speleonics

SOUR POWER AT

A CAYE RESEARCH

fIELD STATION

page 4

o1

(J)

7 19B7

SPRING

"BETTER c~v:~~ T~ , -.- -.'

. .... . ~ '1(~;.],? I r nunbe"- 3

-'~J 00

"r,! y}l }'Y')L" J

DOUBLE-SIDEBAND

~O"CE CAYE RADIO

Tf:ANSCEI VER FROM

'~-)"1"

~ ,

00LJ-,

~.; },

!/

/

SPELEONICS 7

ANIIOUNCEJlENTS

Info. Wanted: Cavemobile ElectronicsErr a t um . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

LETTERSIan DrummondDick GloverJim McConkeyWWVBinformation. ... .2,3

EHERIiEICYWATCH-REPAIR FOR CAYERSFrank Re1d 3

WHERE THE SUI SOMETIMES SHIIES: SOLAR POWERAT A CAVE RESEARCH FIELD STATION

Howard A. Hurtt, KB6KSO 4

CAVE RADIO M-85Bo Lenander, SM5CJW 8

MAGJlETlC MIIMEUS 15: THE PllASE PROBLEMIan Drummond ll

ORP TRAISMITTII' AID RECEIIIIIG 011800-1000 Hz (J05.000 meters!) [reprint]

Rick Wright 13

Vo1ume II number 3 Winter-Spring 1987-87

COIlTENTS

RESOURCES 14

RADON MONITORIIIG III CAVESSteven Clark 15

RADON SAMPlIIG III THE MAMMOTH CAVE SYSTEM

\mi. Karl Pitts"."""...""""""."",,16

Publication reviews:THE OGOFDNE [BCRA Caves & Caving]NPS RADIO FREQS [Popular Communications] 16

Rescue communications:PHONE PATCH COIIIECTSCAVE TO HOSPITALS

Fran k Re i d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

CAVE RESCUE COMMUNICATIONS EQUIPMENT CHECKlIST..18

Abstracts (1987 NSS Convention papers):IMPROVING THE ORGAN CAVE RADIO

Ray Co1eIMPROVISED TELEPHONES FOR CAVE RESCUE

Frank Reid 18

Humor:IAT POWERpatch lBNC.. . . . . . . .. . . . . . . . ... . . . . . . . .. . . . .. .. . .. ... .3

-=-=-=-=-~-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Modified .CAT DIESEL POWER" patch

(originator unknown)

.--------------------------------.---.-----------

(Top): Dave Zoldoste inspects the photovoltaicarray that powers radio, cave telephone, andinstrumentation at the Cave Research Foundation'sstudy site at Lilburn Cave in Kings Canyon Nation-al Park, California. The installation is 130 feetup in a fir tree. [See article by Howard Hurtt]

ANIIOUNCEllEILTS

Information lIanted: CAVEMOBILE ELECTRONICS

Many cavers spend more time travelling to and fromcaves than they spend undergro'und. If you haveunique ways for making this most dangerous phaseof caving safer or more pleasant, please write anarticle or send a letter to the editor. We'd liketo hear about radios, sound systems, lights, radardetectors, navigation, heaters, coolers, auxiliarypower systems, anti-theft systems, also ingeniousnonelectric devices or strategies (tools, safetyequipment, ways to hide valuables, etc.).

ERRATUM

We apologize for omitting Mexico from the list ofcountries represented by our foreign members[SPELEONICS 6].

COVER -------------------------------------------------

(Bottom:) Swedish caver 10 lenander's 32-kHzdouble-sideband cave radio (top view, actualsize). The 6.4cm-thick unit contains the battery.Complete plans in this issue!

1

Dear Frank. 87-01-20

...Ju1ian Coward and myself are about to makesome more ASS Cave Radios [SPELEONICS5J, so wewill be getting a batch of PC boards made-up. Wewill sell extra sets at cost, so if you know ofanyone who is interested, tell them to write.

I tested my "giant" antennas last weekend.Using 10 watts PEP, we were able to get two-wayspeech between two points on the surface, one 480m abo'e the other with 1100 m separating the twosites. The 13 m square antennas are not moveable,of course, so there was no rotation to try and getan optimum orientation. We just slapped them downand turned on. I am hoping to try them in Cast1e-guard this spring. We can get about 550 ~ depthat one point in the cave. At this range andfrequency we will have lost the classic direc-tional properties of the magnetic field, so thegiant antennas are only of use for communicationand not for surveying.

Ian DrU8llond 5619 Da1wood Way NWCalgary, Alberta

CANADA T3A lS6--------------------------------------------------Dear Ian, 28-Jan-87

As you know, I have been interested in the devel-opment of rel iab1e and "idiot-proof" cave radiosystems for over 20 years, but it is only withinthe last 10 years that advances in micro-electronics have resulted in the availability ofsmall, light-weight and cheap integrated circuitsfor use in low frequency magnetic induction two-way speech systems.

While working at Lancaster University in the1970's, I collaborated with... Bob Mackin todesign and build a prototype SSB system operatingat 102.4 kHz. and generating lOw of transmitterpower. We used 12-way ribbon cable, mounted oncollapsible X-shaped perspex frames, to give 1m by1m square loop antennae, for both underground andsurface sets. We experimented with this equip-ment, which we called the SPELEOPHONE, mainly inthe Gaping Gill system, and found that the rangefor both speech and tone... was in excess of 350feet, except where the surface was covered with anappreciable (10m) thickness of peat bog andglacial drift. This reduced the range signifi-cantly, to about 100~150 feet, due to the rela-tively high conductivity of the boggy groundcover... The other major limitation on range thatwe found was the occasional very high level of LRFsignal we encountered with the surface set, par-ticularly when operating on top of the limestonebenches in certain south-westerly facing Dales.We never positively identified the SOurce of theinterference, but assumed it to be some sort ofaircraft navigation beacon system, or VLF radar.The curious feature was the way the shape of thevalley appeared to focus the interference, almostas if the valley was acting as half a horn antenna!

In the late 70's, Bob Mackin and I parted com-pany... He was grant aided by Yorkshire Tele-vision to produce a version of the Spe1eophone foruse by cave divers, to enable Geoff Yeadon andOliver Statham to talk to the surface. and theirposition followed on the surface, while they com-pleted the Kingsdale Master Cave - Keld Head

.. II no. Jspel_lcs 7

Winter-Spring 1986-87

LETIERS

through dive. The dive was filmed by YorkshireTelevision as it happened, and later broadcast as"The Underground Eiger." ...We never publishedany details of the Spe1eophone, other than a briefabstract in the Proceedings of the 1977 SheffieldISU Conference.

Subsequently, Bob Mackin moved to the EngineeringDepartment at Lancaster, and enlisted their aid tofurther develop the system and market it, underthe name of the MOLEPHONE. This, I am told, canbe purchased from the Engineering Dept, for 1300-1400 Pounds + VAT, for a pair of sets, batteriesand loop aerials. At this price, only the grant-aided Northern Cave Rescue Organizations have beenable to buy it. However, both the Settle-IngletonCRO and the Upper Wharfedale Cave and Fell RescueOrganization now have several systems each, anduse them regularly both on practice and actualrescues. I am told that the equipment is soruggedized and reliable that it is taken forgranted, and that the rescue teams have pre-prepared lists of correlated surface and under-ground locations for all the major cave systems intheir respective areas. There is no doubt thatthe M01ephone now regularly plays an important andtime (and life) saving role in cave rescues in theYorkshire Dales.

I know of three recent British expeditions whichused... cave radios. Two were cave diving expedi-tions to Greece and Norway, both made in 1985, anddocumented in the Cave Diving Group Newsletter No.78, January 1986. Filmed reports of both wereshown on TV in this country late last year. Thethird expedition was last summer's CRO/Army visitto the Gouffre Berger and the Scia1et de 1a Froma-gere. I... will enquire as to what use was madeof the Mo1ephone during the expedition.

As far as I am aware, no use is being made inBritain of cave radio techniques for data transferfrom underground equipment or for measuring groundconductivity.

