IDM GP2000-30E Integrated Service Optical Multiplexing Equipment

The IDM GP2000-30E ultra-broadband integrated service optical multiplexing equipment is a 30-channel telephone dual-Gigabit isolated optical multiplexer developed by Beijing Ruiguang Jiyuan Digital Technology Co., Ltd. (Raytrans). It is used to simultaneously carry 30 voice channels, 2 physically isolated gigabit Ethernet groups, and 1 to 4 E1 channels over a single 2.5G optical fiber link, and is an integrated service access device designed for multi-service scenarios.

The device adopts the PCM30/31 format and is deployed as a pair at both ends. At the site side, dispatch voice, production data, and leased-line services are multiplexed onto the same optical path; at the central side, they are demultiplexed and returned to the existing switching and data equipment through the original interfaces. As a professional optical multiplexer manufacturer, Raytrans has accumulated extensive experience in the development of PCM equipment and optical multiplexing equipment, and this product is also often used as PCM equipment to carry mixed voice and data access. Site communication in electric power and rail transit private networks often requires telephone, gigabit data, and E1 interfaces at the same time. Deploying multiple single-function devices separately increases cabinet space usage and points of failure, whereas consolidating the three types of services into one optical fiber with a single device makes operation and maintenance easier and also allows the advantages of service convergence to be presented intuitively in the product showcase.

Key Specifications at a Glance: 2.5G optical fiber · 30 voice channels · dual-Gigabit isolation · dual-fiber mutual backup · SFP optical port, single-mode (multimode optional) 1310nm/1550nm · E1 1 to 4 channels (HDB3 transparent transmission) · DC-48V/AC220V dual power supply · overall power consumption ≤100W

What Is a 30-Channel Telephone Dual-Gigabit Isolated Optical Multiplexer

A 30-channel telephone dual-Gigabit isolated optical multiplexer is a transmission device that multiplexes telephone voice channels and two independent gigabit Ethernet services onto the same optical fiber channel. It is deployed as a pair at both ends, with one end performing multiplexing and the other end performing demultiplexing. Telephones, switches, and data devices at the site side are connected through their existing interfaces, and the same interfaces are restored at the central equipment room side. The intermediate transmission segment only performs multiplexing and demultiplexing without changing service encoding or frame structure. As PCM equipment designed for multi-service scenarios, it carries voice and data uniformly over the same optical fiber and is also commonly classified as integrated service access equipment.

The PCM30/31 format means that 30 64Kbps voice channel time slots are arranged in a primary group frame, with the remaining time slots carrying synchronization and signaling. Telephone voice is compressed according to ITU G.711 A-law, with an audio range of 300 Hz to 3400 Hz and a loop current of 25 mA per channel. This PCM encoding mechanism ensures the transparent transmission quality of voice over the optical multiplexing equipment.

The E1 side operates according to the ITU-T G.703 standard, with a bit rate of 2048 Kbps, HDB3 line code, and an impedance of 75 Ω/120 Ω. It uses transparent transmission mode to deliver the time slot content to the peer end unchanged, so the existing PCM equipment and relay protection devices at the peer end do not require configuration changes.

The 2.5G optical fiber provides shared bandwidth for the entire unit. The 30 voice channels, 2 gigabit Ethernet groups, and E1 channels each occupy independent channels and do not alter each other's encoding or frame structure. Dual-Gigabit isolation means that the two Gigabit RJ45 ports are independently encapsulated and forwarded within the device, with no bandwidth sharing, so that when a broadcast storm or abnormal traffic occurs on one group, the other group continues to operate normally. For projects that need to showcase multi-service parallel capability, this isolation design is an important consideration for optical multiplexer manufacturers during solution selection.

Figure 1: Front view of the IDM GP2000-30E, showing the layout of the 30 telephone interfaces and the operation and alarm indicator LEDs

What Services Can One Device Carry

The IDM GP2000-30E provides five capabilities in a single device: optical fiber transmission, telephone access, dual-Gigabit isolated Ethernet, E1 channels, and dual power supply, replacing the telephone optical multiplexer and gigabit data uplink equipment that were previously deployed separately. The function items and corresponding interface standards are listed in the table below for item-by-item verification against existing on-site equipment; the configuration sheet and bidding list can reference them directly.

