Spread Spectrum SceneCelebrates 6 Months of

Publication!

V+ made it happen!

RF/SS proudly celebratespublishing six monthly issues ofS p r e a d S p e c t r u m Sc~~ize andwould like to thank our readers.subscribers, advertisers and al:the other supporters who’vchelped us along the way tc“moderate maturity.”

Many people thought SS5would only publish one or tw(issues -- many people thought oucoverage area and targetechnology too narrow -- I gueswe’ll see about those doubters!

We like success -- don’you‘?

tS

‘t IArticle m

Rumors S: Ramblings 2

DecipherinKs 2

Reader Feedback 2

Editorial 3

The Aerial 3New Products 1 4

DSP for SpreadSpectrum 5

International Scene 5M’ashinfton Scene sSS Network Software 6

Cartoon 6New Products II 6

Introduction to The Navy’sPANSAT Project 7October SSS Preview 12

Photo of NPS Monterey PANSAT mockup, for more see page 7.

SSS Exhibits atHAMCON 92SSS shared a booth with

Ham-Pro antennas at the ARRL1992 National Convention(HAMCON 92) in Los Angeles,August 20, 21 and 22. Over 500copies of our August issue weredistributed to some of theinterested 3200 attendees of theconvention.

The convention seemed tobe a big success for all involved,even though sales (and in ourcase new subscriber) orders werea little slow in coming. TheARRL sponsored technicalprograms were very well attended(many were standing room only.)We attended the FCC forumn andheard excellant talks by FCC’sRalph Haller and John Johnston.See you at PACIFICON inOctober.

Septenllwr, IYY2 Spread Sprctrurn SCI'IIC

.-_.-FCC STA Request May

Become Request forPermanent Rulemaking to

Part 97 RulesA lot of behind the scenes

activity is going on about the“new S T A r e q u e s t ” w ehighlighted last month. First, ameeting of 14 SF bay area hamsin Redwood City decided toseperate VHF/UHF SS from HFSS operat ions in any FCCrequest.

S e c o n d , i n f o r m a ldiscuss ions with ARRLWashington staffer Paul Rinaldohas focused the “draft” STXrequest to the bare essentials.Finally discussions with FCCPRE3 C h i e f R a l p h Hailer a tHamcon 92 suggested that theFCC would be interested in arequest for a set STA page 2

1

SPREAD SPECTRUM SCENE isdedicated to the Spread Spectrumprofessional and is committed tobeing the primary source for the iat-est news and information about thegrowth, regulation, and opportunitiesin this emerging science.

SSS provides a forum for publicationof technical information, advertising,editorials, opinions, and newsrelating to the emerging fields of ourcoverage and emphasis. SSS isread by over 5000 technical decisionmakers each month. SSS canpresent your advertising message tothe key designers, programmers,system integrators and end users inthis new industry. Call our 800number Hotline to request a MediaKit.

Publisher: Randy RobertsEditor Lisa S. SmithEditorial Consultants:

Tom Diskin, Dorm Fisher,M. N. RobertsContributors:

Dan Doberstein,John Greene, Matthew

Johnson, Peter OnnigianDirector of Advertisinq

81 Circulation:Koert Koelman

Cartoonhist:Rich Tennant, The 5th Wave

R&D Staff:Walt Jensen,Chris Kilgus,

Dr. Andy KorsakPublished bv: RF/SS

P. 0. Box 2199El Granada, CA 94018-2199

Telephone Numbers:Voice: 415-726-6849FAX: 41 S-726-01 18

IntemetRlUCP Email:hithrQwell.sf.ca.usAMIX- RROBERTSd

AOL: randyrfss

Advertisinq 81 SubscriWlonHotline:

Voice: 800-524-9285

SSS is published monthly and isavailable by subscription. You canreceive a complimentary copy bysending a us a self addressed 9 x 12inch stamped (E.52 US postage)envelope.