In May, June and July 1986, 3 parts of an articledescribing the TROGLOGRAPH,a CWcave radio systemtransmitting at 3.2768 kHz, and designed by MikeBedford, appeared in the British hobby electronicsmagazine ELECTRONICS TODAY INTERNATIONAL,published by Argosy Specialist Publications Ltd.,1 Golden Square London W1R 3AB. I contacted Mikethrough the editor, and found that he was a micro-electronics software/hardware engineer working...on CAD graphics display terminals... We have metseveral times since then, and I have given himcopies of all my articles etc., together withSPELEONICS Nos. 1-6. He is trying to re-createyour A.S.S. system using ICs currently availablein Britain, and operating at the Mo1ephone freq-uency... We hope to commence prototype testssometime this year. In particular, we want toexamine the spectrum in the 100-200 kHz band tofind the frequency with the least RF noise consis-tent with acceptable attenuation through limestonewith 5-10m bog and drift cover, and to experimentwith ribbon cable loop antennae to find a designgiving a depth range of 200m+without being toocumbersome. We will keep you posted...

One of the problems we face in this country whichdoes not appear to trouble you so much in NorthAmerica is one of licencing. It took me a lot oftime and a visit to London to get even a develop-

2

spe1eonfcs 7Y. ! I no. 3 wtnt@r-Sprfng 1986-81

(LETTERS continued)

ment licence for the Speleophone. and I do notknow what 1icencing arrangements are necessary forthe Molephone. Once I find out. I will let youknow so that the details can be published inSpeleonics. In addition. I will try to get ageneral article published in the BCRA Caves andCaving Bulletin mentioning- Speleonics. andrequesting all interested British cavers to get intouch with you and I and suggesting they becomesubscribers. We might end up with our ownspecialist BCRACommunications Section!

Rega rds. 258 CROSS FLATTS GROVE.BEESTON.

LEEDS LSll 7BS.Un ited Kingdom

Phone: (0523) 701062

[Sidebands of the 100.D-kHz LORAN-C navigationsystem (see SPELEONICS 5) might cause interfer-ence. The LDRAN transmitter nearest the BritishIsles is in West' Germany. There are 14 LORANstations in continental US (more are planned) and11 in Canada and Alaska. --F. Reid

Dick Glover

--------------------------------------------------Dear Frank.

Thanks for the Smart Compass plans [see SPELEONICS6]. I've ordered one of the coils to experimentwith. I d isassembl ed the code and found out howit works: T and L are sin 9 and cos 9. They aredivided in software to give tan 9 over 0-450. Anarctan is done via table lookup. corrected forquadrant. and displayed. The accuracy is ulti-mately limited by the coil winding accuracy (i.e..T & L are exactly 900 to each other). To get sub-degree accuracy will require a better A/D andbigger arctan lookup table. but that's easy. I'llkeep you posted.

Ji. McConkey 7304 Centennial Rd.Rockville. MD20855

Someone requested information on WWVB receivers.We lost the letter. but here are some references:

WWVBis a time/frequency-standard station operatedby the National Bureau of Standards at Fort Col-lins. Colorado. The 60-kHz frequency is rela-tively free of propagation-anomaly errors. Timeinformation is digitally encoded; see [2] below:

1. "A WWVB60 kHz Frequency Comparator Receiver"by Ernest P. Manly appared in 73 Magazine.Sept. 1972. The now-obsolete RTL integratedcircuits in this design can probably be re-placed with CMOS. It's similar in function tothe Hewlett-Packard 117A VLF Comparator but hasno phase-locked oscillator output.

2. Don Lancaster published plans for a 60-kHz WWVBreceiver with time-code output. in RadioElectronics magazine. August 1973. p~.Metnoas ot phase-locking are discussed.

3. "Low-Frequency Receiving Techniques." a seriesof articles by R. W. Burhans in RadioElectronics. March-July 1983. describes Stife-of-the-art LF/VLF active antennas. and a methodfor using LORAN-C(100 kHz) for time and freq-uency calibration. These are valuable refer-ences for cave-radio experimenters. A set ofreprints. with errata/addenda. is availablefrom the author for $4.00 postpaid:

Burhans Electronics161 Grosvenor st.Athens. Ohio 45701

Send SASE for catalog. See also Dr. Burhans'three-part article about Omega navigation receiv-ers (10-14 kHz) in Byte magazine, February. March.April. 1977. -

EMERIiE8CY WAltH-REPAIR FOR CAYERS

---------------------------------------------------------------------------------------------------------

Fran k Re id

I've successfully repaired several cavers' digitalwatches which failed after taking water duringcave trips. just by opening the cases (as soon aspossible). removing and drying the batteries. andputting the watch guts in a warm (not hot) placefor a few hours. An electric hand-dryer alsoworks-- A National Cave Rescue Seminar partici-pant was amazed to see an electronic watch re-paired in a National Park campground bathroom.using only a Swiss Army knife!

Clean all battery terminals and contacts beforereassembly (I use a pencil eraser). The onlydifficult part is making sure that pushbuttoncontacts are not bent during reassembly.

Here's more watch-repair advice. received through<rec.ham-radio> an international computer-maildistribution. It was signed "Joe N2XS":

When taking-apart digital watches it is importantnot to touch anything inside with your bare hands.The DNA from your skin is enough to cause a bad

contact. Almost all problems with digital watchesare contact or battery problems. Dampen a VCRcleaner swab or lint-free cloth with tuner-sprayand clean all visible contacts. Do not spray theinside directly from the can. Also. look for bentcontacts; they are very small and easily damaged.

---------------------------------------------------

YOU. TOO. CAN BE A BIG-lAME CAVER!

Just Xerox the above emblem on colored paper. cutout. glue onto an old political campaign button.an wear it at the NSS Convention!

3

WHERE THE SUN SOMETIMES SHIIES:SOLAR POWER AT A CAVE RESEARCH FIELD STATION

spe1_lu 1Y. /I no. J Winter-Spring 1986-87

Howard A. Hurtt, KB6KSO

Lilburn Cave in Kings Canyon National Park,California, has been known to cavers since themid-Fifties, and has been the subject of intensemapping and baseline scientific studies by th!Cave Research Foundation (CRF) since 1980. Lil-burn boasts 12 km of passage and a resurgence withbizarre chaotic ebb-and-flow characteristics.

The cave system's unusual hydrology was discov-ered in 1968, and instrumentation was completed atthe resurgence and at the terminal siphon in thecave in 1973. The equipment consisted of poten-tiometric pressure sensors controlling VCO's ateach location to convert water depth to frequency.This was landlined to a dual-track tape recorderat the fie1dhouse. Segments of the seven-dayrecord obtained were treated with a 2-channe1 "F/Vconverter to produce synchrograms of siphon andresurgence water levels.

Although the project was beset by problems,including lightning damage, destruction of surfacelines by animals and limb-fall, washing away ofthe resurgence instrumentation by record floods,and subsequent loss of the data tape, the siphonand resurgence water levels were proven to mirroreach other. In the bargain, the roughly 6,000feet of quad D (indoor telephone wire) runningfrom the siphon to the surface has remained inexcellent condition for 13 years.

The telemetry line has been used since 1975 aspart of a dry-line telephone system, and hasfailed only twice: once from corrosion at a twist-splice, and once from being mashed by a rockkicked loose by a caver high above. After astring of interim phone systems proved their meritin improving organization and safety in thishostile cave, it was decided that something moresubstantial and permanent be built.

Until 1980, reasonably stout vehicles could bedriven from the nearest paved road down sevenmiles of ruts leading to the door of the fieldstation. At this time, the NPS wisely began man-aging the area as wilderness, a policy which,among other things, excluded motors. This causedan immediate communication crisis. The projecthad been clipped into handy car batteries to runthe cave phone and also the re-tuned Systcoms VTR3mobile phones with which radio contact was main-tained with Park HQ. The cave phone was quicklyadapted to a 6V headlamp battery, which would runit all season. The mobile phone, however, withits 30Wall-tube transmitter, drained a motorcyclebattery every trip, which had to be packed in andout. Electric cavers had also become accustomedto recharging their head lamp batteries on thesite. Wedecided we had to either junk the dino-saur radio or learn to make our own electricity,or both.