Function	Description
2.5G optical fiber transmission	SFP optical port, optical fiber rate 2.5 Gbps, single-mode (multimode optional), wavelength 1310nm/1550nm; one optical fiber simultaneously carries telephone, gigabit Ethernet, and E1 services
30-channel telephone access	Provides 30 telephone interfaces, configurable as FXO, FXS, or magneto; audio range 300 Hz to 3400 Hz; ITU G.711 A-law compression; loop current 25 mA per channel
Dual-Gigabit isolation	Provides 2 groups of physically isolated line-rate 1000M Ethernet ports, 2000M in total; the two groups are independently encapsulated and forwarded, so abnormal traffic on one does not affect the other
E1 channel transparent transmission	Bit rate 2048 Kbps, HDB3 line code, compliant with ITU-T G.703, impedance 75 Ω/120 Ω, PCM30/31 frame structure; provides 1 to 4 E1 channels as configured
Dual-fiber mutual backup	Provides 2 2.5Gbps SFP optical ports, configurable for 1+1 optical port protection; services switch to the backup optical path when the primary path suffers a fiber break or received optical power degradation
Dual power input	Supports DC-48V and AC220V dual power supply access, with the two paths fed from different distribution circuits; when one path loses power, services continue to be powered by the other
Network management and alarms	Provides a standard SNMP network management interface; the chassis is equipped with a function control switch and operation and alarm indications, allowing the central equipment room to check device status remotely
HDMI high-definition video (as configured)	The overview lists support for an HDMI high-definition video transmission interface; when video access is required, confirm with the manufacturer according to the ordering configuration

The four types of services in the table work in parallel over one optical fiber: telephone and E1 use narrowband time slots, gigabit Ethernet is independently encapsulated, and the three types of services do not occupy each other's bandwidth. On site, the telephone ports and E1 ports of the dispatching exchange and the two switches in the station are connected to the two sides of the device respectively; after restoration at the peer end, they are returned to the existing equipment through the original interfaces, so no data reconfiguration is required during service cutover. In the design of this product series, Raytrans integrates the above interface capabilities on a single PCM equipment platform, facilitating unified configuration and operation and maintenance in projects such as government private network optical fiber communication solutions and military emergency communications vehicle solutions.

Key Specifications

The technical specifications of the IDM GP2000-30E cover five parts: optical interfaces, E1 interfaces, Ethernet interfaces, telephone voice interfaces, and power supply and environment. The key parameters are listed in the table below. Values are subject to product documentation and factory testing; verify each item according to the actual configuration during project calculation, and interpret parameters without marked test conditions as applying to an equipment room environment at normal temperature and humidity.

Item	Parameter/Specification	Description/Applicable Conditions
Optical interface type	SFP	Pluggable optical module, easy to replace by distance and to spare
Fiber mode	Single-mode (multimode optional)	Selected according to line distance and fiber core conditions
Optical fiber rate	2.5 Gbps	Shared by telephone, Ethernet, and E1 services
Wavelength	1310nm/1550nm	Two wavelengths selectable, used in pairs at both ends
Transmit optical power	-1 to -3 dBm	Typical single-mode value; subject to actual measurement with an optical power meter
Receiver sensitivity	Better than -24 dBm	The link loss budget can be calculated on this basis
E1 bit rate	2048 Kbps	HDB3 line code
E1 standard protocol	Supports ITU-T G.703	Standard E1 interface specification
E1 impedance	75 Ω/120 Ω	Selected according to the interface of the interconnected equipment
E1 frame structure	PCM30/31	Primary group frame structure, transparent transmission mode
Ethernet interface type	RJ45	2 groups of physically isolated Gigabit electrical ports
Ethernet transmission rate	10M/100M/1000M	Compliant with IEEE802.3, adaptive full-duplex/half-duplex
Voice audio range	300 Hz to 3400 Hz	Telephone voice channel bandwidth
Voice impedance	Three-element complex impedance 200 Ω+560 Ω//0.1 μF	Telephone subscriber line interface standard
Voice compression	ITU G.711 A-law	64 Kbps PCM encoding
Voice loop current	25 mA per channel	Feeding capability of each voice channel
Power supply mode	DC-48V / AC 220V / dual power supply	Dual-path access improves power supply reliability
Overall power consumption	≤100W	Overall value including service interfaces and optical modules
Operating temperature	0 ºC to 40 ºC	Equipment room and temperature-controlled cabinet environment
Humidity	≤90% (non-condensing)	Upper limit of relative humidity

