o o o o Magnetostatic Wave Channelizer (MSWC) Evaluation Naval Research Laboratory CD " CD CD NRL/MR/ February 22, 1999

Transcription

1 Naval Research Labratry Washingtn, DC NRL/MR/ Magnetstatic Wave Channelizer (MSWC) Evaluatin BRIANS. KRANTZ ANTHONY E. SPEZIO STACY L. FARGO EW Supprt Measures Branch Tactical Electrnic Warfare Divisin February 22, 1999 CD " CD CD 10 Apprved fr public release; distributin unlimited. a-tlc QUALITY D?S?! TED 1

2 REPORT DOCUMENTATION PAGE Frm Apprved OMB N Public reprting burden fr this cllectin f infrmatin is estimated t average 1 hur per respnse, including the time fr reviewing instructins, searching existing data surces, gathering and maintaining the data needed, and cmpleting and reviewing the cllectin f infrmatin. Send cmments regarding this burden estimate r any ther aspect f this cllectin f infrmatin including suggestins fr reducing this burden, t Washingtn Headquarters Services, Directrate fr Infrmatin Operatins and Reprts, 1215 Jeffersn Davis Highway, Suite 1204, Arlingtn, VA , and t the Office f Management and Budget. Paperwrk Reductin Prject ( ), Washingtn, DC AGENCY USE ONLY {Leave Blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED February 22, 1999 Final Reprt 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Magnetstatic Wave Channelizer (MSWC) Evaluatin 6. AUTHOR(S) Brian Krantz, Anthny E. Spezi, and Stacy L. Farg 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Research Labratry. Washingtn, DC SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER NRL/MR/ SPONSORING/MONITORING AGENCY REPORT NUMBER 11. SUPPLEMENTARY NOTES 12a. DISTRIBUTION/AVAILABILITY STATEMENT Apprved fr public release; distributin unlimited. 12b. DISTRIBUTION CODE A 13. ABSTRACT {Maximum 200 wrds) This reprt describes the test and evaluatin f the Magnetstatic Wave Channelizer (MSWC). The MSWC was develped fr Electrnic Warfare (EW) systems and applicatins. The mtivatin fr MSWC resulted frm a need fr wide instantaneus bandwidth and large dynamic range. Varius perfrmance parameters f the device were evaluated, including bandwidth, sensitivity, dynamic range, and the selectivity bandwidth. Other MSWC characteristics measured were tw tne intermdulatin, blcking, desensitizatin, and simultaneus emitters. 14. SUBJECT TERMS Magnetstatic Electrnic Warfare (EW) Channelizer 15. NUMBER OF PAGES PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT 18. SECURITY CLASSIFICATION OF THIS PAGE 19. SECURITY CLASSIFICATION OF ABSTRACT 20. LIMITATION OF ABSTRACT UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED UL NSN Standard Frm 298 (Rev. 2-89) Prescribed by ANSI Std

3 CONTENTS 1. INTRODUCTION Develpment Mtivatin Develpment Accmplishments Perfrmance Summary Equipment Evaluatin Summary Evaluatin Reprt Summary 3 2. SUMMARY OF TEST RESULTS Perfrmance Characteristics Sensitivity Characteristics Dynamic Range Characteristics Pulse Rate Characteristics Tw-Tne Intermdulatin Characteristics Tw-Tne Frequency Reslutin Characteristics Blcking Characteristics Desensitizatin Characteristics Reslutin Characteristics CW Emitter Detectin Characteristics 7 3. EQUIPMENT DESCRIPTION Equipment Layut : Receiver Architecture Receiver Functinal Descriptin Evaluatin Equipment Functinal Descriptin 9 4. TEST ANALYSIS Sensitivity Test (Includes Infrmatin fr Frequency Accuracy Test) RF Pwer Test Pulse Rate Capability Test Tw-Tne Intermdulatin Test Tw-Tne Frequency Reslutin Test Blcking Test Desensitizatin Test Simultaneus Emitter Test CW Emitter Test CHARACTERIZATION TEST PLAN Test Prgram Sensitivity Test RF Pwer Test Frequency Accuracy Test System/Channel Bandwidth Test Pulse Rate Capability Test Tw-Tne Frequency Reslutin Test Tw-Tne Intermdulatin Prducts Test Blcking Test Desensitizatin Test Simultaneus Emitter Test CW Emitter Test CONCLUSIONS AND RECOMMENDATIONS 40 iii

4 FIGURES Fig. 1 MSWC Equipment 2 Fig. 2 Sensitivity Pwer Level vs Applied Frequency and Channel Number 4 Fig. 3 MSWC Transfer Characteristic and Interchannel Unifrmity 5 Fig. 4 Pwer Level vs Fixed Signal Frequency as determined frm Tw-Tne Frequency Reslutin Test Data. 6 Fig. 5 MSW Channelizer Equipment 8 Fig. 6 MSWC Receiver Blck Diagram. 8 Fig. 7 Channel Number vs Frequency H Fig. 8 Sensitivity vs Frequency 12 Fig. 9 MSWC Threshld Perfrmance 13 Fig. 10 MSWC Transfer Characteristic and Interchannel Unifrmity 13 Fig. 11 POIvs Pulse Width at GHz 15 Fig. 12 POI vs Pulse Width at GHz 15 Fig. 13 POI vs Pulse Width at GHz Fig. 14 Tw-Tne Frequency Reslutin Test Data 17 Fig. 15 POI vs Interfering Signal Delay 18 Fig Signal Frequency Desensitizatin Test 19 Fig. 17 CW Emitter with Pulsed Emitter Interference 21 Fig. 18 Test Diagram with One Pulsed and One RF generatr 23 Fig. 19 Sensitivity Test Flw Diagram 25 Fig. 20 RF Pwer Test Flw Diagram 27 Fig. 21 Pulse Räte Capability Test Flw Diagram 29 Fig. 22 Test Diagram with ne Pulse Generatr and Tw RF Generatrs 30 Fig. 23 Tw-Tne Frequency Reslutin Test Flw Diagram 31 Fig. 24 Tw-Tne Intermdulatin Prducts Flw Diagram 33 Fig. 25 Test Diagram with Tw Pulse Generatrs and Tw RF Generatrs 34 Fig. 26 Blcking Test Flw Diagram 35 Fig. 27 Desensitizatin Test Flw Diagram 37 Fig. 28 Simultaneus Emitters Test Flw Diagram 39 Fig. 29 CW Emitter Test Flw Diagram 40 TABLES Table 1 Summary f MSWC Perfrmance 1 Table 2 Perfrmance Characteristics f the MSWC 3 Table 3 Simultaneus Emitters 20 Table 4 Tests t be Perfrmed 22 Table 5 PTGS Parameter Summary and Test Equipment 23 Table 6 Sensitivity Test Emitter 24 Table 7 Pulse Rate Capability (PRC) Emitter Parameters 28 Table 8 PRC Test Scenari 28 Table 9 Tw-Tne Frequency Reslutin 34 Table 10 Blcking Test Emitters 36 Table 11 Desensitizatin Emitter Parameters 37 Table 12 Simultaneus Emitter Scenari, Bursts = IV

