and March AN/MPN-13. Interference from these radars was
caused by multipathing of the interfering signal through a
mountain range between the victim and interfering radars.
The interference from these radars was frequent and appeared
blurred on the PPI display due to the multipathing phenomena.
Measurements documenting the multipath phenomena were made
and are discussed in Appendix A. A more detailed discussion
of the interference at this site is given in Appendix E.

San Nicolas Is. AN/APS-20 - Predicted interferers for the
San Nicolas Is. AN/APS-20 radar were:

Radar Interferers Victim INR
Freq. (MHz) Freq. (MHz) {aB)
Santa Cruz Is.
AN/APS-20 2883 2882 59.8
Laguna Peak
AN/APS-20 2886 2882 33.6

Interference from the Santa Cruz and Laguna Peak AN/APS-20
radars was observed on the San Nicolas Is. AN/APS-20 PPI display.
The interference from the two radars covered most of the PPI
display as predicted. The AN/APS-20 radars are used at the
Point Mugu NAS as missile range surveillance radars and DOD

is able to perform their missions with heavy interference

on the PPI display.

Santa Cruz.Is. AN/APS-20 - Predicted interferers for the
Santa Cruz AN/APS-20 radar were:

Radar Interferers Victim INR
Freq. (MHz) Freq. (MHz) (aB)
San Nicolas Is.
AN/APS-20 2882 2883 57.8
Laguna Peak
AN/APS-20 2886 2883 60.8

Interference from the San Nicolas and Laguna Peak AN/APS-20
radars was observed on the Santa Cruz Is. AN/APS-20 PPI display.
The interference from the two radars covered most of the PPI
display as predicted.

Laguna Peak AN/APS-20 - Predicted interferers for the
Laguna Peak AN/APS-20 radar were:



*Ayoayzoedser mq aI TLW pUe Tear

a Be $F 6] 90t- | a oe Oe [ececHo | 0005 stae 06-Sda/nv | itd Oped wes | tc
rs vor” Fiat =oe) “wR oF ee | 90t- | a ee oz [worrs | O00 Sale 9-Saa7 NN WrIqae |e
osez oz-9 9% ce |sot- | ove | ov0z e* | sess | sze Tose 6T-Sah/KY aay spzespa | tz

cost} oc | st e's ot ze | got- Jszrz ott ec | e6ce | ose zoe ET-NGK/RY aay yorex | oz

seez] of | st feSzve ut ze | g0t- |az-e oott o | gass | ose giv ebzcey | 67

sort] o€ | st josey Bt ze | got- | zz Oott c | eee | ose L642 EToNaH/NY at

cast] of | st tT ze | got- |oz-z oott a | sess | ose C642 pT -Kax/Ny et
ot vor | or |eserz ot oc | ttt- | ort ue otc] test | oor 03sz 02-3a¥/N¥ veg wende7

98 doz | ot st oc | itt- | ort soe ove] Tesh | oor oz-sae/tv

| 00s oor or oc ttt oT 6st oz] Tess oot Of-Sds/XV

i
tt red st ole 6z re sot- Lexa oor tse cus
se oc ot 00k te wOt- 986s 009 008 PoNdo/Ne
ost oe | oz fag te | zor- | sez | oost s* | 9ass | 009 aogz pondo/n aE: 1t
fore) (14a) (sp) | (wep) (saa) | (8TM | gane (2k) a8
“aia STONY) “Lou NIYD ‘34371 did | ad agnL RINT AUALN ION DON aSVG/AL1> és
ai1g ea. hee “I “ERY SsrIon LNdiNo | XVGd CSNOISSV ' 3%

