diff --git a/doa_doppler_est.tex b/doa_doppler_est.tex
index 69ca563..7eebaf9 100644
--- a/doa_doppler_est.tex
+++ b/doa_doppler_est.tex
@@ -27,7 +27,6 @@
 \newcommand{\Tran}{\mathsf{T}}
 \newcommand{\Herm}{\mathsf{H}}
 \newcommand{\diff}{\mathop{}\!\mathrm{d}}
-\newcommand{\secref}[1]{第~\ref{#1}~节}
 \newcommand{\appref}[1]{附录~\ref{#1}}
 
 \usepackage{arydshln}