IDM-MUX60 60-Channel SDH Telephone Optical Multiplexer

IDM-MUX60 60-channel SDH telephone optical multiplexer is an STM-1-level multi-service access device built around SDH technology, developed by SDH equipment manufacturer Beijing Ruiguang Jiyuan Digital Technology Co., Ltd. (Raytrans). It carries 60 telephone channels, E1, Ethernet, audio, and V.35 services simultaneously over a 155.52 Mbps optical fiber link, and is a typical optical transmission device for private network access scenarios.

The device integrates SDH optical transmission and PCM service access into a single 440 × 230 × 90 mm chassis, so an access site no longer needs separate transmission devices for voice, data, and dedicated lines. The unit uses a 19-inch 1U structure and occupies only one rack position in a standard cabinet, keeping equipment room renovation minimal and enabling fast product showcase and deployment in existing networks.

A single device provides 60 telephone services. Voice channels are organized at 64 kbit/s granularity in a PCM30/32 frame structure and then mapped into VC-12 containers of the STM-1. The E1 interface complies with ITU-T G.703 with 75 Ω/120 Ω impedance, Ethernet bandwidth is allocated as N×VC12 (N≤50), and audio, codirectional 64K, V.24, and V.35 interfaces are configured according to the site service list. Each service type occupies an independent channel on the same optical link. As an optical multiplexer manufacturer, Raytrans also supports MSTP multi-service transport capability on this SDH equipment series, meeting the voice, data, and dedicated line access requirements of government private network optical fiber communication solutions and military emergency communications vehicle solutions.

Key Specifications at a Glance: 60-channel SDH telephone service · single-fiber STM-1 155.52 Mbps · receiver sensitivity better than -32 dBm · E1/Ethernet/audio/V.35 access in one unit · N×VC12 (N≤50) · AC 220 V/DC -48 V power supply · ≤90 W · -20℃~+50℃

Figure 1: IDM-MUX60 60-channel SDH telephone optical multiplexer front view with SFP optical ports and power indicator LEDs

How STM-1 and VC-12 Carry Services: Basic SDH Access Principles

The SDH STM-1 line rate is 155.52 Mbps. Services use VC-12 as the basic container; one VC-12 carries one 2.048 Mbps E1, and one STM-1 can accommodate 63 VC-12s. STM-1 capacity determines how many E1s and how many 64 kbit/s services can be arranged simultaneously on one fiber. During planning, reserve enough containers for voice and E1 first, then allocate the remaining containers to Ethernet. As a typical access principle of SDH equipment manufacturers, this capacity relationship directly determines the service scheduling capability of SDH equipment in the product showcase.

The E1 bit rate is 2.048 Mbps, the line coding is HDB3, and the frame structure is PCM30/32, with 30 of the 32 time slots in each frame carrying services. A single voice channel is compressed to 64 kbit/s using ITU G.711 A-law and occupies one time slot; 60 telephone channels occupy 60 64 kbit/s time slots.

The 155M SFP optical port sends the STM-1 signal onto the fiber, with receive/transmit rates of 155.52 Mbps, receive/transmit wavelengths of 1310 nm/1550 nm, and transmit optical power of -12~-6 dBm. The optical module is SFP-packaged; single-mode is standard and multi-mode is optional according to the on-site optical cable, and the wavelengths and interface types at both ends must be paired. The available margin of a single-fiber link depends on receiver sensitivity; lines with many splice points must be calculated section by section according to the optical power budget. The interface configuration of such optical transmission equipment is also a key element that optical multiplexer manufacturers highlight in the product showcase.

Functions and Interfaces of the 60-Channel SDH Telephone Optical Multiplexer

Functions are organized into four categories—voice, data, Ethernet, and optical transmission—and listed in the table below for easy verification of configuration items against the site service list. Voice channel direction, interface quantities, and optical module models are confirmed together at ordering; no additional protocol conversion components are needed on site, and no separate card is required for a single service.

Function	Description
60-channel telephone service access	A single unit provides 60 telephone subscriber interfaces, with an audio range of 300 Hz~3400 Hz, compressed to 64 kbit/s using ITU G.711 A-law
E1 interface	Supports ITU-T G.703, bit rate 2.048 Mbps, line coding HDB3, impedance 75 Ω/120 Ω, frame structure PCM30/32, channel-associated signaling
Ethernet interface	RJ-45 interface, transmission rate N×VC12 (N≤50), supports IEEE 802.3, operating mode full/half duplex/adaptive
Codirectional 64K interface	Line coding complies with G.703, bit rate 64 kbit/s, balanced impedance 120 Ω
Audio interface	Audio range 300 Hz~3400 Hz, balanced impedance 600 Ω, compression ITU G.711 A-law, return loss no less than 18 dB
V.24 interface	Transmission rate asynchronous ≤9600 bps, synchronous 64 kbit/s, electrical characteristics comply with CCITT V.28 protocol
V.35 interface	Interface type RJ-45, transmission rate n×64 kbit/s (n=0~31), complies with ITU-T V.35 recommendation, terminal interface complies with ISO2593
STM-1 optical transmission	SFP optical interface, receive/transmit rate 155.52 Mbps, single-mode standard, multi-mode optional, supports point-to-point, chain, and ring networks
Dual power supply	AC 220 V/DC -48 V power supply modes selectable, overall power consumption ≤90 W
Wide-temperature adaptability	Operating temperature -20℃+50℃, relative humidity 095% (non-condensing), suitable for field cabinets and unattended equipment rooms

