740 as ‘ea T a nition UNCLASSIFIED os om ‘dG TALUC S: £ Bf Ges As SE O/T} CLA; ~” } 7 AY ; rf apy at oY LD odiapy fn ROAR hes we e® ow”. gh ator a gh ae wo” Technical « , ee Report distributed by 2% Defense Technical Information Center DEFENSE LOGISTICS AGENCY Cameron Station e Alexandria, Virginia 22304-6145 UNCLASSIFIED NOTICE We are pleased to supply this document in response to your request. The acquisition of technical reports, notes, memorandums, etc., is an active, ongoing program at the Defense Technical Information Center (DTIC) that depends, in part, on the efforts and interests of users and contributors. Therefore, if you know of the existence of any significant reports, etc., that are not in the DTIC collection, we would appreciate receiving copies or infor- mation related to their sources and availability. The appropriate regulations are Department of Defense Directive 3200.12, DoD Scientific and Technical Information Program; Department of Defense Directive 5200.20, Distribution Statements on Technical Documents (amended by Secretary of Defense Memorandum, 18 Oct 1983, subject: Control of Unclassified Technology with Military Application); Military Standard (MIL-STD) 847-B, Format Requirements for Scientific and Technical Reports Prepared by or for the Department of Defense; Depart- ment of Defense 5200.1R, Information Security Program Regulation. Our Acquisition Section, DTIC-DDAB, will assist in resolving any questions you may have. Telephone numbers of that office are: (202)274-6847, 274-6874 or Autovon 284-6847, 284-6874. FEBRUARY 1984 % U.S. GPO: 1984—461-169/24007 TEST CHART s gies Daten Seen fa pelt ES es Gers Lm TT ee NOSC TR 677 4O1 a E AD ALO G E cory’ OTIC Fi Technical Report 677 AIRBORNE MAN-MADE RADIO NOISE ASSESSMENT T.N. Roy 15 April 1981 Final Report: March - December 1980 Prepared for Defense Communications Agency Naval Electrenic Systems Command Approved for pubtic release; distribution unlimited NAVAL OCEAN SYSTEMS CENTER SAN DIEGO, CALIFORNIA 92152 5.) Belief a SEEN 2 10 OG SNS GUE tm ts Carte £L£9 UL ISON CIGAR SGAM-AAM SnAOSriA ' JMAMS238eA 32104 i yor AT - f ——_ f | | 260% siya at ive! er SG0L t9dinessd ~ Weve 097 bon : iSaen® aollasinatama) 9719? 0 Pieramod satay’ airwviasts tev. 4 : y | ul bevagee? ; . Cetin note oedele) 2°0UQ CO PeeeQuA me . 3 ee = OU ere cy o aI Javan Seroe AY iA OOS sA2 See a AN ACTIVITY: OF THE NAVAL MATERIAL COMMARN-D Al Y ae NAVAL OCEAN SYSTEMS CENTER, SAN DIEGO. GA 92152 SL GUILLE, CAPT, USN HL BLOOD Commander Technica! Owector ; i ADMINISTRATIVE INFORMATION Work for this report was performed from March to December 1980, and was sponsored by the Naval Electronic Systems Conimand and the Defense Communications Agency — element 11402N, project X1083-SB, work unit 532-MP43. Reviewed by J.H. Richter, Head EM Propagation Division Under authority of J. D. Hightower, Head Environmental Sciences Department F Py , ; ; i‘4r= @ ite EM ephadnsld i! (Pinata Gnarly 7+ * HONE © v1 pet ate bac SAORD Walk Aaeve:Levtemserns aparece? “erenPOARE Meret sold WP Hlentetre SRL CS Hew dine APUG 4 tacts MLO) ingens eh 7 te J Progen ccbelll Ast) al ow: _ idle A vapreli coh AS A : bv ght oH on He ' vu — +4 ( soeayit (ul reagine jon neath pt fiegery sl ae | — 0 — i (rte reystl _UNCLASSIFIED___ SECURITY CLASSIFICATION OF THIS PAGE (Bren Data Entored} a aes 2p READ INSTRUCTIONS REPORT HUMBER 12 GOWT ACCESSION NO. PY RECIPIENT'S CATALOG HIUIMBER NOSE Technical Report 677 (TR677) / | An PLEO VAZEZ is ~etiile a a Tvgivor REPORT WEP COVERED A SOT Le ee eee ge Final’ 222 a v , AIRBORNE MAN-MADE RADIO NOISE ASSESSMENT, Maro& — Dedsaxver 1980" Kurt o - r wi % a ) erg 4 Bei Pease or evs memmnnrcemene ors oar TaN Hobe a THU ORT, REPORT] NUMBER B CONTRACT OR GRANT HUMBER/(®) 7. AUTHORS as) T.N. Roy etn fr. F is i 10, Lvs ae PROJECT, TASK AREA & WORTCUNIT NUMBERS 11402N,/X1083-SB_! 532MP43 j so ~ PERFORMING ORGANIZATION NAME AND ADORESS Navai Ocean Systems Center San Diego, CA 92152 11. CONTROLLING OFFICE NAME AND ADDRESS Defense Communications Agency Naval Electronic Systems Command 14 MONITORING AGENCY NAME 4& AOORESS(IE different from Controlling Office) 15. SECURITY CLASS. (of thie report) en a faa Unclassified 7 DECLASSIFICATION DOWNGRADING SCHEOULE . 16. DISTRIBUTION-STATEMENT fof wire epety : , j ie 4] \ 2 Py, aS ie, ree casita Nand DUN aN ci Ap area BN Bier go ay Sa) Tih UR CEI eG Se eres ces a es ap nates CB rene Ree j verde oe eae Approved for public release; distribution unlimited. ne ne aT 7. DISTRIBUTION STATEMENT (of the ebstract entered in Block 20, If different from Report) 18. SUPPLEMENTARY NOTES 9. KEY WORDS (Continue on reverse elde if necesoary and identify by block number) airborne man-made radio noise radio noise maps surface man-made radio noise : meteor burst communications 20. ABSTRACT (Continve on reveree elde If necessary and identify by dlock number) rai E An airborne man-made radio noise model has been developed and programmed on a graphics ‘ computer at the Naval Ocean Systems Center. This model provides a useful approximation to the f geographical dependence of airborne man-made radio noise in the continental United States. Radio 5 noise maps produced from this model are used to evaluate the effect of man-made radio noise on the E operation of meteor burst communication systems. & Equations developed by Skomal (E. N. Skomal, Man-Made Radio Noise, Van Nostrand Reinhold 3 Co., New York, 1978) are used to construct the model. Two parametric equations are used to model e the height gain of man-made radio noise as 2 function of distance, 0 to 150 miles, from the sourcee (Copt,) >} DD . ons) 1473 EviTion oF t Nov 68 1s OPSOLETE UNCLASSIFIED es S/N 0102-LF-O14- 6601 SECURITY CLASSIFICATION OF THIS PAGE inca Bare Frteroa Wes = be, BIg ey - 7 Wolly: mutiu weil. saagtya ta. 1 benparegeyA j : = > = ‘ : EE — ately cee ahh dinie fin inte eematinitiratiernmiomt nines vs