&&&ption Rates12 Months - US First Class Mail - $29.9512 Months - Foreign, AIR MAIL - $45.00

US Funds

STA c00t’d fr0m p8ge i -permanent pa r t97 SS operations rule change.Paul Rinaldo and ARRL generalCounsel Chris Imlay are busy onthis latter possibility.

l High speed LANs and WANsare the top subject in SiliconValley rumors about who’s doingwhat and who’s about to showwhat new SS products. Iseverybody too gun-shy to jumpon the 1.8 to 2.4 GHz PCSbandwagon?0 Maxim, the acknowledgedleader in new chip introductionsin any given year, is hard at itstill -- see our new productssection for some interestingtidbits that might help SS systemdesigners.0 Signetics is putting out a lot ofnew chips lately -- some of themtargeted for SS and newercellular radio systems. See ournew products section.l Heard a good rumor -- want to“leak” some info to yourcompetition -- call our 800number and we may print it!

1 Decipherings (

PROGRESS HAS NOTFOLLOWED A STRAIGHTASCENDING LINE, HUT

A SPIRAL WITHRHYTHMS OF

PROGRESS ANDRETROGRESSION, OF

EVOLUTION ANDDISSOLUTION.

- Goethe -

Don’t miss an issue of SpreadSpectrum Scene.Subscribe now!

This month brings morechanges to SSS. We are stillevolving our format and subjectemphasis (focus). You -- dearreader have a great deal ofinfluence in this area. I assumefrom the lack of feedback thatwhatever SSS does is OK. Is thatwhat you mean? If not -- pleasecall, write or FAX us and saywhat you want.

This m o n t h w e aredropping the Business Card adsection, just like we dropped theclassified ad section -- you don’tseem interested. No one iswilling to w for our businesscard ads! So they are nowhistory.

A similar story involvesthe s e r i a l i z a t i o n o f ourforthcoming book, Introduction toSpread Spectrum, we are justgoing to wait until the book iscomplete and published -- thenyou may buy it or not. No readerfeedback -- it goes away! Get it?

As one of our coverstories says August’s feature abouta new request for an STA to FCCpart 97 rules for Ham Radio SSprobably will become a requestfor permanent rulemaking -- untilthis political issue is resolved oruntil you readers show someinterest, any construction articleson the STA-1 or ST,4-l*, orwhatever, are hereby terminated.If you want to see things like this-- let us know. Major amounts(for RF/SS) of time and moneyhave to be invested to bring thesethings and possible kits to you.

Why should this time andmoney be wasted if it falls ondeaf ears’!

Sm-cad Saectrum Scene September, 1992

h

To Spread or Not toSpread

ame m i s t a k e s a s yourompetition. Let me suggest thatsome” applications exist that areest implemented withoutpreading.

K Shahzspeare Pin example may be appropriateplease forgive us h.ere:

Many of RF&S c o n s u l t i n gclients are finding that blindadherence to FCC part 15.247rules is costly or otherwiseundesirable. Is Spread Spectrumalways the most desirablet e c h n i q u e o f unl icensedcommunications?

- Suppose your companyvants to design and buildvireless short range in-home)urgl ar or intrusion or fireJarms. Naturally the first.eaction would be to use SS at315 MHz -- right?

I

Some of these clients are findingout, before it’s too late, that (asthe title of this editorial suggests)it may not pay to always“Spread.” Specifically anotherpart of FCC part 15, paragraph1 5 . 2 4 9 a l l o w s intentionalradiators to occupy the same ISMbands as Spread Spectrumcommunications, but without theb u r d e n o f m u c h w i d e :bandwidths and ha rdwarecomplexity. Of course there is 2penalty: the maximum radiateiaverage signal is limited tc5 0 , 0 0 0 microvolts/metelmeasured at 3 meters.

I

think you would be dead wrongn today’s commercial marketJlace! Why not develop thesame kind of equipment usingNBFM techniques at 915 MHz,with no spreading, and just keepthe range and/or transmittedpower levels down to the limitsof FCC paragraph 15.249? Yourequipment could be developedquicker, at far less NRE cost,with maybe l/2 or l/3 of therecurring cost of an equivalent SSdesign.

