ROIP (Radio Over Internet Protocol) is where radios are linked together using an IP backhaul. This might sound complicated, but it doesn't have to be.

In its simplest form, a radio is connected via some sort of interface to a PC which in turn is connected to the internet or other private network. This is what is known as a "node".
Not every connection has to have a radio, it can simply be a PC (for dispatcher etc).
Two or more "nodes" form an ROIP network. Users can be an infinite distance away from each other, and still talk, as the IP link bridges the gap.

There are professional interfaces that can be assigned an IP address, and once configured, do not actually need a PC to be connected. These are specialist devices and cost upward of £300 each! I will be concentrating on a far cheaper way of "doing business".

So how can we achieve an ROIP network without the cost mentioned above?
  • PC. Lets start from the PC end of things. Just about any PC (within reason) can be used, so long as it has some sort of an internet connection.
  • Software. Next run a piece of software that will pass audio from one PC to another via the internet. There are a few different software releases that you can use, and I will discuss those later in a separate section, but SKYPE is a good example.
  • Now you need some sort of interface to connect the PC to a radio. This is where you need to decide what radio standard (Tetra DMR etc) you will be using. If you are using DMR radio's, they tend to have VOX built in to the actual radio, so all you need is to connect the audio lines from the radio to the PC. Audio output of your PC goes to the MIC input of your radio. This means that any audio you get from the "software" will be available to the radio so that it can re-broadcast that audio via RF. You can then listen to that audio with a handheld. The VOX function of the radio will "see" the incoming audio and automatically transmit.
If your radio doesn't have VOX (most Tetra radio's don't), you will need some sort of external VOX activation to make your radio transmit the incoming audio. This is where the interface starts to get more complex. The interface needs to "hear" the incoming audio from the PC software, activate the PTT (Press To Talk) on you radio AND pass that audio on to your radio microphone input.

The following diagram shows how an ROIP network looks.

 photo ROIP_zps133c3ce9.jpg