Radio Over IPThe network options today have essentially converged on Ethernet. A local “PC World” computer shop and many online shops will sell the components for both a wired or wireless network solution.
IP Operation Overview
The network options today have essentially converged on Ethernet. A local “PC World” computer shop and many online shops will sell the components for both a wired or wireless network solution. For more advanced network applications, an in house or external network hardware source may be required. These sources of information will be able to help with the design of the network as well as provide sources for advanced networking equipment such as routers and hubs from Cisco, Nortel, Net gear and other network vendors. This section is an overview of the protocol that operates on the top of the Ethernet network.
TCP/IP and UDP/IP
TCP/IP is the best-known protocol for use in computer communications. It is the basis for communications on the Internet and World Wide Web. It is a guaranteed method of transferring data between two computers. Being guaranteed means that for every byte of information transferred from one computer to another an acknowledgement packet is returned. Additional handshaking is utilised from the outset of the data communications to guarantee both ends of the connection. Because of this guaranteed communications and its implementation utilising handshaking (no other method is available), TCP/IP ads a great deal of overhead to data Communications that is not desirable for audio traffic over a network. This is where UDP/IP finds is acceptance.
UDP/IP has existed just a long as TCP/IP as an unreliable method of data communications. The term unreliable should not be thought of as a problem for audio communications over a network connection. UDP allows a computer to send a packet of data to another computer without the handshaking sequence required within TCP/IP. Because of this, the computer that sends the packet has no confirmation that the packet arrived at its destination. While the loss of packets can be a problem, it generally is accounted for when the UDP application is developed.
In the case of our VoIP, the loss of a packet, which only contains 10-40ms of audio, is not a problem, as the human ear generally will ignore the loss of that small chunk of audio. In addition, programmers play tricks to make this loss of information difficult to detect to the human ear. The largest single factor in the loss of UDP/IP packets is network design and loading. As long as a network is well designed with capacity for all of its chartered requirements, packet loss will not be an issue. Because of its lower overhead and its ability to Multicast, UDP/IP is the protocol of choice for VoIP development.
RTS systems propose the Operator positions, and the radio interface units.
The following pages provide a description and also an overview of some options to expand the system if required.
A Typical operator’s position is detailed below. A operator position generally comprises of a PC unit, Touch screen monitor, Headset Interface, and accessories (Headset, Footswitch, and Desk Mic). The system has no central equipment, so it connects directly to each radio interface using network messages over the LAN.
The dongle is provided per-position with a suitable amount of lines (each Radio or Telephone required at the operator position) for the scheme. This system will be supplied with 12 line dongles, which will allow each operator access to up to 12 lines
The operator PC is equipped with suitable Network facilities as laid out in the specifications below; it uses the Microsoft Windows XP-Pro or Windows 7 operating system.