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                                                                    Exhibit 4.17

         AMENDMENT NO. 3, dated as of August 5, 2002 ("Amendment No. 3"), among
Acterna Corporation, a Delaware corporation (the "Company"), Clayton, Dubilier &
Rice Fund V Limited Partnership, a Cayman Islands limited partnership ("Fund
V"), Clayton, Dubilier & Rice Fund VI Limited Partnership, a Cayman Islands
limited partnership ("Fund VI") and CD&R VI (Barbados), Ltd., a company
organized under the laws of Barbados ("CD&R Barbados"), to the Registration
Rights Agreement, dated as of May 21, 1998 (the "Registration Rights
Agreement"), among the Company, Fund V and the other parties thereto, and as
previously amended by Amendment No. 1, dated as of May 23, 2000, among the
Company, Fund V and Fund VI and as further amended by Amendment No. 2, dated as
of January 15, 2002, among the Company, Fund V and Fund VI. Capitalized terms
used herein without definition have the meanings given to them in the
Registration Rights Agreement.

         WHEREAS, in order to obtain additional liquidity for general corporate
purposes, Acterna LLC, a Delaware limited liability company wholly-owned and
controlled by the Company ("Acterna LLC"), and the Company entered into an
Investment Agreement, dated as of August 5, 2002 (the "Series 2 Notes Investment
Agreement") with CD&R Barbados, under which Acterna LLC agreed to issue and sell
to CD&R Barbados its Senior Secured Convertible Notes Due 2007, Series 2 (the
"Series 2 Notes");

         WHEREAS, the Series 2 Investment Agreement and the Series 2 Notes
provide for the issuance by the Company of warrants (the "Warrants") to purchase
Common Stock to the holders of any Series 2 Notes repurchased or redeemed by
Acterna LLC prior to their stated maturity; and

         WHEREAS, the Company, Fund V, Fund VI and CD&R Barbados desire to amend
the Registration Rights Agreement to provide registration rights to CD&R
Barbados in respect of the shares of Common Stock issuable upon conversion of
the Series 2 Notes or upon exercise of the Warrants.

         NOW, THEREFORE, in consideration of the premises and the mutual
promises and agreements herein made, the receipt and sufficiency of which is
hereby acknowledged, the parties hereto agree as follows:

         1. Amendment to Section 2. The definition of "Registrable Securities"
in Section 2 of the Registration Rights Agreement is hereby amended to read in
its entirety as follows:

                  "Registrable Securities": (a) The Common Stock (i) received by
                  Fund V, the Manager and the Trusts as a result of the Merger,
                  (ii) issued to each of Fund V and Fund VI pursuant to the Fund
                  Stock Subscription Agreements, (iii) issued to Fund VI (or any
                  permitted transferee) upon conversion of any of the Company's
                  12% Senior Secured Convertible Notes Due 2007 (the "Notes")
                  issued pursuant to that certain Investment Agreement, dated as
                  of December 27, 2001 (the "Investment Agreement"), between the

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                  Company, Acterna LLC and Fund VI, (iv) issued to Fund VI (or
                  any permitted transferee) upon exercise of any warrants to
                  purchase Common Stock received by Fund VI (or its transferee)
                  pursuant to the Investment Agreement or the Notes, (v) issued
                  to CD&R VI (Barbados), Ltd. ("CD&R Barbados") (or any
                  permitted transferee) upon conversion of any of the Company's
                  Senior Secured Convertible Notes Due 2007, Series 2 (the
                  "Series 2 Notes") issued pursuant to that certain Investment
                  Agreement, dated as of August 5, 2002 (the "Series 2 Notes
                  Investment Agreement"), among the Company, Acterna LLC and
                  CD&R Barbados, (vi) issued to CD&R Barbados (or any permitted
                  transferee) upon exercise of any warrants to purchase Common
                  Stock received by CD&R Barbados (or its transferee) pursuant
                  to the Series 2 Notes Investment Agreement or the Series 2
                  Notes, or (vii) issued to Individual Investors pursuant to a
                  stock subscription agreement or other agreement that provides
                  that such Common Stock shall be Registrable Securities, (b)
                  any shares of Common Stock issued pursuant to the terms of,
                  and under the circumstances set forth in, Section 4, and (c)
                  any securities issued or issuable with respect to any Common
                  Stock referred to in the foregoing clauses (w) upon any
                  conversion or exchange thereof, (x) by way of stock dividend
                  or stock split, (y) in connection with a combination of
                  shares, recapitalization, merger, consolidation or other
                  reorganization or (z) otherwise, in all cases subject to the
                  last paragraph of Section 3.3. As to any particular
                  Registrable Securities, once issued such securities shall
                  cease to be Registrable Securities when (A) a registration
                  statement (other than a Special Registration pursuant to which
                  such securities were issued by the Company) with respect to
                  the sale of such securities shall have become effective under
                  the Securities Act and such securities shall have been
                  disposed of in accordance with such registration statement,
                  (B) such securities shall have been distributed to the public
                  in reliance upon Rule 144, (C) such securities shall have been
                  otherwise transferred, new certificates for such securities
                  not bearing a legend restricting further transfer shall have
                  been delivered by the Company and subsequent disposition of
                  such securities shall not require registration or
                  qualification of such securities under the Securities Act or
                  any similar state law then in force, or (D) such securities
                  shall have ceased to be outstanding.

         2. Confirmation of Registration Rights Agreement. Other than as
expressly modified pursuant to this Amendment, all provisions of the
Registration Rights Agreement remain unmodified and in full force and effect.

         3. Miscellaneous. This Amendment shall be governed by and construed in
accordance with the internal laws of the State of New York without giving effect
to any choice or conflict of law provision or rule to the extent such provision
or rule would require or permit the application of the laws of any jurisdiction
other than the State of

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New York. This Amendment may be executed in one or more counterparts, each of
which shall be deemed an original and all of which shall together constitute one
and the same instrument and shall bind and inure to the benefit of the parties
and their respective successors and assigns.

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         IN WITNESS WHEREOF, each of the undersigned has executed this Amendment
as of the date first written above.

                     ACTERNA CORPORATION


                     By:______________________________
                        Name:
                        Title:


                     CLAYTON, DUBILIER & RICE
                        FUND V LIMITED PARTNERSHIP

                     By:   CD&R Associates V Limited Partnership,
                             the general partner

                     By:   CD&R Investment Associates II, Inc.,
                             its managing general partner



                     By:______________________________
                        Name:
                        Title:


                     CLAYTON, DUBILIER & RICE
                        FUND VI LIMITED PARTNERSHIP

                     By:   CD&R Associates VI Limited Partnership,
                             the general partner

                     By:   CD&R Investment Associates VI, Inc.,
                             its managing general partner



                     By:______________________________
                        Name:
                        Title:

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                     CD&R VI (BARBADOS), LTD.

                     By:   Corporate Services Limited,
                           Secretary

                     By:______________________________
                        Name:
                        Title:

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