IDM-30EN Integrated Service Multiplexer

A 30-channel integrated service multiplexer carries 30 channels of 64K services in the PCM30/32 time slots of a single device, configures Ethernet and E1 interfaces as required on site, and then transmits the services over optical fiber to the optical multiplexing terminal at the opposite end. The IDM-30EN integrated service multiplexer belongs to this class of PCM equipment: it uses optical fiber as the transmission medium, employs standard optical fiber or E1 transmission channels (ITU-T G.703), adopts the PCM30/32 format, and converts the telephone service signals or data signals to be transmitted into optical signals for transmission to the remote end. It is developed by Beijing Ruiguang Jiyuan Digital Technology Co., Ltd. and is used for public telephone network access or dedicated line information transmission in industries such as telecommunications, electric power, banking, and public security.

Sites at the edge of a private network usually have many channels and mixed services: a substation or business outlet needs both a batch of telephones and telecontrol data, and an Ethernet channel for running service systems. The IDM-30EN uses one 19-inch 1U device to merge the two types of requirements onto a single optical fiber: a single device provides standard 30-channel data services, plus 2 groups of wire-speed 100M Ethernet and 4 groups of transparent transmission E1. Its receiver sensitivity is better than -34dBm and its receive dynamic range is 34dBm, so it can operate stably even over long-distance weak optical links. As a multi-service optical multiplexer, it can complete the product showcase and unified carrying of telephone, data, and Ethernet services on one device.

Key Specifications at a Glance: 30-channel services · 4 groups of E1 transparent transmission · 2 groups of 100M · 1U chassis · optical port 155Mbps/1310nm · receiver sensitivity better than -34dBm

Figure 1: Close-up of the front panel and alarm indicator LEDs of the IDM-30EN integrated service multiplexer

What Kind of Device Is a 30-Channel Integrated Service Multiplexer?

A 30-channel integrated service multiplexer is an access device that brings narrowband services, Ethernet services, and E1 channels into the same 19-inch 1U chassis. The core of the IDM-30EN is to concentrate 30 channels of 64K data services, 2 groups of wire-speed 100M Ethernet, and 4 groups of transparent transmission E1 into one PCM equipment. After receiving the optical signal, the device at the opposite end restores the corresponding telephone or data interfaces, completing the service product showcase of the entire link.

The IDM-30EN adopts the PCM30/32 format. The frame structure, bit rate of 2048kbit/s±50ppm, and HDB3 line coding of its E1 interfaces are all designed in accordance with ITU-T G.703 recommendations, so it can be directly connected to existing PCM base group links on site or to spare E1 channels of SDH/PDH links. When optical cable is already available on site, a pair of integrated service access devices can form a point-to-point optical fiber link, bringing the 30-channel services and 2 groups of Fast Ethernet from the remote station back to the central equipment room in one pass. The clock mode can be set to master clock or user clock to meet the synchronization needs of various application environments.

Figure 2: Layout of the E1 interfaces, Ethernet ports, and FC optical ports on the rear panel of the IDM-30EN integrated service multiplexer

What Service Interfaces and Functions Does the IDM-30EN Provide?

Function	Description
30-channel service carrying	Provides standard 30-channel data service channels, adopts the PCM30/32 format, and carries telephone or data services in 64K time slots
2 groups of wire-speed 100M Ethernet	Provides 2 groups of wire-speed 100M Ethernet interfaces, supports VLAN partitioning, and can be made into 4 groups as required on site
4 groups of E1 interface transparent transmission	The 4 groups of E1 interfaces support transparent transmission mode, fully comply with ITU-T G.703 recommendations, and can reuse existing E1 transmission channels
64K subscriber interface	Provides ordinary telephone cards with caller ID (FXO, FXS), terminating 64K time slots as voice channels or data ports
Clock mode setting	Master clock and user clock can be set to suit the synchronization needs of different networking environments such as point-to-point and chain networks
Structured chassis	Adopts a 19-inch 1U standard chassis, facilitating rack installation in cabinets in communications equipment rooms
Function control and alarm indication	The front panel provides function control switches and alarm indication, facilitating commissioning and routine maintenance

What services can be terminated on the interface side depends on the 64K subscriber interface cards configured in the device: on the voice channel side, ordinary telephone cards with caller ID (FXO, FXS) can be configured, with an audio range of 300Hz to 3400Hz, a compression of ITU G.711 A-law, and a loop current of 25mA per channel; on the data side, 64K time slots are terminated as the corresponding data interfaces according to the on-site service type. The 30 channels of 64K can carry either telephone services or data services, and the ratio is determined by the on-site service volume.

