![The choose the base station antennas]( "The choose the base station antennas")
Car antenna Vehicle antenna is refers to the mobile communication antenna design is installed on the vehicle, is the most common sucker antenna. Because the sucker antenna installation put easily, so in some simple set occasions sucker antenna is often used instead of base antenna. The on-board antenna structure have shortened, a quarter wavelength, central loading, five 8 half wavelength, double wavelength in the form of the antenna, in theory, in turn, increase their efficiency, the same working frequency band of the antenna length also increases in turn. Due to limited the vehicle itself is high, coupled with a long antenna in the vehicle at high speed wind resistance, little tunnel, into the underground garage are problem, so the car antenna is not as long as possible, general requirements car antenna is not more than 70 centimeters, the van antenna shorter class requirements. Although small antenna size, shorten type gain is not high, but suitable for use in the occasion of hidden antenna. General police vehicles the installation of a high gain antenna is recommended, especially in the activity area larger vehicles, more than 350 MHZ high gain antenna can be divided into five 8 wavelength loading form, at the top half wavelength distance from the antenna has a loading coil. 400 MHZ band double half wave antenna has high gain, its appearance is characterized by antenna vibrator has two loading coil. Five 8 wave antenna and central type loaded antenna also has a higher gain, and the price is cheaper, so widely used. In as a temporary fixed platform can consider to choose high gain antenna using occasions of sucker antenna, the length of the antenna don't have too many restrictions. Since sucker antenna is designed according to the car use environment under which when used as a fixed so suck a radius greater than 1 m metal plate (such as iron) can have a better effect. Due to the import original vehicle antenna price advantage is very expensive and not stand out, so generally choose domestic car antenna. In antenna selection stage mainly refer to the appearance and the gain of the antenna. Suggest choose big manufacturer of famous brand products, authenticity is higher, they provide the parameters of the manufacturing process is guaranteed. If it is bulk purchase can completely to professional custom by using frequency antenna manufacturer, in order to obtain the best use effect. Base station antennas Base station antenna has a key role in the whole communication system, especially as the communication hub of communication stations. High gain antenna can not only increase the radio coverage area, and also to have certain of received signal amplification, can receive weak uplink signals better, improve the quality of mobile station and base station of wireless communication. Base stations are generally choose high-gain antenna, with the condition of the interference can be according to the actual situation considering adding narrow-band filter to reduce the influence of interference. Common base stations FRP antenna with omnidirectional basic no directional antenna, is suitable for base station location is located in the center of communication network. Due to glass fiber reinforced plastic antenna installation is easy, so widely used in various types of base stations. FRP antenna gain up to about 10 db, the higher the gain antenna is, the longer average gain for 5 to 6 db gain of FRP antenna on the length and the price is competitive, manufacturing technology is more mature, more. This kind of antenna in addition to the electrical properties, the quality of the outer FRP radome is there much difference, some bad products in the sun after a year of outer glass fiber reinforced plastic cracking would happen lead to scrap the whole antenna, some big brands of FRP antenna on quality more secure. Directional antenna is equivalent to the energy concentrated on multiple directions to one direction, has the characteristics of the main direction of radiation gain high, commonly used is yagi antenna. Yagi antenna unit number of the more its gain is higher, also suitable for point-to-point communication over a long distance and located at the edge of the network stations use. Suit is located in remote areas of directional contacts with the superior branch of police station, used properly the effect will be better than that of glass fiber reinforced plastic antenna. Sihuan array antenna is characteristic of large power, high gain, under direction gain adjustable, suitable for communication hub and the city bureau (bureau) and relay stations, but the price is quite high. 4th ring oscillator array antenna of four launch direction adjustable, when four oscillator interval of 90 degrees to install the basic characteristics of the antenna is omni-directional, when four vibrator all installed in the same direction when the directional antenna characteristics of gain in the main radiation direction at the same time to improve. The gain direction adjustable features can be used to better adapt to the rules of the service area. If sihuan array antenna gain is high enough to consider eight ring array antenna and its properties are similar to sihuan array but provides a higher gain. General 350 MHZ band sihuan array gain is 8 db (omnidirectional) / 10 db (orientation), eight ring array gain of 12 db (omnidirectional) / 15 db (orientation). 参考网址：http://www.crtegd.com/dgz-8.asp