5 MAGNETOSTATIC WAVE CHANNELIZER (MSWC) EVALUATION 1. INTRODUCTION The Magnetstatic Wave Channelizer (MSWC) was develped under ONR spnsrship t evaluate the feasibility f using magnetstatic technlgy fr channelizer applicatins. The Naval Research Labratry (NRL) prvided technical supprt fr develpment f the MSW Channelizer with the Electrnics Science and Technlgy Divisin perfrming develpment functins and the Tactical Electrnic Warfare Divisin (TEWD) prviding perfrmance requirements as well as Channelizer Test and Evaluatin (T&E). The MSW Channelizer develpment spanned 1989 thrugh 1994 and the T&E phase was cmpleted in Develpment Mtivatin NRL's interest in MSWC technlgy was a respnse t the need fr wide instantaneus bandwidth and large dynamic range in EW systems. Electrmagnetic envirnment signals frm many surces ccupy a large spectral range, and EW systems require rapid signal detectin. Therefre, the wide bandwidth feature f the MSWC cnstitutes a valuable signal prcessing ptential. Als, EW systems require signal detectin and explitatin in envirnments in which lw level threat signals are in range with higher level nearby signals. Apprpriately, the MSWC high dynamic range characteristic ffers the ability t detect weaker signals as well as simultaneusly transmitted mre pwerful signals. Finally, the MSWC is smaller, lighter, and uses less pwer than currently deplyed channelizers. 1.2 Develpment Accmplishments Several MSWC receiver functins were develped during the evlutin and evaluatin perid. A single 500 MHz quadrant f the MSWC was assembled and evaluated, althugh the verall channelizer design used fur cntiguus 500 MHz frequency quadrants t cver a ttal f 2 GHz. The 3.0 t 3.5 GHz MSWC quadrant was evaluated using bth pulsed and cntinuus wave (CW) signals fr testing. Multiple simultaneus signals were applied t determine the MSWC selectivity and multiple signal reprting that included tw equal pwer level signals as well as signals f widely different pwer levels. 1.3 Perfrmance Summary Table 1 shws the majr MSWC perfrmance characteristics determined during T&E as well as the crrespnding receiver design gals. Althugh tw MSWC frequency demultiplexer quadrants were fabricated, nly ne quadrant was peratinal. The 500 MHz frequency span f the develped MSWC equipment, vice the 2.0 GHz receiver design gal, sufficiently demnstrated the capabilities and limitatins f MSW channelizatin fr EW applicatins. Manuscript apprved February 9, 1999.

6 Table 1 Summary f MS WC Perfrmance MSWC Characteristics Instantaneus Bandwidth MSWC Equipment 500 MHz Receiver Design 2000 MHz Input Frequency Range Sensitivity Pwer Level Range Dynamic Range Selectivity Bandwidth (50 db signal separatin) 3.0 t 3.5 GHz -40dBm 50 db 50 MHz 3.0 t 5.0 GHz - 85 dbm 50 db 60 MHz Krantz, Spezi, and Farg ^C lt lt T y WaS measured at - 40 dbm nminall y> thugh sensitivity in sme channels reached -46 dbm Receiver sensitivity is increased by implementing lw nise preamplificatin (ie befre the channehzer) m the MSWC, therefre sensitivity will apprach the receiver requirement by adding lw nise amplificatin. A nminal measured MSWC dynamic range f 50 db addresses the crrespnding receiver design requirements. In channels where MSWC sensitivity extends belw -40 dbm, the dynamic range als exceeds 50 db. The ability f MSWC t detect and characterize sensitivity level signals in the presence f interfering maximum dynamic range signals was demnstrated with a signal separatin as clse as 50 MHz. Pulse Descriptr Encder Detectrs/Lg Vide Amplifiers ;ctrs/lg Vide nplifiers Fig. 1 MSWC Equipment 1.4 Equipment Figure 1 shws the MSWC equipment. The equipment is a brassbard designed fr labratry demnstratin. The MSWC Frequency Demultiplexr is enclsed in a precisin-machined husing alng with the MSWC circuits and the high permittivity permanent magnets. A single wideband 3 0 t 3 5 GHz RF prt drives the MSWC Frequency Demultiplexr. Twenty-seven 20-MHz channel-bandwidth RF utput prts are prvided n the MSWC Frequency Demultiplexr t drive the channelizer detectr and lg vide amplifiers t transfrm the 50 db input dynamic range t a reasnable signal prcessing range The lg vide analg utput drives the pulse descriptr encder, which perfrms signal detectin and qualificatin. The signal is then digitized and frmatted fr utput transfer.

7 Magnetstatic Wave Channelizer (MSWC) 1.5 Evaluatin Summary MSWC evaluatin revealed its strengths and weaknesses vs design requirements. The limited MSWC perating bandwidth was established with nly casual bservatin. In additin, frequency linearity anmalies were nted in several regins f the perating bandwidth. The MSWC evaluatin shwed inperative channels within the perating frequency band, and resulting frequency dmain irregularities bserved included channel numeric rder reversal and large variatins in channel bandwidth. The realized MSWC size and weight physical features achieved were as anticipated and MSWC demnstrated gd selectivity in multiple signal testing. This MSW technlgy shws great ptential fr high perfrmance in electrnic supprt measures (ESM). Hwever, cnsiderable engineering is required t realize the MSWC receiver perfrmance gals. 1.6 Evaluatin Reprt Summary The remainder f this reprt prvides a brief descriptin f MSWC and discusses the test prgram in detail. Sectin 2 prvides a summary f the test results. In Sectin 3, a descriptin f MSWC is prvided as a summary definitin f the equipment evaluated. The functinal elements f MSWC are prvided t indicate the interactin and interrelatinship between the magnetstatic frequency demultiplexer and the electrnic interface t the remainder f the system. Sectin 4 explicitly describes and analyzes the MSWC tests perfrmed. Crrespndingly, Sectin 5 presents a detailed descriptin f the characterizatin test plans used in btaining the data. Sectin 6 ffers cnclusins, recmmendatins, and bservatins addressing tradeffs and ptins necessary t mve MSWC technlgy frward int peratinal use. 2. SUMMARY OF TEST RESULTS MSWC Test and Evaluatin ffers insight int the technlgy maturity in relatin t the perfrmance necessary fr successful peratinal deplyment. MSWC perfrmance measurements included sensitivity, dynamic pwer range, pulse rate capability, tw-tne intermdulatin and frequency reslutin, blcking, desensitizatin, simultaneus emitter detectin, and CW emitter receptin capability. 2.1 Perfrmance Characteristics Table 2 details the perfrmance characteristics f the MSWC as determined during testing. A summary descriptin f the T&E results fllws. Table 2 Perfrmance Characteristics f the MSWC Operating Bandwidth 3.0 GHz 3.5GHz Minimum Maximum Mean Std. Deviatin Sensitivity Pwer Levels -46dBm +10dBm dbm 2.57 db Inperative Frequency 3.15 GHz 3.20 GHz Segments 3.45 GHz 3.50 GHz Channel Order 1-7,9,8, 12-21,23,22 Channel Bandwidth 5.4 MHz 24 MHz MHz 448 MHz Desensitizatin Percentages -2% -45%