WGN SHUTAONVY SOT NI SUVGWY ZHD 6°7%-L°% dO SOILSIYALOWAVHO

GHONILNOD @-b dTavh



Aqtttqedes Aytsazeatq Aouenberzq ,

Staak 9-Sda/NV saowsy [20704 ITV 9b €O T2T vyaquel
T@ Te St

06‘9-Sda/NW auoN MeN |90T0d ITY Zt TZ O2T seTqoU osed
zy €2 SE

06‘9-Sda/NV @UON wen [0204 ITV TS ¥% OTT eunbey *3yW
ce @S Ze

84 A ZT-NdD/NY €T-NdW/NV vovtdey |eor04 ATW Te ve O2T dav biequepuen
ty Eb bE

LL Ra ZI-NdO/NY €T-NdW/NY eoetdey [eor0g ATV ve ST LTT dav YoreN
vo €S €f

LL Ad ZT-NdO/NV ET-NdW/NY soetdey |eox0g ATV zO €@ LIT adv ebx0a5
bS SE vE

BL Ka e-usy ¥-Ndo/NW soe Tdoy Kaen Sv et cit "SI WVI0N

. 8b Th ze obata ues

18 Ad x» 8-USV $-Ndo/NY sortdey Kaen SO S€ BIT |*SI ejUeWaTS URS
zo TO €€

9L Ka ation 0@-Sav/NW eAoUsy Kaen TS €0 61T yeog eunbey
82 90 bE

9L kd SUON 0%-SdV/NV eaouay Kaen 9S LE 6IT “SI ZnaD eRULS
Ov 6S £E

9L Kd * SUON 0%-Sav/NY Seaway Kaen 9T TE IT | “SI SETOOTN UPS
65 VI €€

9L Kd $-usv ouON ‘MON wd 00 Te OTT sbuyadg wred
00 6b te

oC ha = B=asv— SUSY Sse doy Wa 9T 86 BIT yoreg buot
60 6% Ef
adaLIONOT

ava uvawa uvava NOTLOV KONAOV /AQNLIIN'T aSVa/ALIO
GaNNVTd INasaud

b8 Ad AG WAY SAHTAONY SOT AHL NI SAONVHO LNSWNOUTAND GaNNWTd

S-b ATaVL

4-18


Aesol Preliminary Radar Site Measurements

The purpose of these measurements was to verify predicted
interference situations to the extent that the live environment
conditions and parameters used to predict the interference
existed. This set of measurements was not comprehensive with
the main objective to compare predicted interference with the
live environment conditions for 11 victim radar sites. These
measurements were made during normal operation of air traffic
control.

During the preliminary radar site measurements, the victim
radar's controls were set as follows:

MTI: ON
NORMAL: OFF
Stagger: OFF
Integrator: ON and OFF
Polarization: Circular

FAA radars in the Los Angeles area operate in the MTI
mode for full PPI scope range and with integrators on all
the time. However, the radar receivers are generally aligned
such that the integrator is used to enhance desired target
returns, and not to suppress interference. Measurements
made during the investigation show that radars with analog
integrators (ASR-4, 5 and 6) did not suppress interference.
However, the ASR-7 radar at Los Angeles International Airport,
with a digital integrator, significantly suppressed the
interference.

The following is a discussion of predicted and observed
interference. The predicted interferers for each victim are
listed in Table 4-4 with INR's > 10 dB.

Los Angeles ASR-4 - Predicted interferers for the Los
Angeles ASR-4 radar were:

Radar Interferers Victim INR
Freq. (MHz) Freg. (MHz) (dB)

San Pedro

AN/FPS-90 2835 2758 13.4

Los Angeles

ASR-7 2852 2758 21.6

Long Beach

ASR-5 2772 2758 12.3


ZHW 0S8Z-00L2 ebuey Huyuny, uoIzTUbeW vy
ZHW 0987-0SL7 obese, buyyezedo uorytubeH »
a ouenberg paubyssy
A e Aouenberq poubtssy
—» obury buyjeredo rzepey

oe"z soe oe Sle ore Jonanoda
| D1 56-Sda TUTH Orped ues + be
i+ LS Pi 9-saa eTrqued to
SUVCVE OLTNOVUL BOUOd UTV

Fal —>) €t-n Gav Yorn (14
44>) VI-Naw Gay e530 ét
—— | > €t-Nai aay woyrtON at
I} ar-> ¥T-Ndit dav brequepuen LT

SULA HOVOUddY 1UGLIOO Uolud ¥IV
= 0z-Sav Yeoq eunbey By
k——al—— >) Oc-sav TBI ent) eyuvg aT
let a/—t | 0z-Savy “SI SPTOOTN urs ¥I
te ry L-usw RoAh: FUOT et

NATO ay
i+ P=Ndo BOTTUCTY SOT tT
i ~Ndd “ST oueWeTO URS tt
i¢ p-Ndd ‘SI y320N ObsTa ues ot
t E @z00us'T 6
luda 10) ane
f q Fa TeNeI TH v
4 > adv spreaps 7
ry youed buoy 9
+ ¢ OFAeqUO 5
le >| o10L Ta \2
le ela yueqang £
(+ oF >} *3UT sepebuy soy t
+ Be > F-ISY FUY soyoouy SOT cE
SuvoWe DOMVITIS MOIUIN Vad "ON UVC