POWERING DOWN

Project management cast about for proposals tosolve the problem of the power-hungry radio. Amini-hydroelectric plant operating at the resurg-e~ce was seriously considered until the fate ofthe telemetry line across the same route wasrecollected. There was also some concern aboutwhat NPS would think of the idea in a wilderness.

The outcome of that meeting was that we shouldthink in terms of powering-down so that at leastbatteries wouldn't have to be carried in as often.

Chris Royce, KF6IO, donated a Regency HR-2Btothe cause, expressing some doubt whether it couldbe tuned upward 20 MHzto the NPS frequency. Itcould, and the Systcoms was retired. A 3-elementYagi was assembled from 12-gauge (2.053 mm dia.)solid wire hidden in 3/4" Schedu1e-40 PVC. In the1.5 Wlow power mode, the Regency easily brings upthe NPS repeater on a ridge 9 miles away.

The radio was mated to the cave phone so thatthey shared a commonpower supply. The phone linewas matched to the receiver's audio amplifierinput and also to the microphone input, and re-ceiver audio was superimposed on the phone line(Figure 1). This provided something very muchlike a continuous phone patch. Although it hasnot been used in an emergency, the patch has beentested, and work well.

Eight taps were provided along the line in thecave, either at important intersections Qr nearparticularly obnoxious spots on main routes. Whena cave party clips a conventional phone handsetonto the parallel wire pair, a 40 mA current loopis completed which latches an SCR. This powers aring generator (Figure 2), which produces a high-low tone with about a 10 Hz shift rate, inter-rupted about every 2 seconds. This is heardloudly at the receiver speaker, and stays latcheduntil the field station handset is picked up.Picking up the field station handset completes thespeech loop, and also enables the transmitter andstarts a logging recorder.

The phone system uses two of the 4 conductorsin the D wire. The other two are reserved forinstrumentation.

THE POWER SUPPLY

The only sane power supply for the projectappeared to be solar. But where would we find sunin a mature forest where most of the trees werepushing 200 feet? The Lilburn field station is onthe flank of Redwood Mountain, home of the largestof the Giant Sequoia groves. Even a small tree inthese parts can be damn big, and cast a bigshadow. So why not put a solar collector up in atree? Ridiculous! You'd have to go up a hundredfeet or more, and the voltage drop in the down-leads would be unacceptable. Furthermore, themounting bracket would mutilate the tree.

"Not so," said Dave Zoldoske, who just happenedto know where he could get his hands on 200 feetof 6-gauge (4.115 mm) 2-conductor street lightwire. "Not so," added Mike Spiess, a masterwelder and former treetopper, who would build andinstall the gentlest of brackets, with turnbucklesto adjust for the growth of the tree.

With binoculars, clinometers, and well-temperedenthusiasm, we surveyed the five or six most like-ly trees near the field station. The winnerjumped out at us. On a slope about 20 feet southof the cabin was a majestic white fir with a 41inch diameter trunk. The tree had a distinctive

4

.pe1 tcs 7y. II no. ) Wlnhr-Sprlnv 1986-87

compensation curve from the creeping of the soilof the slope, but above was sound and straight.At about a hundred feet up, it looked as though agap in the canopy was illuminated over the tops ofadjacent shorter trees to the south for most ofthe day. We would have to climb it to be sure.

Spiess, dragging a measuring string and free-climbing the bark. got into the lowest branches 55feet off the ground. Here, at last, he could putsling loops around limbs for protection. He at-tained the gap in the canopy at 130 feet, andsurveyed the solar window. With the trimming of afew small interfering branches, it would be nearlyperfect. The trunk was 26 inches in diameter atthat point, and the top of the tree looked to beanother 60 to 70 feet higher. He put in a perm-anent anchor and retreated.

While the tree search was going on, I had beeninvestigating solar collectors. The first pricesheet I saw convinced me that we would have tocharm someone out of a collector. I put outseveral feelers, offering publicity in exchangefor samples. In January of 1983, Gabe Amaro ofARCOSolar International, Inc, responded. ARCOSolar publishes ARCOSolar News, a review of novelphotovoltaic ap'j3'T1CaTIOiiS.-Uurs sounded novelenough, and a week later we were caressing twoshiny new ARCOH-81 modules. These are half-ampcollectors designed to charge deep-cycle lead-acidbatteries. Amaro had also included plenty ofadvice on mounting, charge regulation, and light-ning protection. I turned over the collectors toSpiess for bracket fitting, and began work on thecharging circuitry.

We had bought a Donley 45 AHdeep-cycle batteryand packed it, fully charged, to the field stationin hopes of never having to carry it out again.It ran the communication gear for six months with-out recharging, then promptly came up to fullcharge when the photovoltaic system was attached.Since then, we have added a 105 AHbattery, andboth seem to be faring well.

The charging circuit (Figure 3) consists of aIN6096 Schottky as a blocking diode (Solar PowerCorp. 1980), and a comparator that pulls in arelay to add 5 ohms to the circuit to drop thecharge rate to a maintenance level of about 300 mAwhen the battery reaches 12.6 V (Byers 1984). Thenormal rate is about 900 mA.

As can be seen in Figure 4, most of the systemwiring is devoted to distribution and lightningprotection. There is a 12 V 20 A utility outleton the main panel, and also a 2A instrument poweroutlet with supplementary transient protection.In addition to the communication package, the 12 Vbus also runs two simple headlamp battery chargersand a 30 W self-inverting fluorescent light of thesort used in RV's. The fluorescent was an almostabsurd afterthought. It had been found in a trashbin behind a Winnebago dealership, tubes intact,with its switching transistor burned up from inad-equate heat dissipation. The transistor was justpop-riveted to the thin aluminum reflector. Forthe investment of a more substantial heat sink anda cheap generic transistor, we had acquired a veryefficient way to light the interior of the field-house.

Lightning is a big problem on Redwood Mountain.Warm, wet Pacific air is cooled as it goes up thewest slope of the Sierra Nevada, generating a line

of thunderstorms that can sometimes last forweeks. These storms often produce more electric-ity than water, resulting in frequent fires. Onereason NPS insists that we man a radio at thefield station is for reporting fires. We learnedour lesson about lightning in 1974 when thesurface telemetry line got blitzed, but instead ofretreating we went for technical countermeasures.

The surface line from the field station to theMeyer Entrance, a distance of about half a kilo-meter, was replaced with two parallel runs of 2-conductor copperclad drop wire. This is theabundant, cheap, and tough material used to bringphone service from pole to house. It is miserableto work with, but holds up well against fallinglimbs and gnawing forest fauna. Where the surfaceline enters the fieldhouse, it is attached toWestern Electric signal circuit protectors, as isthe drop wire that enters homes. These are fuse-like devices that respond to spikes of 200 V ormore, shorting the offending line to earth untilthe element is replaced. Signal circuit protect-ors are also used at the fieldhouse tiepoints ofthe solar collector downleads.

Three other types of transient protection areused in the power and landline systems. Where thesolar collector leads enter the distributionpanel, a TII-317A surge arrestor, provided by ARCOprotects both positive and negative leads. Thisis a gas-filled spark gap which fires at about 60V, momentarily shorting the lead to ground. Down-stream of the 317A is an LC network within buffersany voltage with a risetime shorter than about 2.5microseconds. As the telemetry lines enter thepanel, they pass through quick-blow 250 mAinstru-mentat ion fuses, and are then bypassed to groundwith 130-V MOV's. Downstream are LC networks. Ifeither the MOVor the bypass capacitor of the LCpasses substantial current, the fuse will beopened, and subsequent injury to the system pre-vented.

Although some parts of the design may seemcrude by contemporary standards, this system hasbeen in operation for more than five years, andhas yet to suffer even so much as a blown fuse.This testifies either to the robustness of thedesign or to an unseasonable lack of lightningactivity. The ability to recharge caving headlampbatteries using solar power at a long-term caveresearch project site is, as far as we know,unprecedented. It also lends a prosaic twist tothe line in the well-known cave ballad.

I would like to hear from anyone else withexperiences or comments on unusual applications ofphotovoltaics. I believe that, once one getsaccess to the collectors, the rest is easy. Par-ticularly welcome would be commentary and criti-cism of this system.