Am I all wet or are youfollowing me? RF/SS has client:who really need Spread Spectrurr

In other words, why use spreac1spectrum s y s t e m s j u s t tc3

communicate short range, lovV

power data or voice information ‘3

when simpler narrowband, non,-

spread techniques may work juz it

as well? The answer quoted b Ymost equipment developer CEO‘S

and company Presidents and VPEngineering people is simply th;1tis what all the competition :isdoing. Oh boy -- watch out iinthe board room! You guys aIresupposed to make “profits” fc3ryour shareholders -- not make tl:le

-- we also have other clients whcare far better off (or would bejust designing and developinequipment for FCC part 15.249Do you and your products fit ilthis later category? What do yolthink about this subject?

Please write us with youcompany’s (non-proprietar)please) experiences in this area .we will be glad to share aninput received with our readers ithese pages.

Randy RoberrSSS Publishel

I

y Peter Onnigian, P.E., W6QEU

)ETERMINTNG RADIATEDPOWER IN SPREAD

SPECTRUM OPERATION

,ast m o n t h w e discussedantennas, coaxial cable and;onnectors suitable for SS use inhe 902-928 MHz (915) band.rhis concluding article explains.he maximum allowable radiatedbower and how its computed.1:

1j1

;s

n

tl

dimple vertical dipoles over aground plane, mounted on the:quipment chassis, rubber‘duckies” and other forms of.adiators have found their waynto the SS equipment field, for-elatively s h o r t r a n g e:ommunications out to about 800feet. For longer ranges, the lowcost high gain Yagi antenna isthe antenna of choice. Because oftheir small size at this frequency,Yagi antennas can be usedindoors, for greater reliabilitythan possible with built onequipment type radiators, wherenecessary. Outdoor Yagis willincrease the circuit range to 25miles and even more dependingon line of sight conditions andother propagation factors.

Part 15.247 (b) of the FCC Rulescovers antenna gain and radiatedpower limitations. This partstates:

tsr

“The maximum peak outputpower of the intentional radiatorshall not exceed 1 watt. If trans-

September, 1992 Spread Spectrum Scene 3

mitting antennas of directionalgain greater than 6 dBi are usedthe power shall be reduced by theamount in dB that the directionalgain of the antenna exceeds 6dBi.” What does all this mean?Part 15.203 clarifies thisrestriction on SS antennas bystating:

“An intentional radiator shall bedesigned to ensure that noantenna other than that furnishedby the responsible party shall beused with the device . (SStransceiver)... The manufacturermay design the unit so that abroken antenna can be replacedby the user, but the use of astandard antenna jack or electricalconnector is prohibited. . . ..Thisrequirement does not apply tointentional radiators that must beprofessionally installed.”

The intent of these Rules is toprevent the use of high gainantennas which would cause theoperation to have an EffectiveIsotropic Radiated Power (EIRP)of more than 6 dBi.The FCCbelieves an EIRP of 6 dBi willnot cause heavy interference withthe priority users assigned to the915 band.

An isotropic radiator whichradiates equally in all directionsis used as the theoreticalreference antenna in FCC Part15.247 (b). Such an antenna isnot physically realizable. So theisotropic value must be convertedto a dipole value by subtracting2.15 dB.

This Rule says you can radiate upto, but not more than 6 dBi timesone watt. This is 4 watts above

isotropic when using directionalantennas. The FCC may just aswell have stated this as 3.85 dBabove a dipole, since 3.85 dBd isthe same as 6.0 dBi. And 3.85dBd in power over one watt is2.4266 watts.