VaUN SITAONY SOT NI SUVGWY ZHD 6*°Z-L°% dO NOIGYWHOANI LNAWNOISSY AONANOAA

€-p IgV,


The airport surveillance radars are assigned to operate
in a 10 MHz band. These dual-channel radars usually operate
the "A" channel 1 or 2 MHz above the lower end of the 10 MHz
band, and "B" channel 1 or 2 MHz below the upper end. The
FAA standard procedure is to switch to alternate channels on
a 24-hour rotational basis. As a result of operating procedure,
both channels were analyzed separately for potential interference.

All the radars in the Los Angeles environment employ a
conventional tunable magnetron output tube with the exception of
radars 14, 15, 16 and 22 which employ fixed magnetron output
tubes. Table 4-3 shows the operational frequency range, and
the assigned frequency of the radars in the Los Angeles environ-
ment. Additional information on the magnetron tube employed in
each radar, and the magnetron tuning range is discussed in
Appendix B.

4.3 COMPARISON OF PREDICTED AND OBSERVED INTERFERENCE

The following is a comparison of the interference that
was observed during the 2.7-2.9 GHz spectrum resource assess-
ment measurement program in the Los Angeles area and predicted
interference. The Los Angeles area measurement plan consisted
of a two-phase investigation. The first phase involved pre-
liminary radar site measurements which consisted of on-site
verification of predicted interference. Potential interference
situations were identified by using the parametric information
listed in Table 4-2 and applying Equation 3-1. Table 4-4
shows predicted radar coupling situations where the calculated
INR was greater than 0 dB. Only worst case (minimum frequency
separation for dual channel radars) INR's are shown in the
table for coupling with or between FAA ASR radars. Actual
predicted interference situations are those cases listed in
Table 4-4, where the INR > 10 dB. For those cases where the INR
was greater than 10 dB, the PPI Simulation Program was run to
determine the form of the interference on the victim PPI scope.

The second phase involved detailed measurements using
the RSMS van instrumentation to determine why predicted
interference did not appear on the PPI display or why unpre-
dicted interference appeared on the PPI display. The detailed
measurements made are discussed in Appendices A through D.
Appendix E gives a detailed discussion of the predicted and
observed interference at two radar sites using the measured
data discussed in Appendices A through D to explain the
differences between predicted and observed interference.
ippendix F gives a general outline of the Los Angeles area
measurement plan, and Appendix G discusses the RSMS instru-
mentation used in the Los Angeles area radar measurements.


to assess potential congestion will be studied in detail in
a subsequent OT report.

4-19


8°0 O%-SdV/NV “SI znij BjuES st 06-Sd4d/NV TUFH O2peq URS ix
9°1Z y-NdO/NV sojtueTy soy ras 06-Sd4d/NV TTTH O1peqd ues ix4
6°Lt s-usv yoveg SuoT 9 06-Sd4/NV TUFH O4ped ues iz4
te 4 s-usv oyaequ9 s 06-Sda/NV TIFH Olped ues cz
€°6T L-asyv "Quy seTesuy soy z 06-Sd4/NV TUFH O2ped ves x4
6°67 yI-Ndh/NV dav 3anquepue, faq 9-Sda/NV epaquey wz
re yI-Ndh/NV Gav 231099 6T 06-Sd/NV gay Spaenpy Ae4
91% S-usVv aay Spaespz L 9-Sdi/N¥ @iv Spaespa At4
£E s-usv ofaequQ g €T-NdW/NV G4V YAR oz
7° 6T S-asv oFaeIup S ST-Ndk/NY gay voll0N eT
T'6z 9-Sda/NV eyaque) wz yT-Ndli/NV gav S20quepuey as
s8'os 07-SdV/NV *S] znaj ejues st O@-SdV/NV yveg eunsey] oT
9° Te O%-SdV/NV “SI SETOOTN ues 4T O7-SdV/NV yeeg eunse] ot
8° ve L-usyv nang 3Uyog et O0Z-SdV/NV yveg vunsey ot
8°0 06-Sda/NV TIFH O1peq ues x4 O%-SdV/NV “SI znip ejuRS st
SUNLVTONSWON BSV@/ALIO on BUNLVTONSRON BSV@/ALIO ae
UNI : uvavy uvava
YVOVYH SONSYSSAYSLNI YSASOSY  WILOIA