Release date:
2016
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06
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15
Views：3062
![Problems should be noticed when using the intercom]( "Problems should be noticed when using the intercom")
Interphone antenna using the matters needing attention 1, can only use the original or approved by the antenna. Unauthorized antennas, modified or added attachment it might damage the interphone antenna or in violation of the provisions of the radio administration bureau, the ministry of information industry. 2, when use, don't get the antenna with the hand, not to mention carrying antenna will intercom to jilt to jilt to. 3, walkie-talkie antenna can't back off, otherwise the launch easily when the power tube (pa) burn out. 4, do not use the damaged antenna. Otherwise, when the launch, the damage of antenna skin contact, may cause slight burns. Battery matters needing attention 1, should use the original or approved by the battery. 2, if the metal conductor such as jewelry, key or bead practice hitting a bare electrode of the battery, all battery may cause damage or personal injury. Please beware of is good battery, especially when put it in my pocket, wallet, or other metal container, special attention should be paid. 3, charging shall be carried out in an environment of 5 ~ 40 degrees. If over the temperature range, the battery life is affected, at the same time may charge under rated capacity. 4, emi/emc, to avoid the problems caused by electromagnetic interference and/or electromagnetic compatibility, the occasions with "intercom off" logo should be closed walkie-talkie, such as in gas station, hospital, or other use the occasion of instruments and equipment; When in a plane, also the intercom should be closed. Intercom operation matters needing attention 1, when the radio is sending, keep the interphone in the vertical position, and keep the receiver and the mouth of 2.5 5 cm distance. Launch, intercom at least 2.5 cm away from the head or body. 2, in use process not to boot off many times, at the same time the volume adjustment to fit your audio volume. Intercom use safety considerations 1, on a car with airbags, don't put intercom airbag may involve in the range. If the interphone in airbag launch may involve area, once the airbags expand rapidly, intercom may be as great impact injury and the car. 2, in potentially explosive atmosphere environment or situation, unless the intercom is through special certification explosion-proof interphone, otherwise you must close the intercom. Potential explosion in atmospheric environment, the electric spark can cause fire or explosion. 3, do not replace the battery in a potentially explosive atmosphere environment or on the battery. Install and remove the battery when contact may cause electric spark and cause explosion. 4, near the blasting area and detonator area before, must first close the intercom, lest cause possible explosion. Intercom routine maintenance 1, intercom after using for a long time, according to the health, control knob and casing is easy to become dirty, please remove the control knob on the intercom, and neutral detergent (do not use highly corrosive chemical agents) and wet cloth clean casing. Use such as stain remover, alcohol, spray or oil preparation and other chemicals are likely to damage to the surface and the shell of the interphone. 2, light to take light put intercom, not portable mobile radio antenna. 3, when not in use of headphones and other accessories, please cover dust cover (if equipped). State radio monitoring center, testing center of shenzhen laboratory in shenzhen Guide language: in order to accelerate the pace of radio management work in the service of economic construction, in order to comply with the demand of rapid development of electronic industry, in order to further enhance the level of customer service, the state radio monitoring center to the requirements of the shenzhen municipal government, the decision to set up the state radio monitoring center test center in shenzhen futian district in shenzhen lab. Guide language: in order to accelerate the pace of radio management work in the service of economic construction, in order to comply with the demand of rapid development of electronic industry, in order to further enhance the level of customer service, the state radio monitoring center to the requirements of the shenzhen municipal government, the decision to set up in shenzhen futian district "state radio monitoring center test center in shenzhen lab". The testing