Figure 2: Rear panel layout of the IDM GP2000-30E, showing the 2.5G SFP optical ports, 2 groups of Gigabit RJ45 ports, E1 interfaces, and dual power supply terminals

The optical power budget is the prerequisite for stable long-distance links: with transmit optical power of -1 to -3 dBm and receiver sensitivity better than -24 dBm, the loss margin left between the two ends can cover optical cable attenuation, splice points, and patch cord loss. Include the optical cable length, number of connectors, and patch cord loss in the calculation. If the received optical power approaches the threshold, first clean the flange and patch cord end faces; if it is still insufficient, replace the SFP module with a higher power budget. This PCM equipment can be networked with intrinsically safe mining communication equipment in smart mining communication solutions, and has proven deployment experience in government private network optical fiber communication solutions and military emergency communications vehicle solutions. As an optical multiplexer manufacturer, Raytrans provides complete technical support from equipment selection to link budget.

How to Configure Dual-Fiber Mutual Backup and Ring Networking Without Link Disruption

A dual-fiber mutual backup optical multiplexer lays two optical fibers between the same pair of sites, with the primary link carrying services and the backup link on standby; when the primary link suffers a fiber break or received optical power degradation, services switch to the backup link. The IDM GP2000-30E provides 2 2.5Gbps SFP optical ports and can be configured for 1+1 optical port protection, so that voice, E1, and gigabit data are all maintained after switching.

The networking topology is selected according to site distribution and fiber core resources. This 2.5G optical fiber multiplexing equipment supports four topologies used standalone, and they can also be mixed within the same network. A chain network is suitable for connecting sites along a route in series; a ring network allows services to detour in the reverse direction when a fiber breaks at one point; a star network aggregates multiple endpoint sites into the central equipment room; and point-to-point is used for direct connection between two stations.

• Point-to-point: deploy one unit at each end, with the two optical fibers routed through different paths and terminals to avoid simultaneous interruption of both paths during construction in the same conduit;
• Chain network: sites along the route are connected in series, with the first station accessed at the central side; suitable for lines with evenly spaced sites and limited fiber cores;
• Ring network: the first and last sites are closed into a loop, so that when a fiber breaks anywhere, services detour from the other side, and voice and data are not interrupted by a single point of failure;
• Star network: deploy one aggregation equipment in the central equipment room and one unit at each endpoint site, allocating interfaces and bandwidth according to service volume.

Figure 3: Dual-fiber mutual backup point-to-point networking diagram of the IDM GP2000-30E, with both ends interconnected through two 2.5G single-mode optical fibers

Switching verification is a step that must be carried out thoroughly during commissioning: after disconnecting the primary optical fiber, the 30 voice channels should maintain uninterrupted calls, and the 2 groups of isolated gigabit Ethernet should continue forwarding. Once verification passes, record the fiber numbering, power supply circuits, and interface assignments in the as-built documentation, so that subsequent expansion can be carried out according to the drawings without re-tracing the wiring sequence.

Typical Application Scenarios

The IDM GP2000-30E is mainly deployed point-to-point, but can also aggregate sites along a route in a chain network, ring network, or star network. Telephone, gigabit data, and E1 services at the site side are restored at the central equipment room and then connected to the existing dispatching exchange and data equipment. Electric power, rail transit, and military and government private networks each have their own emphasis, described below by industry.

Electric Power Private Network: Substation Dispatch Telephone and Production Data Backhaul over One Fiber

Between substations and dispatch stations, E1 channels for dispatch telephone, telecontrol and protection signals, as well as in-station production data channels, are required at the same time. IDM GP2000-30E is deployed one unit per site, multiplexing 30 dispatch telephone channels, 2 groups of isolated gigabit Ethernet and E1 channels over a single 2.5Gbps single-mode optical fiber, so the cabinet no longer stacks telephone optical multiplexers, E1 media converters and standalone data devices.

