Airport Wireless PCM Information Transmission Access Equipment

📅Jan 31, 2023

Brief：In the process of airport information communication construction, operation and maintenance, it is common to encounter situations where new or temporary information points have no fiber optic cable, or locations unsuitable for fiber deployment, or damaged fiber optic cables. In such cases, a wireless PDH transmission system is required. PDH and SDH transmission equipment offer advantages such as constant transmission delay, stable bandwidth, dedicated bandwidth for user terminal services, excellent signal quality, and strong confidentiality, providing irreplaceable advantages over IP service terminals. PDH and SDH systems support fiber optic and wireless transmission modes, providing clock-synchronized or pseudo-synchronized transmission methods. Optical terminals are widely used, while wireless SDH uses frequencies above 10 GHz, making equipment costs relatively high. Wireless PDH also uses different uplink and downlink frequencies, making commissioning inconvenient and applications relatively rare.

MESH Wireless PCMWireless PDHWireless PCMWireless E1 TransmissionWireless Integrated Service TransmissionMicrowave E1 TransmissionMicrowave Multiplexing Equipment

Keywords: MESH Wireless PCM, Wireless PDH, Wireless PCM, Wireless E1 Transmission, Wireless Integrated Service Transmission, Microwave E1 Transmission, Microwave Multiplexing Equipment

I. Overview

In the process of airport information communication construction, operation and maintenance, it is common to encounter situations where new or temporary information points have no fiber optic cable, or locations unsuitable for fiber deployment, or damaged fiber optic cables. In such cases, a wireless PDH transmission system is required.

PDH and SDH transmission equipment offer advantages such as constant transmission delay, stable bandwidth, dedicated bandwidth for user terminal services, excellent signal quality, and strong confidentiality, providing irreplaceable advantages over IP service terminals.

PDH and SDH systems support fiber optic and wireless transmission modes, providing clock-synchronized or pseudo-synchronized transmission methods. Optical terminals are widely used, while wireless SDH uses frequencies above 10 GHz, making equipment costs relatively high. Wireless PDH also uses different uplink and downlink frequencies, making commissioning inconvenient and applications relatively rare. Currently, there is also a pseudo-wire emulation technology using IP transmission that can transmit E1 information, thereby satisfying the access of traditional PCM terminals. Pseudo-wire emulation technology enables traditional E1 access technology to be transmitted via wireless bridges. The vast market advantages of the wireless bridge industry ensure that traditional PCM terminals continue to provide high-quality applications, delivering wireless PDH transmission performance.

The wireless bridge market is enormous, with high-quality and cost-effective products. Transmission frequencies can be adjusted over a wide range to avoid wireless interference with airport facilities. As frequency bands are generally relatively high, and airport line-of-sight conditions are favorable, directional antennas can be selected to enhance transmission performance and anti-interference capability.

Wireless bridges support point-to-point transmission, point-to-multipoint transmission, and MESH relay transmission modes, offering flexible deployment. Through improved frequency customization technology, they can operate on ideal frequency points, effectively avoiding environmental interference.

The IDM brand product series provides an integrated wireless PDH+PCM information access transmission mode, which can be deployed as conveniently as wireless network products while offering a variety of PCM service access interfaces, such as FXO/FXS, E&M audio 2-wire/4-wire, synchronous/asynchronous serial data interfaces (RS232/RS422/RS485/RS429/V.35, etc.), and video interfaces.

II. Wireless PCM Equipment Applications

III. Wireless PCM Technical Principles

IV. Wireless PCM Technical Specifications

Wireless PCM integrates PCM technology, PDH technology, pseudo-wire emulation technology, and wireless bridge technology. It is a highly integrated all-in-one access device that allows users to maintain the high performance of traditional PCM interfaces while enabling rapid transmission deployment.

4.1 Wireless Transmission Specifications

Ø 49206100MHz, RF MIMO adopts 2T2R architecture, wireless bandwidth supports 5/10/20/40MHz configurable, physical layer bandwidth 300Mbps, maximum transmit power 400mW, receive sensitivity up to -96dBm, built-in 18dBi directional dual-polarized antenna, recommended bridge distance 15 km.