The telephone interface in the table is directly related to subscriber line provisioning: audio range 300 Hz~3400 Hz, compression ITU G.711 A-law, three-element complex impedance 200 Ω+560 Ω//0.1 μF, and loop current 20 mA per channel for telephone power feed. The Ethernet interface allocates bandwidth as N×VC12 (N≤50), is full/half duplex adaptive, and can be directly connected to on-site switches and routers without additional optical-to-electrical conversion equipment. In government private network optical fiber communication solutions and military emergency communications vehicle solutions, Raytrans SDH equipment supports on-site access precisely through this combination of multi-service interfaces.

Figure 2: IDM-MUX60 rear panel layout with E1 interfaces, Ethernet ports, audio and V.35 interfaces, and power terminals

How to Verify Key Specifications: Optical Port, E1, Ethernet, and Power

Specifications are listed in four groups: optical interface, E1 and Ethernet, service interfaces, and power and environment. When verifying, first perform the optical power budget, then check voice channel and E1 directions, and then confirm the power supply mode and cabinet space. All items are subject to product documentation; special interface requirements should be stated at ordering.

Item	Parameter/Specification	Description/Applicable Conditions
Interface type	SFP	Single-mode standard, multi-mode optional
Receive/transmit rate	155.52 Mbps/155.52 Mbps	STM-1 line rate, receive and transmit consistent
Receive/transmit wavelength	1310 nm/1550 nm	Wavelengths and interface types paired at both ends
Transmit optical power	-12~-6 dBm	Available optical power range at the transmit side
Receiver sensitivity	Better than -32 dBm	Sensitivity threshold -32 dBm, margin remains on weak optical links

Item	Parameter/Specification	Description/Applicable Conditions
E1 bit rate	2.048 Mbps	Line coding HDB3
E1 standard and impedance	Supports ITU-T G.703, 75 Ω/120 Ω	Coaxial or balanced interface selected on site
E1 frame structure and signaling	PCM30/32, channel-associated signaling	32 time slots per frame, 30 carrying services
Ethernet interface	RJ-45	Electrical interface, can directly connect to switches and routers
Ethernet transmission rate	N×VC12 (N≤50)	Bandwidth determined by the number of allocated containers
Ethernet standard and operating mode	Supports IEEE 802.3, full/half duplex/adaptive	Adaptive negotiation with on-site IP devices

Item	Parameter/Specification	Description/Applicable Conditions
Telephone interface	300 Hz~3400 Hz, ITU G.711 A-law	Three-element complex impedance 200 Ω+560 Ω//0.1 μF, loop current 20 mA per channel
Codirectional 64K interface	G.703 standard, 64 kbit/s	Balanced impedance 120 Ω
Audio interface	300 Hz~3400 Hz, balanced 600 Ω	Return loss no less than 18 dB, compression ITU G.711 A-law
V.24 interface	Asynchronous ≤9600 bps; synchronous 64 kbit/s	Electrical characteristics comply with CCITT V.28 protocol
V.35 interface	RJ-45, n×64 kbit/s (n=0~31)	Complies with ITU-T V.35 recommendation, terminal interface complies with ISO2593

Item	Parameter/Specification	Description/Applicable Conditions
Power supply mode	AC 220 V/DC -48 V	Two modes selectable, chosen according to site power conditions
Overall power consumption	≤90 W	Power supply access and heat dissipation load for long-term online operation
Operating temperature	-20℃~+50℃	Suitable for field cabinets and unattended equipment rooms
Relative humidity	0~95% (non-condensing)	Normal operation under non-condensing conditions
Dimensions	440×230×90 (mm)	Length × depth × height, 19-inch rack installation

The power supply row determines whether a site can draw power directly: communications equipment rooms and substation DC distribution panels can use DC -48 V, while office buildings and wiring closets can use AC 220 V. Overall power consumption is ≤90 W, so the site does not need an additional power distribution panel or cooling fan. With an operating temperature of -20℃+50℃ and relative humidity of 095% (non-condensing), field cabinets and unattended equipment rooms can operate online long-term. For government private network optical fiber communication solutions and military emergency communications vehicle solutions using MSTP networking, the above optical port, E1, and power supply parameters are the basic basis for selection verification.