eqoTxoed Aepey buyszezrzejur oy yRTM HuttTdnop weequteW Tepey wWtzIOTA 70g UNT

penutquoD p-f A1dvi

oY


SECTION 4

LOS ANGELES AREA INVESTIGATION

4.1 INTRODUCTION

This section discusses the investigation and measurement
program conducted by OT in the Los Angeles area to assess the
capability and techniques used to predict radar-to-redar inter-
ference, and to make refinements to the prediction model. The
investigation was made during the period of February to July
1975 with measurements being conducted from May 26 to June 8, 1975.
The environment included all radar deployments in the 2.7 to
2.9 GHz band within 200 statute miles of Los Angeles. Included
in this section is a comparison between predicted and actual
observed interference at 11 radar sites visited in the Los Angeles
area, and environmental observations. A detailed comparison of
the measured data taken during the investigation with the various
component models used to predict radar-to-radar interference is
given in Appendices A through E.

4.2 ENVIRONMENT OF 2.7-2.9 GHz BAND

The environment for the Los Angeles area was determined
from three sources: 1) Western Area DOD Frequency Coordinator
(Reference 11), 2) Western Region FAA Frequency Manager (Refe-
rence 10), and 3) Government Master File (GMF). Comparison was
made of the environmental lists received from the three sources,
and differences resolved by contact with the area frequency
coordinators. It was determined that there are a total of 23
radars within a 200 mile radius of Los Angeles operating in the
2.7-2.9 GHz band. Table 4-1 lists the location, nomenclature,
and function of these radars. Figure 4-1 shows the location
of these radars on a Los Angeles area map. The equipment
characteristics of the radars are given in Table 4-2.

During this Los Angeles area investigation, the RSMS van
was used to verify the fréquency assignments obtained from
the area coordinators. Most of the radars in the area were
found to be operating within a few megahertz of their assigned
frequency, with the exception of the following radars:

Radar # Assigned Frequency Operating Frequency
Roe N I (MHz) (MHz)

14 (San Nicolas Is.) 2866 2882.5

15 (Santa Cruz Is.) 2871 2883.1

16 (Laguna Pk.) 2880 2886.8

4-1


San Pedro radar occurred when the Burbank radar was pointing
in the direction of a mountain range to the north and north-
east of Burbank. This tended to indicate that the San Pedro
signal was being reflected off the mountain range. Measure-
ments were made with the RSMS van to verify this multipath
phenomena and are discussed in Appendix D.

Ontario ASR-5 --Predicted interferers for the Ontario
ASR-5 were:

Radar Interferers Victim INR
Freq. (MHz) Freq. (MHz) (dB)

Norton

AN/MPN-13 2801 2810 12.5

San Pedro

AN/FPS-90 2835 2818 21.5

A few interfering strobes were identified from the Norton
AN/MPN-13 radar at approximately 66°, the bearing of the
Norton radar, when the Ontario ASR-5 was operating on the

low channel (2810 MHz). However, these strobes were infre-
guent and only occurred in a 2° sector. During these measure-
ments, the San Pedro AN/FPS-90 radar was not operating.
Therefore, potential interference from the AN/FPS-90 was not
verified during these measurements.

Long Beach ASR-5 - Predicted interferers for the Long
Beach ASR-5 were:

Radar Interferers Victim INR
Freq. (MHz) Freq. (MHz) (dB)

Los Angeles

ASR-4 2758 2772 10.3

El Toro ASR-5 2738 2772 14.8

San Pedro

AN/FPS-90 2835 2777 2et

Burbank ASR-6 2788 2777 11.8

Los Alamitos

AN/CPN-4 2801 2777 50.7

Identifiable interference from the Los Angeles ASR-4 and

El Toro ASR-5 radars was not observed on the PPI display while
the Long Beach radar was operating on the low channel. Inter-
ference from the San Pedro AN/FPS-90 was observed on both
radar channels. The interference from the San Pedro AN/FPS-90
would appear over 30° sectors randomly over the PPI display
and not always at the bearing of the height finder. These


There was no identifiable interference from the Long Beach
ASR-5 radar. However, interference was observed from the Los
Angeles ASR-7 and San Pedro AN/FPS-90 radars at their respec-
tive bearings from the Los Angeles ASR-4. Interference from
these two radars was infrequent and random, and was not
periodic as predicted. The interfering strobes from the ASR-7
were approximately 5° wide. The interfering strobes from

the AN/FPS-90 were 3° wide.

