Elevator Intercom System Fiber Transmission Design Solution

The National Elevator Industry Standard Committee introduced the new standard GB7588-2003 Safety Rules for the Construction and Installation of Electric Lifts in 2004, and began nationwide implementation from 2005. Clauses 5.10, 8.17.4, 8.17.5, 14.2.3, and 15.12 of the standard specify clear requirements for elevator communication systems, covering not only multi-party calls in single-elevator communication systems but also communication systems in multi-elevator cluster applications. The release of the new standard provided a scientific basis for the production, inspection, and acceptance of elevator installation projects for elevator communication systems in cluster applications.

With the widespread adoption of elevators, elevator communication systems have evolved from simple single-elevator emergency call systems into multi-elevator group communication systems capable of large-scale networking. This enables dozens or even hundreds of elevators in large residential communities to be networked into an integrated elevator group communication system. In this system, each elevator has a fixed code, and the car main unit, car-top sub-unit, pit sub-unit, and machine room sub-unit in each elevator can all make call communication with the management center in emergency situations. The management center can also initiate call communication with the car main unit, car-top sub-unit, pit sub-unit, or machine room sub-unit of any elevator, and can support group calls and broadcast calls.

With long-term technical accumulation, elevator five-party intercom equipment has become increasingly mature, and elevator intercom devices have developed into products with low cost and stable performance. The main technologies are categorized near the elevator into two types: common-line intercom (which does not distinguish terminal location) and star-type intercom (which can distinguish car top, car bottom, car, and machine room). The former uses simpler technology with lower equipment prices. Correspondingly, the central-end equipment differs: the former corresponds to multi-station direct-key terminals (such as the commonly used Otis five-party intercom), while the latter is mostly bus-type dialing terminals (such as Mitsubishi five-party intercom).

Traditional five-party intercom systems are implemented over twisted pair cables, which limits the transmission distance. To address this, some manufacturers use ISM band radio, but since it operates in unlicensed frequency bands, rights are not protected and interference is likely. Others use GSM for remote transmission, which solves the long-distance transmission problem but requires periodic recharging, resulting in significant ongoing costs.

The elevator five-party intercom solution over fiber or IP networks not only solves the long-distance transmission problem but also saves investment through a one-time deployment cost. Additionally, through digital audio processing, voice recording can be conveniently implemented, and the system can be easily integrated with video surveillance systems. It can also be connected to a multimedia command & dispatch system for interoperability with wireless trunking radios, fixed telephones, and mobile phones.

The five-party intercom fiber transmission equipment (referred to as five-party intercom optical terminal) provides access channels for existing elevator intercom devices. While keeping the original remote equipment unchanged, it provides one audio channel per elevator (identifying which terminal is currently speaking through signaling encoding).

When providing the optical transmission channel, the equipment at both ends remains unchanged. This only solves the transmission problem without enhancing other functions, and the system cost is relatively high.

Therefore, we provide a comprehensive terminal solution. On the central-end equipment (DTZX), we offer 2 telephone interfaces, a computer communication interface, emergency answer buttons, indicator lights, and an alarm horn. It can be networked with other devices, supports expansion of additional optical ports, and provides an Ethernet interface for IP recording. It can connect up to 120 elevators.

The emergency answer button is used when no computer is involved (e.g., shutdown, crash, power failure). Pressing this button automatically connects to the currently alarming elevator. After handling, if the alarm light remains on, pressing again connects to the second alarming elevator.

Additionally, the advantage of using fiber is that each elevator has an independent channel without competing for the voice bus, facilitating centralized recording at the central end.

The fiber transmission system has the capability to automatically detect the lines of each node device, with automatic fault alarming.

Central-end equipment functions: When any remote intercom device goes off-hook or triggers an alarm, the alarm light on the central-end panel lights up, the channel number and alarm content are sent to the PC, the corresponding button on the screen turns red, and when bound to images, the image information of that elevator is displayed. Pressing the corresponding button on the touchscreen establishes five-party communication between the first telephone and that elevator. If the first telephone is busy (already connected to an incoming call), the second telephone is automatically connected (if off-hook, direct communication; if on-hook, ringing).

The central end can directly call the remote end by going off-hook first and pressing the button for the corresponding elevator, enabling five-party communication.

In emergency situations, pressing the emergency button allows the central end to broadcast to all elevators.

The PC can generate statistical reports.

There is an elevator data input field (allowing entry of all elevator data for each building, as well as maintenance personnel mobile numbers and trunking frequencies). When an alarm occurs, the specific location of the elevator is displayed (such as building number, elevator number, number of elevators, number of floors, etc.).