8 Krantz, Spezi, and Farg The MSWC cvered its 3.0 t 3.5 GHz perating bandwidth with the exceptin f several inperative frequency channels. Anmalies in MSWC frequency cverage included inperative channels and instances f channel frequency reversal. As seen in Table 2, the specific spectral segments that were inperative are frm 3.15 t 3.2 GHz and frm 3.45 t 3.5 GHz. MSWC measured signals acrss pwer levels ranging frm a minimum value (mst sensitive) f -46 db m t a maximum pwer level f +10 dbm. The average measured sensitivity was dbm with a standard deviatin f 2.57 db (see Sectin 4.1 fr details). The actual appearance f channels is als listed in Table 2 under Channel Order. It is nted that channels 9, 8, 22, and 23 are ut f numeric rder, and that channels 10, 11, 0, and 24 are inperative. Als listed are the measured channel bandwidths. Nte that the average channel bandwidth is within ne standard deviatin f the design channel bandwidth f 20 MHz. Finally, the table ntes the desensitizatin percentages when a desensitizing signal was intrduced during testing. The MSWC received signal prbability f intercept was reduced between 2% and 45% when subjected t a desensitizing signal cmpared t nminal MSWC sensitivity. 2.2 Sensitivity Characteristics The Sensitivity Test measured the minimum RF input pwer level int the MSWC that prvided a reliable signal detectin and measurement (i.e., the MSWC received all applied pulses). The test signal was sequentially applied at 1 MHz frequency intervals acrss the MSWC bandwidth, and the emitter signal pwer was initialized at -60 dbm and increased by 1 db until all applied pulses were detected (Sectin 4.1 prvides further details). The expected pwer level at which all pulses were received was dbm with a standard deviatin f 2.57 db and a minimum sensitivity pwer level f -46 dbm. is'.3000."'. 305G."3100: T 10 ". 15 MSWC Ctnnl Number Fig. 2 Sensitivity pwer level vs applied frequency Figure 2 shws the Sensitivity Pwer level readings as a functin f applied input signal frequency as well as MSWC channel number. The applied input signal frequency spans 3.0 t 3.5 GHz. The fluctuatins in sensitivity pwer level within single channels as well as between different channels are shwn here. As shwn, the Sensitivity Pwer levels are centered abut a nminal level f abut -40 dbm acrss the frequency band. Exceptins are seen between the MSWC channels as spikes in the sensitivity pwer. Als, by examining the Sensitivity Pwer levels vs the MSWC channel number, vids can be discerned in channels 9 (3.18 t 3.2 GHz), 10 (3.2 GHz), 23 (3.46 t 3.48 GHz), and 24 (3.48 t 3.5 GHz).

9 Magnet static Wave Channelizer (MSWC) 2.3 Dynamic Range Characteristics The MSWC dynamic range was measured in the RF Pwer Test. A signal, similar t that applied in the Sensitivity Test, is applied ver a range f pwer levels frm 3 db belw the sensitivity pwer t a maximum f +10 dbm (Sectin 4.2 prvides further details). Measured received signal amplitudes were in units f V REL, the relative vltage measured ut f the MSWC detectr circuitry. Fr these measurements, the high pwer dynamic range measurements are established by a maximum generatr pwer level f 10 mw (+10 dbm), since n hard limited saturatin was bserved in MSWC testing. Figure 3 shws the MSWC transfer characteristic, representing the channelizer dynamic perating range, and the interchannel unifrmity resulting frm the RF Pwer Test data. Each frequency channel has a slightly different transfer curve. A least-squares fit line was generated fr each set f frequency data. The mean transfer curve, as well as the standard errr estimate (shwn by the errr bars), were calculated and are shwn in Fig. 3. -s HtO RF Input Pvrer(dBm) Fig. 3 MSWC transfer characteristic and interchannel unifrmity 2.4 Pulse Rate Characteristics The Pulse Rate Capability Test measured the MSWC's ability t detect signals with shrt pulse repetitin intervals (PRIs) at varius pulse widths. A maximum f fur PRIs was applied at each f three different frequencies (Sectin 4.3 prvides further details). The MSWC shwed a higher prbability f detectin with the smaller pulse widths/pulse repetitin interval cmbinatins than with large intervals. 2.5 Tw-Tne Intermdulatin Characteristics The Tw-Tne Intermdulatin Test determined the perfrmance f the MSWC-when simultaneus cpulse signals are present within the active bandwidth. Dual cpulse emitter signals with frequencies selected t prvide intermdulatin prducts in varius channels within the active bandwidth were emplyed t evaluate MSWC intermdulatin perfrmance. Hwever, MSWC intermdulatin prducts were nt bserved with the maximum (10 mw) pwer levels applied. MSWC respnse t the applied