Los Angeles ASR-7 - Predicted interferers for the Los
Angeles ASR-7 were:

Radar Interferers Victim INR
Freq. (Miz) Freq. (MHz) (dB)

Los Angeles

ASR-4 2758 2852 21.9

San Pedro

AN/FPS-90 2835 2858 39.7

Santa Cruz Is.

AN/APS-20 2883 2858 12.4

Interference from the Los Angeles ASR-4 did appear on both
channels of the ASR-7 at approximately the bearing of the

Los Angeles ASR-4 radar. However, the interference was very
infrequent and random in nature. Measurements made with the
RSMS van indicate additional propagation loss due to building
attenuation and also shielding of the backlobes of the ASR-4
antenna pattern due to foreground clutter, may be factors which
contributed to the lack of predicted periodic interference.
Interference was also observed on both channels from the San
Pedro AN/FPS-90 radar. The interference was seen over sectors
of 30° to 180° indicating that the interference was occurring
when the height finder was nodding approximately in the direc-
tion of the Los Angeles ASR-7. Interference from the Santa
Cruz Is. AN/APS-20 was not observed during the measurement
period. It should also be noted that the ASR-7 is a digital
radar which has the capability of suppressing interference
when operating in the enhanced mode which is used 100% of the
time on this radar.

Burbank ASR-G6 - There were not any predicted interferers
for the Burbank radar with an INR greater than 10 dB. However,
frequent interference was observed from the San Pedro AN/FPS-90
radar (Predicted INR = -8.0 dB) when the Burbank radar was
operating on both the low channel (2888 MHz) and the high

channel (2893 MHz). The San Pedro radar is at a bearing of
182° from Burbank, but the interference was observed in a
sector of 330° to 180°. Most of the interference from the

4-11


8°09 OZ-Sa¥/NY weed wundey 9 0@-Sav/NV *s] zna9 eques st
BLS O@-SaV/NY ST SUTOITN UES cas 0%-Sav/NV ‘SI znaj ejuRs st
OEE 0z-SaV/NV ywog eunsey 9 0@-SdVv/NV *SI SBTOOTN ues oT
8765 0Z-SaV/NY *s] znz9 eques st 0@-SdV/NV +S] SETOOTN ues 9
8705 0Z-SaV/NY aeod Pundery ot £-asy nny qupog €1
TOI O@-SaV/NY *s] znag wiueg st t-usv NEN IFO £1
z°9% O6~S24/N¥ TUFH o2paq ues 4 y-Ndo/NV soayweTy so] zt
S°st S-asV yoveg Buoy 9 -Ndo/NV sozyueTy soy fas
s'0 S-usy ox0L Ta ¢ Susy AvUeI TH 8
eT 61-Sdhi'NV aay Spaenpy 1z S-asy aay spaenpy t
Tele 06-Sda/NV TTTH 04paq ues €% S-us¥ ypeag 8u0T 9
Los 9-NdO/NV sojzue[y soy ra s-asv yoeeg Bucy 9
8°yT sus o10L Ta oY S-usy yavag Suoy 9
ect 9-asv yurqang € s-usv yowag Buoy 9
£01 -usv *qU] seTesuy soy T S-usy weeg Buoy 9
s*lt 06-Sda/NV TUFH Oapag ues €z S-asv oyreqU9 s
zat ST-NaH/NV @ay wozI0N 8t S-usv oFaeaug s
t.t8 06-Sdd/NV TUFH O4peg ues 4 S-usv e101 1a ¥
£9 y-NdO/NV soqFWeTY So7 zt S-us¥ o10L TA »
ay s-usv yoveg Suoy 9 S-usv o10L Ta »
pr g-asv yueqang € S-usv o10L Ta 9
6°8T y-asv *2Ul seTesuy soy T s-asv o10L Td ¢
s‘8 9-NaO/NV SoIFWETY SOT ras 9-uS¥ yueqang €
Le S-usv yoeog Suoy 9 97uSv ueqing €
9°0 S-usv o10L Ta as 9-usV yueqang £
L°6t 06-Sdd/NV TTFH 0apaq ues & t-usv ‘aul seTesuy soy z
ras O@-SaV/NV “SI znxQ vques st L-usv ‘aul seTeduy soy z
6°Iz y-usy *qUl seToBuy soy T L7usy ‘aul seTesuy soy z
Paras $-usv youeg 8u07 9 y-usv ‘aul seT@suy soy T
976 Susy e101 Td ’ y-asv ‘aul seTeduy soy T
91% L-asv *QUl seTesuy soy z >-UBY *quy setasuy soy t
vet 06-Saa oapag ues €z y-asv *qUI seTesuy soy Tv
BUNLV TONSION SSVG/ALID ot BUNLVTONSWON SSVa/ALIO ou
UNI ~ uvavy uvava
YVdVY = SONSYASYALNI YAAIOSY —WILOIA

