High-frequency walkie-talkie and low-frequency walkie-talkie What is the difference ah?
The first is the difference in the frequency of work ah. There are some bands on the two bands that are allocated to the public and the unit, the frequency range used by the enterprise. So the work of the radio frequency band also concentrated in the 400-470MHz and 136-174MHz. Call distance 150MHz and 400MHz walkie-talkie in the city, then 400MHz walkie-talkie distance to go a little bit, because the antenna gain is higher than the 150MHz machine. In the mountains, then the 150MHz walkie-talkie distance is far away, because there is the existence of radio waves. Function on the words of the two kinds of walkie-talkie are similar.
The greater the output power of the transmitter, the greater the coverage of the transmitted signal, the farther the communication distance. But the transmission power can not be too large, the transmission power is too large, not only power consumption, affect the life of the amplifier components, and strong interference, affecting the call effect of others, but also produce radiation pollution. The radio power management agencies of various countries have clearly defined the transmission power of the communication equipment.
What is a high frequency walkie-talkie?
High-frequency walkie-talkie is a work in the short-wave frequency of high-end walkie-talkie, generally refers to the frequency of 400-470 walkie-talkie.
In the daily use of walkie-talkie, according to the provisions of the China Radio Regulatory Commission, radio frequency generally do the following division:
1, professional walkie-talkie: V section 136-174MHZ, U section 400-470MHZ;
2, the armed police with: 350MHZ;
3, Coast use: 220MHZ;
4, amateur use: 433MHZ;
5, cluster with: 800MHZ;
6, mobile phone: 900 / 1800MHZ;
7, the public walkie-talkie: 409-410MHZ.
Do you have to talk about high frequency or low frequency?
Just call the station is not to relay the direct call to the meaning of radio?
If it is used in the city, high-frequency signal penetration, so the general choice of high-frequency calls;
If it is used in the wilderness, low-frequency signal bypass ability, the general choice of low-frequency calls.
What is the maximum distance for civil walkie-talkies?
Civil walkie-talkie power 0.5-1W, usually the communication distance of about 1 km. But this also has great access. Communication distance and the environmental conditions between the two, such as electromagnetic interference has a great relationship. For example, one in the mountains, one on the ground, the middle line of sight without any obstacles, communication distance to more than 5 km. If the remote grassland communication distance can be very far, if in the city, due to obstacles, electromagnetic interference is serious, the communication distance is very close.
Ordinary civilian, domestic on the line, security, fire, guard what, the output power of 5 watts enough, open 3 km. Frequency points need to apply for no declaration, approved down to buy the corresponding frequency of the radio station. If you need a long distance call, you need to build a relay station, probably covering about 30 km in diameter (plain, no mountain block.)
Radio intercom station
The walkie-talkie relay station is used to increase the distance of the radio communication equipment, when the distance between the two walkie-talkie than the radio signal range, the walkie-talkie will not receive a valid signal, then, you have to use the walkie-talkie relay station. The role of the relay station is to receive the signal forwarded to complete the signal between the relay.
Walkie-talkie relay station, also known as the turntable, forwarding station, bad turntable, IP turntable, wireless communication system is an indispensable important equipment. Is in the wireless intercom system, used to increase the communication distance, expand the coverage of the equipment, such as the expansion of the car station, handheld radio range and communication capabilities, greatly improve your work efficiency.
Currently the most common popular relay station model:
The current common brands are:
Motorola (MOTOROLA) relay station / turntable
Kenwood (KENWOOD) relay station / transit station
VITEX STANDARD repeater / relay station
Hytera repeater / transit station.
External antenna and feeder can form a complete relay system.
Bought a walkie-talkie, how can we laugh at the relay station?
For the new HAM, the first kind of equipment that makes us feel very magical may be a repeater - like all ham in the whole area ... And only wait until the first time and other HAM out to set up short-wave radio, or often participate in relay activities, the relay station halo will slowly fade, return to the daily use of the role of tools to go. What is the relay station inside?
A homemade relay station, you can see inside the two cars loaded
First of all we can from its performance to see some clues: the relay station can make a lot of radio stations can not communicate with each other "through", appeared in the same frequency. This is why it is named "relay Taiwan" reasons. An erection of a well-functioning relay station can hear the signal at an upstream frequency and transmit it again at another frequency (downstream frequency), so that all the friends who are listening to the downlink frequency can copy the Signal, and want to reply to a friend, the same frequency on the launch, so that through the relay station forwarding, the two could not communicate with each other's radio station to be able to complete a communication.
The use of repeater is generally very easy, all you have to do is to confirm the local radio relay frequency and parameters, and then write to your walkie-talkie can be. We just got the walkie-talkie, start their first pass when we only need to agree with a friend a good frequency can be. But if you use the walkie-talkie, but also enter the frequency difference and the tone. These settings generally appear in this form "439.750-588.5", this data is what does that mean?
We all know that when using the walkie-talkie two people can not speak at the same time, radio waves in the air "fight", who can not hear the signal. The use of the relay station is the same time, but for the relay station is "left leg trip right leg" type of interference, most of the relay station will use a different frequency to avoid their own transmission for their own received signal The interference. And the difference between the two frequencies is generally fixed. For the 430MHz segment, the frequency difference is generally 5MHz. While 144MHz, then the frequency difference is generally 0.6MHz. A downlink frequency (that is, the usual listening frequency) is 439.750 of the relay station, the uplink frequency is generally 434.750MHz.
