The signal amplifier is a miniature repeater, also known as a mobile phone signal amplifier/repeater/booster/extender. From its name, we know that the function of the signal amplifier is to amplify the signal. There are many types of signal amplifiers, such as TV signal amplifiers, radio amplifiers, etc. All receivers have signal amplifiers. Amplifiers that specifically amplify mobile phone signals are called mobile phone signal amplifiers, which are mainly used to solve the problem of indoor mobile phone signal blind spots.

        The use of repeaters as one of the necessary means to achieve the goal of "small capacity and large coverage" is mainly due to the use of repeaters to ensure network coverage without increasing the number of base stations, and its cost is much lower than that of existing systems. Microcellular systems with the same effect. Repeater is a preferred solution to solve the ability of communication network to extend coverage. Compared with the base station, it has the advantages of simple structure, less investment and convenient installation. In various places such as highways and islands, improve the communication quality, solve the problem of dropped calls, and optimize the wireless communication network.

Amplify and filter

        The output of the pre-stage instrumentation amplifier is buffered into the secondary amplifier, which is a programmable gain amplifier PGA. The amplified signal has the flattest frequency response characteristic after filtering. The filter is an 8th-order low-pass filter, which can be programmed Set the cut-off frequency from 10Hz to 100KHz, the secondary filter is a second-order active low-pass filter, which is used to eliminate digital interference, the secondary of the low-pass filter can be optionally added with a band-pass filter, and the lower limit cut-off frequency is set by a toggle switch , low-pass and band-pass filters can be controlled to access or skip.

Zero-level self-calibration

        The self-calibration solution realizes the zero-level calibration of the analog channel and eliminates the zero-point error under different gain and filtering states. This calibration is done automatically by the hardware. The relevant calibration parameters have been calibrated before leaving the factory and stored in the EEPROM on the module , the user does not need to operate this function in normal use. If you need to modify the calibration parameters stored in the EEPROM, you need to run the calibration software provided with the product to complete the reset of the calibration parameters.

The repeater is in the downlink. The donor antenna picks up the signal in the existing coverage area of the base station, and the band-pass filter is used to isolate the out-of-band signal. The filtered signal is amplified by the power amplifier and then transmitted again. to the area to be covered. In the uplink path, the signal of the mobile station mobile phone in the coverage area is processed by the uplink amplification link in the same working mode and then transmitted to the corresponding base station, so as to achieve the signal transmission between the base station and the mobile phone. The types of repeaters can be divided into broadband repeaters, frequency-selective repeaters, optical fiber repeaters, frequency-shift repeaters, and trunk amplifiers according to the actual application. For some other special applications, there are also some other kinds of repeaters. Repeater equipment is an electronic device. In addition to some accidental failures due to human factors, various failures often occur due to environmental influences, sudden changes in operating conditions, and aging of component performance during operation.

        This is a relatively common phenomenon, and many residential buildings in urban areas have cell phone base stations installed. Some citizens worry about whether the electromagnetic radiation generated by such a device will harm the human body. Actually, there is no need to worry about this issue. Mobile phone radiation is different from mobile phone base station radiation. Generally, the electromagnetic radiation value of a mobile phone is between 0.03-0.7, while the radiation value of a mobile phone base station is 10 microwatts. The radiation value produced by a cell phone base station is not much higher than that of a cell phone! Speaking of which, it is worth mentioning that when the mobile phone signal is poor, the mobile phone will continue to search for signals, and the radiation generated at this time will greatly increase. It is harmful to the human body to stay in such an environment for a long time.

        In addition, the closer the distance and the longer the exposure time of electromagnetic radiation, the deeper the damage! And the mobile phone base station installed on the roof of our general residential building is a safe distance from us, so everyone can rest assured.

Output power, gain, automatic gain control

        This is a set of interrelated indicators that should be considered together.

        Usually, the maximum output power should be divided into several grades for users to choose if the maximum output power does not exceed the maximum limit specified by the Radio Administration of the Ministry of Information Industry. Therefore, the downside is generally greater than the upside.

        Gain is the amplification of the received signal to the rated output power. The gain should be adjustable to take into account the difference in signal strength where the repeater is installed. The maximum gain can be calculated by considering amplifying the signal level received by the repeater to the maximum output power.

        To ensure stable output power and avoid output nonlinearity, automatic gain control (AGC) with ≮20dB appears to be necessary.

        Regarding tolerance, rated output power and rated gain, it is enough to specify one. Generally, it is more appropriate to specify the gain tolerance. Because the gain is adjusted to the maximum during the test, the input level is changed to bring the output to the rated value. In this case, of course, the power rating does not have to specify a tolerance, and in this case, the input level also varies with the gain.

Bandwidth, in-band fluctuation

        This is a set of interrelated metrics, especially bandwidth and in-band fluctuations.

        Typically, bandwidth refers to the -3dB bandwidth, while in-band fluctuation refers to the in-band unevenness. If the in-band fluctuation is required to be smaller than 3dB, the -3dB bandwidth must be wider than the bandwidth allocated to it, so other channels are bound to be occupied. Therefore, the in-band fluctuation can only be a maximum of 3dBp-p.

Out-of-band suppression

        Out-of-band rejection is primarily a requirement for filter shape. In order not to interfere with others, it is hoped that the shape of the filter should be as close to a rectangle as possible. It is usually measured as the ratio of -60 (or -40) dB bandwidth to -3 dB bandwidth (some people call it the shape factor of the filter).

        Note: Mobile phone signal boosters sold online often use dielectric filters with poor out-of-band suppression, and generally use IF SAW filters to meet the band suppression requirements.

Intermodulation and spurious emissions

        Harmonics, intermodulation, and spurs are all unwanted and unwanted signals that can make the same request.

        For the GSM mobile phone signal booster, it is suitable to meet the requirements of YD/T 883-1999 and ETS 300 609. For the CDMA mobile phone signal booster, it is only required to meet the requirements of YD/T 1047-2000.

Waveform quality

        CDMA base stations have requirements for waveform quality (Rho). After the mobile phone signal booster transmits CDMA signals, this indicator may deteriorate, so one should be specified.

Transmission delay

        After the signal passes through the repeater, transmission delay may occur.

        The transmission delay of broadband repeater is relatively small, generally around 1μs; the transmission delay of frequency selection and frequency-shift mobile phone signal booster is relatively large, which may reach 5μs and 10μs respectively.

Noise Figure

        This is the characterization of the repeater's sensitivity. At the technical level around 2010, the noise figure is about 4-6dB.

VSWR

        In order to ensure efficient power transfer, it is necessary to put forward the requirement of voltage standing wave ratio. Depending on the amount of power being reflected and the actual level, it is feasible to require less than 1.4 to 1.5.

        These are the parameters for judging the performance of mobile phone signal amplifiers, hoping to help you better understand what a mobile phone signal amplifier is.