Lets take a practical example. Wehave a directional Yagi to beused above the building, with arated gain of 9.0 dBd. The 50foot coaxial line run has a loss of2.125 dB at 915 MHz. Antennagain of 9.0 minus 2.125 line lossequals antenna system net gain of6.875 dB. Maximum allowableantenna system input poweroutput from the SS transceiver is3.85 dB minus 6.875 dB. This is-3.025 dB below one watt. Minus3.025 dB is equal to 0.498percent of one watt. (498milliwatts)

Lets work this forward for proof.The 50 foot of line allows 61.3percent of the 498 milliwatts toreach the antenna. This is 305milliwatts or 0.305 watts. The 9.0dB antenna power gain multiplieris 7.94 times 0.305 watts equals2.422 watts radiated. And 2.422watts is equal to 3.843 dBw,close enough to maximumallowable of 3.85 dBw.

CONCLUSIONS:

The maximum allowable ERP islimited to 2.422 watts when usinga directional SS antenna. Powerratio of 2.422 is also 3.85 dBabove 1 watt, which may also beexpressed as 3.85 dBw. Thisvalue is also 6.0 dB overisotropic (6.0 dBi) The 6 dBi and3.85 dBd are equal.

orizontal polarization is best inle 915 MHz band in most partsf the country. Linear vertical,ant, dual, and circularalarization may also be used asjng as the radiated power with:ference to a half wave dipoleoes not exceed 2.422 watts.

lext month we’ll cover methodsf converting from radiated field:rengths in microvolts per meter1s often specified by the FCC)I radiated power at a given-equency for typical SS antenna@es.

lhout t he au thor : Peterkvzigian, President of Hum-Pro‘ntennas, is a registeredrofessional engineer with manyears of antenna design andzarufacturing experience. His‘acramento b a s e d H u m - P r o!ntennus makes wideband 450nd 91.5 MHz spread spectrumntennas in addition to a line ofmateur monobanders -for VHF,nd HF operation.

ANTENNAS

4 new line of Yagi antennas wasmnounced by Ham-Pro Antennas,1 division of Kopps Corporation,n Sacramento. They are idea1 for;pread spectrum, wireless alarms,automated data collection, wirelessirea networks and other FCC Part15 services, where a low power:conomical antenna is desired.

.l Spread Spectrum Scene September, lYY2

DSPfor

Spread Spectrum

by Matthew Johnson

Conclusion of the BasicAll-Purpose Digital Signal

Processor DiscussionLast month we presented

more discussion of the concept of the“BADSP.” This month we concludethis introductory DSP discussion.Remember the BADSP block diagram(shown the last two months)? Wenow discuss the remaining two blocks,the whimsically named NumberCruncher does whatever processing isrequired to extract the desiredinformation from the digitized signal.This c o u l d b e the digi ta limplementation of a familiar functionfrom the analog world, such asbandpass filters or notch filters; itcould be a non-linear filter without ananalog counterpart, such as the medianfilter. Since no information is lost inthe digitization, your imagination isthe limit!

Finally, the name I chose forthe last block makes a more limitingassumption about the intendedapplication of the BADSP. The name“Reconstruction Filter” assumes youare using the BADSP to reconstruct ananalog signal out of your processeddigital signal. For example, if theNumber Cruncher is the identityfunction, i. e. it passes input to outputunchanged, then the ReconstructionFilter takes the Staircase response of aDAC and smooths it out to reconstructthe continuously varying analog signalrepresented by that staircase signal.But this requires a physicallyunrealizable filter, one with thetransfer function:

H(Q) = sync(( l/2)QT)e(“2)R’w h e n 1 S’2 1 < 7~12H(Q) = 0 when 1 S2 1 > n/2

where sync(x) = (sin(x))/x, T =snc

rmpling per iod, S2=2nf, t h eormalized frequency.

ttf’

bI(hbCl

nSi

n1’Efiftln

Here is another exercise for‘e reader: sketch the transfermction.

