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This lesson talks about the GSM 900 call channel of Huawei mobile phones

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Let's first look at its receiving channel

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The receiving channel starts with the antenna,

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which receives high-frequency electromagnetic waves in the air

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and converts the electromagnetic waves into electrical signals

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The seat number of this antenna is J5703

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The antenna sends the electrical signal to the RF1 pin of the antenna switch U5704,

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and after it is turned on, it reaches the RF3 pin to form a LB_PRX signal

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PRX indicates reception

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There is both reception and transmission on this line, because this is the antenna signal

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The receiving signal of this GSM 900 is a low frequency band, so its code name includes LB

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This receiving signal is given to pin 3 of the filter Z5701,

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the filter removes the clutter and is given to the one pin of the filter

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At this time it is named as the main antenna signal of the low frequency band, MAIN_ANT_LB

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The antenna signal continues to go and reaches the three pins of the filter Z4901

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The filter filters out the clutter again, and then conducts to pin 1 to form a low-frequency antenna signal,

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which reaches pin 31 of the antenna switch U4901, and then switches to pin 7 internally

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Pin 7 is the receiving pin

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Pin 7 belongs to pin B8, which is also the pin of PRX

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This received signal is passed to the receiving chip U5501

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After the power is amplified inside the chip,

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it comes out from the F5 pin and reaches the H5 pin of the receiving chip U6301

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Another power amplification inside U6301 finally reaches pin B7

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After coming out of the B7 pin it reaches the RF transceiver

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The RF transceiver down-converts the high-frequency signal

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and finally sends it to the baseband CPU through the DL pin

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The baseband CPU demodulate it

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This is its receiving channel

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Let's take a look at its launch channel

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The transmit channel starts from the baseband CPU

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UL is Uplink, which is to transmit signals

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The transmit signal is given to the RF

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The radio frequency generates a high-frequency carrier signal,

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and carries this signal containing voice onto the carrier

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Output to GSM power amplifier through AC10 pin

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After reaching the six pins of U4601, the power is amplified internally,

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and it goes out from the seven pins to the 16 pins of the low-frequency antenna switch

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At this time, the antenna switch is turned on, and the transmitted signal will reach the filter Z4901 from pin 31

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After the filter filters out the clutter, it goes out from pin 3, reaches the pin of the total filter Z55701,

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filters out the clutter again, and reaches the RF3 pin of the antenna switch U5704

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The three pins and one pin are turned on, and finally the transmitting signal is sent to the antenna base J5703

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The antenna converts the transmitted high-frequency electrical signal

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into a high-frequency electromagnetic wave and transmits it to the base station

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This is the receiving and transmitting channel of Huawei Mate 30 5G version

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It should be noted here that from pin 31 of U4901 to the antenna end,

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the receiving and transmitting of all channels are shared

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From here to here, their reception and transmission go through the same channel

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After they reach the low-band antenna switch, they separate and go their own way

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This is the GSM 900 calling channel of Huawei mobile phones

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That's all for this lesson