Correspondence should be addressed to:

H.A. Hurtt4763 E. Illinois Ave.Fresno, CA 93702

BIBLIOGRAPHY

Byers, T. J. 1984. A photovoltaic battery-chargecontroller. Mother Earth News 1984 (2):98-100.

Solar Power Corporation. 1980. Solar electricgenerator systems. Anon. pamph., 11 pp.

5

-f :YT PATCH BOARD -=,..-------.,:WT 5110 .I

:§I

IRE.'JJyI

IlKI ;;1 I .1~_.J

BLE1r,

7.51<.c.7K l1liSET AU! Figure 1

COMMUNICATION CONSOLE

1.51< r f- r~-__L.J t ,i E..

SET l1li ALS ~: PCIM-IIIIR C1.DCX AD :1 I: E- IJ=

1~- ---------------------

P IEm ALARM

IlK

1I.2V 100220

HANDSIOT

--'-

I

II04ITOR GAIN

,OO~ ~

=J

"1~. ,~

r~ --- ~_J ~I.

KEY &+ /.A.: LATCH ! C . VI

P+ A1

1 IA~ § :

I11II1IIE- 1

I 1I II ,

~ I I- ~ ~

6i!N

TONE GelERA TDR BOARD

-

spel-1cs 1Y. II no. J I/lnter-Sprlng 1986-87

] rn_~on:

LJ' LDV1 I,I

, KEY PO'1ER I

: ~HIGHI II

'1 II II1,11

: 1R-2B MOOC/OI1,1,I111I1I1II

I«JRM :1I

..::r: E"1,,

r1 E--,-= 1,

II11

II1IIJ= IN

TRAHSCElVER

RCVR

GAIN

.I1

.

8:

sa..e..cH1

.1I

1,I1I1,,,1I,,11,I

SPI( 0tfT :

~ l--:::". l PAD

IlKVI

UIIJS ARE CHASSI S CX»O«JN or. P'HONElllE ~ liMIT lit: RESISTORS

Figure 2

TONE GENERATOR BOARD

II(

f£P 1218

LATCH

P+

2.21<101(

TP -:I.'01

.01II(I(

lOOK

&+

-

-6

.12K

Bl.RST

0tfT

RIIt:

LEVEL

.1

21<

BUm'LEVEL

spe11!01IIcs 1Y. 11 no. 3 \lInter-SprIng 1986-87

Fi gure 3

CHARGE REGULATOR

470

OUT

IN6096

IN

470 2.2 k33 k

1M "normal"

50 k IIpeaki ng"

470

33k

10, II, 12, 13.

Figure 4

SOLAR GENERATING SYSTEMR y

.V

PIIJIoE LIIoE

PROTECTION/DISTRIBUTION PANEL PIIJN£ LINE PROTECT CKT.

ICF4

luHJUllPER BlOCK

.0015

R

}~ B PIIJIoE

~ C LINE

~ Y

BDATA

~ } CONSOLE

560

BCONSOLE

'--y--IARRAY

'-r-'EARTH

COPDI-lSOLA'IE)

a..osED-£AATIED)GROUND A

BATTERY

OiASS I S COMMON-::-

. -IFF IEXT . . CHARGERS

ARRAY. CJATA LINE CURR

SWITCH POSITIONS

UTILITY

().JTLET

INSTRUEWT

WTI.£T

7

I1NTEfo/N/1

C>M/C

LH386EX/.

"PKI<.

01/

~eN

SLI{,21

flGe

CAYE RADIO M-85

spe11!01t1cs 1v. II no. J ~1nt.r-Spr1ng 198t-81

Bo Lenander, SM5CJW*

After years of calculation, experiments andjust making the equipment, it is ready-- an easy-to-use direction-finding and communicating device!This equipment uses double-sideband (DSB) trans-mission/reception; the informationless carrier isgreatly reduced and takes less energy from thebatteries. The cave and surface units are ident-ical and weigh 700 g, including batteries. Theantenna weighs an additional 600-1350 g. Trans-mitter peak pover is about 1.5 U and the frequency1s 32768 Hz. The microphone input has automaticlevel control with long decay-time so the modula-tion level will be the same if you are whisperingor shouting into the microphone. The receiveralso has audio AGC, with a decay time of about 1second and that is very convenient when using itfor direction finding. An external headphone canbe used in noisy environments, and then the built-in speaker operates only as a microphone. Speechquality is comparable to MWor LWbroadcast sta-tions. Each unit has eight 1.5 V, size R6 (or AA)alkaline cells. The units are not completelywaterproof, but water resistant. The p-c board isprotected by lacquer and all switches are magnet-ically controlled and glass-encapsulated. Eachunit consists of 13 IC's, 10 transistors and 106other components on a printed-circuit board, 60 x115 RID.

A Short Description of the Function:

ON/OFF is controlled by a relay and indicated by aLED. The high-current double contacts of therelay connect to a 6-volt regulator. A distrib-uting circuit gives voltage to the transmitterwhen the T-button is pressed, and to the receiverwhen the T-button is released. Pushbutton Aactivates a pulse-generator controlling a tonegenerator, making a sequence of short tone bursts.Pushbutton TOlE is used as a key to send morsecode. A microphone amplifier with automatic levelcontrol feeds the balanced modulator. The carrieroscillator is built around an electronic watch

Stab.

118M()(,+

2Jv+3.

2J.i2'ilH

..-/2v )T

I

8~ 1,5V:

1,8AJi:

I

TOV

+

St15CJW,tf/IfTEN NA

32768 Hi!

11-85

crystal, and is used for both reception and trans-mission. The transmitter PA is an audio amplifierIC that has proved useful up to 100 kHz. Thereceiver input is high-impedance and therefore theQ-value of the antenna is high, giving good sensi-tivity and good signal/noise ratio. The twofollowing amplifiers are AGC-controlled. A reson-ant circuit between the amplifiers reduces the HFbandwidth. The demodulator is the same type ofcircuit as the modulator. An audio bandpassfilter with an amplifier drives the audio outputstage and the AGCcircuit. Microphone input andreceiver antenna are not disconnected duringtransmission, therefore, the transmitter andreceiver inputs have protection circuits. Allmicrocircuits of type SL are made by Plessey,for professional communicatrOn equipment.

Antennas:

Two antennas have been made for use in caves.One is a shielded 18-wire cable connected as an18-turn receiver coil with 1 m diameter. Theshield (1 turn) is then used as the transmittercoil. This foldable antenna weighs 1000 g and canbe used for cORlDunication up to 200 m distance.The other underground antenna is made of 12ferrite rods (0 = 10 RID, L = 200 mm) in a bundl ewith a 300-turn receiver coil and a two-turntransmitter coil wound on it. A spirit bubblelevel is mounted in the end, making it easy toorient the antenna vertically when using thedirection-finding mode. This antenna weighs 1350g and can be used for cORlDunication to 80 m dist-ance. The surface unit has a loop antenna of 420mm diameter with a 300-turn receiver and I-turntransmitter coil. The weight of this loop antennais 600 g and it is very useful for directionfinding.

* Kultyxgatan 16S-723 51Vasteras, SWEDEN

Block Diagram

8

'..,' "U'Ij (~ I

"- ---~

Note that some' plns of the res have been cut

T II

.f-...

. +-

+-

+-

...

...

t ... ... ...

+-

+-t

+

+-

+-... .. .f-

++-

... +-..

+

... T + +-...

...

+"''''

II

...'"

'..:

..'"+... 4- t

~i... ...

+-

"...

... ...

....f-

+. +-

. t

. +-

. + . +t t'.. + + +...

... +

10

40

0z...'"..o-'2

20

speleo.tcs 1v. II no. 3 I/tnter~Sprtno 1986-81

MAGNETIC MOMENTS '5:

by Ian DrulllTlond

THE PHASE PROBLEM

Many discussions of cave radio technology havecentred on the problem of obtaining maximum rangeby choosing an "ideal frequency" of operation.