10 Krantz, Spezi, and Farg signals was cnfined t channel filter leakage thrugh the channel filter nearest the signal in frequency. N intermdulatin prducts were bserved (Sectin 4.4 prvides further details). 2.6 Tw-Tne Frequency Reslutin Characteristic The MSWC's ability t receive signals in the presence f a high level cpulse interfering signal was evaluated using the Tw-Tne Frequency Reslutin Test. Tw signals were applied simultaneusly: ne signal was applied at the MSWC center frequency and maximum pwer, and the ther signal was stepped thrugh the frequency bandwidth at varius pwer levels (Sectin 4.5 prvides further details). It was bserved that the variable frequency signal disappeared under interference frm the high level signal when the variable signal perated at lw pwer levels and frequency apprached that f the high level signal. Figure 4 demnstrates channelizer filter selectivity perfrmance. As pwer is increased at the secnd emitter, pulses are detected n either side f the first emitter frequency. As the maximum pwer level is applied t the secnd emitter, a high prbability f detectin ccurs ver a wide prtin f the channelizer spectral range extending t the channels adjacent t the first emitter frequency. Detectins frm Emitter 2 are bserved clser t the center frequency f Emitter 1 as the pwer is increased. Figure 4 als shws that the MSWC detects Emitter 2 ver several spectral segments at cnstant pwer levels O : O : O : O O O O! I -a:-20-30: 6 6 Q u Q Ö O : " : -200 lfij -10ii Frequency Separatin between Fixed and Variable Emitter (MHz) 100 Fig. 4 Pwer level vs fixed signal frequency as determined frm Tw-Tne Frequency Reslutin Test data 2.7 Blcking Characteristics The Blcking Test established the MSWC dual signal time reslutin capability. Tw test signals are applied t MSWC and the interval between respective leading edges was shrtened. Initially, the tw signals applied t the MSWC were ffset by a maximum f 4 ms. This delay between signals was shrtened successively t the minimum delay capability f the generatr (Sectin 4.6 prvides further details). MSWC reprted bth signals 'fr delays between 3.95 ms and 10 us while the leading pulse signal was detected steadily ver the entire delay cycle.

11 Magnetstatic Wave Channelizer (MSWC) 2.8 Desensitizatin Characteristics The MSWC signal receptin perfrmance in the presence f a high pwer level, ut-f-band signal was measured in the Desensitizatin Test. A desensitizing signal set 10 MHz belw the lwer band edge at maximum pwer (10 mw) was applied t MSWC alng with a signal within the active bandwidth set at the previusly measured sensitivity pwer level (Sectin 4.7 prvides further details). Desensitizatin reduced the prbability f detectin fr tw thirds f the channels t zer at the nminal sensitivity signal input pwer level. Signals in the ther third f the channels were desensitized t a prbability f detectin between 0% and 100%. 2.9 Reslutin Characteristics The Simultaneus Emitter Test measured the MSWC dual cpulse signal reslutin fr varius pulse width/pulse repetitin interval cmbinatins. In this test, ne emitter is applied at the channelizer center frequency while the ther steps thrugh the full bandwidth. Bth signals are set at a pwer level f 4 db abve the sensitivity pwer level determined earlier (Sectin 4.8 prvides further details). The MSWC detected bth emitters reliably in ne half f the PW/PRI cmbinatins, but nly detected bth emitters at a prbability near 50% fr the remaining PW/PRI cmbinatins CW Emitter Detectin Characteristics The CW Emitter Test measured the MSWC CW detectin capability. This test has tw parts: in the initial test, a single CW emitter is applied t the MSWC; in the secnd test, bth a CW and a pulsed emitter are applied t the MSWC (Sectin 4.9 prvides further details). The pulsed emitter steps thrugh mst f the active bandwidth at a pwer level 4 db abve the sensitivity level. MSWC was bserved t receive the CW emitter with high prbability when it was 8the sle signal applied t the channelizer. With bth emitters applied, the MSWC received bth emitters with high prbability until they ccurred within the same channel band. In this case, MSWC reliably reprted the pulsed emitter while the CW emitter was nt reprted at all. 3. EQUIPMENT DESCRIPTION The MSWC Receiver accepts signals ver a wide instantaneus RF bandwidth. These signals are channelized and characterized int digital pulse descriptr wrds (PDWs) that quantify the signal amplitude, frequency, time f arrival (TOA), and pulse width (PW). The system design bandwidth is 2.0 GHz, spanning 3.0 t 5.0 GHz. The input RF signal pwer range spans -46 dbm t +10 dbm. Frequency is quantized t a 20 MHz channel, while the amplitude is quantized t 0.1 V REL. TOA quantizatin f 10 ns is prvided in the PDW, while PW quantizatin is 100 ns. Each intercepted signal is characterized with the data fields described abve. 3.1 Equipment Layut Figure 5 shws the MSWC equipment. The equipment is a brassbard fr labratry demnstratin. The magnetstatic frequency demultiplexer is enclsed in a precisin-machined husing with the MSWC circuits and the high permittivity permanent magnets. A single wideband 3.0 t 3.5 GHz RF prt drives the MSWC Frequency Demultiplexer. Twenty-seven 20-MHz channel bandwidth RF utput prts are prvided n the MSWC Frequency Demultiplexer t drive the channelizer detectr and lg vide amplifiers t transfrm the 50 db input dynamic range t a reasnable signal prcessing range. The lg vide analg utput drives the pulse descriptr encder, which perfrms signal detectin and qualificatin. The signal is then digitized and frmatted fr utput transfer.

12 Krantz, Spezi, and Farg Pulse Descriptr Encder Detectrs/Lj Vide Amplifier Detectrs/Lg Vide Amplifiers Fig. 5 MSW Channelizer equipment 3.2 Receiver Architecture As tested, the MSWC was a key element in receiver architecture, as indicated in Fig. 6. In this architecture, a channelized signal prcessing path was prvided fr signal acquisitin, carse parameter measurement, and analysis prcessing; an analysis signal prcessr was prvided t precisely measure the signal. Cntrl Antenna Frnt End/ Receiver LO Divider, +2 Filterbank Signal Fan-ut +N J\ Frequency #1-7\ Frequency #2 Parameter Encder Cntrl Channelizer Receiver Infrmatin Frequency PRI PW Amplitude TOA > EW System Prcessr L I\ Frequency #N? Hi-Speed Tuning Cue Delay T VTVgh Analysis Receivers Analysis Receiver Infrmatin > Fine Frequency Phase Analysis Pulse Mdulatin Fig. 6 MSWC Receiver blck diagram