Technical Specifications and Interface Standards of the IDM-30EN

Item	Parameter/Specification	Description/Applicable Conditions
E1 interface standard	Fully complies with ITU-T G.703 recommendations	Check against this specification when interfacing with existing PCM base group or SDH/PDH link E1 ports
E1 bit rate	2048kbit/s±50ppm	2.048Mbit/s base group rate, with frequency deviation within ±50ppm
E1 line coding	HDB3	Keep consistent with the line coding configuration of the opposite end
E1 impedance	75Ω (unbalanced interface)/120Ω (balanced interface)	An external impedance converter is required when using the 120Ω balanced interface
E1 frame structure	PCM30/32	32 time slots per frame, with 30 time slots carrying services
E1 signaling	Channel-associated signaling	Channel-associated signaling, transmitted together with the voice channel time slots
FXO/FXS impedance	Three-element complex impedance 200Ω+560Ω//0.1μF	AC and DC characteristics of the voice channel interface
FXO/FXS audio range	300Hz to 3400Hz	Voice channel bandwidth, meeting the voice frequency band requirements
FXO/FXS compression	ITU G.711 A-law	Voice encoding at A-law 64K
FXO/FXS loop current	25mA per channel	Feed loop current for each telephone
Ethernet interface rate	10/100M half-duplex and full-duplex	Negotiated according to port capabilities when interfacing with switches and routers
Ethernet interface protocol	Complies with IEEE-802.3u	100BASE-TX Fast Ethernet specification
Ethernet interface type	RJ-45	Port mode is 10/100Mbps adaptive mode
Optical interface rate	155Mbps±50ppm	Optical port line rate, corresponding to the 155M optical transmission platform
Optical interface wavelength	1310nm	Common operating wavelength for single-mode fiber; both ends of a paired device must be consistent
Optical interface transmit power	-4 to -12dBm	Used together with optical path attenuation calculation
Optical interface receiver sensitivity	Better than -34dBm	Lower power limit at which the receiver can make normal decisions
Optical interface receive dynamic range	34dBm	Adaptation range for weak and strong optical links, especially important for long-distance links
Optical interface form	FC	Optical port connector type, used with FC pigtails or patch cords
Power supply mode and overall power consumption	Not yet recorded in the knowledge base	The manufacturer's technical documentation and commercial confirmation shall prevail
Chassis specifications	19-inch 1U standard chassis	Facilitates rack installation in equipment room cabinets
Operating environment (temperature, humidity)	Not yet recorded in the knowledge base	The manufacturer's technical documentation and commercial confirmation shall prevail

How to Select Equipment for Multi-User Access at the Edge of a Private Network?

To select equipment for multi-user access at the edge of a private network, first count three things clearly: how many channels of 64K services the site needs to connect, whether an Ethernet channel is also required, and whether the site provides optical fiber or E1. The IDM-30EN gathers these three items into one 19-inch 1U device — 30-channel services meet concurrent multi-user access at the edge, 2 groups of wire-speed 100M Ethernet backhaul service system data, and 4 groups of E1 transparent transmission reuse existing channels, so there is no need to configure a separate device for each type of service.

Check the capacity first. The 30 channels of 64K time slots on the narrowband side can be mixed between telephone and data: on the voice channel side, count the number of telephones and parallel telephone requirements; on the data side, count the number of low-speed channels such as telecontrol and monitoring. When the sum of the two types does not exceed 30 channels, one device can cover it. When the service volume grows further, the number of devices can be increased or capacity can be expanded according to the interface card configuration; the specific ratio shall be subject to the manufacturer's technical documentation and commercial confirmation.