laboratory located in shenzhen, to support the rapid development of electronic industry, local service in shenzhen's economic construction, and enhance the city competitiveness of shenzhen has extremely vital significance. Because of this, the signing ceremony by shenzhen municipal government attaches great importance to, headed by standing vice mayor of shenzhen municipal government hsu on government leadership dozens of people attended the signing ceremony. The future, the state radio monitoring center will also seek further with the shenzhen futian district government, the competent departments of radio and brothers unit long-term cooperation opportunities. Morning of November 17, 2009, "state radio monitoring center test center in shenzhen lab in signing ceremony" on Mr Fukuda sand innovation science and technology park. Cloud-l, director of the state radio monitoring center, deputy director of the yong-gang xue lead organized the signing ceremony. In addition, also attended the signing ceremony, standing vice mayor of shenzhen municipal government hsu, futian district party committee secretary li ping, warden qing-shan zhang and deputy prefects He Haitao, ministry of industry and deputy director general of Mr Han, ministry of telecommunications research institute leaders, trade and industry as well as the relevant departments of shenzhen letter committee, futian district, head of the relevant government departments, and representatives from electronic enterprise, the news media reporters, a total of about 100 people. State radio monitoring center director cloud-l delivered an important speech on the signing ceremony, and on behalf of the state radio monitoring center and futian district government, zhang long castle peak district signed a cooperation agreement. Cloud-l director said: to establish such a radio equipment testing of southern base, not just for shenzhen and the pearl river delta region of radio equipment manufacturers to provide approval one-stop services, as well as the integration of domestic and international certification services, more importantly by shortening the period of electronic products listed, to speed up the pace of shenzhen's economic construction Standing vice mayor of shenzhen municipal government hsu on behalf of the shenzhen municipal party committee municipal government attended the meeting and delivered an important speech, he pointed out: the signing of two testing laboratory, will further improve the links of the core of shenzhen electronic information industry chain, strengthen the industry's international competitiveness and radiation ability, add new vitality to the construction of national innovative city of shenzhen, will also bring animals networking, wireless, radio frequency identification, perception to the further development of the automotive electronics or related industry. In addition, the ministry of industry and information technology slurry sampling, deputy director of Mr Han on behalf of the ministry of industry and information technology, congratulations on contract. , "said Mr Han, director of the state radio monitoring center set up a lab in shenzhen, is also the ministry of industry and information technology to support the local information industry development, to the nearest service" the important measures for local enterprises. After the signing ceremony, the state radio monitoring center organized award luncheons, deputy director of the state radio monitoring center yong-gang xue thanks gave a speech.
Release date:
2016
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06
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15
Views：3203
![Walkie-talkie batteries attention]( "Walkie-talkie batteries attention")
To everyone's safety and the service life of the battery, when using battery hope that users pay attention to the following three points: 1, with the company approved by the original or the battery. 2, if the metal conductor such as jewelry, key or bead practice hitting a bare electrode of the battery, all battery may cause damage or personal injury. Please beware of is good battery, especially when put it in my pocket, wallet, or other metal container, special attention should be paid. 3, charging shall be carried out in an environment of 5 ~ 40 degrees. If over the temperature range, the battery life is affected, at the same time may charge under rated capacity. In the use of intercom, in order to ensure we use our intercom when using antenna, please pay attention to the following four points: 1, can only use the original or approved by the antenna. Unauthorized antennas, modified or added attachment it might damage the interphone antenna or in violation of the provisions of the radio administration bureau, the ministry of information industry. 2, when use, do not use hand to pick up the antenna. 3, walkie-talkie antenna can't back off, otherwise easy to burn out the power tube during launch. 4, do not use the damaged antenna. At launch, if damaged antenna skin contact, may cause mild burns, please.