The earliest work recognised that the lower thefrequency, the less the attenuation of the mag-netic field by the conductive rock, but littlerecognition was given to the effect of atmosphericnoise. In 1970 Nevin Davis published a quantitat-ive model (1) which predicted among other thingsthat frequencies as high is 1.8 MHz would beuseful for voice communicition. Davis actuallymade the pessimistic assumption thit the magneticfield was subject to exponential attenuation bythe earth. In fact the weakening of the signal isless severe, and consequently the higher freq-uencies will be even more useful than Davispredicted.

A very useful description of the work done bythe US Bureau of Mines is reported by Linfield (2)and gives optimum frequency curves for CW (Morse)signals (Fig. 1). Similar curves could be devel-oped for voice cOlllTlunication. Linfield reportsthe best frequency for voice communication, whenlimited by mine electrical noise, is 30-40 kHz at100 m depth.

I~ 80

60

o~a:

~~ ,0'ua:lono::I

~oS 10ofz..;;;

0.3

300m

o10'0.3

10.10'

-20

10'10'FREQUENCY.H.

10'

Figure 1. Ratio of magnetic field strength toatmospheric noise on the surface directly over atransmitting loop with magnetic moment of 1000(amp.turns.sq metres). Receiver bandwidth is 10Hz. Path 1engths of 100 m and 300 m are shown,with ground conductivity of 0.001 - 0.3 mho/m.

My conclusion from all this information is thatpractical communication systems can work at depthsexceeding 100 m for a wide range of frequencies,from 3 kHz (CW) to over 100 kHz for voice.

There is, however, a further problem not con-sidered in the above models, which may influencethe choice of frequency for a cave radio system.I call it The Phase Problem, and it arises becauseof the way-cavers use the geometry of the magneticfield to locate the position and depth of thetransmitter. All the current methods (3,4) relyon rotation of a loop antenna until no signal isdetected, at which time the plane of the loop isparallel to the oscillating magnetic field. Un-fortunately the effect of the conductive ground isnot just to weaken the intensity of the magneticfield, but also to induce a component which is outof phase. As a result the magnetic field on thesurface above the cave is no longer plane-polarized, but rotating. Its directional charac-teristics are weakened and a broad signal minimumonly can be detected. This effect is more markedwith increasing depth of the transmitter and withincreasing distance on the surface from the null-point above the transmitter. The effect canbecome so extreme that all directional sense inthe signal is lost and a strong signal is receivedwhichever way the antenna is rotated. The effectis much more noticeable when measuring depth thanwhen locating the null-point with the antennaplane vertical.

Based on my own experience with the ASS caveradio operating at 115 kHz, I feel I can getreliable null locations to depths of 150-200 m,but depth determination is difficult when theantenna is deeper than 100 m. Even when theantenna is shallower, there is difficulty gettingdirectional signals at horizontal distances ex-ceeding 2x the depth from the null-point (althoughvoice communication is perfectly clear).

The subject has been treated theoretically byJ.R. Wait (5). Two graphs from the paper areshown here (Figs 2 & 3). The conventional methodof measuring depth assumes H = 0, and P/Q ismeasured directly as 1/Tangent(antenna angle atnull}. In the real world, as H increases (due toincreasing depth of transmitter, or increasingconductivity of the ground) the null angle of theantenna is harder to detect as the phase angle ofP/Q deviates from 00 or 1800 (Fig 3). Moreover,the value of P/Q estimated from the angle ofminimum signal gives increasing error in the depthestimate if it is used in the equations whichassume H = O. (Fig. 2)

All these effects are minimized if the surfacereceiver is near the null-point on the surface (D= O). Therefore if the operator of a cave radio

11

100

SO H'O 180H-O<1

16020

14010

:: 1205

..e;.

-0..°100~.:

2 '0~80

1.0

Q5

Q2PlIo.. (PIOI-36O", H-IO

GIO O!l to l:i 3Ii

does observe these problems, at present the bestsolution is to move closer to the null point.This may involve a box-search of an area if thesignals have no directiona1ity at all, as hashappened to me on occasion.

Conclusion. As radios improve and their rangeextends, new considerations will determine the

Figure 2. The ratio of the horizontal/verticalmagnetic fields on the surface over a horizontalburied loop antenna.

D = horizontal distance from null-point/depth ofthe transmitter.

H = 1.414 x (depth/skin depth)0.0028 x depth(m) x (conductivity x frequency)(See Speleonics I 1 for skin depth concept.)

The classical method of depth determinationassumes the frequency = 0 and therefore H = O.

References----------(1) Davis N. Optimum frequencies for underground

radio communication. Nat. Speleo. Soc. Bul-letin Vol 32, II, 11-26 (1970)

(2 ) Linfield R.F. An Overview ofCommunications. WestinghouseLaboratory, Boulder, Colorado

UndergroundGeoresearch

(3) Mixon W.. Blenz R. Locating an undergroundtransmitter by surface measurements. Re-

spe1_tcs 1Yo II no, 3 I/Inter-Sprlng \986-87

best operating frequency. For long range voicecommunication, frequencies above 30 kHz will prob-ably prove best but position location work will belimited to depths less than 150-200 m. For loca-tion work at greater depths, lower frequencieswill be needed. The common 3.5 kHz frequency willprobably work to depths up to 500-600 m dependingon the conductivity of the earth.

Figure 3. The difference in phase betweenhorizontal and vertical magnetic fields onsurface over a buried loop antenna.

thethe

Classically the frequency is assumed to be 0 Hz,so H = 0 and the phase difference is 0 or 180degrees. (The change from 0 to 180 occurs at D =1.414 where the magnetic field is horizontal).

In practice, as D increasesphase angle increases too,become broad minimums asrotated.

or as H increases, theso the signal nulls

the loop antenna is

printed in Speleo Digest 1964, Page 3-1.

(4 ) Glover R.R. Cave Surveying by magnetic in-duction. Surveying caves. (Editor Ellis B.)British Cave Research Assoc. 1976

(5) osc11-earth.

1971,

Wait J.R. Criteria for locating anlating magnetic dipole buried in theProceedings of IEEE, Letters. June1033-5

12

speleon1n 7

'. i I no. 3 Wlnler-Sprlng 1986-87

QlP TRANSMITTING AND RECEIVIIG ON 800-1000 Hz (305.000 meters!)

Rick Wright

[Reprinted by author's permission from The Lowdown, January 1987, p. 27.]

The October '86 issue of the LOWDOWN listed my"ULF" beacon, 800ULF, at 0.8 kHz. This ELF-typetransmitter is based on an IRF-511 transistor withan automotive spark coil's primary wired betweenthe drain and a +12v to +15v supply. The hightens ion 1ead is connected to an el evated 150 ftlongwire, and the IRF 511 source is attached to anextensive ground system. More than anything, thislow-powered beacon (currently 1.8 watts) offers anopportunity to test ELF-range receiving gear.

In its original mode, the beacon may be driven byan 800 Hz free-running audio oscillator. However,I am now also running an exceedingly coherentsignal at 983.39125 Hz based on network TV'shori zontal frequency. I have external i zed aninexpensive TV's horizontal oscillator output (6vp-p from the emitter circuit). Because of theTV's floating ground, the signal must pass througha buffer amplifier and an optoisolator so that itmay be referenced to the transmitter's ground.The shaped signal is then divided by 16 usingdual-D flip flops to arrive at the above-quotedfrequency. The divider output proceeds through abuffer to the IRF-511. The final buffer is keyedby a C-64 computer. Let the reader beware if hedecides to build such a circuit because high volt-age audio is a shock hazard - the high tensionlead lights neons in proximity!

With a sprig of wire attached to an oscilloscopeand merely held near the coil, the output waveformis easily observed. I can freehand sketch abetter sine wave, but is it a reasonable, fairlysmooth sine approximation - Most of the receivedharmonics are below the 5th. The rig createsquite an E-field. My daughter complains that itis getting into her portable stereo!

