IDM-30EN-32 Integrated Service Multiplexer

A 32-channel voice VLAN isolation optical multiplexer is an optical multiplexing terminal that carries 32 voice channels, 4 groups of E1 transparent transmission interfaces, and 2 line-rate 100M Ethernet channels over a single optical fiber, and can perform VLAN isolation on Ethernet services. The IDM-30EN-32 integrated service access device belongs to this category of PCM equipment and is also commonly classified as a multi-service optical multiplexer.

The IDM-30EN-32 uses optical fiber as the transmission medium, and can also carry services over existing standard E1 channels (G.703) on site, adopting the PCM30/32 format to convert telephone signals and data signals into optical signals for transmission to the remote end. The IDM-30EN-32 is developed by Beijing Ruiguang Jiyuan Digital Technology Co., Ltd. (Raytrans). As a representative product of a professional optical multiplexer manufacturer, it mainly targets telephone and network service backhaul at sites such as electric power private networks, public security private networks, and bank dedicated lines, and can also be used in scenarios such as government private network optical fiber communication solutions, military emergency communications vehicle solutions, and smart mining communication solutions.

Private network edge sites usually need both narrowband channels such as telephone and dispatch data, and an Ethernet channel for service system backhaul. The IDM-30EN-32 optical multiplexing equipment combines these two requirements into a single 19-inch 1U device, providing 32 voice channels, 4 groups of E1 transparent transmission interfaces, and 2 groups of line-rate 100M Ethernet interfaces on one unit, meeting the multi-service access requirements in the product showcase. With receiver sensitivity better than -34 dBm and a receive dynamic range of 34 dBm, services remain continuous even over long-distance weak optical links.

Key specifications at a glance: 32 voice channels · 4 groups of E1 transparent transmission · 2 channels of 100M · VLAN isolation · 1U chassis · optical port 155 Mbps/1310 nm · PCM30/32 format

Figure 1: Front panel of the IDM-30EN-32 integrated service multiplexer, showing alarm indicator LEDs and the FXO/FXS, E1, and FC optical port layout

What kind of device is a 32-channel voice 4-group E1 transparent transmission optical multiplexer?

A 32-channel voice 4-group E1 transparent transmission optical multiplexer is an integrated service access device (integrated service multiplexing equipment) that multiplexes three types of services—voice, E1, and Ethernet—into the same optical fiber. As a multi-service optical multiplexer, the IDM-30EN-32 packs standard 32-channel voice services, 4 groups of E1 transparent transmission interfaces, and 2 groups of line-rate 100M Ethernet interfaces into a 19-inch 1U chassis; after receiving the optical signal, the peer device restores the corresponding FXO/FXS telephone ports and RJ-45 Ethernet ports.

When optical cable is already available on site, a pair of PCM equipment can form a point-to-point optical fiber link to bring the telephone and network services of a remote station back to the central equipment room in one pass. The IDM-30EN-32 adopts the PCM30/32 format, organizing 32 64K voice channels into a 155M optical channel by time slot, in a time slot organization consistent with existing PCM links. Abnormalities such as local optical path interruption and E1 loss of synchronization can be checked via panel alarm indications, and the function control switch facilitates commissioning and routine maintenance.

What service interfaces do 32 voice channels and 4 groups of E1 transparent transmission provide?

The IDM-30EN-32 provides three types of user interfaces externally: voice, E1, and Ethernet. The functions and uses of each type of interface are shown in the table below.

The service termination of the IDM-30EN-32 relies on 64K time slots: the FXO interface side connects to the exchange, and the FXS interface side connects to telephones, restoring 32 64K time slots into actual voice channels. The 4 groups of E1 interfaces are used to interface with 2M channels of existing PCM and SDH/PDH equipment, while the 2 groups of line-rate 100M Ethernet interfaces connect IP services to the station data network. The three types of services are multiplexed within the same device, so the site side only needs one optical fiber deployment to enable all of them simultaneously.

How are 32 voice channels and 4 groups of E1 transmitted simultaneously?

Simultaneous transmission of 32 voice channels and 4 groups of E1 relies on time division multiplexing (TDM) to pack different services into the same 155M optical channel. The IDM-30EN-32 arranges 32 64K voice channels into PCM30/32 primary group frames by fixed time slots, and the E1 interfaces carry the entire 2048 kbit/s primary group in transparent transmission mode. Ethernet services occupy independent bandwidth allocated within the optical channel, and the three types of services are organized by frame and channel on the transmit side and then combined into a single 155 Mbps optical signal.

