Long Line Public Address
A distributed TCP/IP-based Long Line Public Address (LLPA) platform engineered for the demands of multi-station rail networks, transport hubs and large-area infrastructure. Server-redundant at the operations centre, autonomous at every endpoint, and bandwidth-efficient by design — the architecture is built to maintain operational service even in degraded mode.
Built on Ambient System EN 54-16 certified IP-amplifier hardware paired with the INFOPIX iBSC audio decoder and iPIS Passenger Information Server, the system delivers automated train-schedule announcements (driven directly from Darwin RTTI), live operator paging via SIP, and full integration with CIS displays, fire alarm systems and BMS / SCADA platforms — all while preserving WAN bandwidth through local Text-to-Speech synthesis at every station.
SYS
Design Principles
No large audio streams traverse the WAN. Voice announcements are synthesised by Text-to-Speech engines on local decoders, or played from local routine-announcement libraries. Only data and live SIP paging cross the network.
Duplicated Dell servers with hot-backup function at the OCC. Local audio decoders hold their own copy of the train-schedule database and message store, allowing each station to operate autonomously even if WAN connectivity is lost.
The platform receives static and dynamic train information from Darwin RTTI and operates without manual intervention. Operator action is required only in fault or exception scenarios — routine announcements run hands-free.
All inter-site traffic uses unicast IP — even live paging to all stations. This removes multicast routing complexity from the WAN and simplifies integration with corporate network infrastructure.
Suitable for surface and subway stations alike. Capable of interfacing with legacy ASL Vipedia systems, allowing operators to unify all their announcement infrastructure under a single platform during phased modernisation.
The iPIS platform can drive CIS displays, station clocks and information boards, not just audio. The optional iEM Element Manager (Nagios / Icinga2) adds enterprise-grade monitoring, alerting and historical performance tracking.
Two-Layer Architecture
The Long Line PA platform is structured as two clearly-defined layers connected over standard TCP/IP networking.
The split allows centralised management at the operations control centre while keeping every station fully self-sufficient at the local level.
Operations Control Centre (OCC)
Hot-redundant duplicated Dell servers running the iPIS Integrated Passenger Information System. Connects to Darwin RTTI push services, hosts the routine-announcement library, runs the SIP server for live paging, and provides the web-based operator GUI.
- iPIS application servers (Linux, microservice / containerised)
- SIP server for live paging
- RabbitMQ message broker for DB synchronisation
- LDAP / MS AD integration for user authentication
- Web-based operator interface (HTTPS)
At Each Station
An INFOPIX iBSC-P16 audio decoder paired with one or more Ambient System miniVES / midiVES IP-amplifiers. The iBSC holds a local copy of the timetable (48 hours pre-cached from Darwin) and synthesises voice announcements via on-board TTS, allowing the station to broadcast autonomously without WAN connectivity.
- iBSC-P16 audio decoder (X64 industrial PC, embedded Linux)
- miniVES / midiVES EN 54-16 IP-amplifier(s)
- Local paging microphones (ABT-M04N or ABT-DMS)
- Noise sensors + ABT-NSC6 aggregator (where required)
- Zoned loudspeaker circuits with dual interleaved A/B legs
Because announcements are synthesised at each station, only metadata and (when active) live SIP paging cross the WAN. The result is an exceptionally low backbone bandwidth requirement, tolerant of legacy long-line networks.
~100 kbps
RABBITMQ DB SYNC
Filtered timetable data, station-specific. Continuous, low overhead.
~100 kbps
RSYNC MP3 LIBRARY
Routine announcement updates. Triggered occasionally; ~3 MB per file.
~6.8 Mbps
LIVE SIP PAGING (WORST CASE)
100 kbps × 68 stations simultaneously. Most calls reach a single station only.