In the matter of designing ELF-range receivers ortransmitters, I claim absolutely no expertise, andthe enclosed circuit is based on a lot of trialand error and blown field-effect transistors.Using this receiver, I obtained the followingresults: with an eight-foot whip at the FET'sinput and 1.8 watts running at the transmitter, Iwas able to receive 800ULF at exactly one-halfmile - weak, but definitely readable. This mustsurely be the transmitter's antenna field, and itfalls away much more steeply than the inversesquare law would predict. It can't be a trueradiated wave at such low powers and frequenciesand with such a miniscule transmitting antenna.Nevertheless, the range was more than I expected -I thought I was doing well in my earlier testswhen I was able to receive the 800 Hz signal outto 600 ft! The receiver must be fairly sensitiveas it is dominated by static crashes if the gainis turned up.

The preamplifier (high to low impedance match) hasa 10 megohm gate-to-ground resistor, and I suggestclosing the grounding switch when it is not inuse. The tunable audio active filter follows thepreamplifier, and in my opinion, it must be inthat position and not at some later stage - it isanalogous to the preselection of an RF amplifier.However, if the fil ter is bypassed, the OMEGAstations come through very strong. Using theBurhans VLF/LF converter/Sony receiver combin-ation, this front end receives well up to WWVB,

and the LORAN-C signals are still fair at 100 kHz.This circuit is my best means for receiving OMEGA-range signals.

The op amp gain stage after the filter allowsoptimizing the receiver's sensitivity relative tothe noise floor. At the suggestion of RalphBurhans, the output signal is 1 imited to 1. 7 voltsto avoid overdriving and burning out his VLF/LFconverter (or perhaps an audio amplifier). Thereare actually two options in receiving signals.First, if the signal is in the range of goodhearing (such as 983 Hz), the 741 output can berouted to an audio amplifier such as a C-60cassette player, and this works well - I've triedit. The second option is to play the audio intothe Burhans converter ~nd receive the signals near4 MHz. For signals in the best hearing acuityrange, switch the BFO off and tune to bring the 4MHz carrier partly into the receiver bandpass.With the input gain properly adjusted, the 4 MHzcarrier bleeding through the balanced mixer alongwith the modulation sidebands become, in effect,an AM signal. However, the main advantage ofusing the Burhans converter is in being able touse the receiver's BFO, and it even works at 983Hz! You can create a lower beat frequency and usea much narrower active filter on the receiver'soutput. This feature becomes even more importantgoing upwards from 1 kHz. If one uses directaudio ampl ification or the receiver "AM" mode, thefront end just be kept remote from the speaker orheadphones since positive feedback will causeoscillation. A length of coaxial cable is recom-mended. The BFO mode gets around this problem. Inote that the whip antenna will introduce micro-phonics even in a mild breeze.

I have also tried radiating the TV's divide-by-four frequency (3933.565 Hz "4000VLF"). Usingthe BFO option and without an intervening activefilter (I need to brew one for that range), the4000VLF signal reached to one-third mile. Inpart, this was due to a lower antenna voltagethe coil shows a fearful voltage until you attachthe antenna.

I really don't expect vast range increases atVLF/ELF frequencies. In the near future I willtest a spark coil to destruction to find its upper1 imits to input power. I'm more interested inexploiting the coherence already present in the800ULF signal. The carrier may be obtained at thereceiving site (by TV), and if the receiver outputis compared with this coherent reference in aphase detector, true coherent detection becomesfeasible. One should be able to create exceed-ingly narrow bandwidths, but the method willinvolve slow communication rates.

John R. Wright KA5YWH

John R. (Rick) Wright is a professor of chemistryat Southeastern Oklahoma State University. He hasdone caving in Arkansas. A preliminary descrip-tion of his 800-Hz work appeard in Western Update'33 (early July, 1986). Rick is presently usingdigital signal-processing techniques to investi-gate naturally occurring signals at sub-audiblefrequencies.

13

'f70A. -O'/jir

1TO IURHANS CONVeRTeR

100OR AUDIO ANPLIFIER

~(I us. . Sony

IC'-2002with the lurh8RI Cony8nd for .uc-hbettar ..

WHirfln. tualn.. I inject

( ./ "\. .. ..terna. vClavoll.,..)-1.7 v r-/,J

+'1'1

;!-M~TCHi'!?cAMPLI PIeR.

-"IV.J-TL08'tC't (or 7'f1)

flC.TIVCFIL.TER

JOk.lt..IDA.

1".J\..

100.J1..

:5'i:N s ,-n VIry

NOTE REGARDIIG THE FIGURE: The selective element(active filter) shown in this circuit is meant forthe 800-1000 Hz frequency range, but its value maybe changed to select other audio frequency ranges.See H.M. Berlin, -Design of Active Filters withExperiments,- Sams Publications, p139, 1977.

-----------------------------------------------Lindsay Publications Inc.PO Box 12Bradley, Illinois 60915-0012tel. (815) 463-3668

Our readers should find things of great interestin Lindsay's TECHNICALBOOKSCATALOG It featuresa N10st techno10gyN series of hard-to-find booksabout old .steam and gas engines, metal casting,tool and die making, machining. There are old andnew books on electrical things including rotatingmachinery, Tes1a coils, alternative energy. Bookson storage batteries are directly applicable tocaving. There are unusual books on explosives,perpetual motion, embalming, even a calculuscomic-book! Reasonable prices, fast service.--------------------------------------------------

Meadow1ake Corp25 B1anchard Dr.Northport, NY 11768(516) 757-3385

NTEC-200N image film makes printed-circuit etch-resist masks in electrostatic copiers or laserprinters. NXerox" the artwork on the specialplastic film (if necessary, reverse the imagefirst), use a hot iron to transfer the toner (ink)from the film to a clean copper board, then it'sready to etch. Small quantities cost about $1 per

spel""tcs 1Y. II no. J Winter-Spring 1986-87

If a strong AM station is nearby, it mfnimizesintermodu1ation if you wire an audio transformer'sprimary between the gate lead and the antenna, asshown. In my case, AMstation KSEO is not a mileaway. r just wait for it to leave the air beforedoing experiments, and in that case a choke is notnecessary. KSEO gives me a grace period betweensign-off and night propagation conditions.

RESOURCES -----------------------------------------------8.5 x 11N sheet. See Don Lancaster's' NHardwareHackerN column in Modern Electronics magazine,March 1987, p. 62. we haVen"t trlea this stuff;it seems promising!--------------------------------------------------

Edmund Scientific101 E. Gloucester PikeBarrington, NJ 08007

Edmund is back in its old format, fOllowing anallegedly disastrous adventure in marketingNyuppieN toys! The new EDMUNDSCIENTIFIC CATALOGFOR INDUSTRYAND EDUCATIONis filled with wonder-ful optical, electrical and other interestingdevices for experimenters. They have two cata-logs; to get the big "industrial" one, give them aschool or company address.--------------------------------------------------

Earthly ImpressionsP.O. Box 791Farmington, NM87499

Caver/geologist Barbara a.Ende's newly-foundedrubber stamp factgory specializes in cave and geo-logical themes (see examples in this issue). Sheis looking for new designs, and does custom work.Write for catalog.

14

spele08tcs 1v. 11 no. 3 Wtnter-Sprlng 1986-81

Steven Clark

RADON MONITORING II CAVES

NSS 17221

It seems that the public media have found yetanother subject in which they are attempting toincite mass paranoia. The press has discoveredthat pervasive noble gas, radon, and is distract-ing the public's attention to its evil nature. Wehave been told it even lurks in such innocuousplaces as our basements, crawlspaces, and yes,even caves! As a consequence, agencies control-ling access to caves visited by the general publicare becoming concerned. This has resulted ininterest in developing methods of radon monitoringwhich are affordable, and suitable to the caveenvironment.

The carcinogenic nature of prolonged exposure tohigh levels of radon daughters in mine environ-ments is well documented. Reports of the problembegan surfacing nearly 100 years ago. Federal lawrequires that records of mine employees' radonexposure be kept. Exposure is stated in workinglevels, and it is currently recommended thatexposure be limited to 4 working-level-months(WLM)per year. (One working level is the amountof alpha energy present in a liter of air contain-ing 100 pCi each of the radon decay productsp0218, Pb214, and 8i214.)

