Walkie-talkie PCB copy board and technical principles of analytical

  Walkie-talkie is very common in the field of various types of residential security systems, community mobile communication terminals, Tang Technology has many years of development experience in the walkie-talkie reverse technology, and continue to follow the latest technology trends successful generic development a series of high-end type walkie-talkie.
    For all types of walkie-talkie products, customers need only provide a complete set of prototypes, Tang will be able to provide a complete set of walkie-talkie technology file from the PCB copy board, the decryption chip, circuit board cloning, shape, mold imitation, to provide customers with software anti- compilation of generic components, the entire clone of the prototype, prototype debugging, mass production, processing and complete technical service.
    At present, many Tang science and technology in the field of the interphone reverse engineering the outcome of cases, involving more than one product model and type, and accumulated a wealth of products and a full set of technical information, and provide product technical data transfer services and products to assist the majority of electronics researchers technology research and routine maintenance repairs. In this, the inconvenience to the various models and detailed information list, Tang Technology engineers only a brief analysis of the technical principles of the walkie-talkie and regular maintenance for your reference.
    Walkie-talkie composition of the structure:
A transmitter:
RF carrier signal phase-locked loop and voltage-controlled oscillator (VCO) to produce the launch, incentive enlarge buffer amplifier, power amplifier, resulting in nominal RF power, antenna, low-pass filter, and suppress the harmonic components, and then through the antenna out .
2, receiving parts:
Receiving part of the double-conversion superheterodyne way from the antenna input signal through the transceiver circuit and band-pass filter after RF amplification, amplify the signal from the RF bandpass filter into a mixer, and to since the PLL frequency synthesizer circuit of the first local oscillator signal and generates a first intermediate frequency signal in the mixer at mixing. The first intermediate frequency signal through the crystal filter to further eliminate the clutter of the adjacent channel signal. Filtered first IF signal into intermediate frequency processing chip, again mixing with the second local oscillator signal to generate a second IF signal, the second IF signal is filtered through a ceramic filter unwanted spurious signal after amplification and frequency discrimination to produce the audio signal. Audio signal through amplification, band-pass filter de-emphasis circuit, zoom into the volume control circuit and power amplifier drives the speaker to get people the information needed.
3, the modulation signal modulation circuit:
The human voice through a microphone to convert the audio signal, audio signal amplifying circuit, pre-emphasis circuit and band-pass filter into the VCO direct modulation.
4, signal processing:
The CPU generates CTCSS / DTCSS signal after amplification adjustment, enter the VCO modulation. Receive low-frequency signal after the frequency discriminator, in part through amplification and sub-audio band pass filter to filter shaping, into the CPU, and the default value to compare to control the output of the audio amplifier and speakers. That is, if the preset value, then turn on the speaker, if different, then turn off the speaker.
* Use the walkie-talkie will have radiation?
Walkie-talkies designed to comply with the relevant provisions of the Ministry of Information Industry [2001] No. 869 document, will not harm the human body, and when not to use the walkie-talkie to call close to the body, but from the body 5-7 cm call.
* Affect the walkie-talkie call distance and the effect of factors in the following areas:
1, the system parameters:
1) Transmitter output power, the stronger the greater the emission signal coverage, the communication distance is farther. Transmit power can not be too large, the transmit power is too large, not only power consumption, affecting the life of the amplifier components, but also interfere with the strong influence others talk performance, but also produce radioactive contamination. National radio regulatory organ for the transmission power of the communications equipment are clearly defined.
2) communication machine, the higher the receiver sensitivity, communication from the more distant.
3) the antenna gain, antenna and machine match Typically, the antenna height increases the ability of receiving or transmitting. Hand-held walkie-talkie antenna is generally spiral antenna, its bandwidth and gain than other types of antennas to be smaller, more vulnerable to human impact.
Two environmental factors:
Environmental factors, the main path, the density of trees, environmental electromagnetic interference, buildings, weather conditions and terrain and differences. These factors and other parameters directly affect the signal field strength and coverage.
Other influencing factors:
1) low battery, low battery, call quality will deteriorate. Severe, there will be noise and affect the normal call.
2) The antenna matching, inconsistent band antenna and machine band, the antenna impedance mismatch, will seriously affect the distance calls. For users, switching the antenna to pay attention to tightening the antenna, the other can not just use the antenna provided by non-manufacturers can not use the machine frequency antenna.