Release date:
2016
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06
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15
Views：3067
![Rechargeable lithium ion battery using common sense, application note]( "Rechargeable lithium ion battery using common sense, application note")
Rechargeable lithium ion battery has been widely in radio, but it is "temperamental", in use do not overcharge, discharge (can damage the battery or scrap). As a result, have protection components or protection circuit on the battery to prevent damage of expensive battery. (most of counterfeit inferior products without the protection circuit) high demand for lithium ion batteries, to ensure that the termination voltage precision is within 1%, the current major semiconductor device factory has developed a variety of lithium ion battery charging IC, to ensure safe, reliable and fast charging. Now intercom has widespread and radio part is nickel metal hydride batteries, but to poach intercom is lithium ion battery. Proper use of lithium ion battery is very important to extend battery life. Lithium ion battery is the most widely used lithium battery, it according to the requirements of different electronic products can be made flat rectangular, cylindrical, rectangular and button, and there are composed of several cells in series with the battery pack. The lithium ion battery of the rated voltage of 3.6 v (some products of 3.7 v). Fully charged when the termination of charging voltage related to battery anode material: 4.2 v for graphite anode materials; Anode material for coke 4.1 v. Different internal resistance of the anode materials are also different, coke anode resistance slightly larger, its discharge curve also slightly different, generally called 4.1 v lithium ion battery and 4.2 v lithium ion batteries. Now use the most is 4.2 v, the termination of lithium ion battery discharge voltage of 2.5 v to 2.75 v (battery or termination of the discharge voltage, voltage range is given the parameters is slightly different). Below terminate discharge voltage continue to discharge called discharge, discharge the battery will be damaged. Lithium ion battery is not suitable for used as large current discharge, large current discharge will reduce the discharge time (internal will produce high temperature and energy losses). So give maximum discharge current battery production factories, in use should be less than the maximum discharge current. Lithium ion batteries have certain requirements for temperature, the factory gives the scope of charge temperature, discharge temperature range and temperature range. Lithium ion battery is very high to the requirement of charging, it requires that the precision of the charging circuit to ensure the safety of charging. Termination of charging voltage accuracy tolerance for rating plus or minus 1% (for example: 4.2 v lithium ion batteries, the tolerance is + / - 0.042 v), overvoltage rechargeable lithium-ion batteries, permanent damage. Lithium ion battery charging current should be on the advice of the battery factory, and ask the limited current circuit in order to avoid happened flow (overheating). Charge rate usually used is 0.25 c ~ 1 c (c is the capacity of the battery, such as c = 800 mah, 1 c charge rate the charging current is 800 ma). Tend to detect when large current charging battery temperature, to prevent overheating damage to the battery or explosion. Lithium ion batteries are divided into two stages: the first constant current charging, to about the termination voltage to constant voltage charge, this is a 800 mah battery, the capacity of the termination of the charging voltage of 4.2 v. Battery at 800 ma (charge rate for 1 c) constant current charging, battery voltage with a larger slope booster at the beginning, when the battery voltage close to 4.2 v to 4.2 v constant voltage charging, gradual decline current, voltage change is not big, the charging current to 1/10 c (about 80 ma), close to full, may terminate charging (some charger to start the timer after 1/10 c, after a certain time end charging). Lithium-ion batteries in charging or discharging process if happened or over-current etc. To top it off, will cause damage to the battery or reduce the service life. Application note: Lithium ion battery application considerations in addition to the same as the above non-rechargeable lithium batteries, also in charge should be paid attention to the following: 1. Lithium ion battery is 4.1 v and 4.1 v charging termination of different varieties, so pay attention to when charging is 4.1 v battery can't use 4.2 v charger, otherwise there will be a charge of dangerous (4.1 v to 4.2 v charger sputters charger IC is different!) . 2. The battery charging, the environment temperature cannot exceed product features the temperature range listed in the table. 3. Can't reverse charge. 4. Cannot use rechargeable nickel cadmium battery charger (three nickel cadmium battery charging for rechargeable lithium ion batteries (although the rated voltage, 3.6 v), but different charging ways, easy to cause the overcharge. Discharge aspects should be paid attention to the following: 1. The lithium ion battery discharge current can't more than product features maximum discharge current is given in the table. When the discharge current is larger, can produce high temperature (energy loss), reduce the discharge time, unless otherwise stipulated in the battery protection components will cause overheating and damage to the battery. 2. Different temperature lowering electricity curve is different, in different temperature, the discharge voltage and discharge time is also different. In the worst - 20 ℃ discharge. In terms of storage: 1. The battery if long term storage, keep in 50% discharge state. 2. The battery should be stored in low temperature, dry environment. 3. Stay away from heat source, also do not put in direct sunlight place. The principle of image analogy: will now principle of lithium ion battery and charging and discharging mechanism, common bubble phenomenon analogy with life. Lithium ion batteries as a heap of soap bubbles, stored inside the bubble is electricity. When charging, the bubble will be increasing with charging time extended, the bubble will burst when over the limit, at this time that damaged the lithium electricity crystal type, causing permanent damage. When excessive discharge can cause bubble collapse and disappear, so the next time the charging bubble also filled up, and cause lithium electricity failure. How to control the bubbles don't charge blasting and bubble collapse? Is to use protection circuit must be strictly controlled. Of course, the high quality batteries and precise control circuit can greatly prolong the service life of batteries.