The Mine Safety and Health Administration (MSHA)has developed a standard procedure for monitoringradon in mines. It requires that a known volumeof air, typically 10 liters, be pumped for a knownperiod of time (5 minutes) through fine-meshfiberglass filters to trap the airborne daughterparticulates. The daughter products continuedecaying through the uranium 4n+2 series. A 50-minute-wide window, beginning 40 minutes aftercomplet ion of the sampling, then opens and theP0214 alpha decay activity is counted for a fixedperiod of time. This count is then converted toWL, taking into account a number of factorsincluding counter gross counting efficiency for7.7 Mev alphas, air volume filtered, and timefactor correction.

Scintillation counters are typically used to countthe alpha activity on the filter. Ionization-chamber counters are not popular due to low sensi-tivity. Scintillation counters are typicallyoutside the average caver's budget, they don't fitinto reasonable-sized cave packs, and they don'tlike bumping and jarring. (It should be notedthat radon can be detected via other methods suchas activated charcoal and specialized plastics,with the latter being used in detectors sold byTeradex. However, their use in cave environmentsleaves much to be desired. Experience has shownthat accuracy, repeatability and reliability arepoor.)

Experiments currently underway at Mammoth CaveNational Park are investigating the use of silicon

detectors to count alpha activity. The detectorbeing used has an active area of 450 mm2. Thedetector contains the p-i-n diode, diode biascircuitry, a charge-sensitive preamp, a shapingampl ffier, and a single-channel analyser (SCA).(The SCA can be used to perform spectroscopy meas-urements; this feature is not currently beingused.) The detector package is 1.56 inch outsidediameter, 1/2 in. high, and weighs just a fewounces. It can be powered by a -12 to -9 voltsource.

The detector output is fed through a level-shifting circuit to a simple counter with LEDdisplay, powered by 9-volt batteries. The entirepackage of sampl ing and counting equipment iseasily carried in protective packages in standardcave-packs.

The results to date are very encouraging. Initialcrosschecks between the silicon detector/counterand a scintillation counter show excellent corre-lation. The silicon detector has yet to be cal-ibrated against an MSHAstandard and until thatstep is performed, the data acquired cannot be.converted into WL exposure values.

The silicon detector method is very promisingbecause of its portability. The use of a scintil-lation counter in the cave is generally impracti-cal (even if one could afford it); its size anddelicate nature limit sampling to passages whi~hcan be exited in less than 90 minutes. Thisseverely limits radon sampling in many caves. AtMammoth Cave, it basically restricts potentialsampling to the tourist areas. Using the silicondetector, the range of passages sampled is limitedonly by the endurance and desire of the caverrunning the experiment.

The major problem of the silicon detector is. itscost. The hybrid package used costs about $800.Consequently, other approaches are being in-vestigated. One potential method would incorp-orate p-i-n silicon photocells that have surfaceareas on the same order as those used in thecurrent experiments at Mammoth Cave. This wouldnecessitate development of custom gain stages forthe preamp and shaping amplifier, however, thiscould be accomplished with off-the-shelf compon-ents and could also incorporate the counterelements and further reduce the package size.

The sampling project in progress at Mammoth CaveNational Park has shown that accurate radonmonitoring inside the cave is feasible. While thecost of the equipment has been brought down sig-nificantly, it is felt that the cost for thedetector can be reduced further with additionalwork.

15

y. II no.)

Spe1eo.1cs 1Vlnt..-Sprlng 1986-81

WIn. Karl Pitts

RADON SAMPlING IN THE IWMOTH CAVE SYSTEJI

NSS 25074

A study is currently underway in Mammoth Caveto measure radon and thoron levels in situ. Asdescribed by Steve Clark, this work is carriedout using a sophisticated detector which containsboth the detector and its associated amplificationcircuitry in a single integrated package. Theadvant.age of this type of detector is that it iseasily portable, and it is possible to measureradon levels anywhere in the system. While thereis an active sampling program carried out by theNPS, their sampl ing is necessarily 1imited due tothe use of large, bulky scintillator detectors.One must be within 90 minutes (travel time) ofthis detector to use the MSHA-approved Kusnetzmethod. The small size and rugged nature of thesilicon detector free us from this limit, and wecan sample at will throughout the system. Itshould also be pointed out that other methods,such as track-recording plastics and charcoalcanisters, are not reproducible to the 10% levelneeded for this study.

The purpose of this sampling program is two-fold. One major part of the project is to gener-ate a more complete data base for areas which arenot routinely sampled by the NPS. The other majorgoal is to unravel the airflow patterns in thecave using the natural variations in radon concen-tration due to climatic factors. Mammoth Cave ispredominantly flat, and it is known from the NPS

monitoring results that the outside air tempera-ture and pressure control the airflow, and hencethe radon diffusion in the cave. It should bepossible to use the variation of air flow with theoutside temperature to passively airtrace thecave, using only the radon and thoron measure-ments. The preliminary results of our work isencouraging. Various sampling trips have re-vealed differences of up to 50% along a singlepassage where there is a known connection toeither other passages or an entrance. Forexample, a trip to Black Kettle Avenue (CoralAvenue on the Kaemper map) showed that the radonconcentration varied by nearly 50% on either sideof the connection to Big Mother Pit. This pit waspossibly Felicia's Dome, and on a subsequent tripthe airflow was sampled from Rose's Pass (on thetour route) through the pit, and on into BlackKettle Avenue. This ser1esof measurements indi-cated that there was indeed a significant aircurrent through the pit, and this current wastraced from the upper level to the middle level ofthe cave. One would expect that the method wouldwork just as well when one doesn't know that thereis an air connection!

The assistance of the National Park Service hasbeen crucial to this study, and their cooperationand assistance is gratefully acknowledged.

-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-=~-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-

In Review:

THE OGOFOHE

Bob Williams & Ian Todd, S. Wales Caving Clubin

Caves & Caving, Bulletin of the British CaveResearch Association, Number 35 - Spring 1987.

The article fully describes an 87.5 or 125-kHzsingle-sideband voice transceiver for cave-to-surface communication and direction finding, usedin Wales' famous Ogof Fynnon Ddu cave system.Range is 500 feet (150m), transmitter power isabout 10 Watts peak. The antenna is an inductiveloop made from 4 metres of flexible 64-conductorflat cable.

The sophisticated and compact Dgofone is lesscomplex than earlier SSB designs (7 IC's, 13bipolar transistors, 4 FET's). It uses a NECuPCI037H balanced modulator chip, an L-C sidebandfilter, 12-volt / 6 Ampere-hour sealed lead-acidbattery, and telephone-style handset. An analog-gate IC handles all low-level transmit/receiveswitching; a relay switches the antenna. A report-

ed problem with receiver response to the firstsyllable of transmissions might be remedied by afast-attack / slow-release AGC circuit.

The Ogofone's ingenious "pip. mode transmits atone-burst every 3 seconds, with the receiveractive in between. This feature is especiallyuseful for establishing initial contact. There isalso a continuous-tone mode for direction finding.

contributed by Angelo George and Bill Wilson--------------------------------------------------

NATIONAL PARK RADIO FREQUENCIES PUBLISHED

Popular Communications magazine, February 1987,featured an article about U.S. National ParkService radio communications. A comprehensive"scanner list" even includes frequencies of priv-ate concessionaires that operate within nationalparks. This previously-hard-to-find information isvaluable to cave-rescue and other SAR groups.

contributed by Frank Reid

16

Rescue Communications:

PHONE PATCH CONNECTS CAVE TO HOSPITALS

Frank Reid

It is important to provide direct communicationbetween med ical personnel durTri"g"a cave rescue;relay operators waste time and garble messagescontaining unfamiliar terminology. Four inter-connected radio and telephone links allowed Dr.Noel Sloan to talk to an Indianapolis hospitalfrom inside Buckner Cave (near Bloomington, IN; 45miles from Indianapolis) during the rescue of aperson with serious back injuries in February,1987.

Army-surplus field telephones connected thecave entrance to the patient's location, through600 feet of crawlway. Dwight Hazen (WB9TLH), anexperienced caver, supervised communications atthe request of rescue coordinator Don Paquette(WB9TLI). Hazen manned the entrance telephone,and used a handheld 2-meter FM transciever tocommunicate via the K90K autopatch repeater 8miles away.

