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                                                                    Exhibit 4.64

THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED
(THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAW AND MAY NOT BE SOLD,
TRANSFERRED OR OTHERWISE DISPOSED OF UNLESS REGISTERED UNDER THE SECURITIES ACT
AND UNDER APPLICABLE STATE SECURITIES LAWS OR SPEEDCOM WIRELESS CORPORATION
SHALL HAVE RECEIVED AN OPINION OF ITS COUNSEL THAT REGISTRATION OF SUCH
SECURITIES UNDER THE SECURITIES ACT AND UNDER THE PROVISIONS OF APPLICABLE STATE
SECURITIES LAWS IS NOT REQUIRED.

                          SPEEDCOM WIRELESS CORPORATION

                             SECURED PROMISSORY NOTE

U.S. $100,000.00                                              New York, New York
                                                                  April 14, 2003

     FOR VALUE RECEIVED, the undersigned, Speedcom Wireless Corporation, a
Delaware corporation (the "Borrower"), hereby promises to pay to the order of
SDS MERCHANT FUND, L.P. or any future permitted holder of this promissory note
(the "Lender"), at the principal office of the Lender set forth herein, or at
such other place as the holder may designate in writing to the Borrower, the
principal sum of up to ONE HUNDRED THOUSAND DOLLARS (U.S. $100,000.00), or such
other amount as may be outstanding hereunder, together with all accrued but
unpaid interest, in such coin or currency of the United States of America as at
the time shall be legal tender for the payment of public and private debts and
in immediately available funds, as provided in this promissory note (the
"Note"). This Note is the Note referred to in the Letter Loan Agreement dated
April 14, 2003 between the Borrower and the Lender (the "Letter Loan
Agreement").

          1. Principal and Interest Payments.

               (a) The Borrower shall repay in full the entire principal balance
then outstanding under this Note on the earlier (the "Maturity Date") of: (i)
December 31, 2003, or (ii) the acceleration of the obligations as contemplated
by this Note. The Maturity Date may be extended as agreed upon in writing
between the parties.

               (b) Interest on the outstanding principal balance of this Note
shall accrue at a rate of fifteen percent (15%) per annum. Interest on the
outstanding principal balance of the Note shall be computed on the basis of the
actual number of days elapsed and a year of three hundred and sixty (360) days
and shall be payable by the Borrower and shall be payable by the Borrower in
cash in full on the Maturity Date. Furthermore, upon the occurrence of an Event
of Default, then to the extent permitted by law, the Borrower will pay interest
to the Lender,

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payable on demand, on the outstanding principal balance of the Note from the
date of the Event of Default until payment in full at the rate of twenty percent
(20%) per annum.

          2. Security Agreement. The obligations of the Borrower hereunder shall
be secured by, and the Lender shall be entitled to the rights and security
granted by the Borrower pursuant to, the Security Agreement dated as of April
14, 2003 by the Borrower for the benefit of the Lender.

          3. Payment on Non-Business Days. Whenever any payment to be made shall
be due on a Saturday, Sunday or a public holiday under the laws of the State of
New York, such payment may be due on the next succeeding business day and such
next succeeding day shall be included in the calculation of the amount of
accrued interest payable on such date.

          4. Borrower's Prepayment Option. The Borrower may prepay, at the
option of its Board of Directors, all or any portion of the outstanding
principal amount of this Note and the accrued and unpaid interest thereon upon
five (5) business days prior written notice to the Lender (the "Borrower
Prepayment Notice") at a cash price equal to 150% of the sum of the outstanding
principal amount and any interest accrued and outstanding (the "Borrower
Prepayment Price"). The Borrower may not deliver a Borrower Prepayment Notice to
the Lender unless the Borrower has clear and good funds for a minimum of the
amount it intends to prepay in a bank account controlled by the Borrower. The
Borrower Prepayment Notice shall state the date of prepayment (the "Borrower
Prepayment Date"), the Borrower Prepayment Price, the amount of the Note of such
Lender to be prepaid, the amount of accrued and unpaid interest through the
Borrower Prepayment Date and shall call upon the Lender to surrender to the
Borrower on the Borrower Prepayment Date at the place designated in the Borrower
Prepayment Notice such Lender's Note. The Borrower Prepayment Date shall be no
more than five (5) trading days after the date on which the Lender is notified
of the Borrower's intent to prepay the Note (the "Borrower Prepayment Notice
Date"). If the Borrower fails to pay the Borrower Prepayment Price by the sixth
(6th) trading day following the Borrower Prepayment Notice Date, the prepayment
will be declared null and void and the Borrower shall lose its right to deliver
a Borrower Prepayment Notice to the Lender in the future. On or after the
Borrower Prepayment Date, the Lender shall surrender the Notes called for
prepayment to the Borrower at the place designated in the Borrower Prepayment
Notice and shall thereupon be entitled to receive payment of the Borrower
Prepayment Price.

          5. Replacement. Upon receipt of a duly executed, notarized and
unsecured written statement from the Lender with respect to the loss, theft or
destruction of this Note (or any replacement hereof), and without requiring an
indemnity bond or other security, or, in the case of a mutilation of this Note,
upon surrender and cancellation of such Note, the Borrower shall issue a new
Note, of like tenor and amount, in lieu of such lost, stolen, destroyed or
mutilated Note.