In practice following thelumber Cruncher, we usually have a)w pass filter with cutoff below theIyquist frequency. Of course, thislock, like the Anti-Aliasing filter,onsists of analog components, so Ilight deliberately choose a highampling frequency just to ease theequirements on this filter! Now that‘ve covered all the blocks of theLADSP, I will discuss the interestingeatures of the new digital proposalor HDTV, with some comparisons tohe previous analog proposals -- nextnonth.

(From the WSYI Report - Sept. 1992)

New electromagnetic compatibility(EMC) regulations coming to

Great Britain and the EuropeanCommunity.

A new European CommunityEMC Di rec t i ve (89/336/EEC)requires manufacturers of virtually allelectrical and electronic equipmentand their authorized representativesto ensure that the products they sellin the Community comply with EMCprotection requirements.

Manufacturers must constructtheir products so that (a) the“electromagnetic disturbancegenerated does not exceed a levela l l o w i n g r a d i o a n dtelecommunications equipment andother apparatus to operate as intendedand (b) products have an “adequatelevel of intrinsic immunity toelectromagnetic disturbance” to

enable it to operate as intended.

athNb:mtr;SC

EalE.hce:C(

tr

bI

irc

Approved products will carry“CE” approval marking, even ifey are sold in the UK only.on-compliant products will beumed from the marketplace. The:w rules go into effect after aansitional period - current ly:heduled for the end of 1995.

Each m e m b e r o f theuropean Community will assign an;ency t o i s s u e Eh4C T y p examination Certificates. Whileome-brew ham radio rigs aretempt from the new directive,>mmercially available amateur radioansmitters will require an EMC‘pe examination certificate. (Source:992 Radiocommunications Agencytformation sheet, London, England.K)

1

The dust has just settlediom the two major parties,olitical conventions, H. Ross‘erot still can’t decide to run orlot and much of Washington isitill out to lunch, but the FCC isrtill busy with its own NO1notice of inquiry) on PCS. Howvi11 this all turn out? Will theIhone companies, cable companies)r other common carriers pick upnieces of the 1.8 to 2.4 GHzland? Time and political vagarieswill certainly decide these criticalIssues. We feel its time to “playhntle” and wait to see how it allturns out. You might do some5readboarding or re-tune some of{our 2.45 GHz equipment down a‘ew hundred MHz -- but don’taunch any new products yet!

September, 1992 Spread Spectrum Scene 5

Most Serial CommunicationControllers are intended to be used in some sortof wired environment. I say this mainly becausethe ConboIlers seem to be really capitalize onbeing able to use certain encoding schemes whentransmitting the data. Most of which cannot beused with a radio modem because of bandwidthlimitations. This can cause some minorproblems when adapting for use with a radiomodem, one of which I will go into here.

Ideally the SCC likes to use a dataencoding scheme that will embed the clockwithin the data. FM1 , FMO, and Manchester area few examples of this. However, this requirestwice as much bandwidth when modulating acarrier than a NRZ or NRZI encoded signal.The 8530 SCC that I am familiar with pmvidesa Digital Phase Locked Loop to do clockrecovery when us ing NRZ or NRZI sorecovering the clock is not a real problem.When you start looking at how an abort ishandled, the plot of the story begins to thicken.

An abort sequence is define as eightconsecutive “1 s” being transmitted. A conditionthat would normally not exist because of thezero insertion mechanism of the XC. Tile ideabehind the abort function is if the packets tend tobe very large and an error occurs on the transmitside of the link, the !mnsmitter has a way oftelling the receiver that the packet is bad,disregard and immediately set up 10 receiveagain. This starts to get a little sticky whenusing wireless modems. With FMl, FMO, orh4anchester encoding, you always have at leastone transition per bit. However, with NIU orNRZI encoding, a zero or one can be asteady-state condition and an idle line can looka lot like a continuous stream of aborts. Well, Inever intended to use the abort fimction so howabout I just don’t enable abort interrupts andign,>re them? That works line until the firsttime you suffer a loss of carrier in the middle ofa packet. l‘his is a problem because of the waythe SCC handles abort, whether the intcmipt isenabled or not’