13 Magnetstatic Wave Channelizer (MSWC) 3.3 Receiver Functinal Descriptin The receiver antenna intercepts signals frm the envirnment. A frnt-end/receiver prtectin functinal element prvides pwer limiting prtectin fr the sensitive preamplifier and frequency cnversin elements f the receiver. Envirnment signals are transmitted thrugh the frnt-end/receiver prtectin circuits and cnverted int the 2.0 GHz wideband receiver IF that spans a frequency range frm 3.0 t 5.0 GHz. The IF signal is divided int tw prts, ne driving the channelizer and the ther driving the analysis prcessr. The channelizer's frequency demultiplexr and encder prcess the 2.0 GHz bandwidth IF in 500 MHz quarters f the entire bandwidth. The IF bandwidth is divided int quadrants and prvided t respective MSWC elements. The channelizer encder perfrms signal detectin, lgarithmic amplitude cmpressin, and carse signal measurement and prvides the resulting descriptrs fr frmatting The carse signal descriptrs are incrprated int the cmpsite receiver descriptr wrd fr disseminatin t the EW system signal srting prcessr. Li additin, the frmatting circuit prvides the carse frequency descriptr f the signal t cue the Analysis Receiver. The Analysis Receiver prt is driven with the secnd utput frm the IF pwer divider Cherent memry fr the wideband IF envirnment prcessed in the channelizer is prvided in the Analysis Receiver channel wideband delay line. The cherent memry prvided by the delay line enables the Analysis Receiver t prvide precise parametric measurements n the same pulse measured in the channelizer. The wideband delay line utput is cnverted int the analysis channel IF frequency fr subsequent precisin parameter measurement. The analysis channel bandwidth is much narrwer than the channelizer IF bandwidth t enable the required precisin measurements with the currently available receiver signal parameter measurement elements. The Analysis Receiver tuning cmmand is the carse frequency descriptr prvided by the channelizer. The Analysis Receiver includes precisin signal measurement and encding, and the precisin signal descriptr generated in the Analysis Receiver is prvided t the signal frmatter fr integratin int the signal descriptr wrd. The cmpsite signal descriptr is prvided as an utput t the EW system signal srting prcessr. Figure 6 shws the MSWC receiver blck diagram. A signal is received thrugh the antenna at left demultiplexed, and characterized by the filterbank, the Analysis Receivers, and the parameter encder' The parameter encder then sends a digital PDW cntaining infrmatin characterizing the frequency time f arrival, pulse width, and amplitude f the input frequency t the EW system prcessr. The MSWC receiver filters, detects, and encdes incming signals. Mre specifically a received signal is pwer limited in the frnt end/receiver prtectin t prevent damage by high pwer radar signals (see Fig. 6). It is then divided, with ne signal applied t a 25-channel filterbank and the ther t Analysis Receivers. The filterbank signal is divided int multiple parts and filtered by cntiguus frequency band filters. The channel electrnics include a tuned bandpass filter, a buffer and a lg amplifier. The bandpass filter defines the frequency segments f each channel. Ideally, these segments are cntinuus, cvering the entire bandwidth f peratin. The utput f the filterbank is applied t a parameter encder, which als receives the utput frm the Analysis Receivers. The parameter encder applies channelizer receiver data, frequency, PRI, PW, amplitude, signal time f arrival Analysis Receiver data, fine frequency, phase analysis, and pulse mdulatin t the EW system prcessr in the frm f a digital PDW. 3.4 Evaluatin Equipment Functinal Descriptin The MSWC equipment evaluated included a frequency demultiplexing filterbank with assciated lg amplifiers, a parameter encder, and a pulse descriptr wrd interface prcessr. The MSWC frequency demultiplexr equipment spans the frequency range between 3.0 and 3.5 GHz, prviding nly a single

14 10 Krantz, Spezi, and Farg quadrant f the design frequency cverage fr evaluatin. The frequency demultiplexing filterbank is based n magnetstatic wave technlgy. Each filter channel is implemented as a dual resnatr MSW filter. The filter elements are driven by a single stripline that transfers frequency channel energy int the respective MSW filter thrugh prximity cupling. Filter tuning t the frequency f interest is accmplished by using magnetic field biasing. Because high permittivity permanent magnets prvide the magnetic field bias ptential, the magnetic field applied t each filter is adjusted using the magnetic ple spacing. The RF input test signal is applied t the 25-channel frequency demultiplexer filterbank. Signals prceed thrugh the filterbank as explained abve and amplified befre being applied t the parameter encder. The parameter encder generates the digital PDW including frequency (5 bits), which is reprted as channel number; amplitude (6 bits); pulse width (5 bits); and time f arrival (16 bits). The MSWC pulse descriptrs are utput thrugh a first-in, first-ut (FIFO) buffer t subsequent prcessing elements. 4. TEST ANALYSIS The MSWC was evaluated t determine the level f perfrmance achievable in EW applicatins. This sectin presents the results f the evaluatin, where the analysis results are prvided with the testing perfrmed. The results are based n a cmprehensive assembly and reductin f the data accumulated. Analysis f the reduced data is then prvided t indicate the EW system impact f measured MSWC perfrmance. 4.1 Sensitivity Test (Includes Infrmatin fr Frequency Accuracy Test) The Sensitivity Test measures the minimum pwer level at which the MSWC recrds all pulses applied. The test is perfrmed ver the entire bandwidth (3.0 t 3.5 GHz) at 1-MHz intervals. The pwer level is initially set at -60 dbm and increased by 1 db until either all 10 pulses applied in a data sample are detected by the MSWC r the maximum pwer level f +10 dbm is reached. PDW measurement validity is based n the crrelatin f channel number, pulse time f arrival, and pulse perid with the applied signal. Ten pulse-grup sets f 10 pulses each drive the MSWC fr each pwer level/frequency cmbinatin t ensure data accuracy. The ttal number f valid PDWs fr all 10 runs is then divided by the ttal number f pulses prvided (100 in this case) t find the average prbability f intercept fr the specified frequency/pwer level cmbinatin. The MSWC was designed t prvide a bandwidth f 20 MHz in each f its 25 cnannels, prviding a ttal peratinal bandwidth f 500 MHz. The 25 MSWC channels cver a frequency range frm 3.0 t 3.5 GHz. The design als indicated a linearity between the channel center frequency and the channel number. The Sensitivity Test data shw that nt all 25 channels are functinal nr d they respnd in numeric frequency rder (see Figs. 7 and 8). Channels 10 and 11, designed t cver the frequency range f 3.15 t 3.20 GHz, are nt perating. Immediately prir t this spectral segment, channels 8 and 9 appear in reverse frequency rder, as d the final tw perating channels, 22 and 23. The tw channels crrespnding t the extremes f the spectral segment cverage, 0 and 24, are als nnfunctining. A linear relatinship exists between the measured channel center frequency and the channel number with a standard deviatin f frequency errr f MHz. In fact, the linear frequency relatinship is nly interrupted by the tw missing channels, 10 and 11, and the tw sectins where channels are in reverse frequency rder.

