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News Details
Understanding the E1 Interface
Release time:
2026-03-27
The European 30‑channel pulse code modulation (PCM) system, known as E1, operates at a rate of 2.048 Mbit/s. China adopts the European E1 standard, and E1 interfaces come in two types: G.703 unbalanced 75‑ohm and balanced 120‑ohm. Below, we’ll provide a detailed overview of three common ways to use E1, along with important considerations—let’s take a look!
1. Three methods for using E1:
a. Use the entire 2 Mbit/s channel as a single link, such as DDN 2M;
b. Use 2M as several 64k channels and their combinations, such as 128K, 256K, etc.; this is CE1.
c. When used as a digital trunk for a voice switch—this is the most common application of E1—it treats a single E1 line as 32 64-kbps channels; however, timeslot 0 and timeslot 15 are reserved for signaling.
Common PCM multiplexing equipment: Guangzhou Guangqiao GQ4030;
2. Precautions for using E1:
When interfacing E1 ports, neither end should experience signal loss, frame slip, multiframe slip, or code‑slip alarms. However, the E1 interface parameters on both sides must be completely identical; even minor discrepancies in certain characteristic settings may not trigger any indicator lights or alarm notifications, yet they can lead to issues such as data‑channel failure, bit errors, code slips, or frame slip. These key parameter settings include impedance, frame structure, and CRC4 checksum. Impedance can be either 75 ohms or 120 ohms, while frame structures may be aligned or unaligned. Therefore, when interconnecting equipment, it is recommended to use products from the same manufacturer and pair them accordingly. For long‑distance transmission, PDH optical transceivers are commonly employed; the Guangzhou Guangqiao GQ2008, for instance, is an excellent choice.
Guangzhou Guangqiao Communication Equipment Co., Ltd. specializes in the R&D and manufacturing of communication equipment. Its main product lines include industrial switches, industrial Ethernet switches, industrial PoE switches, fiber optic transceivers, fiber optic switches, multi‑port transceivers, PoE switches, telephone optical terminals, video optical terminals, protocol converters (bridges), PCM multiplexing equipment, PDH optical terminals, E1 protection switching devices, serial‑port optical terminals, wireless bridges, SFP optical modules, and more. For inquiries, please call: 400‑8866‑640, 020‑82319301, or 020‑82319302. We prioritize quality and offer competitive pricing.
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