IDM GTD442 Dual-Gigabit Telephone Optical Multiplexer

IDM GTD442 dual-gigabit telephone optical multiplexer is a new-generation optical-electrical integrated device launched by Beijing Ruiguang Jiyuan Digital Technology Co., Ltd. As a representative product of Raytrans, a professional optical multiplexer manufacturer, this telephone optical multiplexer carries gigabit Ethernet, narrowband telephone and serial port data services simultaneously over a pair of optical fibers, and is a typical multi-service optical multiplexer product showcase.

It provides 2 wire-speed 1000M Ethernet interfaces over a 2.5G optical fiber channel, and integrates 4 voice channels configurable as FXO, FXS or MAG magneto formats plus 2 RS485 (or 1 RS422) data channels, allowing broadband and narrowband services to share a single optical fiber line; 2 RS485 or 1 RS422 plus 4 voice channels can be transmitted over one fiber together with gigabit Ethernet data and voice. This gigabit network optical multiplexer meets the requirements of private network users in public security, electric power, railway and mining sectors for highly integrated optical multiplexing equipment, and is widely applicable to scenarios such as government private network optical fiber communication solutions, smart mining communication solutions and military emergency communications vehicle solutions.

Key specifications at a glance: 2.5G optical rate · dual gigabit channels (each with 1 electrical port GE + 1 optical port GX) · 4 voice channels FXO/FXS/MAG · 2 RS485 or 1 RS422 · 18 E1 bandwidth · FC single-mode 20km · AC220V/DC-48V · ≤90W.

What kind of device is the IDM GTD442 dual-gigabit telephone optical multiplexer?

The IDM GTD442 dual-gigabit telephone optical multiplexer is an optical fiber access device with multi-service access on the user side and optical fiber aggregation on the line side, and is also a multi-service optical multiplexer product offered by Raytrans for private network communication scenarios. The unit's optical interface rate is 2.5G, providing 2 wire-speed 1000M Ethernet channels, each equipped with 1 electrical port GE and 1 optical port GX; this 2.5G bandwidth can also provide 18 E1 bandwidth transmission channels for narrowband services such as voice and data as required. As a gigabit network optical multiplexer, it often features dual gigabit channels and multi-service access capability as its core selling points in product showcases.

Compared with ordinary Fast Ethernet optical multiplexers, the single-fiber 2.5G rate and dual gigabit channels each containing 1 electrical port GE and 1 optical port GX double the bandwidth, and can simultaneously support concurrent transmission of high-definition (HD) video surveillance, gigabit intranet and telephone access.

Figure 1: Front panel interfaces and indicator LEDs of the IDM GTD442 dual-gigabit telephone optical multiplexer

For line transmission interfaces, the IDM GTD442 dual-gigabit telephone optical multiplexer can be configured with two groups of optical interfaces, forming mutual backup optical ports, or forming chain network, ring network and other network structures; on the user interface side it provides voice channel and RS485/RS422 data access, and the Ethernet interfaces can be configured in physically isolated or VLAN isolation mode to meet secure networking requirements such as intranet/extranet separation. The front panel concentrates interface indications and status indications, while the rear panel holds service interfaces and the power connector, as shown in the figures below.

Figure 2: Rear panel service interfaces and power connector of the IDM GTD442 dual-gigabit telephone optical multiplexer

Working principle of the IDM GTD442 dual-gigabit telephone optical multiplexer: how do single-optical-port and dual-optical-port transmission work?

The working principle of the single-optical-port form of the IDM GTD442 dual-gigabit telephone optical multiplexer is as follows: 2 gigabit Ethernet channels, 4 voice channels and 2 RS485 (or 1 RS422) services are processed separately inside the unit in PCM mode and Ethernet packet mode, then multiplexed into one 2.5G optical fiber channel for transmission to the opposite end; the receiver then demultiplexes the multiplexed signal back into the individual service interfaces, achieving point-to-point multi-service over a single fiber communication.

The single-optical-port form suits ordinary telephone optical multiplexer applications with direct connection between two ends, with clear networking relationships and simple installation and commissioning.

Figure 3: Single-optical-port working principle: Ethernet and PCM voice channels multiplexed and transmitted point-to-point over a 2.5G optical port

The dual-optical-port form of the IDM GTD442 dual-gigabit telephone optical multiplexer configures two groups of optical interfaces on the device; the two groups of optical ports can either serve as mutual backup or connect to adjacent sites in different directions, thereby cascading multiple devices along the line into chain network, ring network and other structures.

In the dual-optical-port form, when a single point of interruption occurs in one optical fiber, services can be rerouted from the other direction without interruption, making it suitable for occasions requiring high reliability or multi-node access along the line, such as tunnel construction communications, river monitoring and treatment, and electric power and railway line private networks; up to two groups of optical interfaces can form a mutual backup ring network, which can both use mutual backup optical ports to ensure uninterrupted critical services on the private network and reduce the number of trunk optical fibers by means of a chain network.

Figure 4: Dual-optical-port working principle: two groups of optical ports form mutual backup and can be cascaded for networking

Core functions and service interfaces

The IDM GTD442 dual-gigabit telephone optical multiplexer provides access and optical multiplexing for three types of services—Ethernet, telephone and serial port data—on the same device. The core functions are shown in the table below.