15 Magnetstatic Wave Channelizer (MSWC) 11 Figure 7 depicts the channel number as a functin f applied input signal frequency. The center frequency f the channel respnding is the abscissa while the channel number is the rdinate. These data were taken frm the Sensitivity Test. The applied signal frequency spans the 3.0 t 3.5 GHz channelizer design bandwidth. The rdinate range, 1 t 25, indicates the MSWC channels that span the 3.0 t 3.5 GHz frequency cverage. 825 r~ mmm 201 Jf a I- Z >10 _J I I L,..i! i frequency (Ml iz) Fig. 7 Channel number vs frequency Figure 8 shws the sensitivity pwer level readings as a functin f applied input signal frequency, which spans 3.0 t 3.5 GHz. Sensitivity pwer level fluctuatins acrss the entire MSWC bandwidth are shwn. The sensitivity pwer levels are centered abut a nminal level f abut -40 dbm acrss the frequency band. Spikes in the sensitivity pwer levels dente frequencies that fall between the MSWC channels. Vids can be discerned frm 3.18 t 3.2 GHz (channel 9), 3.2 t 3.22 GHz (channel 10), 3.46 t 3.48 GHz (channel 23), and 3.48 t 3.5 GHz (channel 24). The expected value f the sensitivity pwer level is dbm with a standard deviatin f 2.57 db. The expected sensitivity is fund by averaging the center frequency sensitivity pwer f each channel. Sensitivity pwer levels vs frequency data fr a single channel are used t determine the channel center frequency, which is defined as the channel midpint between the frequency with sensitivity 3 db less than the channel maxima. The frequency interval between the channel 3 db sensitivity pints is the measured channel bandwidth. The average measured bandwidth is MHz with standard deviatin f 4.48 MHz (see Fig. 8).

16 12 Krantz, Spezi, and Farg X X It X x sc xx x xxxxx x x»x x: x «C XX X XX.. xx - «JO«X- XXX X XX xxx:xx x XX x x-x- X x< xxx : uw KX X X XXK xx xx xxxc xxx: x : K -46i -50' : 3000! : i 3150 i ; Frequency (MHz) 3350 i Fig. 8 Sensitivity vs frequency MSWC shws sme sensitivity unifrmity amng channels, althugh certain channels have a much better respnse than thers. Sensitivity fluctuatins between channels are mdest, as is indicated by a standard deviatin f 2.57 db. The sensitivity pwer levels range, hwever, frm -36 dbm t -46 dbm, the mst prevalent being -42 dbm, as shwn in Fig. 8. Sensitivity fluctuatins within a channel span a wide range. In channel 2, fr example, the sensitivity pwer levels fluctuate inversely such that there is an inverted U-shape sensitivity curve and n well-defined center frequency. Channel 20, hwever, shws a well-defined center frequency and a channel bandwidth f MHz, nearly the design bandwidth f 20 MHz. Figure 9 shws the prbability f intercept (POT) pltted vs the Sensitivity Pwer Level fr the center frequencies f all 25 channels. The pwer level is the abscissa while the POI is the rdinate. It depicts the range ver which all the channels begin receiving 100% f the pulses applied. The mst sensitive channel reaches 100% POI at an input level f -46 dbm while the least sensitive desn't reach 100% until -30 dbm is applied. The range in maximum POI is als shwn in this figure. Sme channels attain 100% POI while thers never reach mre than 80% POI. The MSWC POI characteristics generally exhibit a bivalued transfer functin. 4.2 RF Pwer Test The RF Pwer Test prvides MSWC dynamic range data. The signal used in the Sensitivity Test, with a pulse repetitin interval f 250 (J.s and pulse width f 2.2 ixs, is applied t the MSWC in bursts f 10 pulses. The test signal pwer level is incremented frm 3 db belw the MSWC sensitivity pwer level t a maximum level f 10 dbm at each frequency. Each pwer level is repeated 10 times t ensure data accuracy. Valid PDWs are identified using the same criteria used in the Sensitivity Test. The amplitudes are then averaged t determine the mean amplitude fr the specified frequency and pwer level.

17 Magnetstatic Wave Channelizer (MSWC) 13 11AI I III i i «)\i I _: 1 / : = = i 90 - ix vm \ i \ i -\ i \ / l \ i\/ :v i v ; g :'/J J 4» h'fl' if s 1' a : I 1 J / 1 J / i 1 I : : : 1 ; i ; 1 ' - : : : 1 ' ; "I : 1 ;. : :.1, i i i -10 c I g g r ' RF Input Pwer Level (cfbm)... : Fig. 9 MSWC threshld perfrmance As is shwn in Fig. 10, the average amplitude increases linearly with pwer fr measurements at the channel center frequency. Output amplitude variatins ccur amng channels as shwn by the span f the utput at each input pwer level. The MSWC was nt bserved t reach hard-limited saturatin even near the maximum input pwer level. Sme channels shw utput amplitudes that level ff smewhat at higher pwer levels, but the slpe f the transfer characteristic is psitive fr all RF Pwer Test data. Figure 10 shws the MSWC transfer characteristic and the interchannel unifrmity resulting frm the RF Pwer Test data. A least-squares fit line was generated frm all data fr all channels retrieved in the RF Pwer Test. The standard errr estimatin f this line and the actual data range were then calculated and pltted ver the least-squares fit line at an input pwer level increment f 10 db. Nte that the standard errr is much smaller in the pwer level central perating range than at either input perating pwer range edge. The average amplitude als increases linearly with pwer level. 4.3 Pulse Rate Capability Test The Pulse Rate Capability Test determines the MSWC's capability t detect shrtened pulse repetitin interval signals at varius pulse widths. Thirteen signal cmbinatins f pulse widths and PRIs are used at each f three different frequencies (3.174, 3.234, and GHz). Each frequency is repeated 10 times t ensure data accuracy. PDW validity is determined using the same methd as in the Sensitivity Test. The sum f valid PDWs fr all 10 repetitins is then divided by the ttal number f pulses applied (five bursts per repetitin) t find the average percentage f detected pulses.

