Auracast™ deployment: get the signal to every seat

Welcome – what you’ll be able to do

Auracast™ sends audio over the air to an unlimited number of listeners. Where you put the CASTER decides who hears it. This course shows you why – step by step, with live examples on the right.

What blocks or weakens the signal

Auracast™ is a low-power 2.4 GHz radio wave. It spreads out from the CASTER and fades with distance – and it behaves more like light than sound:

• Passes through light materials (glass, wood, drywall).
• Is absorbed by water – and people are mostly water.
• Bounces off metal.
• Casts shadows behind solid obstacles – it doesn’t bend around them the way sound does.

How much each material costs

The audience is part of the radio plan

The human body is mostly water, and water absorbs 2.4 GHz signals. At head height, every person in the way weakens the broadcast. Mount the CASTER above the crowd and the signal travels over them instead of through them.

Mount high – line of sight is king

Two identical CASTERs on the same wall, same power. Only the height differs – and it changes everything.

1. Mount high and central – 3 m or more, clear of metal, aimed at the audience.
2. Every listener should “see” it – each body, pillar or wall in the path costs margin.
3. Design for the farthest seat – if the last row is fine, the whole room is fine.

Behind a raked audience: the back problem

A CASTER on the back wall of a stand or a raked hall looks convenient – it is high and close to the last row. But everyone faces the stage, so every listener turns their back to it.

It depends on where the receiver is worn

Signal strength (RSSI): how much is enough?

RSSI tells you how strongly the broadcast arrives at a receiver, in dBm. Closer to 0 = stronger.

Receivers: sensitivity and where they’re worn

The same broadcast can sound perfect on one receiver and break up on the one next to it. Two things make the difference.

1. Sensitivity – how weak a signal the receiver can still decode. An RTX has a larger antenna and is more sensitive. Earbuds and hearing aids have tiny antennas next to the head, so they need a stronger signal – hearing aids the most.
2. Wearing position – an RTX hangs on the chest, low and with the listener’s own body and the people around them in the path. Earbuds and hearing aids sit at ear level, usually above the crowd, with a clearer path to a high CASTER.
3. Plan for the weakest receiver – if your audience uses hearing aids or earbuds, design the coverage for them, not only for the RTX.

A crowded band: interference

RSSI is a must – but not the whole story

1. Strong isn’t enough – the signal must stand clearly above everything else on the band. That margin is the signal-to-noise ratio (SNR).
2. Quiet band – a good RSSI means a big margin and clean audio.
3. Busy band – 2.4 GHz Wi-Fi and other broadcasts raise the noise. The same RSSI now leaves only a thin margin, and packets collide.

The RSSI meter only sees your signal – not the noise or the other radios colliding with it. Broadcast audio is unacknowledged – receivers never confirm a packet or ask for it again. Instead, Auracast™ transmitters send each packet several times (typically 3 to 5 copies), so a receiver only needs to catch one. When interference wipes out every copy, you hear a dropout – even with a good RSSI.

A shared band

Auracast™ shares 2.4 GHz with Wi-Fi and many other devices. The CASTER hops between channels automatically (adaptive frequency hopping) to avoid busy ones – but it can’t outrun a saturated band. Every busy source raises the noise floor and eats into your SNR.

The playbook

1. Measure first – scan at the busiest realistic hour and find the main source.
2. Separate – keep CASTERs at least 2 m from Wi-Fi access points.
3. Offload the band – ask venue IT to move Wi-Fi clients to 5 / 6 GHz and free as much of the 2.4 GHz band as possible. The more of it is free, the better.
4. Add density, not power – a CASTER closer to the listeners beats maxing the power.
5. Re-test after every change and document the final state.

Antennas: match the pattern to the project

The antenna decides where the signal goes. A more directional antenna focuses the signal into fewer directions, so it reaches farther there and less elsewhere. Every CASTER has a built-in antenna; CASTER X and XD also accept an external antenna (RP-SMA connector) – a pole antenna or a directional panel.

