Our GPS audio technology
One engine that runs in the phone’s browser and knows where the listener is, which way they face and how fast they move. It says which way to look, it can tell whether they are walking towards a place or away from it, and it needs no fixed route: wander, ride or drive, and the stories arrive as the places do. Six uses are live in Sydney today, each filmed below. Designed, built and operated by Antratel Pty Ltd, Sydney; every word written by a licensed Sydney guide since 2006.
What the engine does
The same core runs under every use on this page. Only the points, the trigger geometry and the audio change.
🧭 Which way to look — and which way you are going
The guide says look on your left or look on your right, not “attraction ahead”. It also reads your direction of travel: a story plays as you approach a place, and stays silent when you are walking away from it — nothing is announced about a building you have already passed. The map can turn to Heading-Up, so left on the screen is your actual left.
🗺 No fixed route
There is no set path to follow. Walk, ride or drive wherever you like and the guide tells the story of whatever you pass; the list of places re-sorts itself around you as you move, and a route on the map is only ever a suggestion. A hotel walk, a marathon course and a festival precinct are the same engine with different points.
🎧 Never silent, with a player made for a moving listener
A podcast fills every gap between places, steps aside when a story plays and resumes from the same second — even days later. There is no seek bar to aim at on a bumpy road: ⏮ and ⏭ skip by paragraph, not by fifteen seconds, and speed, volume and day-night are each one tap, with menus that never cover the map.
⏱ One database, every speed
The trigger zones are rebuilt from your real speed: tight and directional on foot, wider on a bicycle, early and decided once in a car or a tram, because a driver gets one chance to look. The same points serve 4 km/h and 60 km/h without a separate build.
📱 A web page, not an app — and a small app where it earns its keep
Open a link or scan a QR code and the tour starts: no store, no account, no download, no review process between you and a content change. The same engine also ships as a 5 MB app for the one thing a browser cannot do — keep guiding with the screen off or another app in front. Content lives on the server, so a change is live in both within seconds.
💬 Written by a guide, voiced by AI, in two languages
Every word is written by a Sydney guide with 20 years on the road and voiced with an AI model of his own voice, which is how one guide covers 180+ places and sounds the same at the last stop as at the first. One content set covers English and Russian, and the guide opens in the visitor’s browser language from a single link.
Light rail: a free guide that rides with the tram
A QR poster at the stop, a phone, headphones — and the tram becomes a guided tour. The guide tracks the vehicle along the line, announces each stop and tells the story of what is passing the window right now; between stops the podcast keeps talking, so a thirty-minute ride is never dead time. Free to the passenger: no payment, no signup, nothing to install. Live on Sydney Light Rail today.
From the hotel door and back
A walk a hotel orders for its guests: it starts at the hotel’s door, takes them around the city and brings them back. Reception hands out a link or a QR code, the guest opens it in the phone’s browser, and the GPS tells the story of each place as they pass it. Nothing to install at the hotel, nothing to download — filmed in Sydney, from a hotel to Hyde Park, Macquarie Street and back.
This is the engine at walking pace: the tightest trigger zones, the direction cue at the doorway, and a list that keeps re-sorting itself as the guest wanders off the suggested loop and back onto it. The loop is built around any address from the existing library of narrated places.
For Sydney hotels: the walk is free
We build the tour from your hotel around the city and back at no charge, and add a podcast about your hotel to it — its story, told in the guest’s ear as they set off. The one condition is that the guide is promoted in your lobby: a stand or a QR poster at reception, so guests know it exists. Write to [email protected] with the hotel’s address and we come back with the loop.
Events: audio that unlocks when you walk into it
A festival is a dense field of geofences in a few hundred metres, at night, in a crowd. Each installation gets its own trigger zone, sized to it; the visitor wanders in any order and the commentary starts by itself as they step in, on a night-mode screen that does not blind anyone around them. Content is swapped between editions in hours, not through an app release.
A marathon is the same engine with a route: the whole 42 km course loads on the map the moment the guide opens, free and without a signup, and the landmarks along it are narrated as a runner, a spectator or a driver passes them. A route is a configuration, not a project — drawn, filmed end to end and published for one weekend of the year. The same geometry works as a property guide: give the zones to addresses instead of artworks, and each listing speaks for itself as the buyer arrives.
In the field at a light festival. The visitor is standing in front of the artwork with the phone already in hand: the commentary started by itself the moment they crossed into the zone. Nothing was typed and no number was matched to a plaque.
The whole festival mapped as geofences. Each pink circle is a trigger zone, wide for a building-scale projection and tight for a sculpture you have to walk up to. The circles are drawn on the map on purpose: the visitor can see where the audio will start and step closer. Whatever is nearest rises to the top of the list, and anything already heard sinks to the bottom.
