this system, and these devices are connected in series with optical fibers in a ring structure, so it is called MOST (ring network). The advantage of this series connection is that control data and music data can be easily transmitted through a single optical fiber; The disadvantage is that in these devices connected in series, if one of the devices has a problem and the signal transmission is interrupted, then the whole system is paralyzed and cannot be used.

The plastic optical fiber connection cable used for MOST is composed of a special plastic optical cable for MOST with pins, housings, housing covers, dust caps, bellows, etc., which meet MOST standards. It is mainly used in multimedia entertainment system, GPS, car phone and other functions, with the characteristics of large amount of transmitted data, small loss, fast speed and strong anti-interference.

It is based on PMMA fiber as well as red LEDs (650 nm) and is used to connect to the optical data bus standard for in-car entertainment systems. For example, it enables optical interconnection between CD and DVD players, tuners, LCD displays, and GPS navigation systems.

The bus is operating at a rate of 25M, but is planning to increase to 50M and 150M. The standard was developed in 1995 after the German property rights company united more than 10 European and American car manufacturers.

In the past, BMW in Germany laid 50 meters of plastic optical fiber in the BMW 7 series, which was launched in March 2002. This long optical fiber system contains two data transmission methods: one is the "MOST" of the information system, and the other is the "safety system critical circuit" of the control system. The length of plastic fiber used in the entertainment system MOST is 7 meters, and the length of fiber used in the safety critical circuit is 43 meters.

Since then, at least 16 models in Europe have been equipped with the MOST communication system.

Thinking of this, Ye Kai straightened his waist and said to Hamer: "Your idea of designing entertainment equipment according to the optical fiber system of the switch is really very good, but it can't be transformed according to the current system. Because there is already a digital switch on the market, I think it is better to set this communication system according to the data structure level of the telecom digital switch. ”

"Data is transferred using defined blocks, each of which contains synchronous, asynchronous, and control data in addition to the preamble and other internal management bits. The buses are fully synchronized, and designers can designate any device in the network as the master, and all other nodes get their own clocks from the master. The network is completely plug-and-play, and there is a process of finding devices when there is power on or when there is a change in connectivity. A central registry of connected devices is maintained on the primary node. ”

"The above is about the software setting of MOST, and the hardware is also designed with reference to the optical fiber circuit of the switch." Ye Kai saw Hammer nodding and continued. "First of all, there is no need for such a high-power photoelectric conversion module as the switch, but this module still retains the transmitter and receiver that are only available in the switch, as well as their respective amplification, data slicing, and pulse width correction circuits, the former is used to send the electrical signal in the form of light, and the latter is naturally to receive the light emitted by the previous circuit and convert the light into an electrical signal."

"Both of these signals need to be handed over to our specially customized fiber processing integrated circuits, which process the audio data and control data contained in the fiber optic signal separately, because the sound system with the fiber optic system is to separate the individual components and then connect them with optical fiber."

In the previous life, a simple MOST system was composed of a control panel, a multimedia processing box, a front-mounted six-disc CD player, a radio component, and a power amplifier.

The control signal of the control panel is converted into optical signals through the MOSTIC of the multimedia control box, and when this system is designed, the front six CD, radio components, power amplifiers, etc. have been numbered in the software, tentatively set as 1, 2, 3. When it is necessary to transmit data to that functional module, at the time of transmission, the optical fiber data sent has been numbered, and after receiving the data, the MODTIC of each module first judges whether the data is sent to itself, if not, then it is transmitted to the next module intact.

If so, then the instructions will be parsed out, passed to the CPU of this function module to execute the command, and at the same time, the working status of this module will be transmitted to the media box, of course, if it is detected that it is audio data, then it will be directly passed to the power amplifier.

Ye Kai continued to talk about the above ideas to Hammer in a different language, and Hammer was greatly inspired, and immediately said that he would have a good understanding of the working principle of the optical fiber circuit and the underlying protocol of the digital switch.

"Boss, what's the name of this system?" Finally Hammer asked.

"Let's call it a ring network." Ye Kai replied without thinking. "Abbreviated as the MOST system."