
<PAGE>
 
                                                                   EXHIBIT 21(1)
 
                         SUBSIDIARIES OF THE REGISTRANT
 
<TABLE>
<CAPTION>
                                                                     STATE OF
      NAME                                                         INCORPORATION
      ----                                                         -------------
      <S>                                                          <C>
      Precision Aerotech, Inc.....................................  Delaware
      Speedring, Inc..............................................  Delaware
      Speedring Systems, Inc......................................  Delaware
      Teletrac, Inc...............................................  California
</TABLE>
 
  Certain subsidiaries, considered in the aggregate as a single subsidiary, do
not constitute a significant subsidiary.