Protocols & Data Flow
| Protocol | Purpose | Endpoints |
|---|---|---|
| Darwin RTTI | Push-service feed of real-time train schedule data, 48 hr lookahead | Network Rail Darwin ↔ iPIS server |
| RabbitMQ | Database synchronisation between OCC server and station decoders | iPIS server ↔ iBSC-P16 |
| rsync | Routine MP3 announcement library distribution to local stations | iPIS server ↔ iBSC-P16 |
| SIP / RTP | Live operator paging (unicast to target stations) | SIP dispatcher console ↔ iBSC-P16 / miniVES |
| SMS proprietary driver | Control over Ambient System hardware: zone select, message trigger, status read | iPIS server ↔ miniVES / midiVES |
| SNMPv2 / SNMPv3 | Health and fault reporting to enterprise monitoring (PSIM / BMS / SCADA) | iPIS / iBSC → third-party NMS |
| REST API / WebSocket | Modern third-party integration with TMS, PIDS, BMS systems | iPIS server ↔ client systems |
| LDAP | User authentication via existing corporate directory (e.g. Microsoft AD) | iPIS server ↔ client AD |
| FDAS Dry Contact | Hard-wired EN 54-compliant fire-alarm interface to trigger evacuation messages | FDAS panel ↔ miniVES / midiVES |
Equipment by Function
Equipment by Function
All-in-one EN 54-16 certified IP-amplifiers featuring integrated audio matrix, message player, power amplifier, loudspeaker line monitoring, DSP processor and network interface. Front-panel emergency microphone, monitor loudspeaker and touchscreen built in.
miniVES 4002LNR
2 × 320 WTwo built-in power amplifiers, each rated 320 W RMS @ 100 V. One amplifier can act as integrated standby. Eight separately-addressable loudspeaker outputs, powering up to four sound zones.
- 2 × 320 W amplifiers (1 active standby capable)
- 8 addressable loudspeaker outputs / up to 4 zones
- 2 × SFP slots (redundant network)
- 2 × RJ45 LAN (1 PoE-capable)
- 9 programmable inputs / 5 programmable outputs
- Internal redundant non-volatile message memory
- 19″ rack mount
midiVES 8003LNR
3 × 500 WThree built-in power amplifiers, each rated 500 W RMS @ 100 V. One amplifier can act as integrated standby. Sixteen separately-addressable loudspeaker outputs, powering up to eight sound zones.
- 3 × 500 W amplifiers (1 active standby capable)
- 16 addressable loudspeaker outputs / up to 8 zones
- 2 × SFP slots (redundant network)
- 2 × RJ45 LAN (1 PoE-capable)
- 9 programmable inputs / 5 programmable outputs
- 2 simultaneous broadcasts per unit minimum
- 19″ rack mount
Broadcast System Controller
The local intelligence at every station — receives information from the iPIS server, synthesises and routes voice messages, and controls the IP-amplifiers via a dedicated software driver. Operates standalone with a 48-hour pre-cached schedule when network connectivity is lost.
INFOPIX iBSC-P16
AUDIO DECODERIndustrial-grade X64 PC running embedded Linux in a 2 mm stainless-steel 19″ enclosure. Receives the train timetable database from the iPIS server (Darwin lookahead), generates voice via on-board Text-to-Speech, decodes SIP/RTP audio for live paging, and stores routine announcements in local file storage.
Hardware
- X64 industrial PC, embedded Linux
- OLED status display
- 2 mm stainless steel housing, 19″ rack-mount
- Tamper-protected power switch (rear)
- NTP-synchronised clock
Connectivity
- Dual Ethernet (1 to PA system, 1 to OCC LAN)
- Receives data from iPIS via RabbitMQ + rsync
- SIP/RTP digital audio reception
- SMS-protocol control of miniVES / midiVES
- SNMP fault reporting to external NMS
- Web-browser interface for setup & diagnostics
Control System & Software
A server-client integrated PIS / PAS control platform that can serve multiple railway lines simultaneously. Modern microservice / containerised architecture allows features to be deployed server-side or client-side as required.
iPIS Server / Client Platform
INTEGRATED PIS / PASDuplicated fail-safe servers connect to Darwin Real-Time Train Information push services and store all events in a local database. Operators access the system via standard HTTPS web browser to set up, configure, monitor and operate. SIP server runs on the same platform to enable live paging from the OCC dispatcher to any station.
Operator GUI
- Welcome dashboard
- Line dashboards per route
- Route-level status visualisation
- Announcement schedule editor
- MP3 library upload & sync
Server-Side Services
- Darwin RTTI receiver
- SIP server for live paging
- RabbitMQ broker
- rsync file distribution
- LDAP / MS AD authentication
Audit & Compliance
- All operator activity logged
- Per-zone status retention
- Historical performance tracking
- Container-level health monitoring
- Database synchronised across redundant pair
Paging Microphones & Operator Consoles
Three tiers of paging device cover everything from local platform staff to OCC dispatchers. All devices interoperate with the same iPIS / miniVES backbone.
ABT-M04N
STANDARD STATION MIC
4-zone paging microphone with analogue input. Line-level + dry-contact interface. Up to 35 microphones can be daisy-chained on CAT-5. Gooseneck microphone, 4 zone buttons, talk button, AUX activation.
