Interoperability Configuration

Interoperability can mean many things and depends on the situation and requirements to really define the best options. Sharing radios, common channel frequencies, common talkgroups and interoperability switches all make it sounds easy to provide technical solutions for Interoperability.

This section includes a variety of items intended to describe some of the options for interoperability connections and also some of the challenges that may be encountered.

Multiple Analog-Digital Conversions

At the beginning and end points of a radio transmission, the audio is converted between Analog and Digital. Our voice and ears are analog, while the radio transmission equipment is digital. As a minimum there is an Analog to Digital conversion in the talkers radio and a Digital to Analog conversion in the listeners radio.

When connecting systems together through base station, mobile or portable radios, the most common interface is analog audio, TX and RX. Radio ports on digital radio systems and interoperability switches are analog, either direct connection to the radio, or 4 wire audio interface for tone remotes. 

While not being a major problem, it is important to consider in systems that may have multiple links, or where gateway devices are used within one of the networks being connected for Interoperability. Wireless earpieces and headsets also add an analog to digital conversion in the audio stream.

Analog audio adjustments on each interface become critical to ensure quality audio end to end.



Here is an example using an Interoperability Switch to link two radio systems together.

Conversion 1: (Analog to Digital to Analog)

The analog audio from the person speaking into their microphone in the Police car is converted to digital for transmission. Even in a large multi-site trunking system, the audio will remain as digital until it gets to the other radios or consoles on the system. The audio exits the radio system through a mobile radio connected to an interoperability switch. The radio is connected to the switch and takes the digital audio from the radio system and brings it back to analog audio for connection to the switch.

Conversion 2: (Analog to Digital to Analog)

The interoperability switch takes the analog audio from the radio and converts it to digital, for routing within the switch. The output of the interoperability switch is converted back to analog for connection into a radio that operates on another radio system.

Conversion 3: (Analog to Digital to Analog)

The radio connected to the interoperability switch takes the analog audio from the switch and converts it to digital to send it across the radio system. At the far end, the digital audio is received by a radio, which converts it to analog and sends the signal to the speaker on the portable so it can be heard.

Possible Conversion 4: (Analog to Digital to Analog)

If one of the end users has a wireless Bluetooth headset, it will add another analog-digital-analog conversion. The analog audio of the person speaking is converted to digital for transmission over the Bluetooth link. Through a device at the radio, the digital audio is converted back to analog and enters the radio through the microphone connector.