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GIAC memo 1999/06/17

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<TITLE>GIAC Memo: Implementation of the Third Civil GPS Signal</TITLE>

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	<td><img src="fgcsicon.gif" width=110 height=115 align="left" border=0></td>

	<td align="right" valign="center"><FONT SIZE="+3"><STRONG>GIAC </STRONG></font>

	<FONT SIZE="+2"><STRONG>GPS Interagency Advisory Council</STRONG></font>

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<tr><td colspan="2" align="right">June 17, 1999</td></tr>

<tr><td colspan="2"><p>&nbsp;</p></td></tr>

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	<td valign="TOP">MEMORANDUM FOR:  </td>

	<td valign="TOP">Colonel Richard Skinner, USAF

<br>Office of Deputy Assistant Secretary of

<br>Defense for C3ISR and Space Systems

<p>Joseph F. Canny

<br>Deputy Assistant Secretary for Transportation Policy

<br>Department of Transportation

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	<td valign="TOP">FROM:      </td>

	<td valign="TOP">          Charles W. Challstrom

<br>               Chair, GPS Interagency Advisory Council</td>

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	<td valign="TOP">SUBJECT:</td>

	<td valign="TOP">Early Implementation of  Civil Signal</td>

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<p>This memorandum provides input to the Interagency GPS Executive

Board (IGEB) Senior Steering Group for Third Civil GPS Signal

Implementation based upon the discussions of the May 12, 1999,

meeting of the GPS Interagency Advisory Council (GIAC).  The GIAC

discussions included the topics of the IGEB meeting of May 11,

1999.  In particular, the early implementation of the new civil

signals was of very great interest to GIAC.</p>



<p>The GIAC enthusiastically endorses the implementation of the L5

signal (1176.45 MHz) at the earliest possible opportunity.  The

greatest benefits to civil applications would come from the L5

deployment.  The new hybrid signal structure under consideration

for L5 is more robust, and has more accurate pseudorange

resolution than the current C/A and P(Y) signals.  L5 will have a

major impact on geodesy and precision navigation; where we could

get robust, single-epoch, carrier-phase positioning and ambiguity

resolution over 40 km, to better than 10 cm accuracy through dual

widelaning.  And, we expect to increase that distance and

accuracy through support models of ionosphere and troposphere.</p>



<p>At the Chief Executive Officer Roundtable, held at the Department

of Commerce in December 1998, numerous economic benefits of GPS

were described.  Those participants wholeheartedly advocated

early implementation of the GPS civil signals and expressed the

needs for the highest possible positioning accuracy.  GIAC

recognizes that the greatest number of benefits described in the

CEO report will be obtained through the deployment of the L5

signal, and that funds allocated to early implementation will

have maximum leverage if spent on early L5 deployment.</p>



<p>The GIAC envisions that the L5 signal will be of major benefit,

not only to aviation, but to agriculture, automotive, banking,

communications, construction, lumber, shipping, space systems,

surveying, and transportation sectors.  The amount of economic

benefit will be related to how widely and how quickly GPS

technology can be deployed.  The GIAC respectfully recommends

that the cost analyses conducted by the GPS Joint Program Office

include the scenarios of early L5 deployment.  This would be of

great support in providing the IGEB with the information it

requires to give the leadership and vision for the realization of

GPS as a true national resource.</p>



<p>GIAC recognizes that the addition of a C/A code on the L2

frequency (1227.6 Mhz) will add additional costs to the early

deployment of civil signals.  However, the agencies represented

by GIAC will be able to collaborate with NASA in building a

proposal for monitoring the civil signals under discussion.  If

this monitoring proposal can be implemented, there could be an

estimated $20 million cost savings that may ease the decisions on

early civil signal deployment.</p>



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<font face="Arial" size="-1">

for information write:

<br>GPS INTERAGENCY ADVISORY COUNCIL

<br>FEDERAL GEODETIC CONTROL SUBCOMMITTEE

<br>NOAA, National Geodetic Survey, N/NGS

<br>1315 East-West Highway, Room 8657

<br>Silver Spring, Maryland  20910-3282</font>

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