MDU cable network channel S parameter measurements - Tested in Wuxi city, Jiangsu province

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Grace Blake
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1 MDU cable network channel S parameter measurements - ed in Wuxi city, Jiangsu province Zhao Cui - Cable TV technology research institute, ABS, SARFT Gao Xiaojun Jiangsu Cable Network 1

2 Contents items program topology and environment results 2

3 items Scenario: Node+ passive cable network at MDU items: channel S parameters equipment: Network analyzer ( Agilent E57B ) Selected 3 s in Wuxi, and tested on 畅舜苑小区 2 -- 广丰二村 3 -- 金河湾家园 Considerations on test s selection: mainly according to upstream CNR measured on the CMTS side. Dividing the network transmission performance into excellent/good/bad 3 classes. Tall building (32 floors) and multi-floor building (5-6 floors) Mainly test passive tree topology network (with cascaded tap/splitter) 3

19 1 -- 畅舜苑小区 2 -- 广丰二村 3 -- 金河湾家园 Considerations on test s selection: mainly according to upstream CNR measured on the

4 program Full spectrum bandwidth test & multi- trunk test (divide whole spectrum into several segments) Full spectrum test: 1MHz~2GHz; 161 sampling points multi- trunk test: 1MHz ~1.5GHz 64MHz segment, 161 points/per 64MHz Network analyzer calibration Note: results described herein can only be used for the analysis of coaxial network characteristics trends, does not apply to the channel modeling system design Network analyzer 电子校准件 Calibration plane Short cable Long cable First stage tap/splitter Distribution network Last stage tap/splitter Passive cable network at MDU 4

5GHz 64MHz segment, 161 points/per 64MHz Network analyzer calibration Note: results described herein can only be used for the analysis of

5 Topology - test 1 ( building 11#) Building infos: 11# is a 6-floors building, 4households per floor N31 33'4",E12 17'3 Altitude of 11m time/environment morning Start time - 1:35 End time - 12:5 environment Temperature: 15 C Humidity : 42% 6F 5F 4F 3F 2F 1F Cut off Open Cut off VNA (E57B) Notes: 1. all coaxial cable are 75 cable; 2. Imperial F -type connectors 5

6 Topology - test 2 (building 22#) Building infos: 22# is a 5-floor building, 4 households per floor N31 35'56",E12 19'3" Altitude: 9m Only one subscriber connects with network, other ports are all. time/environment afternoon Start time: 14:2 End time: 16:33 environment Temperature: 16 C Humidity : 28% 5F 4F 3F 2F 1F Cut off Impe dance matc hed Notes: 1. all coaxial cables are 75 cable 2. Imperial F-type connector 21# VNA (E57B) 6

afternoon Start time: 14:2 End time: 16:33 environment Temperature: 16 C Humidity : 28% 5F 4F 3F 2F 1F Cut off 24

7 Topology - test 2 (building 31#) Building infos: 31# is 32-floor building, 3households per floor N31 36'4",E12 18'24" Altitude 5m time/environment morning Start time: 1:25 End time: 12: environment Temperature: 14 C Humidity : 52% 18F Cut off F 用户 18F 用户 17F 用户 16F 用户 28F 用户 27F 用户 21F 用户 2F 用户 3F 用户 29F 用户 23F 用户 22F 用户 33F 用户 31F 用户 26F 用户 F 用户 35F 用户 F 用户 13F 用户 12F 用户 11F 用户 1F 用户 F 用户 7F 用户 6F 用户 5F 用户 4F 用户 3F 用户 9F 用户 33F 用户 F 用户 75ohm VNA (E57B) Notes: 1. all coaxial cables are 75 cable 2. imperial F-type connectors 7

8 results - S21 & S12 S21 S12 8

9 Amplitude(dB) Amplitude(dB) Amplitude(dB) results micro-reflection1 X: 1.735e-7 Y: X: 1.262e-7 Y: X: 8.8e-8 Y: ~833MHz; 161 points Blackman windows +IFFT

27 1 2-1 -1-12.5 1 1.5 2 2.5 3-12.5 1 1.5 2 2.5 3-1 3-3 X: 8.

10 Amplitude(dB) Amplitude(dB) Amplitude(dB) results micro-reflection2 X: 7.886e-8 Y: X: 6.46e-8 Y: ~125MHz; 161 points Blackman window +IFFT

2 1.4 1.6 1.8 2-12.5 1 1.5 2 3-1 -3 X: 6.46e-8 Y: -17.

11 Some conclusions Bi-directional characteristics of passive coax networks are basically the same (S21=S12) Channel transmission loss is gradually stepping down under 1.5GHz, and decreased rapidly at 1.5G ~ 1.8GHz according to the test results at test 2. The channel response is quite flatten below 1GHz spectrum. But above 1GHz, the channel response has significant fluctuations. Parts of network exist strong micro-reflections According to test results, some views on passive coaxial cable network channel characteristics Multi path (micro reflection) do exist in passive cable network Poor connections between cable/splitter/tap can cause serious reflections. Splitter/tap port impedance unmatch/poor connections will cause frequency selective fading. Poor network consistency: channel performances differ significantly on different spectrum Cable channel changes slowly over time. 11

Parts of network exist strong micro-reflections According to test results, some views on passive coaxial cable network channel characteristics Multi path (micro reflection) do exist in passive cable

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