Dictionary for wireless technology
Below are definitions of terms used in descriptions of wireless technology on our website.
Index of concepts:
- directional antenna
- polarization antenna
- antenna MIMO
- types of transmission interfaces
- Standard RS-485
- Standard RS-232
- receiver and transmitter RS-485
- wireless signal transmission RS-485 and RS-232
- modes relays
- momentary mode
- bistable mode
Characteristic feature this antenna is that device radiates in one direction almost all the power. Power such antennas can be up to serval tens of dBi.
We offer the following directional antennas:
- AK-58 5,8GHz of profit 5 dBi
- AK-19 5,8GHz of profit 19 dBi
- GD-24dBi 5,8GHz of profit 24 dBi
- GD-27dBi 5,8GHz of profit 27 dBi
The role of the antenna in the radio system is transmitting electric signal in form of electromagnetic waves and receive them. Polarization antenna means the return and the angle at which the waves propagate. The most common types of polarization are: linear, circular, elliptical. More about polarization you can find on Wikipedia.
Antenna MIMO (Multiple Input Multiple Output)
The solution increases the network bandwidth by using multiple antennas. In other words it means that in one antenna are two antennas. Additionally every antenna can have different polarization.
Types of transmission interfaces
Standard serial transmission: RS-485
Standard RS485 was developed by EIA (Electronics Industry Association) in order to enter parameters for standard devices supplied by different manufacturers. It consist of a differential transmitter, two-wire transmission path and the differential receiver. It doesn’t require conducting the return line. Standard RS485 supports up to 32 transmitters and receivers. Communication takes place through twisted-pair. By using a single pair or two pairs of twisted wires inside.
The most common topology connection device is bus topology.
The range of data transmission.
Range of that standard is maximally 1200m. Transmission distance is dependent of the speed transmission:
- for 35Mbit/s is 10m
- for 100Kbit is 1200m
RS485 is the one of the most commonly used wired interfaces in industrial networks (automation). This is due to the fact that data transmission is very resistant to external interference (for example, motors of power grids).
Mode of action
Transmitter and receiver working in half-duplex mode, when they don’t transmit, they pass to receiving mode. The master device suitable request to start transmission to child node (slave) by addressing unit. Start but us detected and transmission is automatically activated transmitter RS485. When the signal was given to the unit returns to receive mode.
Standard RS-232 (Recommended Standard) was developed to standardize the parameters of signals and construction of equipment intended to transfer digital telephone networks. In defines a way to connect devices DTE (Data Terminal Equipment), means terminal equipment and DCE devices (Data Communication Equipment) – devices transmitting data (for example radio modem).
- name of the contact connectors,
- signals assigned to the connectors,
- specification of electrical circuits,
- standards of connectors and wiring type serial ports COM.
RS232 bus is used for serial data transmission according to the following specification voltage.
- “1” logic voltage -3V to -15V,
- “0” logic voltage +3V to +15V.
Transmitter and receiver with interface RS-485
Produces by Camsat receiver and transmitter for remote device control by standard RS-485 called CD-06.
Selected advantages of CD-06.
- ✓ remote control over a large distance through RS485 protocol,
- ✓ receiver remembers the last state and restores it in case of failure and resumption of power.
Wireless signal transmission RS-485
Operating modes relays
Receiver can work on momentary mode and bistable mode.
In momentary mode receiver reproduces exactly state input in the transmitter – while short-circuited, exit is also shorted and inversely.
In this mode every rising edge (short entry transmitter) changes the output to the opposite. For example first impulse activates the relay output, the second switch them off, another activates again, and so on.
Visibility optical - LOS
The description wireless technology (transmission ranges) frequently encountered term is „visibility optical” – LOS, Line of Sight. Example: if the maximum transmission distance is 100m LOS, it means that devices send signal to distance 100 meters under the condition that between the transmitter and the receiver, there are no physical obstacles. In other words, the device transmitting and receiving must see each other.
In case if transmission range is too small or between the transmitter and receiver are obstacles, there is possibility to use repeater point. You should find a place, where is optical visibility with both devices, and at this point install on additional set of devices.
The following figure present a situation in which the point is required retransmissions.
The building number 1 is the monitoring centre. There is no way to stop the signal from camera located on the multi-storey car park 4 directly to the receiver on a skyscraper 1. In this case, it was necessary to apply the retransmission point. Transmitter of the building 4 wirelessly transmits a signal to a receiver number 3. Then, the line signal reaches the transmitter number 2, from which it is transmitted to the receiver 1. Receiver on building 1 wire transmits a signal to a recorder.
Power over Ethernet (PoE)
Technology, which allows to transfer electricity through the twister pair to devices that are part of an Ethernet network (IP cameras, wireless communication devices and VoIP).
Radio Transmitter – Tx
Device used to transmit a radio signal (video, audio or data) to the receiver. The number of cameras from which the signal can be transmitted depends on the number of channels supported by the system. Selected analog systems of our production can transmit signals up to 21 channels (the number of channels available depends on the allowed transmission frequency in a given country), or up to 32 digital cameras (IP cameras depends on the type and resolution).
Radio receiver – Rx
The receiving radio signals (video, audio or data) transmitted by the transmitter. In order to increase the range of transmission to the receiver can be connected to an external antenna.
DFS mode (Dynamic Frequency Selection)
Devices operating mode DFS automatically select the best transmission frequency of the frequency range that support. Before starting a radio transmission you should always check, which frequencies are free / they do not require a permit in the country. There is a possibility that the frequency at which operates a set of transmission may overlap with the frequencies “inaccessible” in the country. In this case, switch to manual frequency selection mode.
PTZ cameras also called Pan / high-speed remote control of their parameters. The operator can control the optical zoom/digital (zoom) and rotate them vertically and horizontally.
This is a device (electronics), to detect malfunctions of the system and automatically performing certain operations to fix them.
The use of the watchdog in selected CAMSAT products significantly improves the security of wireless systems. In a situation when the lost connection between the transmitter and receiver, it allows automatic resume the call.
ONVIF (Open Network Video Interface Forum)
Standard ONVIF aims to standardize all interfaces to transmit video and other data between devices CCTV (camera-recorder) to enable them to function correctly. Such a solution enables the selection of any of the devices from different producers’ offers and ensures compatibility with any recorder equipped with this port.