Sz

Make preliminary on-site measurements at several

Los Angeles and San Francisco area radar sites

to validate the accuracy of the predicted radar-
to-radar interference situations. This involved
waking video tape recordings of the PPI scope at

each radar site, and identifying the interferers

by using a pulse train separator or by their re-
spective bearing from the victim radar. A dis-
cussion of the measurement procedure and test plan

for the preliminary site visits is given in Appendix F.

Based on the preliminary site visits, make detailed
Measurements at two radar sites in each area (one

FAA ASR-X radar and one GCA radar site) using the

Radio Spectrum Measurement System (RSMS). A dis-
cussion of the measurement plan and RSMS van measure-
ment system is given in Appendices F and G, respectively.

Compare the data obtained from the detailed measure-
ment program with the various input component models
used to predict potential radar-to-radar interference
to determine the error introduced by each component
model, the deficiencies of the models and also
possible use of alternative models.

Make closed system measurements on two radars:

(1) ASR-5 analog radar, (2) ASR-7 digital radar.
The purpose of these measurements is to determine
the synchronous and non-synchronous pulse PPI MDS
level and the effects of the radar signal proces-
sing on the interfering signal.

Use the information obtained in steps 4 through 7
to assess the present potential radar-to-radar
interfererce electromagnetic environment in the
2.7-2.9 GHz band in the Los Angeles and San
Francisco areas.

Make a literature search to support the findings
resulting from the measurement program.

The findings and recommendations resulting from the Los
Angeles and San Francisco area measurement and model validation
study will be applied to develop engineering and management
aids, spectrum-space utilization methodologies, and frequency
assignment procedures for subsequent use in determining if
future planned deployments can be accommodated in the eight
designated congested areas. The results and findings of the
Phase II program related to these areas will be given in
subsequent reports.

=5


interference situation in the Los Angeles and
San Francisco areas.

The realization of these measurement objectives is
directly related to the future task objectives of:

1. Developing engineering and management aids to
assist the frequency manager in determining
the effect of placing future assignments in the
2.7 to 2.9 GHz band in areas where the environment
is already congested.

2. Determining if future radar deployments in the
Los Angeles and San Francisco areas (and the six
other designated congested areas) can be accommo-
dated using present band sharing criteria.

3. Developing a recommended methodology for determining
the spectrum-space utilization of the 2.7-2.9 GHz
band in the eight designated congested areas.

1.4 APPROACH

In order to accomplish the objectives related to the
measurement and model validation program in the Los Angeles
and San Francisco areas, the following approach was taken:

1. Assemble environmental information and pertinent
equipment characteristics on all radars within a 200
statute mile radius of the two locations. The environ-
mental information and pertinent equipment charac-—
teristics were obtained from the GMF, FAA Western
Region Frequency Coordinator and DOD Western Area
Frequency Coordinator.

2. Select input component models (e.g., emission
spectrum, antenna pattern satistics, propagation,
and Frequency-Dependent-Rejection, FDR) based on
the pertinent environmental information and equip-
ment characteristics.

3. Establish a degradation criteria, and use the
appropriate input component models and PPI simula-
tion model to predict potential radar-to-radar
interference situations in the 2.7-2.9 GHz band
in the Los Angeles and San Francisco areas.


Th

rT



SECTION 1

INTRODUCTION

1.1 GENERAL BACKGROUND

The Office of Telecommunications Policy in accordance
with Executive Order 11556 has tasked (Reference 1) the
Spectrum Management Support Division of the Office of Tele-
communications, U. S. Department of Commerce, to perform
a number of spectrum resource assessments (References 2-5).
The intent of these assessments is to provide a quantitative
understanding of potential problems in each frequency band
of concern as well as to identify options available to
spectrum managers for dealing with these problems. One of
the primary reasons for initiating these- assessments is to
ensure identification of problems during the early phases of
design and planning rather than after-the-fact, i.e., after
a system has been designed and hardware fabricated. By
making these band assessments early, necessary actions can
be taken to assure that appropriate communication channels
are established between agencies whose systems are in potential
conflict. This will enhance the early identification of
solutions which are mutually satisfactory to all parties
involved.

A multiphase approach to the solution of the 2.7 to
2.9 GHz Spectrum Resource Assessment task has been taken by OT.