Orin on ene We, a ine we Rett thew ste wis tg) Fede « 7 a ¢ ee items th Ses eens neaiiedien : ——— ae ry a wt - : APRA PEROT 4 Lew « Mlive cies shaun msn dares - : eetoe) Cibys these pony woslne | ee beeen @ineh ta a err eer arene er Sr oe ee o * Se OC sed peat aiilipaes 6 (Fe boerill Pabtchgi ae > oral Chie be qian oFtiey etaare sar seroetie nA & slp ihe ee Ladi tabs wre > ser eles do reyR Bee 3 tend 043 4 98) Os oth - > DUET Led pctllbe iy ett fe nl RAR ern sertudtie de sodawpeh fa Na+ yy 0 oily olkgre ti bo) 24 Phe 4% alien i oe lola ai ore beulbong ype nebo i by) © wihdpinisinenns Jesse! yapined 1a aottierea + aie} pits: 3 bohrt col dant 3D) taaerdE oh boy vob erAtaug? ws ‘sang ei ost phke® MAL Soe temee wt bers ore (ATO or eet aD 1 gry Gal of + Ay nlm) 4p ecine ribet then: « no day Tete set ee a ee ; " : Use SECM ME ont 82 avis §=EDBT yey , > Marea i HOG RIW-4, core » “ee ~ , TP. — ) ’ —— . —_ — _ ms es = ey _ — — i Tet ~ae de>! ea wwe voi 1 We B68 we ce toy) AN Pea #3 * ‘ 1 oo hee — ~ 9 Magne eo) > | eo — ___ UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (Bren Dete Entered) cE CR A 20. (Cont.) 2" "TL. Coefficients for these equations ere calculated from data measured over Seattle (W.E. Buehler and C.D. Lunden, IEEE Trans. Electromagnetic Compatibility, EMC, 143-152, 1966). Two hundred of the nation’s largest cities and 62 of the largest counties and military installa- tions are used as sources of radio noise in the computer program. Day and nighttime contours can be produced in the 25 to 75 MHz range for altitudes betwcen 30 and 70 thousand feet. fo, S/N 0102- LF- 014-6601 UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAG=(When Date Entered) Meehan ak Arde C AT IEE Ui ten wats eis ¢ ” - —) oo, a HEN Open Naan : f Y 2 A — A TT A OL LA I — = ve : Tit som, “et ove-ore 4) -taed Or _ = ES etm a 7 = —- - Tite ut teehee va wkd 9 al 3 ee eg PD a | ee te ete —es A» nes i i cl a a alli net andl SN cats asa SUMMARY An airborne man-made radio noise model has been developed and programmed on a graphics computer at the Naval Ocean Systems Center. This modsl provides a useful approximation to tha geographical dependence of airborne man-made radio noise in the continental Unite? States. Radio noise maps produced from this model are used to evaluate the effect of man-made radio noise on the operation of meteor burst communication systems. Equations developed by Skomal (EN Skomal, Man-Made Radio Noise, Van Nostrand Reinhold Co., New York, 1978) are vsed to construct the model. Two parametric equations are used to model the height gain of man-made radio noise ap a function of distance, 0 to 150 miles, from the source. Coefficients for these equations are calculated from data measured over Seattle (WE Buehler and CD Lunden, IEEE Trans. Electromagnetic Compatibility, EMC-8, 143-152, 1966). Two hundred of the nation's largest cities and 62 of the largest counties and military installations are used as sources of racio noise in the computer program. Day and nighttime contours can be produced in the 25 to 75 MHz range for altitudes between 30 and 70 thousand feet. fi ais i aioe af bg a Ae igh x 7» eu ee? ¢4" = wal y Srptiy een , ae eee san 7 nia Des nit : ' - , a ; vie 4 ri — & the ed INTRODUCTION J) 2. a); SURFACE MAN-MADE RADIO NOISE ,. . . ALRBORNE MAN-MADE RADIO NOISE CONTENTS aN MY Ot is at alee AIRBORNE MAN-MADE RADIO NOISE MODEL . 4.1 Vertical Profile ( 4.2 Horizontal Profile, ,....., 4.3 Contours. .... 4.4 Comparison of Model Predictions with CONCLUSIONS .... . REFERENCES. .... .~ are ema e teint’ EADY LSU SOE TU MMOECE NY DHE TM SC YD COCR a pa Ui Height Gein) . . 7 8 © © e@ © 8 © oy Recent Data va ° persegnen atucacaal — ) ol hy ee, ~ aad lb ots Q es. . rn vik gt Die gle age go aimee oe ys “ Stat Sokeee tats ashitvites’? Lebeh ta Wot - : of. ~ & » eplareta aan 6 * 1 & ~ wee 8 es he - * > _ = a a eee ree ree ¢ g AN a alae Nam EO eas a * - . f Le TENG 4 Aa ARRIETA Uy) ORT Oe eR ERLE: 7 1.0 ZINTRODOCTIOCN The assessment of airborne man-made radio noise began es an effort to more completely understand the factors influencing performance of Meteor Burst Communication Systems (MBCS). These systems are under investigation here at the Naval Ocean Systems Center (NOSC) to determ:ne their potential application to the Minimum Essential Emergency Communizetacn Network (MEECN) .! Operation of MBCS depends upon the reflection of ni (30-100 :Mz or more) radio signals from ionized meteor trails as shown ‘n ficure 7. ‘Tss*ing required to evaluate the performance of these systems invol.c. transmissi ~ and reception of vhf signals both on the ground and when airborne. Ext ""Ai terierence affecting the reception of these signals includes galactic 1%, local atmospheric noise, and man-made noise. Of the three types of .. “+ “)2nce encountered during airborne tests, man-made noise near metropolits!. a.* .3 was the most severe. The effect of this interference on a MBCS is to incrsase the system waiting time for transmission of an error-free message. The airborne MBCS experiments have shown that man-made radio noise can be measured at distances in excess of a hundred miles from large metropolitan areas. Noise was found to increase with altitude and the minimum noise level, galactic noise, was found only over open ocean. In general, the level of man- made radio noise was worse than expected and it was decided that an assessment of the characteristics of airborne man-made radio noise would be necessary to evaluate the utility of Meteor Burst Communication Systems. METEOR REGION 1200 MILES MAXIMUM Figure 1. Meteor Burst Communication System. 4 Bie ere ; op ea Th . Y a Oe Ne Be ci rte. & i= aac ied aro oA a AN a i dha fina h® rag i ae 6 = we adh ogre) ty 14 whe a 2 .. cr 7 sai ('>50/ 6 ad ton ime i Me eee was om mt are ww 8 ES ar cle Bo 4 ol DM a & abs Fe wer wepaseie etrieisy ie fe WS nok : older sheg-amm tu!) ne een =( mk omelet, iam epial wet etite (ovine +° piieeee a8 2 er eateeh axaicin ats he sbu2 Jie necorehi BY Bade wase Yo Seve! ais even ot Ribsc OSs HA MAAS hhwo? ja sed? bebivad ean 34: } Ota jad suit aod an ed bide ealan Get pl (sw wt seiodt.