The material test of Cell Phone Jammers cannot be cancelled

 The material test of Cell Phone Jammers cannot be cancelled.
In the case shown, the signal after the mixer through C460 anyone to FL457, FL457 selected by the 400MHz IF signal, IF signal amplified by Q480 to IF ICU200 demodulation, Q480 bias voltage of C7 by the U200 sent by SW-VCC pin provides. It should be noted: in a conversion superheterodyne receiver circuit, there is an IF amplifier; in the second conversion superheterodyne receiver is usually the first and second intermediate frequency amplifier; in linear direct conversion receiver , there is no IF amplifier. In cell phone communications and cell phone circuit, commonly used demodulation techniques are phase-locked demodulator, quadrature frequency discriminator demodulator. Phase-locked loop (PLL) tracks the input signal can also be used for demodulation. Figure 4-12 is a block diagram of a phase-locked demodulator. Motorola 928 cell phone use is the phase-locked demodulator. Phase-locked demodulator reference signal comes from a 430MHz oscillator. The production task of Cell Phone Jammers of this month is very tense.
Phase detector input by phase comparison of the two signals, the output signal of a frequency modulated signal tracking, through a low pass filter to filter out high frequency noise obtained after demodulation output. Motorola, Nokia and Samsung cell phones are used in phase-locked demodulation circuit. Figure 4-13 for the orthogonal frequency discriminator block diagram. In orthogonal frequency discriminator, the phase shift network will transform the phase change of frequency changes, phase changes in the multiplier will be transformed into voltage changes. FM signal with the phase shift number multiplied by the multiplier low-pass filter output signal to filter out high frequency components, we obtain the demodulated signal. Typically, the circuit in the modern communications equipment, in addition to quadrature coil, the frequency discriminator of the other circuits are integrated on-chip. The workshop arranges three shifts to manufacture Cell Phone Jammers .
It must be noted is this: here said demodulation means to receive radio frequency circuit will contain information on RF or IF signal to restore a 67.707kHz baseband signal demodulation (for GSM cell phones). In logic there is an audio circuit GMSK demodulation, it is 67.707kHz signal to restore the digital signal. Receiver RF section of the demodulator circuit output is the baseband signal receiver, the signal of the center frequency of 67.707kHz. The director is in charge of manufacture supervision of Cell Phone Jammers .