The data line on a RF modem isusually squelched when canier is lost If it ir.squrlched m the pmper polarity such that i!looks like a ‘1’ to the XC, it is intcrprcted as arabort. The SCC, upon receiving an abort, wilinuncdiatcly return to ‘HUNT’ mode and bcready 10 receive again. The CK(: checker i:rc~t and everything looks just line. 1 loweverI)hU has written the first part of the packet intonwrnory and unless the DMA counte r an<p~~mlcr is reset, it will stari wriling the n c x

Placket onto the end of the partial first packet.1llis will continue on until a valid EOF isTeceived by the SCC. This can make for somee:xtremely long packets if the carrier is droppingcBut frequently. If you enable the abort intermpt,4IOU will be deluged with interrupts at the end ofevery packet when the line goes idle.

a

I‘

‘

t

t

11,

t

So, you need to either 1) enable theshort interrupt only after a valid sync character1a.s been received and disable it after the EOF isfete&d. These interrupts must be servicedquickly if the packet size is small. Or you could2) make sure that the polarity of the squelchedhta line is the opposite of a ‘1’ when using NRZmcodmg. NRZI is not an option here because3olarity doesn’t malter. Unfortunately thehardware I received was in the worse possibleconfiguration causing me to use solution number1 and write everything in assembly to be fastenough. Even then, I would sufFer around 50abort interrupts at the end of every packet before1 could disable it. To work around this 1 foundthat 1 could set a ‘active-receive’ flag faster thanI could disable the interrupt so the state of thisflag determined how I processed the abortinterrupt. If I had received the EOF I would justreturn from any abort intern@. This wouldcontinue until I received another sync interrupt.If an abort was detected, the SCC and DMAwere set up to receive again. The rest of thepacket would be ignored because a synccharacter was not received and worse case theflag at the end of the packet would cause a syncintern@ immediately followed by an abort. Theabort would cause the SCC and DMA to besetup again to receive after which the line wouldhave finally gone idle.

T h e n e w Signetics UMA1014T c h i pprovides a cost-effective solution for newhattery powered SS frequency synthesis.

The new MAXIM MAX291 family of 8thorder low pass filters for less than $3.00.

The new Maxim MAX910 4ns SOICcomparator with digital threshold setting.

6 Spread Spectrum Scene September, 1992

Introduction toThe Navy’s

PANSATProject

by Randy Roberts,KC6YJY & RFlSS Director

The author visited the NavalPostgraduate School (NPS) in Monterqv,California on July 28, 1992. Randy wasgraciously hosted by Professor RudyPanhoIzer, PANSAT P r i n c i p a lInvatigator and his staf, Most qf ourquestions about PANSATand how it willoperate were answered at a weeklydevelopment/project status rrrviewm e e t i n g chakd by PANSAT ProjeclL e a d , Profssor E d Euler: Thefollowing article highlights the mission,current status and plans for the 1995launch of PANSAT.

The NPS is situated in abeautiful part of the Monterey peninsulaand is the home of the Navy’sprestigious graduate school for its c,areerofficers. Rear Admiral Ralph W. WestJr., USN, Superintendent, NavalPostgraduate School described NPS inthe May/June, 199 1 issue of “Defense9 I ” mag‘azine:“The Naval Postgraduate School inMonterey, Calif., was created to keepthe Navy abre‘ast of critical new tech-

nologies. The institution, a fully ac-Credited graduate university, providesr:igorous, fast-paced and challengingacademic programs along with analpportunity to work directly with afhculty that has earned acclaim for itsexpertise in science, engineering,nnanagement and national securityaIffairs. Its programs are available toCofficers from all U.S. services andfiiendly nations to prepare them fortethnical and strategic leadership rolesin the 21st century.”