« to evi spereyh. coi fan lo) OD se 4 ; i OIA NOLI6Oirwermd sonJam ee ee ee as i ey — en '. 2 Ces ’ ‘ ad, © * = - > ™“% 1: Fu - “~—-* . = , be “2 t g An airborne man-made radio noisa model was developed and programmed on a graphics computer at NOSC to aid in the evaluation. Parametric equations developed by Skomal~ are used to model the height gain of man-made radiv noise as a function of distance from the source. Coefficients, for these equations are calculated from data measured over Seattle by Buehler and Lunden.? To provide a useful epproximation to the geographical dependence of airborne man- made radio noise in the continental United States, two hundred of the nation's largest cities and 62 of the largest counties and military installationg are used as sources of radio noise in the model. Radio noise maps are produced using this model and are used to evaluates the effect of man-made 1adio noise on the operation of MBCS. These maps show that very little of the continental United States is free of airborne man-made radio noise. Minimum noise levels are found during the night at lew altitudes for distances greater than 100 miles from most metropolitan areas. 2.0 SURFACE MAN-MADE RADIO NOISE Perhaps the first known case of Man-made interference to radio signals occurred in 1902 when Dr- A. Hoyt Taylor heard ignition noise from a two- cylinder automobile. Today, man-made radio noise extends to all continents and is detectable at subsynchronous satellite altitudes in the frequency range of 30 Hz to 7 GHz. Man-made radio noise is of three types: (1) incidental radiation from electric power lines, ignition systems, electric motors, home electrical ap- pliances; (2) intentional radiation such as wireless announcing systems, cam~ pus radio stations, walkie-talkies, door-opener transmitters, and licensed transmitters; and (3) unintentional radiation from cable TV systems, microwave ovens, industrial heaters, medical diathermy equipment, RF-stabilized arc welders, and many others. The lower portion of the spectrum is dominated by industrial, scientific and medical equipment, with power line and automobile ignition noise becoming major contributors around 30 MHz and ignition noise achieving a position of dominance at and above 100 MHz. Surface man-made radio noise has an impulsive distribution with frequency and approaches a thermalization (Gaussian distribution) with increasing alti- tude. This thermalization increases with increasing frequency also. Figure 2 shows median daytime values of surface man-made radio noise power in terms of Fa (dB above thermal ncise at 288°K) as a function of frequency for business, residential, rural and quiet rural areas. Business areas are defined as the Frequency (MHz) Business Arce Residenus! Arca [ Ruse! Area Wn OB ON wwe Re AOC Table 1. Upper, Due and lower Dpe Gecile values in dB of surface noise power variability within an hour at a given location. BOEING FIELD fo) au OO O2 O4 O6 O8 10 t2 14 ‘4 18 260 22 24 LOCAL TIME Figure 3. Diurnal variation of 73 MHz surface noise power measured at Boeing Field, Seattle for a workday and a Sunday (Buehler et al., 1968}. Prom the observed frequency dependence of surfaca man-made radio nolan Skomal* hag shown that the surface noise power function, P, (£,4), expressed in units of power, watts per bandwidth, displays an inverse dependence upon frequency, £, and distance, d. When #xpresaed in decibels relative to 1 mW per detection bandwidth, b, (dam/b) P, (f,d) = Ey + Ey (d-k) + Ey (6-k)?, a) where k is a constant which when set to 2.5 miles provides a good representa- tion of vhf and uhf wurface radio noise data. Coefficients Ey (Ey = a, + bf, 4 = 3, 2 and 3) in the above equation contain the frequency cependance of the surface noise power function and are determined from three conatrainta placed on the above equation at a specified treguency, f. 1. At the point d = G the derivative cf P with respect to d, aP a condition that has been observed to occur for composite urban man-made radio noise data. 2. At d = 2.5 miles the noise power function at frequency fn in MHz equals a leest-squares-regression line derived fror business zone data in dBm/b, P, = 789.9 - 12.3 log f£,, aad (3) 3- At d = 10 miles the noise power functicn at frequency f equals a4 least-squ res regression line derived from residential zone data in dBm/b, PL + -92.5 = 12.7 log €_. (4) b m Usiny these constraints to solve equation (1) for coefficients Ey; E> and Ey gives iy E, = Poe (5) pare Ba = 5 E3. and (6) : Ey = (Py - Pa)/93.75- (7) 5 ER ano rr renee ot hr suc ance pemansndbonnseay LT LT TLE LTE ET EE TIGL EEE ETS LEE OE IE TT I IO OT ICL ESTEE s po hoe vaca on + are 1B tee entrar) Youn Salen Yrs yin sbertivage w st anlsaiyeapeate mi J sae Slama tah ee ealiid * i: y | on an wi ie ve aS * welt ee P on on ei tS ray Wso 02 bev eat y ve 7 Py, R se wa sort 3 * gdh ropes! weeny, sadene oad see am A - : AA bevireh sala sithenetn a +i uy : . : <5 i ba £) Bem gt pot £6) = Gedb= + 8 a ‘an ; | Te ) # SSOEEN O° eOReRE Fe hoteoam? xery omhen off eulle o * 6 ne a - ew) Sieh #O04 felscetien ee eT oe a | 7 ne ie) tg! SOE FEF - €.80 “i ieee fimo - edo Meet Yass val én) a ssiegh @eies 7 Bnlertzce> vests pide? i nevi 7 - i dé; s + »3 ce i ; : had LO: ee | EE er enn ate rn aa myers SPepeniican Or sete Py. Calculation of surface noise power can now begin with selection of the fre- quency and the determinaticn of the three coefficients of equation (1). Sub- stitution of the coefficient values into equation (1) and setting x equal to 2.5 miles allows the calculation of surface noise power as a function of dis- tance. Figure 4 shows the surface noise power function, Poe in units