The school adopts 15 sets of directional cell phone jammer

It is very important to test shielding radius of  cell phone jammer .Phase detector referred to as PD, PH, or PHD (PhaseDetector). A phase comparator, which changes the phase of VCO oscillating signal is transformed into voltage changes, the phase detector output is a pulsating DC signal, the pulse DC signal low-pass filter (LPF) to filter out high frequency components after control the VCO circuit. Phase detector is a phase comparator, its input reference signal generated by the VCO phase comparison signal input, two output reflects the phase error signal error voltage. Phase detector is varied, with numbers, but also simulated. Such as dual-port phase detector, PFD, etc.  cell phone jammer  can work as long as the antenna is collectively connected.
When using digital phase detector, because of its dual-port output output: In connection with the loop filter on a problem. Usually added in between a double-ended input single-ended output, and can phase detector output phase error signals correctly reflected in the circuit, this circuit is known as the charge pump or the pump circuit. Motorola's GSM mobile phone, its transmitter frequency synthesizer basically uses the pump circuit. In the frequency synthesizer, in order to make accurate phase comparison, the phase detector is working in a low state. In the mobile phone circuit, the phase detector is usually integrated with the divider is a dedicated chip, the chip is often referred to as PLL (phase locked loop), or integrated in a complex chip (the chip that contains a variety of function of the circuit). This kind of cell phone jammer  has its own characteristics
Selling on the internet is also a kind of sales channels for  cell phone jammer . Phone frequency synthesis loop and more loop frequency synthesizer using a different divider different: the receiver first local oscillator (RXVCO, UHFVCO, RFVCO) signal with the channel change, and the frequency synthesizer in the loop divider is a programmable divider, the divider ratio is controlled by the data signal frequency synthesizer (SYNDAT \ SYNCLK, SYNSTR). Two oscillator VCO, also known as the IF VCO (1FVCO, VHFVCO), the signal is fixed, IF VCO frequency synthesis loop in the divider ratio is fixed. Divider output signal to the phase detector, and the reference clock signal for phase comparison.  cell phone jammer  has the various sales channels and selling modes.
When the VCO is in normal working condition, VCO output a fixed frequency. If some external factors such as voltage, temperature can cause the VCO frequency is increased, the frequency output signal is f2 / N n higher than the reference signal, the phase detector to detect the changes, the output voltage decreases, the varactor both ends of the reverse bias decreases.