The outside broadcast (OB) is one of radio’s most distinctive formats: a live transmission from a location away from the main studio, whether a shopping centre, a festival field, a sporting venue, or a community event. Getting live audio back to base cleanly and reliably is an engineering challenge that has evolved considerably over the decades.
Why Outside Broadcasts Matter
OBs bring immediacy and local relevance that pre-recorded or studio-only content cannot match. A breakfast show broadcasting from a new business in town, a live commentary from a local cup final, or a concert relay from a festival stage all connect a station to its community in a tangible way.
Classic OB Links: ISDN
For many years, ISDN (Integrated Services Digital Network) was the workhorse of radio outside broadcasts. An ISDN codec at the remote location compressed audio and sent it over dedicated telephone lines back to the studio. The system delivered reliable, predictable quality and low latency. ISDN lines are being withdrawn across most of Europe and North America, forcing broadcasters to find alternatives.
IP Codecs: The Modern Standard
IP-based broadcast codecs now carry most outside broadcast audio. Devices using the LUCI, Tieline, or Comrex platforms compress audio and send it over internet connections using protocols designed for broadcast quality and low latency. 4G and 5G bonding — combining multiple mobile data connections — gives engineers confidence at locations where fixed internet is unavailable.
Satellite and Microwave Links
Major national broadcasters and sports rights holders still use satellite uplinks for guaranteed, high-quality return paths. Microwave point-to-point links remain common in dense urban areas where a permanent path can be established between a venue and a nearby relay point.
- OBs deliver live location-based content that studios cannot replicate
- ISDN codecs were the standard for decades but are being retired
- IP codecs over broadband and 4G/5G bonding are the current norm
- Satellite and microwave links serve major events where reliability is paramount
The OB truck has shrunk to a rucksack in many cases. A single engineer with a bonded 4G codec, a portable mixer, and a good set of headphones can now deliver broadcast-quality audio from almost anywhere — a capability that would have seemed remarkable twenty years ago.