of power, watts per bandwidth, graphed as a function of distance from the center of a business area for 30, 50 and 70 Miz. 2 | 38 MHz SURFACE RKOTSE POWER P, Seat el 56 MHz x19@714 78 HHz CWATTS/b) ) | eee! 15 18 s 8 bo) 18 15 DISTANCE (MiLlES)> Figure 4. Surface man-made radio noise power, in watts per bandwidth, calculated for 30, 50, and 70 MHz, and plotted as a function of distance from the center of a business area. 3.0 AIRSORNE MAN-MADE RADIO NOISE Airborne man-made radio noise measurements have been made abcve many American cities at various altitudes in the frequency range from 1 MHz to 1 GHz. Measurements using forward-directed an*ennas have detected man-made radic noise in excess of 200 miles from large cities. They indicate that air berne man-made radio noise from a distant metrcpolitan area can be detected once the aircraft rises above the local optical horizon. At high altitudes, above 70,000 feet, measurements made with a low-directivity antenna show a broad noise signature that is representative of the entire metropolitan area. Measurements mode veiow 10,000 feet with a high-directivity antenna show more detail of loca) nois2 sources: dive to the smaller surface area subtended by the antenns vattera. 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Patarseb at we, 030 eandoquried Acectelh # por) walte olbes ppeernhe ety , "Meatsns iatn, it 54. .noebsds iasteyp lqzel eft «vote posts NeswGhe BAD 'oaee 7 + wih 4leeqe qi) Oeegeews! @ Atle pie sireeesgeean toed 6605) evote ~- ‘ : stots Med igen ish eat Tn weksonemergw: oF todd erwsatoie eelod Beort ; ghey sc Maen y Tiel Sot t-velt «© ie goo) 500 OT welet stan esnenezoneet bead wi behadocie sone «vie 1b Reee otf @F at ) raion leoal Y9 Liateh “rveatag sameden Y Measurements over Seattle® using horizonta)ly and vertically polarized antennas indicate that airborne man-made radio noise does not have a predom inant polarization. When viewed from above, the radiation field propagating from a two-dimensional surface distrihution of independent noise sources should be unpolarized. Airborne measurements using downward-directed isotro- pic antennas do not show significantly greater radio noise than linearly polarized antennas. Calculation of man-made radio noise power, Py, at altitude h, depends upon the knowledge of: (1) the losses and pattern function of the measuring antenna; (2) the distribution of the man-made surface noise sources as a runc- tion of position and frequency; (3) transmission path losses; and (4) the degree cf correlation between noise sources of adjacent surface areas. Given the above information, p, may be represented as an integral, which in the general case, requires numerical evaluation. The degree of difficulty in evaluating the integral varies with the power pattern of the receiving antenna, the function representing the surface noise distribution and the surface area covered by the antenna pattern. For an isotropic antenna posi- tioned above the center of a symmetrical surface noise distribution, evalua- tion of the integral is much simpler. In addition, transmission path absorp- tion can be assured to be zero for frequencies less than 3 GHz and observation altitudes of less than 10 miles. j Correlation between man-made noise sources is not well known. Limited data suggest that for altitudes above a few thousand feet there is no correla- tion. This allows the treatment of man-made noise power from single sources as additive quantities. All man-made noise sources can be considered to be dis- tributed two-dimensionally on a plane that is parallel to and near the surface. Also, the noise power emission from any unit a.cea on the two-dimen- Sional distribution may ke assumed to be uniform. MThit assumption implies that the earth and physical surreundings are either good noise-absorbing or noige-scattering media vu. oth. Based on the above assumptions and limitations the integral representa- tion of airborne man-made noise power p, in watts per unit bandwidth b taken from reference 2 is p_(£-d) F(Y,,Y,) As shown in figure 5 the observing antenna is positioned above a business area at height h, with a separation R between the antenna and differential element aA containing the noise sources. A, is the antenna aperture area and F(Y;,Y2) is the normalized (to unity) power pattern of the receiving antenna in terms of angle variables (Yy.Y2)- When the airborne antenna is a dipole, its effective area becomes identi- cally equal to the area of antennas used for most surface noise measurements. The normalized power pattern may be written for a vertical dipole or moncpole antenna in terms of angle variables from figure 5 as: cos* im 1 siné) 5 FY, +¥2) i cos20 ‘ Se a nm ac RR RL TTR PTE NRT 7 STEN TE ES TS SRS ST STS (ajlal) eee atte ied avis a! ert0o eateries ow a) ovat: test trasyet? wet @ é¥ate eeheiete ed oy aan sire pet a -~ olgale a4) $960q eelor sbede~wen Ty foentead! pfs edlis 6% nel us ; #4 of bersbiesos 28 425 deomme saben wite-naw Fle cm?) Hany eater ’ : ot (W Laneg get? atalq 4 we Yidaoolwnmeii-cas ‘ a. : a HO Dee chew gi) euleeiow sews] weloe a12 cy!) ~oh kaye: abe clin ef os Bemreee ot yee mide! irtcth lotebe | Aeniinuorwe feoleude Tea Wvee ods dail? SS Ot oe ahem yd Ws seaa-—ead sell tne -ancleqeyage evede et! ©: aeeet ies en ie ee ee Ce ee *) ¢ © (uated aed te, ,709 {hy 3) she Se ee \ f* A & i SR eeie Sunde Aenaktioog ud annotms pelevende ets @ etegtt ai wecin od Tabsneetih Baa sinstos etd as~outed A nolsmiaqee © f4.4 (of Hipied = aos | Shetnea ats 2s sageeuee gaion wit g6ickedene Ay ni aoe tales oe be coreind “aieea \wiiqw og) bestiatzen ede wh P «lgtepY) eeldatuey signe to : disdehi etek S05> ByldGe}ie 7) jelegit W Wi AqeetRe erodils ont nadtw fetheret/nhea) Oaiya Ea Tiee Shoe we! Doan eaadetne 36 BodH Ot! 09 Serpe yliad : aijqgeees wo eloplt Tealtrer 2 i) aectéaw 8 Qe Atdey Yewoq bewllerson ett ? see € 22013 aust ebidaiaa® Blpne