The review presents a brief history of the program, its management organization, and current and projected requirements, capabilities and program efforts. The overall program growth since September 1975 is presented. The Navy's areas of concern regarding future PTTI development are described

Allen, R. T.

English

NASA Technical Reports Server

A U.S. NAVY PRECISE TIME AND TIME
INTERVAL (PTTI) PROGRAM UPDATE
RALPH T. ALLEN
NAVAL ELECTRONIC SYSTEMS COMMAND
ABSTRACT
A review of the Navy's PTTI Program
was presented at the Tenth Annual PTTI Appli-
cations and Planning Meeting. That review
presented a brief history of the Navy's,PTTI
Program, its management organization, and
current and projected requirements, capabi-
lities and Program efforts.
This paper:
a. Updates those previously identi-
fied Navy requirements, capabilities and Pro-
gram efforts.
b. Outlines new Program efforts.
c. Presents overall Program growth
since September 1975.
d. Projects the Navy's areas of
concern regarding future PTTI development.
A review of the U.S. Navy's Precise Time and Time Interval (PTTI)
Program was presented in November 197JT at the Tenth Annual PTTI" Appli-
cations and Planning Meeting (1). Since that presentation, the Pro-
gram's management organization, its basic mission of providing all Navy
platforms and their communications, navigation and weapon systems with
PTTI information traceable to the U.S. Naval Observatory (NAVOBSY),.
and its PTTI System Concept, see Figure 1, have all remained essentially
'unchanged.
This has provided a stable base from which the Program has conti-
nued to grow and to respond to the increasing PTTI needs of the Fleet.
This growth and response to Fleet needs has resulted in an increasing
awareness of and support for the Program by Navy program sponsors,- plan-
ners, programmers, engineers, support personnel and users.
127
https://ntrs.nasa.gov/search.jsp?R=19810018936 2020-03-21T13:02:24+00:00Z
More specifically, the review at the Tenth Annual PTTI Applica-
tions and Planning Meeting reported that the Naval Electronic Systems
Command (NAVELEX) had submitted an analysis of the Navy's PTTI require-
ments to the Chief of Naval Operations (CNO) in November 1978. The re-
view further reported .that current, medium and long range Navy platform
timing requirements were in the 100 microsecond, the one to ten micro-
second, and the 10 nanosecond ranges respectively. With a few excep-
tions, those values are still valid.
Based on the requirements analysis findings, NAVELEX updated the
Navy's PTTI Program Master Plan. CNO subsequently approved the Master
Plan in January 1980.
Some of the major Navy PTTI efforts addressed in that Master Plan
and reported on at the Tenth Annual PTTI Applications and Planning Meet-
ing include the:
PTTI Maintenance and Calibration Program.
SSN-637 Class Submarine PTTI Platform Distribution System
(PDS) Development.
SSN-688 and POSEIDON Class Submarine PTTI PDS Development.
NAVOBSY Master Clock System (MCS) Upgrade.
AN/URQ-23 Frequency-Time Standard.
Global Positioning System (GPS) Time Transfer Unit (TTU).
PTTI Technology Program.
0-1695 Cesium Beam Frequency Standard.
Rubidium Standard Development.
"Standardized". PTTI PDS.
The following is a brief update on each of. these efforts covering
the past two years.
i - *
" In 1978, the Naval Electronic Systems Engineering Center (NESEC),
Portsmouth was assigned the responsibility of providing maintenance
and repair services for all Navy owned atomic standards and providing
portable clock trips to numerous Navy installations and Army Defense
Satellite Communications System (DSCS) earth terminals under the PTTI
Maintenance and Calibration Program. NESEC, Portsmouth has now been
formally tasked, as the Technical Manager for PTTI, with providing
Field Maintenance Agent CFMA) and Depot Repair Facility services for
128
Navy owned PTTI equipment including the AN/URQ-23 Frequency-Time Stand-
ard and the SG-1157/U Digital Processing Clock. Future projections
indicate that NESEC, Portsmouth's responsibilities as the Technical
Manager for PTTI will continue to increase and expand.
The automatic, no-break SSN-637 Class Submarine PTTI PDS equip-
ment, see Figure 2, was delivered in 1979 and completed Operational
Evaluation (OPEVAL) testing in June 1980. It is currently being consi-
dered for Approval for Service Use (ASU).
A direct result of the SSN-637 Class PTTI PDS development effort
has been a reduction in scope of the SSN-688 Class PTTI PDS to a manual
switch, see Figure 3. Also, current planning is for the POSEIDON class
submarines to use the PDS developed under the SSN-688 Class effort.
While development was initiated on this PDS at the Naval Ocean Systems
Center (NOSC) and the Naval Avionics Center (NAG), reversals and set-
backs have necessitated reprogramming actions. A restart effort is now
being scheduled.
In July 1980, CNO formally approved the Navy Decision Coordinating