Then check the link form. When only optical cable is available on site, use a pair of IDM-30EN devices for point-to-point networking, and a single optical fiber is enough for backhaul; when G.703 channels already exist on site, use the 4 groups of E1 interfaces for transparent transmission and reuse, keeping the original link and the transmission equipment at both ends unchanged. In both forms, check the line coding, frame structure, and impedance specifications at both ends to ensure that the 2.048Mbit/s stream can be properly interfaced.

How Does Ethernet VLAN Partitioning Isolate Services?

Ethernet VLAN partitioning isolates services by assigning ports or tags of different service flows to different VLANs, so that the service data carried in the same optical fiber is invisible to one another. The Ethernet interfaces of the IDM-30EN are RJ-45, 10/100Mbps adaptive mode, compliant with IEEE-802.3u, and the 2 groups of wire-speed 100M interfaces support VLAN partitioning.

Grouping is carried out according to the nature of the services: the office network, service system backhaul, and video data are assigned to different VLANs, each limiting the accessible ports and address segments, so that abnormal traffic on one path does not affect other services. Telephone services run over 64K time slot channels and are carried separately from the Ethernet side at the transmission layer, so the two service planes do not interfere with one another.

When the number of ports is insufficient, the Ethernet can be made into 4 groups as required, and the correspondence between VLAN IDs and ports is configured according to the project network plan. It should be noted that VLAN partitioning addresses Layer 2 isolation; access control across VLANs is still determined by the security policies of upper-layer devices.

What Is the Difference Between 4 Groups of E1 Transparent Transmission and Ordinary E1 Ports?

The difference between 4 groups of E1 transparent transmission and ordinary E1 ports lies in the data flow processing method: in transparent transmission mode, the PCM equipment forwards the 2.048Mbit/s stream to the opposite end as-is, without parsing or altering the time slot and signaling contents therein; ordinary E1 ports, however, need to split the stream into 30 channels of 64K time slots and then load local services into them, making intercommunication difficult once the time slot planning at the two ends differs.

The advantage of transparent transmission is that neither the existing link on site nor the transmission equipment at both ends needs to be replaced. The 4 groups of E1 interfaces of the IDM-30EN fully comply with ITU-T G.703 recommendations. Before interfacing, check three specifications: the line coding must be uniformly HDB3, the frame structure must be uniformly PCM30/32, and the impedance must be uniformly 75Ω unbalanced interface or 120Ω balanced interface; an external impedance converter is required when using the 120Ω balanced interface. The bit rate follows 2048kbit/s±50ppm.

After interfacing is completed, set the clock mode according to the on-site networking requirements. In different networking environments such as point-to-point and chain networks, the master clock or user clock can be set separately to avoid synchronization direction conflicts at the two ends. The number of 4 groups of E1 interfaces corresponds one-to-one with the spare E1 ports of the existing link, so during private network renovation, simply configure according to the number of existing channels.

How to Rack-Mount and Power a 1U Chassis Optical Multiplexer?

To rack-mount and power a 1U chassis optical multiplexer, simply install it in a 1U position of a 19-inch standard cabinet: the IDM-30EN adopts a 19-inch 1U standard chassis and can be rack-mounted alone or installed cabinet-to-cabinet with existing transmission equipment, making it easy to use the 1U space of an existing cabinet.

Construction proceeds in on-site order: first push the device into the 1U position and fasten the panel screws, then connect the FC optical port patch cords (both ends of a paired device must have the same wavelength), E1 cables, and network cables, check the line coding, frame structure, and impedance specifications, and then power on; after power-on, observe the panel alarm indication and confirm that the received optical power at the optical port and the E1 channel status are normal, and commissioning is complete.

Power supply mode, overall power consumption, and operating environment (temperature, humidity) are not yet recorded in the knowledge base; before implementation, the manufacturer's technical documentation and commercial confirmation shall prevail. The front panel provides comprehensive function control switches and alarm indications; during routine inspection, service continuity can be judged by alarm category.