Coverage pattern · side view

weak straight above

weak straight below

strongweakerweak

What it looks like

CASTER X / XD

External pole antenna (omni)

Pattern: a “donut” around the pole – strong all around sideways, weak straight above and below it.

Use it when: the CASTER sits in a rack, a cabinet or above the ceiling, and you bring a small antenna into the room on a cable – or the listeners are all around the antenna at about its height. A typical case: the CASTER at the sound desk (front of house) in the middle of the audience, with the pole on a tripod above the heads.

Watch out: mount the pole vertical. Listeners straight below a high pole sit in its weakest spot.

This is the general picture. A detailed guide to choosing the right antenna for your project is coming soon.

Large venues: two proven coverage strategies

A stadium or an arena is too big for one CASTER. There are two proven ways to cover the whole bowl – spread the CASTERs around it, or put them together in the middle and aim them outwards.

STRATEGY 1

Distributed CASTERs

CASTERs with their built-in antennas, spread around the bowl – each covers the stand in front of it, and the neighbouring areas overlap so every seat is covered.

Strengths: short distances to every seat – a stronger signal and a better SNR in a busy band – works with any CASTER, easy to extend one section at a time.

Watch out: more mounting points, and a network and power cable to each one.

STRATEGY 2

One centre cluster – directional

Four CASTER X / XD units on the centre scoreboard or truss, each with a directional panel aimed at one side of the stands.

Strengths: one mounting point and one cable run, a high position that looks down on every stand.

Watch out: longer distances to the top rows – choose panels whose beam fits each stand, and check the corners between beams.

How many CASTERs? Sizing the system

The question every quote depends on. Plan the number of CASTERs from the floor plan: one for each separate space, and more for large spaces, each covering its own area with some overlap at the edges.

1. Define the listening area.
2. Subtract blocked zones – walls, metal, other levels.
3. Divide into cells of 15–30 m radius.
4. Add 10–20% overlap between cells.
5. Sanity-check on site (or with a planning tool such as Hamina Network Planner with the Bettear plugin).

Two ways to plan a project

Every project starts on the floor plan. How far you take it depends on the venue – common sense and the rules of thumb for most single spaces, a predictive planning tool for large or complex ones.

Path A – plan by the rules of thumb

Common sense plus the rules from this course. Right for most single-space projects.

• When it’s enough: single rooms, clear line of sight, small-to-medium venues.
• Sketch the cells on the floor plan and keep it in the project file – a 10-minute drawing prevents most surprises.

Path B – Hamina Network Planner + Bettear plugin

1. Import the floor plan – scale it, draw the walls and assign materials with realistic attenuation.
2. Place Bettear devices – the plugin provides CASTER models with real transmit power and antennas.
3. Read the heatmap – predictive coverage: weak zones and wall shadows appear instantly.
4. Iterate and export – adjust placement and transmit power, then export the map for the quote or the tender.

Measure, don’t guess: the site survey

One visit with the right checklist saves multiple visits later. Test before you install – and validate after.

Tools in your pocket

Professional tools

When the project – or the tender – demands proof:

Takeaways: seven rules of thumb

Three habits make every deployment succeed: plan with physics, measure – don’t guess, and right-size the system.

1. Line of sight is king. If listeners can “see” the antenna, the link is easy.
2. Mount high and central. 3 m+, clear of metal, aimed at the audience.
3. Keep 2 m+ from Wi-Fi access points. They’re the strongest interferer on site.
4. Plan for the full room. People absorb 2.4 GHz.
5. A solid wall = a new zone. Plan a CASTER per zone.
6. Overlap cells 10–20% for seamless listening while moving.
7. Use the minimum power that works – privacy and a cleaner band.

Playground: try it yourself

This is the full coverage explorer. Move CASTERs, change the room, the audience and the receivers. Complete the challenges – they tick themselves off when you get there.