18 14 Krantz, Spezi, and Farg 120 IKM- 80- f 60 HP- :< : I ! ^ ; RF Input Pwer (dbm) :10 20 Fig. 10 MSWC transfer characteristic and interchannel unifrmity Oddly, the MSWC shws higher prbability f detectin with smaller pulse widths and smaller pulse repetitin intervals. The largest pulse width, 10 us, is never received with a prbability abve 50%, if it is received at all. Als, pulses transmitted with a 1000 us PRI shw a lw detectin prbability regardless f the pulse width. Pulses with the three smallest pulse widths (0.1, 0.5, and 1.0 us), are received with a detectin prbability f nly 60% fr frequencies f and GHz (see Figs. 11 and 12). At a frequency f GHz, 0.1 us PW is received with a detectin prbability f nly 22%, while the crrespnding PW signals f 0.5 and 1.0 us are received with a detectin prbability f 60%. The wrst cmbinatin f signal parameters, 10 us pulse width and 1000 us PRI, yields a mere 50% prbability f detectin at a frequency f GHz, and zer fr frequencies f and GHz. Pr detectin prbabilities fr large PW and PRI signals may be due t a limitatin in the read-time f the MSWC since its maximum 6-ms read-time precludes detectin f all pulses applied at a perid f 1000 us unless all f the pulses are cincident. Figure 11 shws POI decreasing as the applied signal pulse width is increased. The specific data used were btained with an applied frequency f GHz. Each line n the plt represents data cllected at different PRIs. Nte that three f the fur PRIs are reprted with 100% POI fr the lwer pulse widths. The data crrespnding t a PRI f 1000 us are shwn t have a maximum POI f 60%. The remaining pulse width/pulse repetitin interval cmbinatins are detected with high prbability, hwever. In fact, fr the frequencies f and GHz, excluding the perid f 1000 us, nearly 100% f the transmitted pulses are received. The nly exceptins are at PRIs f 100 us and 10 us, with a pulse width f 0.1 us and a frequency f GHz. In these cases, the prbabilities f detectin are apprximately 95%. At GHz, the pulse width f 0.1 us is nly detected with a 75% prbability, while the signals f the ther pulse widths are detected with a prbability exceeding 90% (see Fig. 13).

19 Magnetstatic Wave Channelizer (MSWC) i MW%t(%zz Hjl HlHll ^pp^^^^gs^l^^^^^^^^^^^^^p^ ^^pii ^^^^^^^^^ PRI=2,10,1C ns 90: s; \ 70 i 60 PRI= 1000 ns m > [ 40 [ I 10 ^^^^^^^^m^^^^ ^S i HI 11 iü i P m ^ : : ^^^^^^^^^^^^^^^^^Ä 1 10 Pulse Width {Micrsecnds} i lh Fig. 11 POI vs pulse width at GHz n I 80 PRI=2,10nS : ::::::: PRI=100ns \ inm I 50 PRI=1000ns...:. ' h 10h : : ; : : i ; lllb^lllifflilliiil Pulse WidUi (Micrsecnds) c Fig. 12 POI vs pulse width at GHz

20 16 Krantz, Spezi, and Farg Pulse Width (Micrsecnds) Fig. 13 POI vs pulse width at GHz Figure 12 shws POI decreasing as the applied signal pulse width increases fr an applied signal frequency f GHz. This figure is similar t Fig. 11 except that the applied frequency is GHz. Nte that fr PRIs f 2, 10, and 100 us, the POI is at r near 100% until the pulse width reaches 10.0 us. The same cnditin exists fr an applied frequency f GHz. Als, fr a PRI f 1000 us, bth applied frequencies shw a POI f 60% until the applied pulse width reaches the maximum f 10 us. At this pint, the applied frequency f GHz des nt receive the signal, while the GHz applied frequency receives it at 50%. Figure 13 shws POI decreasing as applied signal pulse width increases fr an applied signal frequency f GHz. Fr this frequency, the smallest pulse width as well as the largest pulse width are nt received well, differing frm the previus tw figures. Fr a PRI f 1000 us, the peak POI is the same as fr the previus applied frequencies, 60%. The remaining three PRIs als peak at r near 100% POI, just as the previus tw applied frequencies. This frequency differs in that all fur PRIs are received at a lwer percentage fr the initial pulse width than fr the middle pulse widths. It des, hwever, exhibit the same decline in POI as the previus applied signals as the pulse width increases t 10.0 us. 4.4 Tw-Tne Intermdulatin Test In the Intermdulatin Test, tw ut-f-band signals are applied t the MSWC t determine intermdulatin prducts ccurring within the active bandwidth. Bth signals are applied at frequencies abve the MSWC upper band edge and are chsen t create a third-rder prduct within the channelizer bandwidth. The test signal frequencies were varied t prvide an intermdulatin respnse in varius MSWC channels, but respnses were bserved nly frm channels at the MSWC bandwidth edges. Endchannel signals were detected regardless f the tw frequencies applied, indicating that the measured respnse results frm signal leakage thrugh the channel filter and that intermdulatin measurements are precluded by the level f channelizer channel selectivity prvided.

21 Magnetstatic Wave Channelizer (MSWC) Tw-Tne Frequency Reslutin Test In the Tw-Tne Frequency Reslutin Test, the MSWC is evaluated t determine signal detectin in the presence f a high-level, cpulse interfering signal in the channelizer passband. The high-level signal is applied at 0 dbm, center frequency (3.234 GHz), while the secnd signal is applied at pwer levels ranging frm the sensitivity pwer level f -46 dbm t the max pwer level (8 dbm) in 3 db increments, ver the entire frequency ränge. Measurements at each frequency are repeated 10 times t ensure data accuracy. Data are validated using the same methd as was used in the Sensitivity Test. The ttal number f 50 pulses applied (five bursts fr each repetitin) is used t btain an average prbability f intercept. Figure 14 depicts the MSWC empirical selectivity prfile with detectin pwer presented as a functin f frequency difference frm a maximum level emitter. A cutff frequency was determined fr each input pwer level as the clsest frequency t the fixed emitter frequency received by the MSWC frm the secnd emitter, bth abve and belw the fixed emitter frequency. As the figure shws, the cutff frequency appraches the fixed emitter frequency as the input pwer level is increased. 10 lf """ rf T ' : i MO q q Q Q O : O O : O Ö 0 i -SO'! -200 MSO Ftequency Separatin between Fixed and Variable Emitter (MHz) il Fig. 14 Tw-Tne Frequency Reslutin Test data Figure 14 shws that the secnd emitter at lw pwer levels can be ttally blcked by the first emitter. As pwer is increased at the secnd emitter, pulses are detected n either side f the first emitter frequency. As the maximum pwer level is applied t the secnd emitter, a high prbability f detectin ccurs ver a wide prtin f the channelizer spectral range extending t the channels adjacent t the first emitter frequency. Detectins frm Emitter 2 are bserved t apprach the center frequency f Emitter 1 as the pwer is increased. Figure 14 als shws that the MSWC detects Emitter 2 ver several spectral segments at cnstant pwer levels.