ABT-DMS
DESKTOP PAGING UNIT
Desktop unit with 9 programmable buttons + talk button + gooseneck. Expandable via ABT-EKB-20M keypad add-ons. PoE-powered (or local DC). BGM line input, headset and monitor speaker support. For large stations / interchanges.
ABT-ICDG-1
SIP DISPATCHER CONSOLE
SIP-based operator console combining IP telephone with paging system. 4.3″ main display, auxiliary display, full keypad, 32 programmable DSS buttons (96 logical, 3 layers). For OCC dispatcher positions.
Ambient Noise Tracking
Continuous real-time monitoring of background noise within each zone, with automatic adjustment of output level to maintain the required signal-to-noise ratio (typically 10 dB minimum) and consistent speech intelligibility under all environmental conditions.
ABT-NSC6
NOISE SENSOR AGGREGATOR
Pre-amplifier and aggregator for up to 6 noise sensors. Digitises sensor feeds and transmits to IP-amplifiers via Ethernet. PoE-powered (or local DC). Sensors can be assigned to specific zones in software.
ABT-NSM(A) / NSM(B)
NOISE SENSOR MICS
Two variants: NSM(A) for recessed ceiling installation (indoor only), NSM(B) for wall / ceiling installation (indoor + outdoor capable). Configurable thresholds per zone trigger graduated attenuation.
• 8-band parametric EQ
• Loudspeaker delay (up to 30 s)
• Automatic noise tracking (ANC)
• Feedback suppression
• Limiter / compressor protection
• Timed automatic volume reduction
Loudspeaker Range
A complete EN 54-24 certified loudspeaker range covering every typical station and platform application — from recessed ceiling units in ticket halls to long-throw line arrays for open platforms. All units include 100 V matching transformers with multiple power taps for site-specific tuning.
| Model | Type | Power | Max SPL | Frequency | Dispersion | IP / IK | Best For |
|---|---|---|---|---|---|---|---|
| ABT-S206F | Recessed ceiling | 6 W | 97 dB | 82 Hz – 20 kHz | 180°/85° | IP54 / IK07 | Ticket halls, waiting rooms (with fire dome) |
| ABT-W6F | Cabinet (wall/ceiling) | 6 W | 99 dB | 120 Hz – 20 kHz | 110°×135°/80° | IP44 / IK07 | Concourses, surface-mount circulation |
| ABT-P20 | Sound projector | 20 W | 102 dB | 130 Hz – 20 kHz | 230°/65° | IP66 / IK07 | Platforms, lamp-post mounted |
| ABT-LA40B | Column line array | 40 W | 104 dB | 160 Hz – 20 kHz | 200°/120°×40° | IP65 / IK07 | Platforms, large open areas |
| ABT-LA60B | Directional line array | 60 W | 106 dB | 160 Hz – 20 kHz | 200°×35°/125°×10° | IP65 / IK07 | Acoustically challenging long platforms |
Broadcast Priority
Priority hierarchy follows Network Rail recommendations — emergency and life-safety messaging always overrides operational paging, which in turn overrides routine and BGM content. The miniVES / midiVES amplifiers can simultaneously broadcast at least two messages per unit, with one of three internal amplifier modules configured as active standby.
| Priority | Source | Trigger |
|---|---|---|
| 1 | Emergency microphones | Local manual override at the station |
| 2 | Pre-recorded evacuation message | Automatic on FDAS dry-contact activation |
| 3 | Other pre-recorded messages | Stored in amplifier non-volatile memory |
| 4 | Local PA | Desktop paging microphones (ABT-M04N, ABT-DMS) |
| 5 | Long Line PA | Audio injected via iPIS interface (OCC announcements, TTS, schedule) |
| 6 | BGM players | Local sound source / audio inputs (background music) |
Integration & Interoperability
- Darwin RTTI push services
- Worldline Server Train Descriptor Service
- Alstom TMS
- Solari control protocol
- Funkwerk systems
- Ketech K680 / K780 PAPC
- SNMP traps to PSIM / BMS / SCADA
- REST API for modern integrations
- WebSocket real-time data exchange
- XML-based legacy enterprise interfaces
- ECS protocol (LCD display systems)
- LDAP / MS AD authentication
- SNMP traps to PSIM / BMS / SCADA
- REST API for modern integrations
- WebSocket real-time data exchange
- XML-based legacy enterprise interfaces
- ECS protocol (LCD display systems)
- LDAP / MS AD authentication