3) The sound quality is good or bad depends largely on the pre-emphasis and de-emphasis circuit, there are more advanced voice processing circuit voice compression and expansion circuits and the application of low-level expansion circuit, have a good effect for fidelity voice.
4) factors that affect the distance and the effect of push to talk with the seasons, summer better than winter.
The walkie-talkie host What are the main components?
1, housing:
Professionals are generally very good performance plastic material PC + ABS, the appearance of gloss, easy to aging, wear, durable products; commercial machine often used in engineering plastic ABS, in appearance, strength, resistance to abrasion, aging and other aspects can be good to meet the requirements; key to using silica gel, wear-resistant and difficult to aging, feel good; aluminum case with lightweight materials aluminum alloy ADC12, easy molding and subsequent processing.
2, the host:
Generally include the shell surface, the PTT button, headphone, and power jack plugs, PCB components, LCD part of the volume / switch button, encoding knob, the light, the MIC and so on. The PTT button to launch the switch, usually in the side. LED indicates the working state, generally at the top. Walkie-talkie at the top of there volume / switch button and encoding knob (to select the channel). LCD part of the visual display the working status of the walkie-talkie. PCB assembly is a core part of the walkie-talkie, important devices on the PCB, non-professionals are not allowed demolition. Most of the walkie-talkie because of technical performance and anti-fall features, specialized shield Lvqiao (fixed the PCB) and other. Professional machine water requirements, more complex structure.
3, the battery:
Points in the Ni-Cd, Ni-MH batteries and Li-ion battery, the battery capacity of 600mAh, 800 mAh, 1100 mAh, 1500 mAh ranging. Cost of lithium batteries are more expensive, is still in development stage. Ni-Cd and Ni-MH battery use is more prevalent, the general large-capacity battery is recommended to use Ni-MH batteries. Battery surface, the bottom shell by ultrasonic welding, solid and reliable.
4, the belt clip:
The role of the walkie-talkie fixed for customers easy to use, the belt clip removable belt.
5, the antenna:
Divided into two parts of the antenna jacket and antenna core. Coat the antenna with a high-performance TPU material, the flexural resistance and aging properties of good; antenna core general thread structure and connected to the host, to facilitate the demolition.
6, the cradle:
Shared with the AC adapter to charge the battery or the whole. The structure generally has a DC outlet, charging shrapnel, lights, buttons and other. DC socket connected to the AC adapter, shrapnel and battery pole piece connected to the light displays charge status button to play the role of discharge. The Charger generally charge the battery and the machine.
7 Furthermore, the walkie-talkie, holster, headset, and other ancillary products
Why * the use of walkie-talkie frequency limit?
To ensure that the vast majority of users to call interference and rational use of frequency resources, the management committee of the national wireless units on the use of frequency division, requiring different industries using the appropriate frequency range. Buy the walkie-talkie radio to the local management committee for the frequency.
* What is a public radio?
Public radio means: launch power less than 0.5W, walkie-talkies work in the specified frequency, the radio transmitting frequency, power and other RF technology indicators shall meet the following requirements:
1, the operating frequency (.9000; 409 Unit: MHz): 409.7500, 409.7625,409.7750,
   409.7875, 409.8000, 409.8125, 409.8250, 409.8375,
   409.8500, 409.8625, 409.8750, 409.8875, 4099125, 409.9250,
   409.9375, 409.9500, 409.9625, 409.9750,409.9875;
2, the modulation method: F3E;
3, the effective radiated power (EIRP): <0.5W;
4, the emission frequency tolerance: <+5 ppm;
5, the transmitter spurious radiation: <50uW;
Receiver spurious radiation: <20nW The;
7, the channel spacing: 12.50kHz.
* Interphone regular maintenance
1, walkie-talkies long-term use, according to health, control knob and the case is very easy to dirty, remove the control knob from the transceiver, and a neutral detergent (do not use strong corrosive chemicals) and a damp cloth to clean the cabinet. The use of chemicals such as detergents, alcohol, spray or oil preparations may cause the the interphone surface and damage to the shell.
2, gently put the walkie-talkie, not hand-held antenna mobile walkie-talkie.
3 NA attachment, covered with dust cover (if equipped).
* Walkie-talkie to use safety precautions
A car with airbags, not to the possible scope of the walkie-talkie on the deployment of the airbag. If the transceiver is in the deployment of the airbag may be involved in region-wide, once the balloon rapidly, walkie-talkies may hurt the officers inside with great impact.