Phase I: The first phase involves the identification of
systems existing in and planned for the band in question,
determination of available technical and operational data

for each system, identification of the potential interactions
between systems, and the generation of a plan that leads to
an overall assessment of the bands' potential congestion.

A Phase I report (Reference 6) for the 2.7-2.9 GHz Spectrum
Resource Assessment has been completed.

Phase II: The second phase encompasses a quantitative analyses
of potential interactions between existing and planned radar
systems in eight designated congested areas. A measurement

and model validation program, and radar processing circuitry
investigation of existing and planned radars will be under-
taken to assure that the Spectrum Resource Assessment will

be based on the best available technical procedure. Findings
from these investigations will be applied to assess the degree
of congestion and spectrum-space utilization in the eight
designated areas. Potential congested areas will be identified,


and alternatives for meeting the specified planned deployments
will be provided either singularly or in combination.

Additional Phases: These phases would be conducted as
required. Additional periodic assessments will take into
account new inputs such as design or other system changes.
They will continue until satisfactory solution to the problem
is obtained or until the point where sufficient decisions have
been made such that further assessment is unnecessary.

This report is the first in a series of Phase II reports
related to the Spectrum Resource Assessment of the 2.7-2.9
GHz band. The nature of the 2.7-2.9 GHz spectrum resource
problem requires that a rigorous measurement and model vali-
Cation study be made in typical congested areas in order to
accomplish the objectives of the task. This report contains
measurements made in the 2.7-2.9 GHz band in the Los Angeles
and San Francisco areas, and compares the measured data with
radar-to-radar interference prediction models. Subsequent
Phase II reports related to this Spectrum Resource Assessment
will include:

a. Preliminary Signal Processing Study
b. Investigation of Congested Areas and Band Efficiency
c. Phase II Summary Report

1.2 2.7-2.9 GHz BACKGROUND

During the period of August 1971 through April 1973,
the OTP/IRAC had under study the accommodation of DOD, FAA
and Commerce radar operations in the band 2.7-2.9 GHz. A
series of meetings were held between the agencies (Reference
7 and 8) to determine if the addition of new FAA air traffic
control radars to the band could be accommodated without
degrading their performance and what impact these radars
would have on the performance of the existing radars in the
band. An initial assessment of the problem (Reference 6)
determined that the addition of new radars to the band could
create a potential problem. To resolve the immediate problem
of accommodating the new FAA air traffic control radars, the
following actions were taken:

a. The band 3.5-3.7 GHz was reallocated to provide for
co-equal primary Government use by both the Aeronautical
Radionavigation and Radiolocation Services. A footnote
was appended to the allocation table, reading as follows:


Gii0 - Government ground-based stations in the
aeronautical radionavigation service may be authorized
between 3.5-3.7 GHz where accommodation in the 2.7-2.9
GHz beré is not technically and/or economically feasible.

Agencies were requested to cooperate to the maximum extent
practicable to ensure on an area-by-area, case-by-case basis
that the band 2.7-2.9 GHz is employed effectively.

b. The FAA has stated that they plan to develop their
new dual frequency radars in the 2.7-2.9 GHz band and their
“low cost" radars in the 3.5-3.7 GHz band. It is expected
that compatibility problems may develop in certain geographical
areas in the band 2.7-2.9 GHz as the FAA implements its new
radar program.

c. The Spectrum Planning Subcommittee was tasked to
develop a long-range plan for fixed radars with emphasis on
the 2.7-2.9 GHz and 3.5-3.7 GHz bands. The SPS plan (Reference
9) has been completed and approved by the IRAC and forwarded
to OT.

1.3 2.7-2.9 GHz OBJECTIVE

In order to promote effective use of the band, OT has
been tasked to determine the electromagnetic compatibility
of present and future radars planned for deployment in the
2.7-2.9 GHz band for the eight congested areas identified in
Reference 9. The Phase I report (Reference 6) identifies
the overall objectives of this task in detail. The first
part of the Phase II program encompassed a detailed measure-
ment and model validation study in the Los Angeles and San
Francisco areas. The objectives of this extensive measurement
program were to:

1. Determine the relative contribution of each
input component model (i.e., propagation,
emission spectrum, antenna pattern, and
Frequency-Dependent-Rejection, FDR) to the
total error in predicting radar-to-radar
interference.

2. Verify predicted interference situations
through on-site investigations to determine
the accuracy of present radar-to-radar inter-
ference prediction techniques.

3. Assess the present potential radar-to-radar