By bicycle: the same guide, wider and earlier
On a bicycle the same points run with wider, earlier trigger zones, and the interest filter carries dedicated bicycle trails so the suggested route follows cycleways rather than footpaths. The rider does not touch the phone: the story of the next place starts by itself, with the side to look on, and the podcast covers the stretches in between.
What the rider and the walker get
- Listen on demand for anything in the list, or leave Guide Mode on and let the GPS do it.
- Navigate hands a place to the phone’s map app for turn-by-turn directions.
- Download Route exports the suggested loop for offline planning.
- The card of whatever is being narrated lights up, the nearest few glow behind it, and anything already heard fades back.
- Interrupt a story halfway and the guide remembers where you were; walk away mid-podcast and it is still there tomorrow.
By car: decide early, speak once, say which window
The hardest case, and the one the platform was born for. At road speed the guide has to decide early, speak once and say which window to look through — without asking the driver to touch anything. It runs on the phone and plays through the car speakers over Bluetooth, the same pairing every driver already uses for music, so hands and eyes stay where the law wants them. Nothing is installed in the vehicle, which is why a rental fleet can offer it on day one across every model in the yard.
It keeps talking while Google Maps drives you
A browser tab sleeps when the phone locks: positions stop arriving and the guide goes quiet in a pocket. The small companion app holds a foreground location service instead, so the tour carries on with the screen dark, the phone away, or another app in front — and a notice sits in the status bar for as long as the tour runs, because the listener is entitled to know. Filmed on a real drive: Google Maps has the screen and is doing the navigating, and underneath it the guide keeps naming what has just been passed and which way to look, through the car speakers.
Operator side: console, simulator and one database for many tours
A guide is only half the system. The other half is what the operator sees: who used it, where they started, where they gave up, and whether a new trigger fires before anyone is sent out to test it.
Session console
Every tour is logged: start and end time, duration, start and end position, device, browser, and how the visitor got in — free trial, demo link or paid key. Headline numbers sit on top and the whole table exports to CSV. Access links are generated from the same screen: pick a duration and a language, press Generate, hand over the link. Keys bind to the device, so one link does not quietly become a hundred.
Design mode and GPX simulator
Design mode draws the invisible layer on the map: every trigger circle, every directional pair, every bearing vector, so an overlap or an over-generous radius is visible at a glance. The simulator then replays a recorded route at up to 5× speed from a desk: a whole tram line or a full driving loop is regression-tested in minutes, before anyone gets in a car. Visitors get a version of it too — press START SIMULATION in the guide and the route runs itself.
One database, many tours
Points carry group tags, so one content set publishes as a heritage walk, a family wildlife route, a shopping loop or a cycling trail. The visitor ticks what they want and the list re-numbers itself; the operator maintains one database instead of six apps.
📢 Not only an information system — an advertising channel
Everything the engine knows in order to tell a story — where the listener is, which way they face, how fast they move and what time it is — is exactly what makes an advertising slot valuable. The same trigger that plays a landmark can play a sponsored message, at the only moment that matters: while the business is passing the window.
Geofenced audio spots
A restaurant precinct, a shopping centre, a winery on the highway: the insert fires as the vehicle enters the zone and nowhere else. Radius, direction of travel and speed are all conditions you can set.
Sponsored points in the list
A branded card with its own Listen and Navigate buttons sits in the visitor’s list — a one-tap path from an audio mention to the front door.
Route-level sponsorship
An operator, council or brand can present an entire line or trail: opening credit, closing credit, and a matching QR poster campaign at the stops.
Measured, not estimated
The console counts real sessions, durations and positions, so an advertiser is quoted delivered plays inside a zone, not printed circulation.
Editorial discipline: sponsored audio is frequency-capped, kept clearly apart from the narration, and never fires while a story is playing. A tour that nags is a tour that gets switched off.
🗺 The map: no licence, no per-view fee, labels that stay upright
Most audio guides rent their map from a tile vendor, priced per view, and the meter runs faster the better the product does. Ours is our own.
Our own basemap
Vector tiles built from OpenStreetMap data, served from our own storage as a single file, with no third-party API key in the page — in production on every live guide since August 2026. No per-view fee, no quota, no vendor who can reprice or revoke access mid-contract. The only obligation is the visible “© OpenStreetMap” credit, which is on the map.
Rotation, tilt and perspective
A rented map arrives as finished pictures with the street names painted in, so when it rotates the names end up upside down. With vector tiles the names are drawn by the browser and stay level at every angle, and in Heading-Up mode the view tilts towards the horizon like a car navigator.
What it means for a licence
Nothing in the map layer has to be re-licensed to hand the platform over: the tiles are a file the customer can hold, and the escrow deposit can include it. One less external dependency in a tender.
Light on the network
A vector tile carries geometry rather than pixels, so the map loads quickly on a crowded 4G cell and re-draws instantly when the visitor rotates or zooms.