aqoTyord Tepey HuTrezzequT ey yRTM HutTdnop weoequtewW repey WTFOTA Og YNT

b-b ATAVL



£v9THO 20 9Lzxa ‘9aSs ESN Aew

Kyoayqoodsor ‘ng

aI

sxeppa usy vez,
Tak pure Te

iT oc it4 oSL°E cad ac tor- ste 0ST s 9ess 009 o8lt FeNdO/RY at |
See e? ee st ve 90T- sor’ oot te" gess oor G-ksy $j
ts 09 tt os tas 90T- Par 00k ete” 49355 cor S-8sy
0 se oe te 90T- ars orl cts |. 2eexa ocr $-e3l £
09 co [a4 oo lf Ed ve 9G1- oSL°S Gre tts" 4285S ous 45
$66 oo tr ost ts ve 90T- oS'L'% Océ ter 49855 009 Czee “use ojseaun | ¢
~Ol8t
vor oF tT oS ft ve guT= «SLT OBL cts" 49855 coo OFLe $-es¥
—08Lz
tee oo oT ost Ez} oe 90T- rar a Sct ete" 4985S oor S6Lt
saz
ott oF $t eS Ee 0 bt ci) wel’ i339 tts 9Lexa Sth 098z ese
poles ~056t
~bets
ott 09 cad o0°E st ve 90T- we ois tes" 4985S ost
Trac Tavy Tan) | sea) | (S%) | aaa | (aa
Siva TION] NIYD *g aI ad “até Sans | Wise
Zits % LALO} AI

* one]

Waa SHTHONVY SOT NI SuvdVd 2HD 6°@-L°2@ dO SOILSTYALOVAVHO

e-b alavh



Radar Interferers Victim INR

Freq. (MHz) Freq. (MHz) (dB)
Point Mugu
ASR-7 2862 2886 34.6
San Nicolas
AN/APS-20 2862 2886 31.6
Santa Cruz
AN/APS-20 2883 2886 50.8

Interference was observed from the three predicted interferers.
The interference from each of the predicted interferers covered
most of the PPI display as was predicted. The AN/APS-20 radars
at Point Mugu will be replaced, by March 1976, with the
AN/FPS-114 radar which operates in the 2890-3110 MHz band. The
AN/FPS-114 radars most likely will not be operating in the
2.7-2.9 GHz band.

Norton MPN-13 - Predicted interferers for the Norton AFB
AN/MPN-13 radar were:

Radar Interferers Victim INR

. Freq. (MHz) Freq. (MHz) (dB)
Ontario

ASR-5 2810 2800 19.4

Interference was observed from the Ontario ASR-5 radar. How-
ever, it was not at the bearing of the Ontario ASR-5 radar
(246.6°). The interference came in at bearings from between
285° to 10° magnetic. It was not determined whether the
interference randomly coupled in through the Norton AN/MPN-13
antenna backlobe from the Ontario ASR-5 mainbeam or was being
coupled in by reflections off the San Bernadino Mountains.
One factor which may have contributed to unpredicted random
interference is that the Norton AN/MPN-13 antenna has a tilt
angle of 4.25° which was assigned by the FAA. This increase
in antenna tilt angle will cause about 3 dB decrease in main-
beam gain.

San Pedro AN/FPS-90 - Predicted interferers for the San
Pedro AN/FPS-90 radar were:

Radar Interferers Victim INR

Freg. (MHz) Freq. (MHz) (dB)

Los Angeles ASR-7 2852 2835 £953

Long Beach ASR-5 7s By he § 2835 17.9
Los Alamitos

AN/CPN-4 2801 2835 21.6


conducted by ECAC at Calspan (Reference 15) and FAA at NAFEC
(Reference 16). An informal working group consisting of OT,
ECAC and the FAA has been established for this task. The

fact that 10 of 11 radar sites visited had some form of
interference on the PPI display indicates that potential con-
gestion does exist. Considering all factors, it appears that
frequency assignments for the 2.7-2.9 GHz band radars deployed
in the Los Angeles area at the time of the investigation are
engineered to the extent possible to provide satisfactory air
traffic control operating conditions.