2, in a potentially explosive atmosphere or occasion, unless the walkie-talkie special certification or to close down the walkie-talkie. In a potentially explosive atmosphere, the spark can cause an explosion or fire.
3, do not replace the batteries in a potentially explosive atmosphere or charge the battery. Installation and removal of the battery may cause the contact spark and cause an explosion.
4, near the blasting area and detonators region must switch the transceiver in order to avoid a possible explosion.
* Interphone Handling Precautions
1, when the walkie-talkie is being launched to keep the walkie-talkie in a vertical position, and keep the microphone and mouth 2.5-5 cm distance. Launch, the walkie-talkie from the head or body of at least 2.5 cm. If the hand-held walkie-talkie carrying the body on the launch, the antenna from the body of at least 2.5 cm.
2, the process of using multiple boot off action, while the volume was adjusted to a volume suitable for your hearing.
* Precautions when using batteries
Original or recognized by the battery.
2, if the metal conductor such as jewelry, keys, or beads practice reach the bare battery electrode, all the batteries may cause damage or personal injury. Please be careful to treat the battery has been charged, especially when it into a pocket, wallet or other metal containers, need special attention.
3, the charge should be 5 to 40 degrees in the environment. If you exceed this temperature range, battery life be affected, while there may be sufficient dissatisfaction with the rated capacity.
* Antenna to use precautions
1, can only use the original or approved antenna. Unauthorized antennas, by the modified or added attachments antenna may damage the walkie-talkie or a breach of the provisions of the Radio Administration Bureau of Ministry of Information Industry.
2, when used, do not hand pick the antenna.
3, the radio antenna can not unscrew when it launched easy to power tube burn.
4, do not use a damaged antenna. If a damaged antenna contacts skin, it may lead to minor burns launch
Precautions when using batteries
1, the company's first wife or approved battery. 2, if the metal conductor such as jewelry, keys, or beads practice reach the bare battery electrode, all the batteries may cause damage or personal injury. Please be careful to treat the battery has been charged, especially when it into a pocket, wallet or other metal containers, need special attention. 3, the charge should be 5 to 40 degrees in the environment. If you exceed this temperature range, battery life be affected, while there may be sufficient dissatisfaction with the rated capacity.
Electromagnetic interference / electromagnetic compatibility
To avoid electromagnetic interference and / or electromagnetic compatibility problems caused by the occasion of the "turn off the walkie-talkie" logo should turn off the walkie-talkie. Such as hospitals or other health care equipment occasions. In the fly, according to the requirements of the transceiver OFF.
Walkie-talkie operating precautions
1, when the walkie-talkie is being launched to keep the walkie-talkie in a vertical position, and keep the microphone and mouth 2.5-5 cm distance. Launch, the walkie-talkie from the head or body of at least 2.5 cm. If the hand-held walkie-talkie carrying the body on the launch, the antenna from the body of at least 2.5 cm.
2, the process of using multiple boot off action, while the volume was adjusted to a volume suitable for your hearing.
The interphone use safety precautions
A car with airbags, not to the possible scope of the walkie-talkie on the deployment of the airbag. If the transceiver is in the deployment of the airbag may be involved in region-wide, once the balloon rapidly, walkie-talkies may hurt the officers inside with great impact.
2, in a potentially explosive atmosphere or occasion, unless the walkie-talkie special certification or to close down the walkie-talkie. In a potentially explosive atmosphere, the spark can cause an explosion or fire.
3, do not replace the batteries in a potentially explosive atmosphere or charge the battery. Installation and removal of the battery may cause the contact spark and cause an explosion.
4, close to the blasting area and detonators region must switch the transceiver in order to avoid a possible explosion.
Walkie-talkie routine maintenance
1, walkie-talkies long-term use, according to health, control knob and the case is very easy to dirty, remove the control knob from the transceiver, and a neutral detergent (do not use strong corrosive chemicals) and a damp cloth to clean the cabinet. The use of chemicals such as detergents, alcohol, spray or oil preparations may cause the the interphone surface and damage to the shell.
2, gently put the walkie-talkie, not hand-held antenna mobile walkie-talkie.
3 NA attachment, covered with dust cover (if equipped).
    Intends to obtain a walkie-talkie a full set of technical information, or seek product imitation and development project partners, please call the Tang Technology Business Centre for details.