Typical Application Scenarios of IDM-30EN

Electric Power Private Network: Service Access for Substations and Power Supply Business Halls

Edge access in electric power private networks emphasizes link stability and simple O&M. Sites such as substations and power supply business halls usually have narrowband services including dispatch telephone and telecontrol data, and also need an Ethernet channel to backhaul service system data. The 30 channels of 64K service on IDM-30EN can carry such narrowband channels in a centralized manner, 2 groups of wire-speed 100M Ethernet satisfy office and service system backhaul, and 4 groups of E1 interfaces support transparent transmission, allowing reuse of existing G.703 transmission channels on site without replacing existing transmission equipment during link upgrades; the device uses a 19-inch 1U standard chassis and can be rack-mounted alongside existing cabinets on site.

Public Security Private Network: Service Backhaul over a Single Fiber for Police Stations and Checkpoints

Public security private network sites are distributed and links are long, and on site often only a single optical fiber or a single E1 is available. IDM-30EN brings back 30 channels of service and 2 groups of Fast Ethernet to the center over a single optical fiber at one time, with receiver sensitivity better than -34dBm and a receive dynamic range of 34dBm, making it easy to handle links with high optical cable attenuation over long distances. The network ports support VLAN partitioning, so office, video and service data can be carried separately; after the device is rack-mounted, commissioning and fault location can be completed through the function control switches and alarm indications on the front panel, reducing maintenance trips.

Bank Dedicated Line: Telephone and Service Data Transmission over the Same Fiber for Business Outlets

Banking and financial dedicated line scenarios are sensitive to line resources, and business outlets often need to enable telephone service and service data channels at the same time. IDM-30EN places 30 channels of service and 2 groups of wire-speed 100M Ethernet in a single 19-inch 1U device, and the network ports support VLAN partitioning, so different services can be divided into different VLANs for transmission, making it easy to distinguish service flows within one optical fiber channel; the 64K subscriber interfaces provide ordinary telephone cards with caller ID (FXO, FXS), and outlet telephones can be configured according to on-site traffic.

Figure 3: Application diagram of point-to-point networking for IDM-30EN integrated service multiplexer telephone optical multiplexer

Differentiated Value of IDM-30EN: One 1U Device Carrying 30 Channels of Service and 2 Groups of Fast Ethernet

A single unit provides standard 30 channels of data service and adapts to multi-user access at the edge of private networks, which is the value of IDM-30EN in carrying capacity. When narrowband services and Ethernet services are transmitted separately, edge sites usually need one PCM device for 64K services and a separate channel for service system backhaul; IDM-30EN combines 30 channels of service and 2 groups of wire-speed 100M Ethernet into one 19-inch 1U device and a single optical fiber, reducing cabinet space, associated cables and commissioning workload at the same time.

4 groups of E1 transparent transmission, compatible with G.703, directly connecting to existing electric power/public security transmission channels, is the value of IDM-30EN in link compatibility. In transparent transmission mode, the device forwards the E1 stream as-is without changing the time slots and signaling content within it, and spare E1 ports on existing PCM and SDH/PDH links on site can be reused directly; the bit rate of 2048kbit/s±50ppm, HDB3 line coding and PCM30/32 frame structure all follow ITU-T G.703 recommendations, and interfacing only requires checking the impedance and line coding at both ends.

2 groups of wire-speed 100M Ethernet, supporting VLAN partitioning, for more secure service isolation, is the value of IDM-30EN in service isolation. The network ports are RJ-45, 10/100Mbps adaptive mode, compliant with the IEEE-802.3u standard, and different flows such as telephone management, office and service system backhaul can be configured to different VLANs, so service data within the same optical fiber is invisible to each other; together with receiver sensitivity better than -34dBm and a receive dynamic range of 34dBm, service channels remain stable even on weak optical links.

Summary

The IDM-30EN 30-channel integrated service multiplexer packs 30 channels of service, 2 groups of wire-speed 100M Ethernet and 4 groups of transparent transmission E1 into a 19-inch 1U chassis, completing multi-user access at the edge of private networks with a single device; the 4 groups of E1 transparent transmission are compatible with existing G.703 links, the network ports support VLAN partitioning for service isolation, and receiver sensitivity better than -34dBm with a receive dynamic range of 34dBm accommodates long-distance weak optical links, making it suitable for access and upgrade projects in scenarios such as electric power private networks, public security private networks and bank dedicated lines.