Combiner

In a communication system:

Close way is mainly used to multiple system signal close road to a set of indoor distribution system.

In practical application, you need to 900MHz 800MHZ C nets and the G nets two kind of frequency close road output. Using close way, can make a set of indoor distribution system at the same time working on CDMA and GSM frequency band.

Also like in the radio antenna system, to bring several different frequency band (such as 145MHZ and 435MHZ) input and output signals through close way, with a close road after root feeders with radio connection, it not only saves a root feeder, avoids the switching different antenna of trouble.

Principle:

Will signal mobile phone is received and sent to a combination of root aerial. In GSM system, because transceiver were in the same time, so mobile phones can save used to isolate transceiver a duplex device, and just use simple transceiver close way can be a mail, sending signals to a combination of root antenna without mutual interference.

On receiving circuit, signal receiving antenna will close down through the way into receiving channel, and receive the vibration signal (namely frequency synthesizer signal generated receiving VCO) frequency mixing, will become the high frequency signal frequency signal, and then to signal the orthogonal demodulation, produce receiving I, Q signals, And then gaussian filtering GMSK (minimum FSK) demodulation, the analog signals into digital signals, then into baseband processing unit.

To launch circuit, by baseband part sent TDMA frame data flow (rate for 270.833 kbit/s) GSMK modulated launch I, Q signals, again to mail up converter modulation to launch frequencies, through power amplifier after the way the antenna emitted.

Frequency synthesizer for sending and receiving unit provides necessary vibration frequency of the signal, using phase locked loop technique to stable frequency, it from the benchmark circuits get KMZ benchmarks.

Clock benchmark circuits is commonly 13MHz clock, on the one hand, for frequency synthesis circuits provide clock benchmark, on the other hand to logical circuit provide job clock.