Cable Channel Data

Origin

Two (2) snapshots of received cable channel data streams and two (2) channel models extracted from the original streams are provided. The cable data sequences in data1.mat and data2.mat have 64K complex samples each. The channels in chan1.mat and chan2.mat are modelled by 128 complex taps. The data is sampled at twice per symbol and the carrier frequency has been mixed close to 0 Hz. There is some residual FM on the carrier.

Matlab code

The code below uses the channel model to find a perfect fractionally spaced equalizer (FSE). The FSE can then be used to equalize the received sequence. The equalizer output eye diagram is plotted in blocks since the residual FM phase residual causes a rotation of the constellation in time.

 
%%%%%%%
clear
load chan2;
HH=convmtx(C,128);
H=HH(1:2:size(HH,1),:);
tau=zeros(size(H,1),1);
tau(64)=1;
f=H\tau;
load data2;
y=conv(f,data);
plot(y(2:2:1000),'.');
title('Eye diagram of equalized cable data');

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10/10/96