📄 How licensing works
Two different things can be bought here. Either you resell the Sydney guide that already exists — a finished product, nothing to build — or you license the engine for your own line, city, hotel or event, which means a route gets built. The second is what a transport operator, a council, a hotel group or a festival needs, so here is how it runs.
Step 1 · Pilot on your own route
Two to three weeks, no procurement needed to start. We take a short section of your actual line, route or loop, build a handful of real trigger points on it and give you an unlisted link. Your team walks or rides it with their own phones. If it does not convince you on the ground, it stops there.
Step 2 · The route build
The route is walked or driven and recorded as a GPS trace at real operating speed. Every point gets its own geometry — radius, approach direction, entry and exit vectors — then the words: written for that spot, voiced, and cut into paragraph maps. Priced per point, quoted once the route length and point count are known.
Step 3 · Acceptance on the ground
We cover the whole route with you and tune until it passes written criteria: every point fires within an agreed distance at operating speed, in both directions, with no double-firing and no silence longer than the agreed gap.
Step 4 · The licence itself
Three deployment choices: hosted by us, self-hosted in your own Azure, AWS or on-premises server with Australian data residency where required, or white label on your brand and domain. Term, service levels, escrow and territory exclusivity are settled here — one operator per line, city or precinct in a category.
Step 5 · Handover and console
Your staff get the operator console and the simulator. Training takes an hour, because there is no app to administer and no devices to manage.
Step 6 · Ongoing
An annual licence covers the platform, updates and support. Content changes as the city does and are quoted as they arise. Where the advertising layer is on, sponsorship revenue is split on agreed terms and reported from real session data.
Who owns what
Stays ours
The engine, the platform and the operator console remain our intellectual property and are licensed, not sold — which is why the escrow below exists.
Becomes yours
Your route data, branding, sponsor content and visitor statistics are yours. Scripts and recordings written for your route are licensed for the term and can be bought out permanently.
What we need from you
Four things, none technical: the route or permission to trace it, a content source or sign-off on ours, a decision on branding and domain, and one person who can accept the result.
Government procurement
NSW agencies buy ICT through the ICT Services Scheme (SCM0020), and we are a registered supplier. Capability statement, accessibility position, data residency, escrow terms and insurance come back the same week.
🔒 A risk-free proposition: full technology escrow
Buying a platform from a specialist team raises one fair question: what happens to our service if that team disappears? Under contract we lodge a complete working package with an independent escrow agent, sufficient for any third-party IT team to redeploy the platform from scratch.
1. Technical base
- Platform source code.
- Every external service, API and dependency, listed.
- Step-by-step deployment documentation, from zero.
2. Content and data
- The points database: coordinates, trigger radii, direction vectors and texts.
- Studio-quality master audio files.
3. Infrastructure and access
- A mechanism for transferring the domain, DNS records and certificates, so visitors never have to find a new address.
4. The map
- The basemap tile file, so the map layer needs no re-licensing.
Release conditions
The package sits in the escrow agent’s safe and is opened only on a critical event:
- Our company declares bankruptcy or liquidation.
- The service is unavailable for more than 30 consecutive days.
- A critical breach of the SLA occurs and is not remedied.
Implementation: .NET, JavaScript and scaling to 500,000 listeners
A procurement question we get early: what happens when it works too well? A festival opening night, a cruise ship arrival, a stadium crowd, all reaching for the same link in the same ten minutes.
🖥 Server: ASP.NET Core on .NET 10
Pages, access keys, session logging and audio streaming run on ASP.NET Core, .NET 10 Long Term Support. Audio is delivered with HTTP range support, which is what makes seeking, resuming and paragraph skipping work on a mobile network.
💻 Client: plain JavaScript
The whole guide — GPS loop, trigger geometry, bearing maths, map, player, filtering — runs in the visitor’s browser in vanilla JavaScript. No framework to go out of support, no binary to rebuild, nothing a government network is likely to block.
☁ Azure-ready autoscaling
The stack deploys to Microsoft Azure App Service without a rewrite, with autoscale on instance count and a CDN in front of the audio. Capacity is a setting: raise it before opening night, lower it on Monday.
📈 Why it scales at all
The guide holds no per-listener state on the server. Position, progress and playback live in the visitor’s own browser; the server hands out static audio and records sessions. There is no shared bottleneck for a crowd to collide with.
📊 How this compares with other audio guides →
The well-known platforms are excellent at what they do. The comparison is about what a guide built for moving through a city can do that a library of recorded walks cannot: twelve platforms on coverage, hours of audio, install size and background playback →
Want it on your line, your hotel, your event or your fleet?
Every use above is live in Sydney today. Open the guide on your phone and walk outside — or press START SIMULATION and watch it run from where you are sitting. If you operate transport, run a hotel or an event, rent cars or manage a destination, the same engine can carry your route, your voice and your sponsors.
Antratel Pty Ltd (ABN 24 122 328 492) — tourism technology, Sydney. Content authored by a licensed Sydney guide since 2006.