to wea? nt ennadun iOala « Ao‘ eso - 0 | = Tikaeg Nghe x Figure 5. Coordinate system for an airborne antenna, 0- located at an altitude, h, above a surface distribution of man-made radio noise sources. Substitution of the dipole antenna power pattern into the integral representa- tion of the airborne man-made noise power equation and further derivation for offset, business locations performed in reference 2 yield the following param- etric equations. For airborne man-made radio noise directly over a business area when the ratio of altitude, h, to distance, d, is small the limit of the integral is Py = Pg - A in (h/hQ). (10) In the limit of large h/d the integral approaches SULhTe P, = kh“. (11) As h approaches infinity Py reaches galactic noise as a limit. For airborne man-made radio noise offset from a business area in the altitude range of 0 < h S 7.5 miles, a second-order approximation of the inte- gra). is Ph = Pg + Bh - cH. (12) & sen tee obua els Wot nd MEE SS es tet ieee re aaa ia 1 . 5 0 inaeo ie aatediin th 14! cava planing ae 2) it Nie Sikl) $3806 Monies « eveda sil 4 SO YTi2TR na 20, Petasal «" TT ae a 7 eo7ge? ARIOn edhe, abee~cim 25 \ e Pepe. ys) leeink bcs oom eleqnade a sanene Biieibh eft Ip askance yy ATS Sees Seb Leer etd bein ABIES 29609 Galton HREM dared yin mis’ Yo nds Pease five (lot 419 blehy Sesh adete: oJ) Beeotyety anolse ial yeanicud ’ 4000 be , 7 sah Mavis Tiede RT rtoty. nk Tow] Gove YiagsElS selon oiisy seein etreisia 204 ek tas Ry o.t) 2d Sie) wre, Ede oi 7 ,eoaareTs “aI ‘in eh 3ttle ta otseu ‘or} esiteowgns iapesah gly b\ivencel Go ciMil add wf 4tee igo "tA : aa “ui 6 o5 °° 7 a2oateg madsen yo Wen tial aaiieosdae et RA ‘a OOS Gt AEA Bea to. & O22 la seta OfGhs woearnont smiodtia yak “OPeE ei SOW) Jb inlxe s+)» 2-ficoes » aie 2,0 > pkgs agiks straeste pi Tpke (st) ; J t n) Ad nee. me eres hs mec Novo ate is Asie SAI To use parametric equations (10), (11), and (12) for the calculation of airborne man-made radio noise power the values of integration constants A, hor k, B and C must be known. Calculation of these constants requires airborne man-made radio noise data for at least two different altitudes directly above and offset from a business area. 4.0 AIRBORNE MAN-HADE RADIO NOISE MODEL To evaluate how well the above parametric equations describe airborne man-made radio noise, a search te locate airborne man-made noise data as a function of altitude and distance from a metropolitan area was initiated. The goal was to find data with sufficient detail to allow construction of an air- borne man-made radio noise model valid for altitudes between 30 and 70 thou- sand feet and horizontal distances from the city center out to 300 miles in the frequency range of 30 to 70 MHz. It was felt that a model in this region would be most useful for a MBCS radio noise model. An extensive search located only a limited amount of data at frequencies and distances of interest. However, one set of contours was quite complete, showing vertical (0 to 100 thousand feet) and horizontal (0 to 100 miles) values of daytime 1 MHz airborne radio noise power measured and computed for the Seattle area.? These contours were replotted by Gierhart, Hubbard and Glen’ and noise power curves for 30 and 80 thousand foot altitudes were digitized to provide data for the airborne man-made radio noise model. At distances greater than 10 miles, the above curves were extended using the 1/R2 distance dependence exhibited by the near field data at low angles. To make use of this 1 MHz data for a radio noise model in the 30-70 MHz frequency range, it was assumed that the curves of reference 7, properly scaled, would be representative of the spatial distribution of man-made radio noise at higher frequencies. Additional Seattle data taken at three other frequencies of interest but at only one aititude and two different horizontal distances, were used te check this assumption.2/4"© Table 2 shows airborne vhf radio noise power data at an altitude of 5000 feet for frequencies of 29, 49, and 73 MHz compared to corresponding scaled data points from the complete set of data at 1 MHz. Distance (miles) Data (refs 2, 4, 6) Scaled 1 MHz data Factor Table 2. Comparison of radio noise power, F (d@B/kTb) as a function of frequency for distances of 0 and 16 miles. As can be seen, the scaled 1 MHz curve was found to fit the 29 to 73 MHz noise data at 5000 feet to within about 1 dB. It was assumed that scaled curves at the higher altitudea of 30 and 80 thousand fcet would also fit. The scaling factors shown at the bottom of table 2 are used in a Lagrange interpolation formula to scale the 1 MHz noise power data to any frequency in the range from 29 to 73 MHz. The Lagrange interpolation formula is 3 3 Sify et (ea (eee = 8 sy (13) i*x where S(f) is the desired scaling factor for frequency, £f, and fy are the three frequencies for which scaling factors, She have been calculated. Evaluation of the parametric equations using the NOSC computer and day- time radio noise power data at 30 thousand feet, pz), and 80 thousand feet, Pgor indicates that for horizontal distances of 0 to 7 miles and altitudes between 5 and 80 thousand feet the equation for noise power in watts per bandwidth, Py, = Ps - A ln (h/h,), (14) where A= (Pg — P39)/1n (h39/hga) (15) fe (p.