Radiotelephone

Under radio or telephony wireless services means the wireless transmission of voice information using handheld radios, mobile phones or base stations. Here, a radio communication takes place. In most cases, radio traffic exchange (half- duplex): can talk at only one participant, while the others listen. A few technologies also allow full-duplex operation, similar to a phone where you can listen and talk at the same time.

For the area of ​​voice communications include, for example, citizens' band radio, CB Radio, PMR radio, taxi radio, portions of the web - radio, bad radio, trunked radio, aeronautical radio, marine radio, Inland Waterways, part areas of amateur radio and much more.

If you want to bridge to Ultrakurzwelle greater distances or send over mountains of time, usually a " central office " interposed, so a relay radio station ( shortened also called relay ) or a satellite. This exchange takes on the radio waves of the transmitter and sends it directly to a different frequency on, usually with higher transmission power. This requires that the participating walkie-talkies send all received at the transmission frequency of the relay and at the receiving frequency of the relay. In Germany this principle is ( authorities and organizations with security tasks) used mainly in the BOS area, ie in the area police, emergency services, fire brigade, civil protection. Usually, a common wave system is operated there within a county in which to send multiple channels on the same frequencies and are controlled by the control station as a relay station.

For special propagation conditions or on the shortwave eliminates the need to, because there, the signals are reflected on part of the atmosphere.

Modes of transport

In radio you know the different types of transport devices that are used depending on the technical equipment.

Variable

The most common mode of transport in the radio is cross traffic. In this send and receive all participants on the same frequency. When a subscriber sends something, the others listen. Once this is finished, another person can only respond. This can be found for example in the CB radio, bad radio, amateur radio, commercial radio, or even a simple children's walkie-talkies ( walkie -talkies ).

Conditional oncoming traffic ( semi-duplex )

Send The Semi - duplex mode and receive the radios on two different frequencies, but it is not technically possible to receive during transmission also. The system may have an antenna relay which connects the antenna to either the receiver or the transmitter portion. Switching is done via the activation of the voice key. This mode of transport is used in radio operation via relay station.

Oncoming traffic (duplex )

The oncoming traffic, the radio transmits and receives on two different frequencies which are designated as upper belt and lower belt. The system may have a duplex filter, a kind of fork circuit, which connects the antenna at the same time to both the receive and the transmit part, however, transmit energy passes only to the antenna and not to the receiver, so that it will not be " plugged " or even damaged. While the wireless device to the one frequency transmits and can therefore received simultaneously at the different frequency. True full-duplex operation is only possible with a remote station, which then sends in a reversed tape position and receives. The frequency spacing between the upper band frequency and the lower frequency band of the radio channels of a wireless network is referred to as an intercom or duplex spacing distance.

By interposing a relay station greater distances bridges and structural or landscape obstacles can be overcome. The relay station receives this, the voice message of the sender, and transmits them simultaneously at the second frequency further. The relay station for most (eg hilltop ) mounted on a geopraphischen increase.

Forms of transport

Based on the form of communication within radio traffic circles, so who can talk to whom, one distinguishes different forms of transport.

→ See: Voice communications form

Gallery

Air operator's certificate