Information on planned deployment changes in the 2.7 to
2.9 GHz band in the Los Angeles area was obtained from the
various government agencies (References 48 through 50), and is
given in Table 4-5. The AN/APS-20 radars used as range
clearance radars are planned for removal by March 1976. These
range clearance radars are planned to be replaced by AN/FPS-114
radars which operate in the 2890-3100 MHz band, and most likely
will not operate close to the 2.7-2.9 GHz band. There are
three radars planned for replacement by AN/GPN-12 radars which
are identical to an ASR-7. Also, there are three radars
scheduled to be replaced by ASR-8 radars which have a dual
frequency diversity capability. The ASR-5 radar planned for
replacement at Long Beach by an ASR-8 will be relocated at
Palm Springs. ‘The height finding radars (AN/FPS-6, 90),
planned for deployment in the area at Mt. Laguna and Paso Robles,
are scheduled to be part of the joint FAA/DOD surveillance
system. The height finding radar at Cambria is planned to
be phased out once the joint FAA/DOD surveillance system be-
comes operational.

The FAA has indicated that due to ducting problems from
the Miramar radar, the lower portion of the band cannot be
utilized in the Los Angeles area. When assigning frequencies
to the new dual frequency diversity radars (ASR-8) planned
as replacement units at San Clemente Island and North Island,
the ducting phenomena will also have to be taken into con-
sideration. Another factor required for consideration in
making frequency assignments is the reported decrease in con-
ventional magnetron tube lifetime when the radars operate at
the band edges of the 2.7-2.9 GHz band.

Taking into consideration the above frequency assignment
factors needed to be considered, the information obtained during
the measurement program, and the known planned environment
changes listed in Table 4-5, it is apparent that a detailed
Spectrum Resource Assessment of the 2.7 to 2.9 GHz band in the
Los Angeles area is required. Accommodation of these planned
depleyments in the 2.7 to 2.9 GHz band in the Los Angeles area


WHuW SH TAONY SOT AHL NI GNV& 2HD 6°7-L°2 AHL NI SYWdWY dO NOILWOO' tiny wdvid

000911 00 od II 00 Bil 00 61I 00 021 ,00 let
£ ,00 o€€
e
Ble
00 obE
82 §
6l¢
2i¢
Le
.
Te 00 oS€
00 o9&
6% °



TABLE 4-1

LOCATION OF 2.7-2.9 GHz RADARS
IN LOS ANGELES AREA

RADAR
NO. CITY/BASE NOMENCLATURE LATITUDE: LONGITUDE:
Present FAA Airport Surveillance Radars
1 Los Angeles Int. ASR-4 33 57 12 118 24 00
2 Los Angeles Int. ASR-7 oo oo 67 118 24 23
3 Burbank ASR-6 34 12 15 118 21 14
4 El Toro* ASR-5 33 39 46 117° 42 «43
5 Ontario ASR-5 34 03 15 117° (35 «41
6 Long Beach ASR-5 33 49 09 118 08 416
2 Edwards AFB** ASR-5 34 52 22 117 54 «38
8 Miramar *** ASR-5 32 52 29 117° 08 «23
Present Navy Ground Control Approach Radars
9 Lemoore ASR-5 36 20 44 119 54 18
10 San Diego North Is. CPN-4 32 41 48 117, («12 «445
11 San Clemente Is. CPN-4 33 O01 02 118 35 05
12 Los Alamitos CPN-4 33 47 «#417 118 02 57
Present Navy Range Clearance Radars
13 Point Mugu ASR-7 34 07 06 119 07 25
14 San Nicolas Is. APS-20 33 14 57 119 31 16
15 Santa Cruz Is. APS-20 33 59 40 It9) 37. 56
16 Laguna Peak APS-20 34 06 28 19 03 «51
Present A.F. GCA Radars
17 Vandenberg AFB MPN-14 34 43 42 120 34 31
18 Norton AFB MPN-13 34 05 45 117. («14 «#12
19 George AFB MPN-14 34 35 54 117° 23 02
20 March AFB MPN-13 33 53 04 117° (#415 #34
Present A.F. Tracking Radars
21 Edwards AFB MPS-19 34 56 43 117 «54 45
Present A.F. Height Finding Radars
22 Cambria FPS-6 35 31 21 121 03 46
23 San Pedro Hill FPS-90 33 44 48 118 20 09