Paper (NDCP) for the NAVOBSY MCS Upgrade, see Figure 4. Presently,
various component equipments required to upgrade the Data Acquisition
System (DAS) of the MCS have been procured and installed. AlsOj the
first of two Environmentally Controlled Monitor Stations (ECMS) have
been procured and installed. The first procurement of hydrogen-masers
is now scheduled for Fiscal Year (FY) 1982.
The AN/URQ-23 Frequency-Time Standard which will replace the
AN/URQ-10A as the Navy's quartz crystal reference standard was granted
ASU in August 1979. The first AN/URQ-23 production contract was
awarded the following March and the first production units are now
being delivered to the Fleet. The next procurement of AN/URQ-23's is
scheduled as a competitive, multlyear procurement in FY-82.
The GPS TTU (2) feasibility model was delivered to the NAVOBSY in
December 1979 where it is currently completing a one year testing
program. Initial findings indicate that its performance is better
than the specified 100 nanosecond time transfer capability. A pro-
duction decision is scheduled for April 1981.
The PTTI Technology Program to investigate (a) time transfer via
GPS using laser technology, (b) environmental effects on atomic clocks
and (c) high performance standards and advanced timing has gone unfunded
for the second year. NAVELEX will continue to pursue this effort by
showing the potential impact of these advanced research programs on
systems and equipments which are currently scheduled for installation
in the Fleet.
Cognizance of the 0-1695A/U Cesium Beam Frequency Standard was
129
scheduled for transfer to the Navy's PTTI Program in FY-79. While
responsibility for the maintenance and calibration of the 0-1695A/U has
now been assumed by the Program, full technical cognizance of the unit
has, at the request of the VERDIN Program Manager, not been transferred
because of reliability problems associated with the equipment. A tran-
sition plan has been developed and will be implemented upon final reso-
lution of those reliability problems.
The development of a rubidium standard for the Navy which was
discussed in 1978 is now being held in abeyance. A Preliminary Design
and Life Cycle Cost Analysis for the "Standardized" PTTI PDS, see
Figure 5, was initiated in late FY-/9. The Preliminary Design and Life
Cycle Cost Analysis is to develop alternative designs for a modular
PTTI PDS comprised of Standardized" equipments which could be recon-
figured to meet the needs of a particular platform, i.e. surface ship,
submarine, aircraft or shore installation, and compare the technical,
operational and economic advantages and disadvantages of those alterna-
tives. It was decided that it would be premature to initiate the devel-
opment of a rubidium standard for the Navy prior to the completion of
that Preliminary Design and Life Cycle Cost Analysis.
Similarly, final approval for full scale development of the
"Standardized" PTTI PDS is being held in abeyance pending the comple-
tion of the Preliminary Design and Life Cycle Cost Analysis. The
"Standardized" PTTI PDS is the heart of the Navy s PTTI Program. For
that reason, NAVELEX is currently attempting to recoup after the fail-
ure of the contractor to complete the Preliminary Design and Life Cycle
Cost Analysis within cost and schedule constraints and to finish the
effort via other alternatives. NESEC, Portsmouth again under the PTTI
Technical Manager assignment has taken the lead to insure timely comp-
letion of the effort.
New Program efforts have also been kept to a minimum over the
past two years for two reasons. First, the PTTI Program Manager made
a concious decision in 1975 to minimize new Fleet, operational equip-
ment developments until the Navy's requirements had been defined and
then reasserted that decision in 1978 pending the completion of the
Preliminary Design and Life Cycle Cost Analysis. Secondly, there has
been a lack of sufficient personnel in the Program office to manage and
administer the various Program efforts. Recently, this latter reason
has caused NAVELEX to notify its sponsor that it could not accept addi-
tional PTTI responsibilities.
Taking this into account, the Program has still taken on new
efforts to support immediate Fleet needs. For example, in 1979,
NAVELEX procured several TRANSIT Timing Receivers to support NAVOBSY
requirements. More recently, NAVELKX procured a clock distribution
system to meet an urgent requirement at Naval Communications Station,
Japan.
130
These were relatively small tasks, but, as stated previously, the
PTTI Program has continued to grow and to support the Fleet. Figure 6
is an updated Program Milestone chart which depicts some of the preced-
ing efforts and reflects that Program growth. Figure 7 provides a
funding profile, including RDT&E, OPN and O&MN funds, of the Program
from FY-75 to FY-80 which again reflects that Program growth.
Most of this is, however, history. What projections can be made
regarding the future?