Adjust the frequency difference option
While the tone (88.5Hz) is to avoid interference, imagine if the relay station for the uplink frequency of the signal unconditional forwarding, then the downlink frequency is bound to receive a lot of unwanted signals. So we set the relay station, so that it only forwards the signal contains sub-audio radio signal, we set the radio when the same time to set the sub-audio. So that when using the repeater station, the relay station only forwards those signals that contain sub-audio, that is to use the relay station, and ignore the other signals. Many friends just get the walkie-talkie, the old ham to remind "you did not go up relay!", In many cases are the relay station set up some of the problems.
In order to achieve a wider range of coverage, the relay station will generally be set up in the region's high ground to get as far as possible in the radio sector. And now a lot of relay using the Internet or UV segment of the link will be a lot of relay station together, "one hundred call." A relay station receives your signal and forwards it to multiple repeater stations.
A repeater cabinet, the following is a duplexer
Many relay stations use the same paragraph forward, such as our previous example: 439.750-5 relay station. In order that the signals at these two frequencies do not interfere with each other, the antenna system of the repeater station is equipped with a duplexer to isolate two very close signals so that the same antenna can be used for reception and transmission. In the management, the relay station is generally able to use the DTMF signal (that is, we press the radio button when the launch of the audio) control, in order to achieve remote control functions.
In 1988 China's first amateur radio relay station through the telecommunications network and the US relay network interconnection success so that amateur walkie-talkie from the Great Wall and the United States and Canada tens of thousands of amateur radio to achieve dialogue
If you want to use the daily repeater, in fact, just to figure out its parameters can be set. But if you have a greater curiosity on it, then a small relay station which also contains a lot of radio knowledge waiting for you to find it! We can learn happily while playing with radio!
Military walkie-talkie up to a few kilometers away?
Military walkie-talkie (since you are asking the walkie-talkie, as the name suggests is holding a walkie-talkie, then here I do not mention infantry kneeling radio and car tai iron) military walkie-talkie from the frequency, roughly divided into VHF - UHF Segment (short-range), 30-80 MHz HF segment (medium proximity)
As for each frequency section of the specific models on the more, we do not waste time to introduce.
The frequency of the VHF segment is good in terms of diffractive capability and ground wave propagation capability, but its signal to the building is very good, but the frequency of the VHF segment is very good, The penetration of the material is poor! So generally as a mountain or field manuscript short-range communication use, the communication distance can generally be maintained at about 3-10 km
Man, the city combat force, the general use of UHF segment, the frequency of the penetration ability is very good, but the ground wave propagation ability and diffraction ability worse than VHF, it is usually used as a city combat force, the communication distance from the city and civil walkie-talkie Not much as much as 2-3 kilometers
Command, man, mountain, field. Finally, this is the HF segment, which is 30-80 trillion! This frequency section of the walkie-talkie relative to the V / U section of the radio installed a lot less, after all, the application of different regions and departments. This frequency section to pay attention to the use of skills, and perhaps for the soldiers brother, the key moment can call to the air blow can, and do not care about the skills of things ~ ~ ~ this frequency in the spread of a good time out of thousands of kilometers It is normal, the spread of the poor when more than a dozen kilometers, the use of technology and communication problems, and its complete voice signal can be heard in 35 km away. This is the charm of HF! Less than 30 trillion military walkie-talkie no! (Unless it is customized special equipment, we really did not play special goods!)
With 120W digital short-wave manned backpack radio, with cable-stayed antenna can be 1000 km of effective communication. Of course, the same can be done civilian, but the civilian domestic is currently not allowed to use digital shortwave machine, even if the current analog signal shortwave machine 100W can call the whole of China! As long as the antenna get good, nothing can not do! It is normal.
IP relay development
IP relay station can achieve local intercom signal relay, through the IP network can achieve real-time voice and PTT signal without error transmission, no matter in which city, or in the VHF or UHF standard use, IP relay station can be the system Coverage to expand to any location in the world, easily meet the different geographical space, different frequency bands, network interconnection to share voice, to achieve one-click calls, to solve the radio transmission by the transmission environment, transmit power, receiver sensitivity and other constraints of the transmission distance , Do not have to worry about the short distance of communication, coverage of small problems.
IP relay station through the IP network not only to achieve the purpose of ultra-long distance without relay network interconnection, through the relay station at the same time can be achieved in the towering building architecture distributed intercom signal coverage system.
Intercom repeater case
Walkie-talkie relay station, the power is divided into 5W / 10W / 15W. How to choose the power? First of all, according to the use of the environment; Moreover, the use of the walkie-talkie power to choose these two points to modify the relay station power. But not the greater the power the better.
Simple to draw the use of repeater ring mirror Case:
This is the urban environment, a customer to provide information, mainly for the walkie-talkie extension distance, to achieve long-distance calls. As can be seen from the figure, the call range diameter is 5km. Due to the building is more intensive, the floor is not high state, resulting in intercom call distance is limited. Walkie-talkie power is 5w, launch distance of 2 ~ 2.5km. The relay platform at the midpoint, so that the relay station can receive the radio signal. Then you can choose 5w power relay station can be.
This is also an extension of the distance from the radio to solve the talkie. But the environment and geographical location is different.
This case is to solve the signal blind spot.
Note: The installation of the repeater must meet a condition that the repeater must be installed within the transmitter's transmit signal range. In simple terms, the installation location of the repeater must be able to receive the signal from the radio. This is the condition that all the repeater stations must meet.