          6. Parties in Interest, Transferability. This Note shall be binding
upon the Borrower and its successors and assigns and the terms hereof shall
inure to the benefit of the Lender and its successors and permitted assigns.
This Note may be transferred or sold, subject to

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the provisions of Section 8 of this Note, or pledged, hypothecated or otherwise
granted as Security by the Lender.

          7. Remedies, Characterizations, Other Obligations, Breaches and
Injunctive Relief. Upon an Event of Default (as defined in the Letter Loan
Agreement), the Lender shall have all the rights and remedies contained in the
Letter Loan Agreement. The remedies provided in this Note shall be cumulative
and in addition to all other remedies available under this Note or in the Letter
Loan Agreement, at law or in equity (including, without limitation, a decree of
specific performance and/or other injunctive relief), and no remedy contained
herein shall be deemed a waiver of compliance with the provisions giving rise to
such remedy and nothing herein shall limit a Lender's right to pursue actual
damages for any failure by the Borrower to comply with the terms of this Note.
Amounts set forth or provided for herein with respect to payments and the like
(and the computation thereof) shall be the amounts to be received by the Lender
and shall not, except as expressly provided herein, be subject to any other
obligation of the Borrower (or the performance thereof). The Borrower
acknowledges that a breach by it of its obligations hereunder will cause
irreparable and material harm to the Lender and that the remedy at law for any
such breach may be inadequate. Therefore the Borrower agrees that, in the event
of any such breach or threatened breach, the Lender shall be entitled, in
addition to all other available rights and remedies, at law or in equity, to
seek and obtain such equitable relief, including but not limited to an
injunction restraining any such breach or threatened breach, without the
necessity of showing economic loss and without any bond or other security being
required.

          8. Compliance with Securities Laws. The Lender of this Note
acknowledges that this Note is being acquired solely for the Lender's own
account and not as a nominee for any other party, and for investment, and that
the Lender shall not offer, sell or otherwise dispose of this Note other than in
compliance with the laws of the United States of America and as guided by the
rules of the Securities and Exchange Commission. This Note and any Note issued
in substitution or replacement therefore shall be stamped or imprinted with a
legend in substantially the following form:

          "THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT
          OF 1933, AS AMENDED (THE "SECURITIES ACT"), OR ANY STATE
          SECURITIES LAW AND MAY NOT BE SOLD, TRANSFERRED OR OTHERWISE
          DISPOSED OF UNLESS REGISTERED UNDER THE SECURITIES ACT AND
          UNDER APPLICABLE STATE SECURITIES LAWS OR SPEEDCOM WIRELESS
          CORPORATION SHALL HAVE RECEIVED AN OPINION OF ITS COUNSEL
          THAT REGISTRATION OF SUCH SECURITIES UNDER THE SECURITIES
          ACT AND UNDER THE PROVISIONS OF APPLICABLE STATE SECURITIES
          LAWS IS NOT REQUIRED."

          9. Borrower Waivers. Except as otherwise specifically provided herein,
the Borrower and all others that may become liable for all or any part of the
obligations evidenced by this Note, hereby waive presentment, demand, notice of
nonpayment, protest and all other

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demands and notices in connection with the delivery, acceptance, performance and
enforcement of this Note, and do hereby consent to any number of renewals of
extensions of the time or payment hereof and agree that any such renewals or
extensions may be made without notice to any such persons and without affecting
their liability herein and do further consent to the release of any person
liable hereon, all without affecting the liability of the other persons, firms
or Borrower liable for the payment of this Note, AND DO HEREBY WAIVE TRIAL BY
JURY.

               (a) No delay or omission on the part of the Lender in exercising
its rights under this Note, or course of conduct relating hereto, shall operate
as a waiver of such rights or any other right of the Lender, nor shall any
waiver by the Lender of any such right or rights on any one occasion be deemed a
waiver of the same right or rights on any future occasion.

               (b) THE BORROWER ACKNOWLEDGES THAT THE TRANSACTION OF WHICH THIS
NOTE IS A PART IS A COMMERCIAL TRANSACTION, AND TO THE EXTENT ALLOWED BY
APPLICABLE LAW, HEREBY WAIVES ITS RIGHT TO NOTICE AND HEARING WITH RESPECT TO
ANY PREJUDGMENT REMEDY WHICH THE LENDER OR ITS SUCCESSORS OR ASSIGNS MAY DESIRE
TO USE.

          10. Governing Law. This Agreement shall be governed by and construed
in accordance with the laws of the State of New York without giving effect to
the choice of law provisions. This Agreement shall not be interpreted or
construed with any presumption against the party causing this Note to be
drafted.

          11. Notices. Any notice, request, demand or other communication
permitted or required to be given hereunder shall be provided in the manner
specified in the Letter Loan Agreement.

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          IN WITNESS WHEREOF, the Borrower has executed and delivered this Note
as of the date first written above.

                                            SPEEDCOM WIRELESS CORPORATION


                                            By:
                                                --------------------------------
                                                Name:
                                                Title:

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