repair and maintenance of 3g cell phone jammer

Improve the selectivity: the receiver frequency selectivity is generally close to the IF amplifier passband by the width of the decision. For the IF amplifier, not only need high gain, good selectivity, but also have enough good pass-band and frequency response, large dynamic range. The receiver adjacent channel selectivity is generally from the IF amplifier pass band width of the decision, the IF signal into a single fixed frequency, the passband can be done to maximize the small, to improve the adjacent channel selectivity. In practice, the general multi-stage amplifier, and to achieve a certain technical requirements for each level. Whether using one or two frequency receiver technology, IF amplifier frequency is always ranked in the following. In order to avoid mirror-frequency interference, improve the image frequency selective, receiver usually the first local oscillation frequency is reduced to improve the first IF frequency and multiple frequency method, the signal from the radio frequency spectrum and gradually move to a lower frequency. Phone circuits are mostly used in all on their own dedicated chip. IF amplifier circuit component separation of form and the form of low-noise amplifier circuit is very similar, but also a common emitter circuit, but their work is not the same frequency. The working instruction also contains the repair and maintenance of 3g cell phone jammer.
The subfactory is putting more money to enhance technology of cell phone jammer . Frequency conversion superheterodyne receiver unit generally have self-excited converter, and it excited converter. If the local oscillator and mixer circuit is completed by the same, for the self-excited inverter; if the local oscillation frequency conversion and signal generation by different devices constitute claimed it as its excited inverter. All phones are powered by it-excited inverter circuit. In this inverter circuit, which we call frequency conversion unit for the mixer. So the drive and the mixer are two different concepts. Self-excited inverter and it excited inverter circuit diagram shown in Figure 4-8 and 4-9. Phone mixer has two inputs and one output, namely: a signal input terminal, a local oscillator input and a signal output. The customer has the stricter requirements for quality of cell phone jammer.
When the inverter output frequency of the LO signal and, and higher than the signal frequency when the inverter is used as top up-conversion. When the inverter output signal for the signal and local oscillator signal frequency difference, and higher than the signal frequency, the frequency used is known as bottom up-conversion. The inverter main circuit for the transmitter. When the inverter output frequency of the LO signal is poor, and lower than the signal frequency, this frequency for the next drive. Phone receiver circuits are down-converter mixer. To do with the non-linear mixing element diode mixer circuit called the diode mixer circuit.