-Pg9)/(Pg9-P30 Jin (h39/hgg) ) h, = hgg (16) gives gcod agreement to within a few dB of the scaled Seattle data. This is shown on the right side of the graph in figure 6 where the solid line repre- sents the model and crosses indicate Seattle data taken directly over the city and scaled from 1 MHz to 45 MHz. For horizontal distances of greater than 7 miles and altitudes from 5 to 80 thousand feet the equation for noise power in watts per bandwidth, Py = Pz + Bh - Ch’, (17) where B= (P39 - Pg)/h3q + Ch397 ure) and C= (Pg - Pg)/(h397hgg - ho?) - (P39 - Pg)/(h3q? - Hyohgo?) — 19) also gives good agreement to within a few dB of the scaled Seattle dats. This is shown on the left side of the graph in figure 6 where again the solid line represents the model and crosses indicate Seattle data taken 50 miles from the city and scaled from 1 MHz to 45 MHz. 10 DUST TERT TANT a BT 168 D = 30 MILES b= @ MILES 88 SCALED DATA + a MODEL - L T 68 I T U D 48 E é HEIGHT GAIN Fe (dB7kTb? Figure 6. Comparison of daytime 45 MHz man-made radio noise model (solid line) and scaled Seattle data (crosses) directly above and 50 miles froma business area. Height gain, F (dB/kTb), is plotted as a function of altitude in thousands of feet. The airborne man-made radio noise model has been programmed on a graphics computer at NOSC. A series of programs generate graphs of radio noise power in three different formats. In the first format, the vertical profile program produces height gain curves for any frequency and horizontal distance from the source that are selected in the range of the model. In the second format, the horizontal profile program produces radio noise power curves, for a selected frequency and altitude, as a function of horizontal dist e- In the last format, the contour program produces contours of co...ant radio noise power, for a selected frequency and altitude, for the continental United States. Each of the three types of model formats will be discussed in the following sections. 4.1 VERTICAL PROFILE (HEIGHT GAIN) This program produces height gain curves over the following ranges; fre- quencies from 30 to 70 MHz, distances from 0 to 300 miles from the source, altitudes from 1 to 90 thousand feet for business, residential and rural areas for day and nighttime conditions. To produce a vertical profile, the frequen- cy is selected first. This allows calculation of surface noise and galactic background roise values similar to those shown in figure 2. Once the hori- zontal distance is selected, the proper parametric equation is chosen. Equation (17) is used for distances of 7 miles or less and equation (20) is used for distances greater than 7 miles. Cosfficients are then calculated and scaled for the proper frequency as discussed in the previous section. If the vertical profile is to be evaluated at night, the calculated daytime radio ma - Freee Tw ee RRL eee —_ = ae) ~ (d7\e) 28 Midd THOLRH S010 GEBAY sheen HH co ontiysh Io soaizeqagd +8 oes =lioerts Pansies) 230d 917.408 bolase bas lanai bitce) tobow wep Atpsen ..cete esantayd «cos? eali@ OF Bee evade SbpeeIT? Fi stu tivia Yo noidaned «© os tasrola at , dtte\Gb! @ «#207 to WiAtgete 6 FO fetemeyorg pool ved [shen *elon Cfbet ebaeenee Oeeadada © /T Pe) WEP CAbRY Yo etary eJa7808p Sa7pO7g Wi aeiTee A ASEGH fe heap Mang @h18eig fenigiey of2 sect gett 20 al se yenTOS SpewweTIA eons) 32 on) ea! goptagesh fagnesisod bas Yoasepes? ye i) ee0de oigg Jip det ner -borsg WS , 0ST Greope os nt .fehce wf 46 *eret wd al begonier sxe ah4y » cube 'é3>8leq 4 eo? (80> yew] gelon clhas seoubory wig gig oli 50%¢ datnes tsar Shab ade Wl le e4sth Isdnordint Ys rolling? -s we ~theogisin bap ‘anagpet? Savey bere @IGAr Bap5. 09 Yo engotaen eeietuIgq meIPsIg Sunn eh deervo? O0ES32 SSPER Setardhiwss ot 70) thosisis tee yortbped) Bbesoeies 8 303 Pweticl wit Wi beséooeth af ffiw etecro? inboe ts aeyet aeziy e469 36 dont sand ize (4IAD THOLSN) BLU Gases 1.8 Wl) .ogpaer “pean e719 Geve verre: alias gteied eeouhoty a ‘erg ont Mee “di, srs) a¢fie GOL oF @ wor? agorageis <2 OF oF Of weed wee ere bee lating ige’ jeeentear! ied ses hieouvote 02 af ¢ aay? SIEs "ROCpet) Ady Ol ite ODI Sey w wouborg oT .anoltibagd Se: syeula ba yab ‘eo Liheligd 4Ab ativn yeti amigelvoinn awolla eld? dev’ » alee ‘a & “Reee AU) OO) oS Oregeee Be menite omats 63 weisnts galiler esto Bpbtyptond TARRY OL ei tea dy - aig isyosx, matt tedomtan a) >hadei féamed o2° UC) mi oe, » 4) Jo efits © ta as eat2sb 003 Rapp «| (FE esIre 38 Ged Barciieiie 5 rh SSIS 79 Shao aul ie ¥ aai- Pee ts v-.o84gED 409 teen AF T2 ola a3 + ah Beegeoedh an qoadagedt kuyos, ot) cos helace Othe: selsyeh 6,35 > 2 (200) 16 Chinwiave wl Gf as ellitaag Sesdssev PORE te arene reper aren reece mena a a noise power is reduced by the diurnal variation similar to that shown in figure 3. Finally, the classification of the area to be modeled is selected ana if residential or rural areas are selected, the calculated radio noise power is reduced from the business area value as shown in figure 2. Daytime 45 MHz vertical profiles at distances of 0, 8, 50 and 100 miles from the center of a business area are shown in figure 7. Altitude, in thousands of feet, is plotted on the vertical axis with the height gain, a6 plotted in aB/kTb along the horizontal axis. Note the increase in height gain at 4 distance of 50 miles from the business center. 168 p=100 .D#5Q D=Q D=B mocarosorD CkKFT> 10 20 3a” 48 HEIGHT GAIN Fa (d8~kTb? Figure 7. Daytime 45 MHz man-made radio noise model for distances of 0, 8, 50 and 100 miles from the center of a business area. Height gain (F_(dB/kTb), is plotted as a function of altitude in thousands of feet. 4.2 HORIZONTAL PROFILE This program produces horizontal profiles of airborne man-made radio ¢ noise from the city center out to 150 miles for altitudes from 1 to 90 thou- sand feet. Operation of the horizontal profile program is the same as the vertical profile program except the variable to be selected is the altitude at . which the horizontal profile is to be plotted. Figure 8 shows horizontal pro- files at altitudes of 10 and 80 thousand feet above a business area center during the daytime for 45 MHz. Antenna noise factor, Fa, in dB/kTb is plotted on the vertical axis and distance from the area center in miles is plottec along the horizontal axis. Note how the noise peak above the city widens with increasing altitude. ee EE EEE SNL IE ST SE SA ; Saas PES --~/ n Nie Ht tevk > = ini, i Ta fy ey lle a Wt he, ame a a Blan cule ‘arias, ty Mokena eta we Ad empath | se ona tan ow a ee Res I apd i ] y ce eee |e A 7. : — = 7 : iu (ati\Ge) 29 wWiag tholaW # te ates 1 vee ee ibn/eifins * Grea tiem zn, Oh ontted of g2apit nor, | ee arog Lat 32. Gylbe GO hee OF \H VO Ya amienseip : Och “rol ecg eer nkey Siglo sane Reenleod : ‘ - Se «Jan? Te ct Meets at rapdilw te aol sfocert 2029004 cAtHOLAON grt :** GIO WOeeHen _outediin Yn elites Andanebrol! esndbow aazpesd wat? 4 pL tas eer ny eae ores O40 aa) Jue Sbdase 4915 ont a3) eben GAT in PRR el? ay TN) at ey Selgeeigert “ety So HOl tec 6300) bnew 7 WU FIATa-Oil oi BrroWien At on “dati at dqenne misperg af} tosq ie Wf nGe ised. ee io 6 write besIels af OF al ali tond. lercoeteat ong fold a TOS OPER, CRB aeK 2 wend) ont Sern @ tas Of to evbotisie 24 an2)9 : oe <2 Ae) ented soitegal OM 2 207 wiry pabsub mite 44 Yise, ) > tween ot pepe) eonetalh bas eben Laatires ed? ao , RNMb Pagie YS hs str vente dog. tion ael-we Aaa mime Teton Tran ond Qnoda ee. @bud Ils eqtaap yous | 5 q | SS wveneranes < e be aanimeentinmen » a Space eS Sg ete NRT TEP RE ha ns testy tenn npmnnann 50 48 12 KFT ane [\ : ANTENKA sues 80 KFT 4 FACTOR | 20 Fa (dBskTo? 16 8 158 1e3 50 G) 58 130 158 DISTANCE FROM AREA CENTER (MILES? Figure 8. Daytime 45 MHz man-made radio noise model for altitudes of 10 and 80 thousand feet above 2 business area- Radio noise power, F (aB/kTb), is plotted as a function of distance in miles from the city center. 4.3 CONTOURS The airborne man-made radio noise model can produce contours of constant radio noise power using the contour computer program. phis program has been developed to provide a useful approximation to the geographical lJependence of airborne radio noise in the continental United States. Fadio noise maps produced by this program are used to evaluate the effect cf man-made radio noise on the operation of MBCS. Two hundred of the nation's largest cities and 62 of the largest counties and military installations are used as sources of man-made radio noise in the computer program.® Noise calculations are made for the sontinental United States on a rectangular grid with intervals every 50 miles. Contours are cal- culated from this grid of data for frequencies between 30 and 70 MHz at alti- tudes from 5 to 30 thousand ‘eet for day and nighttime conditicns. Figure 9 shows daytime 45 MHz contours for an altitude of 5 thousand feet. Contours of constant radio noise power in GB above kTb are plotted for values of 15, 20, and 25 dB. Shaded areas in the continental United States represent «reas containing noise power 3 dB or iess above galactic nois2.e At this altitude the 30 4B contours are too small to be resolved on a map >of this scale. 13 . a a a5 ei | ‘¢ “ROAUN; 43TH Kain Knows Juaterg io faba $210 ctecs sbae-rem SH ae amkouad 1B seopl4 sires mene * S¥Ods Jeol Dinaucite 06 bee O1 Ya vow izi« oe ee Weliola «) .(CRANEDD © seem) aetan elbaa : 12828") "Slo afe whey tellia ni sonateit » SS = 7 f Pies SBNIRTH Hoties Lasian)s ; a ' wis 84 BATpORg Gin? 9 " . Saks 54 bos Bellin Joworal whe *ta. tol > adirales ealow m= é o . Sha omer thes OA Hh 06924 Debaty OOO Rhy omits | eget es “@Veds" iat sa Bc Wes salon rhe 62) 1: eee Alen. * od s (enwttbboe « sete eae x60) ns Jeo? Eetahyods 69 04 2 ) SEGMOS Lae BUNT S\ Be where 1 2 BOTs rede @ el ewes @eten alhax mer Wit al egton OLBe: éntedt3e SOO GAs stduleve es 6 et Bepvteng +22N Yo MLAS IGo 243 mG shies - O'nOisad ait Bs Bexbaud ow 34 9>>/0n on Swed ote Snotons Spiant Posi iin beg 'O* Tenep Of. bra Painiataos Oo ditt coos wa *3000KO £6 Of addy pS OD Qo Figure 9. Daytime 45 MHz airborne man-made radio noise map of the continental United States for an altitude of 5 thousand feet. Shaded areas represent noise power 3 dB or less above galactic noise. In figure 10, daytime 45 MHz contours for a 10 thousand foot altitude are shown. Smaller shaded areas indicate increasing noise at large distances from business areas characteristic of the height gain illustrated earlier. The 30 a@B contours are still too small to be resolved. The effects of height gain are clearly shown in figure 11. Daytime 45 MHz contours for a 30 thousand foot altitude are shown on this map. Note the large 30 dB contours above the most populous areas of the country and the disappearance of shaded areas indicating low noise. Tae full effect of height gain is shown in figure 12. Daytime 45 MHz contours for an altitude 9f 70 thousand feet are shown. Notice that the 30 dB contours have expanded to cover a major portion of the eastern United States. Comparison of figures 13 ard 14 with the preceding two figures shows the diurnal variation of airborne radio noise. Nighttime 45 MH2 contours for 39 and 70 thousand foot altitudes are shown on these maps. Note the reappearance of shaded areas in the western United States indicating low noise. Figures 15 and 16 show the effect of frequency on airborne man-made radio noise. As can be seen, these daytime radio noise maps calculated for an altitude of 3¢ thou- sand feet show decreasiny radio noise with increasing frequency. 14 f sgt FTE STU aR RE EP RETO A EAT EE ROLL os WORE. ‘ BW Sbep om etocrte zi ft eel eet #8 ON anced beoltat Lagdonbinep peondind a mn trsaslgs1 aee7s babeds. sek rs geen etl ol paatay wate saat feevott 0! 