The receive side demultiplexes layer by layer, terminating services onto their respective FXO/FXS, E1, and RJ-45 interfaces. The advantage of this multiplexing approach is that services do not contend with each other: voice uses fixed time slots with controllable delay and jitter; E1 transparent transmission does not change the original frame structure, so peer switches and PCM equipment do not need to reconfigure time slots. The Ethernet channel supports VLAN partitioning and can be transmitted in parallel with telephone channels over the same fiber core.

What are the technical specifications of the 32-channel voice VLAN isolation optical multiplexer?

The optical interface, E1 interface, voice channel interface, and Ethernet interface parameters of the IDM-30EN-32 are shown in the table below; selection and link budget are calculated according to these specifications.

The optical interface parameters directly determine whether a link can be enabled: transmit optical power -4～-12dBm, receiver sensitivity better than -34dBm, and receive dynamic range 34dBm. Measure the received optical power at the opposite end on site with an optical power meter; as long as it is above the sensitivity with margin left, services can run stably. The power supply mode, overall power consumption, and operating temperature and humidity are subject to the product documentation supplied with the unit and commercial confirmation.

How Is a Telephone Optical Multiplexer Wired for Interfacing with the Existing Network?

Wiring of a telephone optical multiplexer is handled separately for four types of interfaces: optical path, E1, telephone and network cable. Wiring and enabling of the IDM-30EN-32 can proceed as follows:

• Optical path: Connect the optical interface (FC; SC and other interfaces can be customized) to the ODF via a pigtail. Two optical multiplexing equipment units form a point-to-point 155M optical channel. Use an optical power meter to check the transmit optical power and the receiver sensitivity margin;

• E1: For the 4 groups of E1 interfaces, select 75Ω unbalanced (coaxial) or 120Ω balanced wiring according to the opposite-end interface. When the 120Ω balanced interface is used, an external impedance converter is required. Keep the line coding and frame structure consistent with HDB3 and PCM30/32;

• Telephone: Connect the exchange side to the FXO card and the user side to the FXS card. The voice channel has an audio range of 300Hz～3400Hz, ITU G.711 A-law compression, and a loop current of 25mA/channel, and can be directly connected to the existing telephone system;

• Ethernet: Connect the 2 groups of RJ-45 interfaces to switches or routers. The ports are 10/100Mbps adaptive; configure VLANs according to service planning;

• Clock: Set the master clock and user clock according to the networking topology. For a point-to-point link, set one end as the master clock and the other end to follow;

• Rack mounting and alarms: Install the 19-inch 1U chassis into a standard cabinet and secure it. Check the front panel function control switch and alarm indication, and then enable services item by item once normal.

Figure 2: Wiring diagram of the E1 coaxial interfaces, voice channel card interfaces, Ethernet RJ-45 ports and power supply terminals on the rear panel of the IDM-30EN-32

After wiring is complete, first check the optical path and E1 channels, then enable voice channels and Ethernet services one by one. As a professional optical multiplexer manufacturer, Raytrans can provide wiring guidance and commissioning support for private network scenarios such as electric power, public security, and banking, helping PCM equipment interconnect smoothly with existing network switches and SDH/PDH equipment; in government private network optical fiber communication solutions, military emergency communications vehicle solutions, and smart mining communication solutions, this multi-service optical multiplexer can serve as a site-side integrated service access device. You are welcome to contact Raytrans for product showcase and selection materials.

Do the 2 groups of wire-speed 100M Ethernet interfaces support VLAN partitioning?

Yes. The 2 groups of wire-speed 100M Ethernet interfaces on the IDM-30EN-32 support VLAN partitioning, which is a capability that distinguishes the IDM-30EN-32 from an ordinary telephone optical multiplexer. The 2 Ethernet ports can logically isolate networks of different natures, such as dispatching, office, and surveillance, by VLAN and then transmit them in parallel over the same physical link.