Ø Supports TDMA protocol and TDMA bandwidth uplink/downlink allocation function, effectively improving transmission bandwidth in PTMP mode;

Ø Supports Dynamic Frequency Selection (DFS) function;

Ø Supports automatic transmit power adjustment (IEEE802.11h); manual adjustment step 1dBm.

Ø Supports uplink/downlink bandwidth allocation, client isolation, bandwidth control, and client signal strength access control functions;

Ø Supports IP68 waterproof rating, operating temperature -40~75°C;

4.2 E1 Line Specifications

Ø Equipment supports jitter compensation of 1.5ms to 125ms packet delay variation;

Ø Clock accuracy up to 16ppb, meeting the clock accuracy requirements of 3G base stations, effectively ensuring data backhaul;

Ø Multiple clock modes selectable: internal clock, user clock, recovered clock, and external clock;

Ø Low data transmission delay, low signal jitter and wander, ensuring TDM service quality;

Ø Complete indicator alarm functions for easy fault location;

Ø Excellent IP network transmission performance;

Ø Configurable packet buffer space, enabling E1 end-to-end delay as low as 1ms;

Ø Bandwidth adjustment function, allowing adjustment of E1 interface quantity based on the number of E1s or IP network bandwidth conditions;

Ø Configurable packet size balanced with PSN throughput and latency, delivering excellent transmission performance over Layer 2 Ethernet switching networks.

E1Interface Bit Rate

2048Kbpss±50ppm

Number Supported

Standard Protocol

Supports ITU-T G.703 /G.706/G.704

Line Code

AMI/HDB3

Physical Interface

RJ45 (balanced)/ BNC (unbalanced)

Jitter Characteristics

ITU-T G.823

Impedance

75Ω (unbalanced)/120Ω (balanced)

Clock Recovery Accuracy

100ppm/16ppb

E1Interface Configurable

E1 interface supports local or remote configuration via software

4.3 PCM Interface Specifications

4.3.1 FXO, FXS

Compression Rate

A-law in ITU G.711

Audio Range

300Hz~3400Hz

Input/Output Impedance

200Ω+560Ω//0.1μF

Loop Current

25mA/channel

4.3.2 EM2/4-wire

Compression Rate

A-law per ITU G.711

Audio Range

300Hz―3400Hz

Impedance

Balanced 600Ω

Return Loss

≥18dB

4.3.3 V.24

Transmission Rate

Asynchronous≤9600bps

Synchronous64Kbps

Electrical Characteristics

Compliant withCCITT V.28protocol

4.3.4 V.35

Transmission Rate

N×64Kbps (N=1~30)

Electrical Characteristics

Compliant with ITU-T V.35 Recommendation

4.3.5 Co-directional 64K

Line Code

G.703 Standard

Line Rate

64Kbps±100ppm

Impedance

Balanced 120Ω

Fully compliant with ITU G.703 recommendation

4.4 Video Codec Technical Specifications

Input Interface

HDMI

Supports up to 1920x1080P@60fps

Supported resolutions: 1080P, 720P, 1600*1200, 1440*900, 1366*768, 1280*1024, 1024*768, 800*600, 360P, etc.

Audio

Supports 3.5mm audio signal input and output

Supports embedded digital audio over HDMI

Audio Coding

Sampling Rate

8k, 16k, 32k, 44.1k, 48k

Bit Rate	Arbitrarily configurable, recommended 64k~256k bps
Encoding Format	AAC, PCMA, PCMU, MP3, MPEG2

Video Encoding

Bitrate Control

CBR, VBR, AVBR, FIXQP

Bit Rate Range	16kbps~40Mbps
Encoding Format	H264, H265

Network Protocol

Transport Protocol

HTTP, HLS, RTSP, RTMP push streaming,RTMP pull streaming,UDP, unicast, multicast(Multicast)

Stream Forwarding

Supports secondary forwarding after remote stream decoding

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