Differentiated Value: Single-Fiber 155M Weak-Light Transmission and Multi-Service Access in One Unit

The three differentiated capabilities each have verifiable criteria that can be written directly into technical specifications and bid parameter tables during the design phase. All three hold simultaneously under the site conditions of electric power, public security and military, and banking and telecommunications data private networks, and are the main differences between this STM-1 multi-service access device and ordinary PCM optical multiplexers that carry voice only, reflecting the technical orientation of a professional SDH equipment manufacturer in the product showcase.

Differentiation Point	Customer Value
Single-fiber STM-1 155.52 Mbps, receiver sensitivity better than -32 dBm	Receive margin remains on weak-light long-distance links; lines with many splice points do not require repeated optical module adjustment to improve received optical power
E1, Ethernet, audio, V.35, and other multi-service access in one unit, with Ethernet bandwidth allocated as N×VC12 (N≤50)	One device handles voice, dedicated line, and data access; the site does not need to cascade multiple single-function devices, and rack positions and cabling are reduced accordingly
-20℃+50℃, 095% non-condensing	Field cabinets and unattended equipment rooms can operate online long-term, and sites require no additional environmental control or heating and dehumidification

Typical Application Scenarios

The following three scenarios are drawn from the private network sectors the device serves. Each type of site uses voice, E1 leased line, and data interfaces simultaneously, and the networking approach is determined by site distribution and fiber routing. Point sites use point-to-point, sites distributed along a route are chained, and ring sites use a ring with a rerouting direction reserved.

Electric Power Private Network: Substation Dispatch Telephone and E1 Leased Line over the Same Fiber

Between substations and dispatch centers, both dispatch telephones and office telephones must be carried, along with E1 leased-line data such as telecontrol and metering. An IDM-MUX60 is installed in the substation: telephones are provisioned through subscriber interfaces, E1 channels are transmitted transparently per ITU-T G.703, Ethernet ports backhaul in-station IP services, and a single-fiber 155M link carries all services at once, reducing the incoming optical cables and rack positions accordingly. This networking is a common station-side access form in electric power private network communication, and also a typical product showcase of SDH equipment on the private network side.

Unattended substations vary widely in power supply access and environmental conditions. The in-station DC distribution panel can supply DC-48V directly, while an AC equipment room can use AC220V. With an operating temperature of -20℃+50℃ and humidity of 095% non-condensing, no additional environmental control is needed inside the cabinet; when new bays are added, channels and interfaces are supplemented accordingly, while the external optical path remains unchanged.

Public Security and Military Private Networks: Centralized Backhaul of Voice Channels and Low-Speed Data at Duty Posts

Duty posts, storage areas and command posts of public security and the military are scattered, voice channels and leased-line data need centralized backhaul, and most sites are unattended. The IDM-MUX60 packs 60 telephone channels, E1 and V.35 data interfaces into one 1U device and sends them upstream to the command center over a single-fiber 155.52Mbps link; voice is encoded in G.711 A-law, delivering call quality on par with the PSTN. Such military emergency communications vehicle solutions place high demands on device size and link margin, and the 1U chassis with single-fiber transport matches them well.

Link availability is ensured by the optical power margin: the receiver sensitivity is better than -32dBm, so weak optical links with many splice points and long distances can still receive normally. V.24 and V.35 interfaces carry low-speed data and private network device control signals, each occupying an independent channel on the same optical link as voice and Ethernet without affecting one another.

Banking and Telecommunications Data Private Networks: One Device at the Branch Side Completes Provisioning and Data Access

Services at banking business outlets and telecommunications access points are mainly voice channel provisioning, leased-line data and office networks, while branch equipment rooms are small with limited cabinet space. The IDM-MUX60 provides 60 telephone channels and multiple data interfaces in a 440×230×90mm 1U chassis, so the branch side needs only one device and one optical path, reducing rack position occupancy and wiring workload.

Upper-level nodes are configured in paired configuration according to the number of branches, and the call handling and data of multiple branches are aggregated at the central side before entering the switching and data networks. Ethernet bandwidth is allocated as N×VC12 (N≤50); when branch service volume grows, only the number of containers needs adjustment, without replacing optical modules or the chassis. The entire government private network optical fiber communication solution aggregates at the central side under the MSTP mechanism, and the SDH equipment at the branch side interfaces with the central MSTP node, giving a clear networking hierarchy.

Figure 3: IDM-MUX60 point-to-point and chain networking schematic; telephone, E1, audio and Ethernet share a single-fiber 155M link