For private network users, the direct value of this VLAN isolation is clear service boundaries: one group of Ethernet interfaces carries production data, and the other carries office or video services. Even when they share the same fiber core and the same 100M channel, they remain logically independent of each other. Together with the transparent transmission capability of the 4 E1 interfaces and 32 voice channels, a single 1U PCM equipment can carry voice, E1, and Ethernet services by category and, as an integrated service access device, complete unified multi-service backhaul for the site.

Typical Applications of the IDM-30EN-32 in Private Networks

Electric Power Private Network: One-Fiber Backhaul of Substation Dispatch Telephone and In-Station Data

Between an electric power substation and a dispatch center, narrowband services such as dispatch telephone and telecontrol data must be transmitted, as well as Ethernet data for in-station office and monitoring. One IDM-30EN-32 is installed at each site, and a single optical fiber carries 32 voice channels and 2 Fast Ethernet channels back to the dispatch equipment room together. The FXO/FXS interfaces use ITU G.711 A-law encoding with a loop current of 25mA per channel and can be directly connected to dispatch and administrative voice channels.

The 4 E1 interfaces use ITU-T G.703 transparent transmission, and interconnecting with existing PCM and SDH/PDH equipment usually requires no adjustment to the time slot configuration; only a pair of fiber cores is occupied between stations. The 19-inch 1U chassis is suitable for rack mounting in a standard cabinet in an electric power equipment room and can be installed together with the in-station communication panel, serving as optical multiplexing equipment for the product showcase and implementation of site services.

Public Security Private Network: One-Time Multi-Service Access for Police Stations and Command Centers

Between police stations, duty posts, and command centers, official telephone, office network, and video backhaul channels are all required. The IDM-30EN-32 multiplexes 32 voice channels and 2 groups of wire-speed 100M Ethernet into a single optical fiber, and the telephone interfaces bring the voice channels back to the command center in one pass. The Ethernet interfaces use VLAN partitioning to carry the office network and the video surveillance network in isolation, preventing the two types of services from affecting each other.

The 4 E1 transparent transmission interfaces can connect to the 2M channels of existing PCM and SDH transmission networks, so capacity expansion on the basis of an existing private network does not require changing the backbone time slot planning. The front panel provides alarm indications, so link anomalies can be detected on the central side even when a duty post is unattended, making the device suitable for incorporation into the edge access design of government private network optical fiber communication solutions and military emergency communications vehicle solutions.

Bank Dedicated Line: Same-Fiber Transmission of Branch Voice and Service Data

Between a bank branch and the branch data center, counter telephone and service data usually need to be backhauled at the same time, while equipment room space and optical cable resources are both tight. The IDM-30EN-32 uses one 19-inch 1U device to combine 32 voice channels and 2 channels of wire-speed 100M Ethernet onto the same optical fiber; the counter voice channels use ITU G.711 A-law encoding with a loop current of 25mA per channel.

Service data is carried over RJ-45 Ethernet ports and can be isolated from voice channels by VLAN partitioning; the 4 E1 interfaces provide transparent transmission compatible with the branch's existing PCM and SDH channels. One device replaces multiple stacked units, saving optical cable fiber cores and cabinet space, and the construction workload of branch upgrades is reduced accordingly.

Figure 3: Topology diagram of electric power substations, police stations, and bank branches networked point-to-point through the IDM-30EN-32 and aggregated at the central equipment room

Correspondence Between Differentiated Capabilities and Private Network Value

Conclusion

The 32-channel voice VLAN isolation optical multiplexer (IDM-30EN-32 integrated service multiplexer) uses one 19-inch 1U chassis to simultaneously carry 32 voice channels, 4 groups of E1 transparent transmission interfaces, and 2 groups of wire-speed 100M Ethernet over a single optical fiber. The Ethernet supports VLAN isolation, so office, surveillance, and production data run in parallel on the same fiber without mixing; the E1 interfaces use ITU-T G.703 transparent transmission and are compatible with existing PCM and SDH/PDH channels.

With receiver sensitivity better than -34dBm and a dynamic range of 34dBm, service continuity is maintained even on weak-light long-distance links. One-time backhaul of single-site services saves both optical fiber and cabinet space, making the device suitable for edge access in electric power private networks, public security private networks, and bank dedicated lines, as well as for multi-service carrying in scenarios such as smart mining communication solutions; as an optical multiplexer manufacturer, Raytrans can provide selection and configuration confirmation, and you are welcome to contact the manufacturer's sales team.