*¥Joint FAA-MC use
**Joint FAA-AF use
***Joint FAA-N use


30° sectors of interference were most likely occurring when
the height finder was nodding in the direction of Long Beach.
Interference from the Burbank ASR-6 was also observed at the
bearing of the Burbank radar (319°) on both radar channels.
The interference from the Burbank radar appeared on the PPI
display approximately 1 out of 5 scans and covered approxi-
mately a 3° sector. Interference from Los Alamitos AN/CPN-4
radar was only observed on the Long Beach high channel and
was infrequent. When the interference was observed, it
appeared over a 10° sector. Interference to the Long Beach
radar is discussed in more detail in Appendix E.

El Toro ASR-5 - Predicted interferers for the El Toro
ASR-5 were:

Radar Interferers Victim INR
Freq. (MHz) Freq. (MHz) (dB)
Los Angeles
ASR-4 2752 2738 18.9
Los Alamitos
AN/CPN-4 2801 2738 14.8
San Pedro
AN/FPS-90 2835 2738 11.2

The El Toro PPI display was observed for one hour during which
there was no observed interference.

Los Alamitos AN/CPN-4 - Predicted interferers for the
Los Alamitos AN/CPN-4 were:

Radar Interferers Victim INR
_ Freq. (Miz) Freq. (MHz) (aB)
San Pedro

AN/FPS-90 2835 2801 2555
Long Beach

ASR-5 2077 2801 26.2

Interference was observed from the San Pedro AN/FPS-90. When
the height finder was not nodding in the direction of Los
Alamitos, the interference from the San Pedro AN/FPS-90 radar
covered approximately a 5° sector. When the height finder

was nodding in the direction of Los Alamitos, the interference
covered approximately 3/4 of the PPI display. The interference
from the San Pedro radar was of a periodic nature. During the
measurements at Los Alamitos, interference from the Long Beach
ASR-5 was not identified. However, interference was identified
from three unpredicted radars: Ontario ASR-5, Norton AN/MPN-13,


The AN/FPS-90 only has a dicke fix operating mode. Interference
was observed from the Los Angeles ASR-7 when the height finder
is nodding at bearings of 320°-345°. ‘The interference appears
on each nod at low elevation angles of the radar antenna.
Interference from the Long Beach ASR-5 was not positively
identified on the RHI display. However, an unidentified
interference source was observed on one occasion. The pre-
liminary site visit to the AN/FPS-90 was made on a Saturday
when the Los Alamitos AN/CPN-4 radar is normally shut down.
Therefore, potential interference from the Los Alamitos
AN/CPN-4 could not be verified.

4.3.2 Summary of Observed and Predicted Interference

For the 11 radar sites visited during the preliminary
radar site measurements, there were 27 predicted interference
cases of mainbeam-to-backlobe coupling. The total number of
actual observed interference cases during the preliminary site
visits was 21. Of the 21 observed cases, there were 17 pre-
dicted and 4 unpredicted. Therefore, 63 percent of the pre-
dicted interferers were observed on the victim PPI display,
and 19% of the observed interferers were unpredicted. The 4
unpredicted cases were due to multipath phenomena. Most of
the predicted interference cases that were observed were not
of the periodic nature that was predicted. Therefore, in
general, most of the predicted interference was pessimistic
when compared to the actually observed interference.

it was estimated that in most cases the predicted inter-
fering signal power levels were approximately 10 to 20 dB too
high. The difference between predicted and actual interference
signal power level can be generally attributed to the statis-
tical nature and bias associated with the antenna and propa-
gation related variables not included in the models. Based on
measurements made during the Los Angeles investigation and
information obtained from a literature search, empirical
modifications to the antenna and propagation model were made
and incorporated in the interference prediction technique used
in the San Francisco investigation. These empirical correction
factors to the models are discussed in detail in Section 5 and
Appendices A, B and D.

4.4 ENVIRONMENTAL OBSERVATIONS

It is difficult to make a quantitative assessment of the
Gegree of congestion in the Los Angeles area without the
esteblishment of controller performance-keyed PPI degradation
criteria. PPI degradation test programs are currently being

4-16