IDM GTD442 dual-gigabit telephone optical multiplexer technical specifications

Optical interface parameters

Ethernet Interface Parameters

Voice Channel Interface Parameters

Power Supply, Power Consumption and Environmental Parameters

Networking Approaches and Typical Scenarios of Dual Optical Port Telephone Optical Multiplexers

The IDM GTD442 dual gigabit telephone optical multiplexer comes in two forms by number of optical ports, single optical port and dual optical port, and supports point-to-point, chain network, star network and ring network topologies. As a professional optical multiplexer manufacturer, Raytrans offers this dual optical port device, which in addition to point-to-point use can also form mutual backup optical ports, a chain network or a ring network. Common networking topologies are illustrated below.

Chain Network: Suited to Multi-Node Access along the Line

Chain network networking is suited to scenarios with sites distributed along the line, such as tunnel construction communications, river monitoring and management, and community information point construction. One dual optical port device is placed at each site along the line, with the two optical ports connected to the upstream and downstream sites respectively. Service data is forwarded site by site, and multiple devices share one trunk optical fiber to complete telephone and Ethernet access at each point along the line. This networking approach is also a common form of node access along the line in smart mining communication solutions.

Figure 5: Dual Optical Port Chain Network Application: Topology of Multi-Node Cascading along the Line

Star Network: Suited to Point-to-Multipoint Aggregation at a Central Point

Star network networking takes the central station equipment as the core and radiates connections to multiple remote stations. It is suited to public security checkpoint optical multiplexer applications and information point construction in communities and factories where the central equipment room serves as the aggregation point. Each remote station needs only a pair of optical fibers to intercommunicate with the central point, which facilitates centralized management.

Figure 6: Star Network Application: Topology of Radiating from a Central Node to Multiple Points

Ring Network: Suited to Occasions with High Reliability Requirements

Ring network networking connects the optical ports of the devices at each site in turn into a ring. When a single point of interruption occurs on the optical fiber, services can still be rerouted in the other direction. It is suited to private network scenarios such as electric power and railways that have high requirements for communication reliability. This is exactly the typical value of dual optical port mutual backup capability in long-distance communication along the line, and it is also common in the backbone networking design of government private network optical fiber communication solutions.

Figure 7: Ring Network Application: Topology of Optical Fiber Ring Networking

Point-to-Point Application: Fiber to the Office and Magneto Telephones

The single optical port point-to-point approach is a widely adopted networking topology. Two IDM GTD442 dual gigabit telephone optical multiplexers are directly connected through a pair of optical fibers, and both ends simultaneously provide Ethernet, voice channel and data services. Point-to-point applications can be used for fiber to the office to achieve physical isolation between the internal network and the external network; they can also be used for public security checkpoint information point construction and community and factory information point construction, where one device simultaneously solves the problems of broadband Internet access and telephone access.

Figure 8: Point-to-Point Ordinary Telephone Optical Multiplexer Application Networking (Fiber to the Office, Public Security Checkpoint)

When magneto telephones need to be transmitted between the two ends, the 4-channel voice channel interfaces can be configured for the MAG magneto telephone format, realizing interconnection of magneto telephones at two sites. In places such as underground mines and tunnels where there is no SPC switching environment, MAG magneto voice channels can be transmitted together with services such as 2-channel wire-speed gigabit Ethernet over the same pair of optical fibers, realizing point-to-point voice communication in an environment without switching.

Figure 9: Point-to-Point Magneto Telephone Optical Multiplexer Application Networking (MAG Magneto Voice Channel Transmission)

Transmission Distance and Optical Module Options of Telephone Optical Multiplexers

The transmission distance of the IDM GTD442 dual gigabit telephone optical multiplexer is determined by the optical module fitted and the optical fiber line. The transmission distance of the standard single-mode configuration of the unit is 20 km, with a receive/transmit wavelength of 1310nm/1550nm; if the actual on-site distance exceeds 20 km, a long-distance optical module can be selected to achieve optical fiber transmission over a longer distance.

The optical port adopts a pluggable SFP structure, and the optical module can be configured as required. The same device can adapt to line conditions of different distances and different fiber modes (single-mode or optional multi-mode) simply by replacing the optical module.

The unit operates normally in environments from -10℃ to +50℃ with relative humidity of 0–95% (non-condensing), and can be powered by either AC220V or DC-48V. When selecting an optical module, it is recommended to confirm the specific model with the optical multiplexer manufacturer based on the actual optical fiber length, optical fiber type, and interfacing requirements of the equipment at both ends, so as to ensure that the transmission margin meets project requirements.

Conclusion

The IDM GTD442 dual-gigabit telephone optical multiplexer uses a 2.5G optical fiber channel to simultaneously carry gigabit Ethernet, PCM voice channels, and serial port data. The 2.5G optical port carrying 2 channels of wire-speed gigabit Ethernet provides far greater bandwidth than ordinary 100M optical multiplexers; dual optical port mutual backup and ring network networking allow services to be rerouted without interruption when a single point of interruption occurs on the optical fiber; the 4 voice channels are compatible with FXO, FXS, and MAG magneto formats, enabling calls even in exchange-free environments such as underground and tunnels. With multiple networking topologies including single-port point-to-point, dual optical port mutual backup, chain network, and ring network, it is an integrated choice for reliable private network communication in public security checkpoints, along electric power and railway lines, and in mining underground and tunnel construction scenarios.

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