Release date:
2016
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06
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15
Views：3201
![Introduction to the classification of the walkie talkie..]( "Introduction to the classification of the walkie talkie..")
Headphones in the intercom function in the use of the whole machine is great, not only can liberate the caller hands, sometimes have the effect of hidden calls, which related to its specific work environment. At present, in the walkie-talkie machine market growing at the same time, the headset market also has the attention of people. Intercom headset products brand is numerous, species classification and use way also each are not identical, sometimes different brands and models of the whole machine the headphones also have different configuration, it is easy to let the consumer confusion. In this paper, we use the intercom often wear headphones are classified, the hope can give users a certain help and reference. 1. From wearing way points have ear plugs, ear hanging, head-mounted (light, medium, heavy) Ear plugs, ear hanging headphones small volume, easy to carry and is quite popular headphones on the market at present, is also the most commonly used in the intercom headset. Generally speaking, there are two forms combined microphone, built-in microphone. Cost-effective, ear plugs hanging headphones user does not need to remove the intercom's from the machine set of use cases, so as to improve the work efficiency of the user. Suitable for retail, hotel, catering and other industries. Head-mounted is compared commonly big, have a certain weight, so not very convenient to carry, but its performance is strong, the external disturbance is small. Headphones to create conditions for a speakerphone communication, so is the effective tool to improve the work efficiency greatly. It contains the light head headphones, medium headset, heavy headset 3 kinds. Lightweight headphones for high-definition, a speakerphone, separation of two-way communication create conditions at the same time, also increased the comfort, can be used in moderate noise extension to wear. Applies to the entertainment industry, retail, sports and leisure industry. Medium-sized headphones in providing high-definition voice at the same time, also have limited sound insulation function, is bad to open in a noisy environment clear a double-barrelled communication necessary tools. It is suitable for construction, manufacturing, petrochemical industry and aviation transportation industry. Heavy headphones including rotating microphones, denoising can cooperate or not cooperate helmet to wear. Send by words used in up to 125 db noise intensity. Suitable for mining, construction, manufacturing, and aviation transportation industry. 2. From the sound conduction modes on the conventional vibration, air ducts, ear bone conduction, throat type, etc. Several categories. Regular headphones (mic) refers to the acoustic signal receiver through a wire to the ear (horn) voice, the voice is transmitted through the air in the transformation of sound waves into the microphone and acoustic signal into the transmitter, is the most common type of headphones in the market. Air duct headphones refers to the electroacoustic receiver signal into sound waves travel through the plastic air duct to the ear. Its characteristic is: a, the vibration of sound wave is transmitted through the hollow tube, can filter the distortion generated by the speaker and other noises. In addition, from catheter to transmit sounds, the ear does not again in close contact with the speaker, but also avoid magnetic radiation by the speaker and the speaker coil for a long time in the heat generated by the magnet to work within the effects of stress. B, because of the air duct selection is transparent material, easy to use concealment, therefore also give some special work groups (such as sound entertainment by staff and security staff) and need long time to use the selected. Ear bone conduction headphones has high quality and high noise levels, the transmitter is vibrating microphone. It is the use of vibration sensor with high sensitivity to pick up a person speak vocal cord vibration caused by the body's tissues, and converting vibration signal processing. Bone conduction microphones, the sound waves is not sensitive to air, has a superior ability to resist noise. Without the wind after interference, unique design, quality of a material soft, wear very comfortable. Throat vibration headphones is the use of talking, vocal cord vibration of larynx to pick-up, converts acoustic signal to the transmitter. Throat, ear bones type microphone, because from the throat, ear bones vibration convey directly to the pick-up, can prevent the environmental noise into the transmitter, and the voice of the air transport will be a little different, so the other party will feel voice will be a little different, the so-called fidelity is not high, but the main purpose of clear communication is the communication. In addition, still have a kind of invisible headphones in the market. It is a special headset, with tiny radio receivers, can be completely hidden. User two-way radios received all information in the form of radio relay to the ear of the wireless headset, can be easily hidden in secret operations under the user's clothing. Security guards, the public security officials and private detective can through the subtle communication equipment. Although it is small, but it can provide a full range of audio features, including the static noise, automatic gain control and automatic filter noise.
Release date:
2016
-
06
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15
Views：3346