22 lg Krantz, Spezi, and Farg 4.6 Blcking Test The Blcking Test determines the MSWC's ability t distinguish between pulses while the time between the pulse leading edges is shrtened. Initially the delay between pulses is 4 ms. This is reduced by 100 ns until the delay is at the minimum generatr capability f 65 ns. Only ne burst is applied frm each generatr. This test is run twice, nce with bth emitters set at the center frequency (3.234 GHz) and nce with Emitter 1 at the center frequency and Emitter 2 at 60 MHz abve the center frequency. Valid PDWs frm the first emitter (n delay) are determined in the same methd as was used in the Sensitivity Test. Valid PDWs frm the secnd emitter (delay) are als determined by the Sensitivity Test methd, hwever the delay instead f the PRI is used in validating the TOA f the pulse. The MSWC discerns tw signals until the delay reaches the minimum f 65 ns (see Fig. 14) fr bth Emitter 2 frequency settings (3.234 and GHz). At the minimum delay, neither signal is received. Between the maximum delay f 4 ms and a delay f 3960 us at an Emitter 2 frequency setting f GHz r 3940 us at an Emitter 2 frequency setting f GHz, the first emitter is reprted steadily, but the secnd emitter is nt detected. This bservatin ccurred at bth settings f the secnd emitter. The reduced detectin prbability at the large differential pulse delay may result frm maximum MSWC read time limitatins. Figure 15 is a semi-lg plt f the prbability f intercept as a functin f the delay between leading edges f synchrnized pulses applied t the MSWC. The time delay range used extends frm a minimum f 65 ns t a maximum f 4 ms. The MSWC receives bth pulses at 100% POI fr delays between 10 us and 3950 us. 4.7 Desensitizatin Test The Desensitizatin Test measures MSWC sensitivity lss in the presence f high-pwer utband signals. One emitter is set at 10 MHz belw the MSWC lwer band edge, while the secnd emitter is incremented by 10 MHz frm the lwer band edge (3.0 GHz) t the center frequency (3.234 GHz). The pwer level fr each frequency is set at its sensitivity pwer level determined earlier. Valid PDWs are determined under the same cnditins used fr the Sensitivity Test. Desensitizatin measurements were made n apprximately a third f the frequencies tested. Of this third, there was n pattern in the POI (see Fig. 15). Cmparing the sensitivity f each channel in the presence f a desensitizing signal with the sensitivity measured withut a desensitizing signal, we determined that desensitizatin cnsistently degrades MSWC sensitivity as expected. In ne case, at a frequency f GHz, the desensitized POI is higher than that f the nrmal sensitivity by 3 percentage pints. The POI differences between the nndesensitized and desensitized measurements range frm a minimum f 2% t a maximum f 45%. This difference appears t vary at randm frm frequency t frequency. Frequencies with the same baseline sensitivity (i.e., 3.08 and 3.20 GHz) can exhibit large POI differences (32% and 2%, respectively) in the presence f a desensitizing signal. Figure 16 indicates the results f the signal frequency Desensitizatin Test. POI is pltted as the dependent variable with frequency f the applied inband signal as the independent variable. A large utf-band signal that desensitizes the receiver t the inband signal is applied. If cmpared with the sensitivity pwer levels, it is nted that the desensitizatin signal lwers the MSWC system sensitivity. 4.8 Simultaneus Emitter Test The Simultaneus Emitter Test measures the ability f the MSWC t distinguish tw cpulse signals at varius pulse width/pri cmbinatins. One emitter is set at the MSWC center frequency (3.234 GHz), while the ther steps thrugh the full bandwidth. The pwer level is set 4 db abve the sensitivity pwer

23 Magnetstatic Wave Channelizer (MSWC) Ö 60< I' 80 tf GO 5 HI ir40! ; 20 Sy-O! -' ' l-l 10. : : /: '. '10' ' ;. :;, i j Delay between leading edges f pulses {micrsecnds} j Fig. 15 POI vs interfering signal delay 100!!!! 80 - O O Ö 60 Pi mm At) ö O j \ O O : : : - - O-O -O O O OO O O : O O O : O i i i I ( Inband Signal Frequency (Mife) Fig. 16 Signal frequency desensitizatin test

24 20 Krantz, Spezi, and Farg level f the emitter frequency. Valid PDWs are determined in the same methd as was described in the Sensitivity Test. The MSWC detects bth emitters fr PRIs f 10 us and 50 us with 100% POI at all frequencies except when the first and secnd emitters are in the same frequency channel. As the secnd emitter crsses the first emitter's frequency, the POI decreases by 30% (see Table 3). The first emitter is nt detected with high prbability when the secnd emitter is within the same channel because f greater sensitivity at frequencies adjacent t the center frequency. Fr example, the sensitivity pwer level fr GHz is -42 dbm, while at GHz, the pwer level is -39 dbm, causing the MSWC t detect the strnger signal when the tw signals interfere. In the remaining tw PRIs (20 us and 100 us), the MSWC POI ranges frm 0% t 100%, althugh mst have a prbability abve 50%. Only when the tw emitters are in clse frequency prximity is it clear that the secnd emitter is received with a higher prbability. The MSWC exhibits a higher POI at a perid f 100 us than at 20 us fr Emitter 1, but there seems t be n such difference fr the secnd emitter. PW Table 3- - Simultaneus Emitters PRI (us) Emitter 1 POI Emitter 2 POI (us) Duty Cycle Emitter 2 Freq. = 3.1 GHz (Emitter 1 set at GHz) Emitter 2 Freq. = GHz (Emitter 1 set at GHz) Table 3 presents multiple emitter MSWC POI perfrmance. The table represents the change in emitter POI with emitters at different frequencies, r with emitters set at the same frequency. POI is measured fr selected cmbinatins f pulse width and pulse repetitin intervals. When the emitters are at different frequencies, emitter POI decreases as the duty cycle increases, but the emitter POI rises as the duty cycle increases when the emitters are set at the same frequency. At all frequencies fr each PRI, Emitter 1 is nt detected when Emitter 2 is in the same channel band. Nte that Emitter 2 is nt received with high prbability. Accrding t the data recrded, the perids f 50 us and 10 us are shwn t have little variance in POI, but it is nted that Emitter 1 exhibits less variance acrss the frequency range than des Emitter 2 at these perids. Emitter 1 is received with a POI near 100% at all spectral lcatins except the center channel. With bth emitters at the same frequency, the first emitter POI drps t 0% except fr a duty cycle f 0.5, where it is received at 26.8%. Emitter 1 POI perfrmance is nt as defined at the 100 us PRI as are the prir tw PRIs (10 us and 50 us), but it fllws the same pattern. At a PRI f 20 us, hwever, Emitter 1 is received nly with a prbability f 70%, and the prbability variatin at the center channel is nt as bvius. Emitter 2 exhibits a similar POI vs frequency characteristic as Emitter 1, but the spectral segments f zer POI near the center channel are nt as defined. Als, at a PRI f 20 us, Emitter 2 is detected at a POI f 100%, althugh there are spradic POI measurements.