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why I|Q channel for DCR(direct conversion receiver) ?

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vivek1214

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fm receiver dcr

hello to all,
I have doubt in direct conversion receiver(DCR) that why we convert signal in to I and Q component whereas hetrodyne doesnt need this I\Q channel.
 

tigana123

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If I/Q will be used or not depends (among others) on the type of modulation. For example a simple FM receiver may not use I/Q and demodulate the signal directly in an IF freq. However in major communication stds like WCDMA, GSM, OFDM (WLAN, WiMAX) etc. I/Q is used in the signal chain even if the receiver is not direct conversion. For example you can down-convert the signal to an IF and then down-convert I/Q from the IF to baseband. Direct conversion is used because it saves the extra down-conversion stage and all the associated hardware.
 

wwfhm2002

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only I/Q can give you phase information, if you want to demodulator signal from phase information, then you need I/Q, else only I or Q is needed such as FSK demodulator with PLL.
 

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