Broad projections indicate that there will be a continuing increase
in the Fleet's need for PTTI and that there will be an accompanying
increase in the Navy's support for PTTI.
Also, while the "Standardized" PTTI PDS Preliminary Design and Life
Cycle Cost Analysis has not been completed, some specific Navy pro-
jections regarding future PTTI developments appear feasible.
First, it appears that currently available reference standards
combined with both operational and planned PTTI dissemination systems,
e.g., LORAN-C, TRANSIT and GPS, will' be capable of meeting the vast
majority of the Navy's projected operational requirements.
Second, there is a need for a properly designed, manual switch
combined with an "update and comparison" equipment capable of (a) com-
paring onboard reference standards with a reference signal from a
dissemination system external to the platform as well as with each
other, (b) providing an alarm when any one standard drifts beyond a
preset limit, and (c) allowing for underway time transfers as required.
Third, there is also a need to reduce the number of reference
signals being distributed on board Navy platforms. Currently there are
three basic frequencies, 5MHz, 1MHz and 100KHz; two timing pulses, 1PPS
and 1PPM; and an untold number of time code signals being distributed.
It appears that long range planning should reduce distribution to a
single reference frequency and single time code. If necessary, this
might be relaxed to include a single timing pulse signal. No decisions
have been reached regarding which signals should actually be "standard-
ized" on, but this action alone would reduce the number of cables which
must be run, reduce the complexity of the PTTI reference signal genera-
tion and distribution equipment and notify designers of future Navy
communications, navigation and weapons systems of exactly what reference
signals will be available on board Navy platforms and to design their
systems and equipments accordingly.
One area of greatest need is that of distribution equipment; i.e.,
a new frequency distribution amplifier and a "time" distribution
131
amplifier. The AM-2123/U Frequency Distribution Amplifier is a good,
reliable amplifier, but it is an old equipment. Modern technology
should be able to provide a distribution amplifier with Improved reli-
ability characteristics and capable of providing more output channels
in the same space as the AM-2123/U. Additionally, the Navy.currently
does not have an amplifier capable of distributing multiple timing
signals, i.e., both time codes and timing pulses, and the need for a
"time" distribution amplifier is increasing. Both units should be
capable of supplying the multiplicity of reference signals required
today, but also be capable ultimately of supplying the "standardized"
signals discussed previously.
A final projected need is for reliable PTTI equipment. The
"Standardized" PTTI PDS will be driving virtually all of the platform
communications, navigation and weapons systems. Loss of a reference
standard or failure of a switch could result in system outage or down-
time at a critical moment and thereby result in damage to the platform
or even a loss of life. Additionally, the Navy and the Nation's tax-
payers cannot afford unreliable equipment; e.g., a reference standard
which requires a tube replacement in excess of $10,000 approximately
every eighteen months. Reliable equipment is a must if the concept of
a "Standardized" PTTI PDS is going to or even should be accepted by the
Fleet.
In summary, the Navy's PTTI Program has formed a solid base with
the Requirements Analysis and the CNO approved Program Master Plan. It
has experienced some setbacks because of personnel shortages, missed
delivery schedules, etc. However, the Program is moving forward and
providing the Fleet with needed equipment and support.
Hopefully, the next two years will see even greater growth and
support both to the Fleet and from Navy sponsors, planners, programmers,
engineers, etc. Hopefully, the "Standardized" PTTI PDS Preliminary
Design and Life Cycle Cost Analysis will be complete and full scale
development of PDS's for candidate platforms will have been initiated.
The Navy PTTI Program office is working to make these hopes
become realities.
132
REFERENCES
1. Allen, Ralph T. , "A Review of the U.S. Navy's Precise Time and Time
Interval (PTTI) Program," Proceedings of the Tenth Annual Precise Time
and Tijne Interval (PTTI)_ Applications and Planning Meeting, NASA Tech-
nical Memorandum 80250, November 1978.
2, Witherspoon, Jackson T, and Schuchman, Leonard, "A Time Transfer
Unit for GPS," Proceedings of the Ninth Annual Precise-Time and Time
Interval CPTTI) Applications and Planning Meeting, NASA Technical Memo-
randum 78104 March 19.78.
133
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A U.S. Navy Precise Time and Time Interval (PTTI) program update

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