Rear Adm. West goes on to:xplain the curriculum emphasis at NPS:‘At the heart of the Naval Postgraduate3chool are its curricular programs,which blend service needs and academicigor. Most curricula integrate severalacademic disciplines to address specialmilitary requirements and applicationsFor example, some of the school’sprograms focus on broad technical andengineering education, physical fun-damentals and analytical concepts thatgovern operational use of militaryplatforms, sensors and weapons systems;and current electronics technology andits application to modem warfare,including DOD command, control andcommunications systems.”

PANSAT ProjectIntroduction

PANSAT is the acronym for“Petite Amateur Navy Satellite”. TheNavy’s experiment is listed asExperiment Number NPS-901. Thebasic concept of PANSAT is to storeand forward a packetized uplink mes-sage until the destination station is inview of the satellite and then re-tmnsmitthe message on the downlink. ThusPANSAT will be functionally anotherPacsat -- the big difference is the signalsneeded to access the satellite will beSpread Spectrum (SS), with direct se-quence modulation. The primary mili-tary objective of the experiment is tosignificantly enhance the education ofmilitary officers in the NPS’s SpaceSystems Curricula by the design, fabri-cation, testing and operation of a low-cost, low e,arth orbit (LEO), digitalcommunications satellite. PANSAT willalso demonstrate the feasibility of asimple,low-cost communicationsatellitefeaturing:

1

I I

l Digital o v e r - t h e - h o r i z o nC:ommunicationst) Orbital mailbox conceptt) Low probability-of-intercept4) Low probability-of-jamming

CONCEPT

PANSAT engineering objectivesinclude:(1) Evaluate the performance of spreadspectrum packet radio communicationsusing amateur community as the userbase.(2) Provide an experiment platform toresearch an innovative method ofmeasuring solar cell parameters andsensing sun direction.The preliminary PANSAT launch date islate in 1995 -- of course, militarypriorities and funding may slip thissomewhat. The actual satellite willweigh about 150 pounds and be about19 inches in diameter. Thecommunications payload is envisionedto be a 1200 Bit Per Second, AX.25protocol, Direct Sequence SpreadSpectrum receiver / demodulator /remodulator / transmitter operating ne<ar437.25 MHz with 1 MHz bandwidth andfull duplex data links. The actual on-the-air modulation type to be used is thesubject of four different Master’sdegree theses -- the best performingmodulation and most cost effectiveground station demodulator willprobably be selected for PANSAT’s on-the-air signal modulation.

Concludes next month

September, 1992 Spread Spectrum Scene I

What RF/Spread Spectrum Does

SSS is published by RF/Spread Spectrum(RF/SS for short). RF/SS is headed up byRandy Roberts, the publisher of SSS. RF/SSis an independent consulting and productdevelopment firm with a staff of severalhighly experienced engineers, programmers,systems designers, strategic marketeers andproject managers. RF/SS is poised to helpthe evolving PCS and Spread Spectrumindustries define, develop and marketprofitable new products. Call us at (415)726-6235 or FAX us at (415) 726-0118 for asummary of our capabilities, experience andstaff specialties.

RF/Spread SpectrumP.0 Box 2199

El Granada, CA 94018-2199

Finallv: Another DanDobcrstein Idea Article on aGeneral Purpose SS Radio(GPSSR) for commercial ,industrial or ham use, designedaround the 49 MHz cordlesstelephone chips.

Interestintz: More on DSP,“Secret” Signals, The Aerialand Technical Education inour columns.

Conclusion: Final part of thea r t i c l e o n t h e N a v yP o s t g r a d u a t e S c h o o l ,Monterey, CA, PANSATsatellite for ham radio & Navyuse, due for launch in ‘YS.

News: Latest news on TheSpectrum Auction, H. R. 73a n d o t h e r l e g i s l a t i v edevelopments.

@p@gJ@J

c3p2x3Gmm Q&ii%xm@An RFISS Publication

P. 0. Box 2199El Granada, CA 94018-2199

FORWARDING & ADDRESSCORRECTION REQUESTED

FIRST CLASSMAIL

U.S. POSTAGEPAID

PERMIT NO. 17SANTA CRUZ, CA

.