Production control and integrated data run over two physically isolated gigabit ports, and the two groups of channels do not cross each other, with the boundary drawn at the interface level; voice is encoded in ITU G.711 A-law with a loop current of 25mA per channel, and can be directly connected to existing dispatch voice channel equipment. On the power supply side, DC-48V and AC220V dual power supply access is supported, and the -48V direct current power supply common in communications equipment rooms can be used directly.

Rail Transit Communication: Train Operation Telephone and Monitoring Data Carried over the Same Fiber Between Section Stations

Between stations, depots and section equipment rooms, train operation telephone, signaling data and monitoring images need to be transmitted, and the sites are distributed along the line with varying distances. IDM GP2000-30E is deployed in chain network or ring network mode, delivering 30 telephone channels, 2 groups of isolated gigabit Ethernet and E1 to the sites along the line over one 2.5Gbps optical fiber, so sections no longer need to lay separate fiber cores for each type of service.

The receiver sensitivity is better than -24dBm, and the received optical power margin of long-distance links in sections is calculated according to the actual measurement with an optical power meter, so optical reception still works normally under weak-light conditions; 1310nm and 1550nm dual-wavelength modules are selected according to section loss. Monitoring and office services run over two isolated gigabit ports, and an abnormality on one path does not affect the train operation telephone and signaling channels.

Military and Government Private Networks: Physically Isolated Boundaries and Dual-Fiber Mutual Backup for Link Continuity

Remote stations of military and government private networks are often unattended, with limited power supply and on-site maintenance conditions, and high requirements on service independence and link continuity. IDM GP2000-30E uses 2 groups of physically isolated gigabit Ethernet to carry classified and non-classified services separately, separated from the interface layer without relying on VLAN or VPN configuration.

The unit is a standard 19-inch 1U enclosure and can be deployed in a temperature-controlled cabinet, with an operating temperature of 0ºC to 40ºC and humidity ≤90% (non-condensing). In dual-fiber mutual backup configuration, when the inter-station optical cable is interrupted at one point, services are switched over to the backup optical path, and with the SNMP network management interface and panel alarm indication, the central equipment room can remotely identify the faulty site.

Figure 4: IDM GP2000-30E ring and star networking application schematic, with sites along the line aggregated to the central equipment room over 2.5G optical fibers

Selection and Commissioning

Selection is checked item by item against three aspects: number of service channels, optical fiber conditions, and power supply and environment; commissioning is verified layer by layer: power supply, optical path and services. The results of the three checks directly determine the interface form, optical module grade and power supply wiring mode, and the ordering configuration is confirmed after the checks, which avoids rework after the equipment arrives.

• Number of service channels: confirm whether the number of telephone channels is within 30, whether the interface form is FXO, FXS or magneto, whether the gigabit Ethernet is 2 groups of physical isolation and the bandwidth requirement of each group, and whether 1 to 4 E1 channels are required;
• Optical fiber conditions: confirm single-mode or multi-mode, whether the wavelength is 1310nm or 1550nm, whether two optical fibers are available for mutual backup, and calculate the loss budget according to the transmit optical power and receiver sensitivity;
• Power supply conditions: confirm whether the site has DC-48V or AC220V, and when dual power supply is required, the two paths are respectively taken from different distribution circuits, with overall power consumption reserved at ≤100W;
• Commissioning sequence: first check the power supply format and grounding, then check the received optical power at the optical port, then verify telephone calls, gigabit forwarding and E1 channels one by one, and finally perform a fiber break protection switching test.

A common rework during commissioning is a mismatch between the telephone interface form and the opposite-end equipment: direct telephone connection requires FXS feeding and ringing current, connection to the outside line side of a switch requires FXO, and a magneto telephone requires a magneto interface. Confirming the type of opposite-end equipment on site before deciding the interface saves time compared with replacing interface boards afterwards; interfaces are shipped according to configuration, and no on-site board modification is required.