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Relay Can Be Easily Used In The Operation Of The Frequency
Jun 12, 2017

1. What is a relay?

The signal between two stations on the ground may not be transmitted to each other due to the shelter of the building or the influence of the terrain. Usually the power of 5W handheld walkie-talkie, outside the city of 2km can not be used.

To do this, people build an antenna in high places and set up a special transceiver station with high power. Responsible for transmitting signals (such as 434.460MHz) on a frequency point to another frequency point (such as $number. 460MHz), so that the radio within its coverage can contact it, that is, through it and other people. The repeater can cover a wider range of communications, helping to expand the signal for small power devices.

The usual repeater stations need to use a pair of frequency points, and a frequency point is used to receive signals from the user's hand-held walkie-talkie or on-board radio (uplink signal, such as 434.460MHz). When received, broadcast on another frequency point (downlink signal, such as $number. 460MHz).

Because the repeater station occupies the good geographical position, simultaneously has the relatively big transmitting power, therefore through the Repeater station can contact more people. Relay user's hand-held walkie-talkie or on-board radio frequency to send and receive relays to the contrary, you can turn on the relay.

2. What is frequency?

Usually the frequency we say refers to the downlink frequency. The so-called uplink frequency refers to the radio frequency of transmission, and the corresponding downlink frequency, is the repeater frequency, that is, the reception frequency (that is, listening frequency).

Because the general use of downlink frequency to indicate a relay frequency, generally known as the downward frequency of the surface frequency, the corresponding uplink frequency is called the base frequency.

3. What is frequency difference?

In general, when communicating using relay devices, the frequency difference between the receiving frequency and the transmitting frequency is called differential frequency (rpt shift) using different transmit and receive frequencies.

The difference frequency is divided into the difference (RPT) and the lower difference (RPT), generally uses the inferior, namely the launch frequency is lower than receives the frequency, takes 460 relays as example: the transmitting frequency is the 434.460MHz, the reception frequency is $number. $number MHz, the difference between the two 5MHz, we call the lower

This is the general amateur radio set method, some amateur radio frequency is fixed, that is, 5MHz, there are some places to set the difference between the special, such as Hong Kong some relay frequency difference set to 9.850MHz.

4. What is a sub sound?

Yan is a method used to prevent radio interference with itself when multiple radio stations are communicating at the same frequency. There are a variety of sub tones, the most commonly used is the CTCSS (continuous audio coding static noise system).

Motorola is called PL, which belongs to analog sub tones, from the frequency of the $number. 0Hz, A. 3Hz, and A. 3Hz, a total of 39 sub-tones.

At launch, the low-frequency audible signal (hence the sub tone) is continuously superimposed on the frequency of the transmitter, and the other party receives it only for the same frequency to resist interference, or to not listen to the signal.

The Yan is divided into two types, the sub sound and the receiving sub. In order to be able to relay, it is used to transmit the sub tone, so as to open the relay. The relay itself is to receive the sub tone, the signal without the sound is rejected. The relayed signal has no sound, but it also has Yan.

Similarly, when receiving, in order to repel unwanted signals, can also be added to receive sub tones. Such two radio stations (or several radio stations) can also be used to eliminate extraneous interference signals.

Although it is called a sub tone, it is actually audible, especially when the sub sounds are set in the vicinity of the high (250Hz), or when the receiver's low frequency is better. Therefore, when we set the sub tone, we try to set the lower, lest unnecessary interference.

In addition, there is a sub tone is DCs (Digitalcoded Squelch), belonging to the digital sub-tone, Motorola is called DPL, there are 104 of sub tones (DPL less).

This is more advanced, which is used in the form of digital encoding before and after the speech. This tone can only be emitted and received at the same time (that is, it cannot be set to be emitted only without receiving).

MYTH: When transmitting Yan, the receiver is only set to the sub tone receiving State to receive. Wrong! In fact, the opposite is true. When transmitting Yan, the receiver set to the non-sub sound receiving State must be able to receive, set to the sub-sound receiving state, must be of the same sub-tone type, at the same time sub-sound code to receive.

5. What is direct frequency?

The so-called direct-frequency communications, is two of stations with the same frequency. Many ham in order to test, the relay is not used when relaying, direct use of the downlink frequency of relaying is to listen to the frequency of communications.

Direct-frequency communications with good signal (not through the relay), the impact of the scope of the small, no interference with the relay, without changing the relay listen to the characteristics, therefore suitable for close-range communications.

For example, the uplink frequency of a relay is 434MHz, downlink frequency (that is, listen to the frequency) is 439MHz, the direct frequency is to send and receive all with 439MHz.

After the adoption of a direct frequency, should be recommended that the other side also change to direct frequency, otherwise the two sides may be able to contact, but the other side of the signal through the relay, will still affect the overall situation. And it sounds strange that only one side speaks. When both sides are using direct frequency, the relay signal is still being tapped in the gap.

6. What is an inverted frequency?

The so-called frequency, is in the relay when one side does not use the relay, but the relay used two of the frequency of the reverse use of a communications, also known as "inverse frequency."

The reverse frequency service has the signal direct (does not pass through the relay), does not change the other side to use the relay way the characteristic, therefore is suitable in the other side to use the repeater the situation to carry on the direct contact test.

For example, the uplink frequency of a relay is 434MHz, downlink frequency (that is, listen to the frequency) is 439MHz, then we use inverted frequency, is to receive 434MHz, send with 439MHz.

In this way, we directly listen to the other side of the uplink frequency rather than from the frequency, the other side received is our direct frequency is not the secondary, because we do not open the relay.

The advantage of this is that the other side can not change any settings, still use the relay mode, while we can test two frequency of direct contact. Frequency is also often used to check the strength and quality of the uplink signal.

The drawback of this approach is that only one side of the signal appears in the relay, and appears to be more bizarre. But if the listener is close to the frequency of the user, he can receive a direct frequency signal at the same time. Generally speaking, if you find that the frequency of the transmission is very smooth, you can change to direct frequency and relay to let out.

It is usually used to check that the signal strength of the other side is sufficient to determine whether the contact is within the range of direct frequency, in order to switch to direct frequency. can also locate the source of interference, looking for malicious interference.

Some walkie-talkie in order to facilitate the operation of frequency, with shortcut keys, so that in the relay operation can be very easy to use frequency. This feature is common in Yaesu and Kenwood handheld radios.

Many ham are mistaken for a cryptographic function. Suppose two walkie-talkie A and B, a machine set the transmission sub-tone and B machine did not set to receive the sub-sound, B machine can still receive a machine launched voice;

If the B machine is set to receive the sub-tone and a machine does not set the transmitting sub-tone, then the B machine will receive the voice of a machine. Relay station in order not to be disturbed by clutter signal to open the transmitter, set up a receiver, then want to open the relay platform to set the launch sub-tone to open.

The use of sub tones in group communications means that the receiver is pure for his ears. Group to set up a sub-tone also has the advantage of making full use of frequency resources.