4 wt ecvodndo ane Maiaye Ot esepld at Me Wlor yulecaiont sseniine wasge babade wiles |. MOVE). niay afeisd offs So SistiteioAtaic wets feec hat mevinaor od oF Shem pod ULb9 wee erelthes wh WOO AGM 28> eteyod, oft asegl) Al wos Giveet= one et ed7 204 sqael sd Be Gwolle ene ahudigla deny wets of! coe yisaubs ed 20. aaore wine Langer fae “a > Bian wOr pal tealtins wi eh rok a wrHets "2 swine af fiee Shpiet Go, zostte figs sat : - ee oi CHAIN are cee pneeveds OC Sc ebothete ae ye Wiwodaue ‘herbie & " Se anise soles 8 wevoO of Bebiaad awa famedacs oie ond & 7 bh. mG df2 (310 Bf bon 2. eetet 23 36 pcedzeqeot Of) a5 47), J ae “nei ot clhe) wpaedtle 36 POlaabyay Jenagii | SOTA» dequ tow ae waers - ) ose golys.3fe Joo] bisgoods OF Baa” af o Vinal 0 a gO ser ‘a . oeseee shits odd mi eeets Bepeda So @iv.d .4alon@ S04>'4 om ywoueepet? Ie Jootie eff vida Sf Bun . “yal 1 Yo paren WEGiwoli= oyis deine olbas atlfyeb weedy jneke od end TSPAMEMSYAL city eatoa cihaa poseeatoed eoila duet bras’ i Ck : B.: 1 \ ~. Figure 10. Daytime 45 MHz airborne man-made radio noise map of the continental United States for an altitude of 10 thousand feet. CONTOURS: Fe (dB/kTb) Figure 11. Daytime 45 MHz airborne man-made radio noise map of the continental United States for an altitude of 20 thousand feet. EEE REI Te ret eres ToT a ¢ Pt Ab og! : iced ; 7 wn. v ee Ly aa: a » ' 4 . Ly TL Selon olbe) sbam-nm anradsid 200 ZS cabo Ob wreply ' Qo «tw itile mm 302 esses? baetell degneaisnos of? to qae a 7 y » beat Baaewort? Of 1h meets. eie-cat scuxtzie £46 26 omloyet off eight We Geethzia ce 29) aete72 Dorji lesoenlsows ot To gas a A -d983 Basavods OF ' é. _ r p a : a. a) SX a ene ie nile CONTOURS: Fe Figure 12. Daytime 45 MHz airborne man-made radio noise map of the continental United States for an altitude of 70 thousand feet. CONTOURS: Fa (dB7kTb> | Figure 13. Nighttime 45 MHz airborne man-made radio noise map of the continental United States for an altitude of 30 theusand feet. 16 * . — > ae —— —_ ae ¢- “eats peal op , 328 4, i> \ AN a ~ : ; 322— i Se \Se a i | fae ) a2 A | ih ee ; \ S ins > ts Vi i ; 5 : é f pt ‘ bd — tA 4 ae 7 z%s vis fj o> 2 ene 6 a) i q -_ 4 % c an es) 3. | $38 4s Be - pe 4 on | es bye — a a | 9 iS £2 : } PS ; .* Lag ; cP : 3 "WIP a3) SS FE " + ae cys _ >. q an ee | ~~). ~ Le} . ‘ a Be: a | WE LS an te i ated! Vil Ts =” etre | anak 1 > o a. a at 7 oa ® 7. e :” Rage ae . Se es > “4 ‘ ‘ “ ri va, vit rs x) i ol ¥ a: r d 3 = : / ; rh i. z = - f & i2tlhe3* . " ‘ q P 4 > & 4, "a : ; selon SET ETT PTT As RLS WEE CREE RI Pe vation wn - teoneeteneneape cutie CONTOURS: Fa (dB7kTb) Figure t4. Nighttime 45 MHz airborne man-made radio noise map of the ccntinental United States for an altitude of 70 thousand feet. CCHTOURS: Fe (dB7kTb> Figure 15. Daytime 30 MHz airborne man-made radio noise map of the continental United States for an altitude of 30 thousand feet. 17 ie * ai ra tetireter of wae. ; * sa © Piesrues ecsodzie sit 23 acizsipin = -B) @ 4 RetEfE Ae 262 652042 basin’ iernakbings id Te! - ten Lansuonts tel Seige Gibes soee—nee eriedttis TH OF scl ayan 21 owplt Bo eBodbeiA 26% 20) cot572 betting lassalineo eth Gae a A : » foe? beaagartis OF Ly weer” . . aterm prs reierarvonneetnnieyiy renevea seen nacercn nl agape meee sr SS SL Abt al ialeabladeleADaNTeSRR ny RAW din) Uae or etiam aieanmenrnensssr naam mee sa eer bs enomcereaneeslnisthiiems vemierwntean nist Nie yany AMAR 0 sone Mb ~ edulianiunens nen shee-cer ernodsie a4 CF entoyia Sal | a _ rss . My “utisie mo 20t vetas2 GowsAl Tajsnanifnga wt Sa: iy -J99! beéseverds Cf ‘— A NTO! Q900TULGEIT JEON WO Melinda |ALS POSP aire teonq MIT) tales esab feetstat Yo Qoasepesk ety de afah Sesielag . 2 | - : Ye a8 ott S62 “egon ssdpi') mee cizes aos3 etek evisasiiaws 2 (25118 Sone : t ee0en: is *8/08 ofa: 2 s of) Loe ohySialé dolw geies wih alee-tee € “nM 7 /SEPSE Aehet WiBee 4)? Asie jnseworya at of Wht? | Geedia 04( Io doooks af : hasten S06 dum oi +> atdy2 "i sad € oid? al aweile ageh Dogh Jaco!’ ace 5 ns vata a ee lic wi 1avo Jgo @pite beolinini [eigede Sok see: PU cletas <1! whiw towie+ igen tg?) igaor L%) ay00 ryt" (95) obwsssts wal? eel Jase! - ee ee a 7. ts . fo0,* Ofeg Soo . 38 2 t< o00,¢ tae eodazur iv 660, tore wosen ih ; “7 € 000,& ‘rad ye e* —" sebtout alte ba sila on 2t ¢ stip — % bis «Jo Jfpiid ee en es arse nae a saan cL eM OUR ORIONERRRRY 408 Fl comer RS FSV ate “et ope tencinl ant Senate 5.0 CONCLUSIONS The airborne man~msde radio noise model is expected to be representative of almost all large cities, New York City being the only known exception. Existing data show that there appears to be a maximum density of man-inade noise sources, such as automobiles, in a metropolitan area. Continued growth shows a tendency to turn surrounding residential noise areas to business noise areas thus increasing the area classified as business. Al) noise sources used to produce the continental tinited States man-made radio noise maps are assumed to be business areas. The airborne radio noise model was developed to cover the frequency range of 30 to 79 MHz and altitudes from 30 to 80 thousand feet. However, the model shows good agreement with scaled Seatcle data for altitudes from 5 to &U thou- sand feet. Further verificaticn af the model must await the collection of data in the frequency range of interest for many different areas. An improve- ment to the model, as indicatea in the data of reference 3, would te the addition of ground conductivity along the propagation path. In addition, other modes of propagation besides line-of-sight should be considered. Examination of figures 9 through 16 showsthat very littie of the conti- nental United States is free from man-made radio noise during daytime. Because of the height vain, increasing the altitud up to 80 thousand feet does not significantly reduce the noise ievel. Changing frequency in the 30 to 70 MHz range has some effect, due mainly to a reductics in galactic noise at higher frequencies. It is recommended that to reduce the interference of man-made radio noise on the operation wf 4BCS reception of these signals be Carried out, as much as possible, at low altitudes, in rural areas, at. night and/or over large bodies of water of at least 100 m les diameter or more. 19 ~ sa Pic acta ihe teens na Cea bse op, 2 Hehe ciao oh 6.0 REFERENCES 1. Haxritage, JL, JE Bickel, CP Kugel, Meteor Burst Comrunication in Minimum Essential Emer. at, yy 3 | ie ji ic I her } UNCLASSIFIED PLEASE DO NOT RETURN THIS DOCUMENT TO DTIC EACH ACTIVITY IS RESPONSIBLE FOR DESTRUCTION OF THIS DOCUMENT ACCORDING TO APPLICABLE REGULATIONS. UNCLASSIFIED