Dr. Sloan wished to consult a neurosurgeon atMethodist Hospital in Indianapolis. Hazen con-nected his Icam IC-02AT transceiver directly tothe underground telephone, and called the Bloom-ington Hospital emergency room via autopatch. TheBloomington E.R. patched the call to Indianapolisvia their own landline facilities. Sloan laterleft the cave and received a call from the neuro-surgeon by telephone at the home of cave ownerRichard 8lenz. He used a handhel d rad io (insimplex operation) to relay instructions to para-medics in the cave, via Hazen's phone patch at theentrance. An additional phone patch could haveprovided a direct link into the cave from Blenz'sphone; such a device was available but had notbeen packaged with the rescue phone equipment.

Pre-planning pays off.

Cave-rescue telephone equipment for the area ismaintained by Frank Reid (W9MKV) and stored ingarage. Reid and Hazen had set their electronicgarage-door openers to the same code, should theequipment be needed in Reid's absence (which wasthe case).

Reid added radio-patch circuitry (Fig. 1) to atelephone, after recognizing a need for it duringa 1984 rescue. Hazen, Paquette and Reid had dis-cussed ways to interconnect communications links,and had conducted experiments during rescue-training exercises. (See SPELEONICS 3.)

Experience Gained

Radios and telephones used inshould be interconnectable. Phoneeasily built fram inexpensive partsRadio Shackl.

cave rescuepatches are

available at

Repeater users should have phone-patch equip-ment at their home locations, whether or not theirrepeater is autopatch-equipped. Autopatches whichnormally restrict toll calls should have anemergency mode allowing long-distance service.Credit-card calls made via radio should, if pos-sible, be entered by DTMF ("Touch-Tone") insteadof voice, to help avoid compromising credit cardcodes.

The 4-layer link required only one radio oper-ator to switch from transmit to recieve. Had therepeater and autopatch been unavailable, a conven-tional phone patch or .simplex autopatch" at anearby telephone would have been necessary. Weare building additional phone-patch devices forhandheld and mobile radios, and encouraging otherlocal hams to do likewise.

Handheld radios should have alkaline-cellbattery packs for emergency service. Alkalineshave much greater capacity than rechargeablecells, and are readily available. (One set ofalkaline AA-cells in an IC-02AT lasted an entire2.5-day rescue in 1985.)

Ham radio, especially the autopatch repeater,is invaluable to cave rescue communications. Oper-ations should be directed by a hamwho is also acaver, thus famil iar with both worlds. Emergencycommunication by ham radio is less likely to at-tract onlookers and news media than is police/fire/ambulance radio traffic.

References:----------

1. Danzer, Paul, "A $10 Phone Patch," 73 Magazine,February 1981, p. 68. -

2. War Department Technical Manual TMII-333:Telephones, EE-8, EE-8A and EE-8B, March 1945.

INDUCTIONCOIl..

GENEAATOq '0RADIO

""CL205MF

Sh"ldcd Cotlilt

1-'--;-;!~r.~I

I

. i'I'~I

POA H,IIL ERADIO

~I<;10'''--'

"''''�I'dll'

Figure 1. Simple phone-patch (heavy lines) con-nects EE-8 (World War II-vintage) field telephoneto handheld radio transceiver (Icam IC-2AT fam-ily). Variable resistor adjusts radio microphoneinput level. Push-to-talk button and level-control may be housed in a 35-mm film can. Cablesto the radio may be several meters long. NOTE:This circuit provides no ground isolation betweentelephone and radio. It should be used only withself-contained battery-powered radios. [Pictorialdiagram by Gene Harrison.]

17

NSS 12460

.pet_In 7Y. II no. 3 Wlnter-Sprtng 1986-87

In "Zip-loco plastic bag with each telephone:batteriespenc ilpencil sharpenernotebookelectrical tapeplastic cable-tiesinstructionslarge plastic trash-bag

1000 m 2-conductor telephone wire (4 spools)

Telephone test equipment:Lineman's test set (handheld telephone)Tone generator/continuity testerCapacitive tone-detector (used with handset and

tone gen.)Volt-ohmmeter

"Bell-Compatible" telephone with rotary dialLocal telephone directoryCave-rescue telephone listARRL Repeater DirectoryAeronautical sectional chartList of emergency radio frequenciesField-phone schematicsExtra microphones for field phonesElectronic telephone-ringer in box w/ terminals100' telephone wire with modular plugs on ends

Telephone connector adapters:Modular: alligator clipsModular double-femaleModular "Y"

VHF radio transceivers (Icom IC-02AT, IC-04AT, IC-28H; Yaesu FT-23R) modified for extra frequencycoverage).

ABSTRACTS

of papers to be presented at 1987 NSS Convention:

IMPROVING THE ORGAN CAVE RADIO

by Ray Cole

BLOOMINGTON INDIANA GROTTO CAVE-RESCUE COMMUNltATIDIS EQUIPMEIT CHECKLIST

Since the initial development of the Organ CaveRadio described in Speleon1cs '3 [v.l #3, Fall1985], methods of improving the performance whilekeeping the design simple to duplicate have beenexamined. One promising technique to improve theperformance of the cave radio in noisy environ-ments is to reduce the bandwidth by addingfeedback to the first stage to produce a highereffective antenna Q. A design incorporating feed-back has been demonstrated on the bench which alsoprovides for full transceive operation with noelectrical switching required between transmit andreceive. While the autotransformer used in theoriginal design is highly efficient, a slightlydifferent resonant frequency may be present for

transmit and receive when using high-QThis problem can be overcome by usingprimary and secondary windings.

antennas.separate

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

IMPROVISED TELEPHONES FOR CAVE RESCUE

by Frank Reid NSS 9086

Underground communication is essential when ani nj ured per son must be ex tracted from a cave. Themilitary-surplus field telephones favored by U.S.cave rescuers are increasingly hard to' obtain.Several ways to construct inexpensive telephonesare described, including a design simple enough tobe built in the field in a few minutes, fromreadily-available components.

18

This list is kept by rescue coordinators and Radio accessories:communications specialists. Some of the equip- Portable phone-patch devicement is kept in a rescue cache; radios and Alkaline-cell battery packs wI spare cellsother expensive items are individually owned "Gain" antennasand amassed when an emergency occurs. Battery-charging and external-power cables

Plastic bags/rubber bands (weather protection)4 Army-surplus field telephones, one equipped Neck lanyards

with phone-patch for Icom handheld radio trans- Speaker-microphonece1vers [See SPElEONICS7]. Headset

Repeater components [see SPELEONICS3]15 m of RG-58/U coax cable w/ BNCconnectorsAssorted RF-connector adapters

Tools:Swiss Army knifeScrewdrivers: flat-blade and Phillips.Wire stripperWire cutterPliersNutdriver setElectrical tapeDuct tapeFelt-tip markerLarge plastic cable-tiesButane-powered sOldering iron / fuel and solderLarge alligator-clip leads (4), 1 m long"Slim Jim" tool for opening locked cars

Signal equipment:Flare launchers}Signal mirror} to mark landing zone forStrobe light} helicopter ambulance.Smoke bomb }Chemical 1 ight-sticksSurveyors' flagging tape

FlashlightRain poncho

"Umbrell a with antenna mount * J"'"2 pkgs "MRE" military food rations q-JPlastic canteen I{I

~"Heat- tabs.Waterproof matches \1JGloves r'Y'

")Woo1 cap '\Socks C1 pr) II',I!-. Donot use in thunderstorms. ~

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-~-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-:-=-=-=-=-=-:-=-=-=-=-=-=-=-

SPELEONICS 7

Volume II, No.3, Winter/Spring 1986-87

SPELEOIICS is the quarterly newsletter of theCommunication and Electronics Section of theNational Speleological Society. Primary interestsinclude cave radio, underground communication andinstrumentation, cave rescue communications, cavelighting, and cave-related applications of amateurradio. NSS membership is encouraged but notrequired.

Section membership, which includes four issues ofSPELEONICS, is $4.00 in USA/Canada/Mexico.$6.00owerseas. Send subscriptions to section treasurerJoe Giddens at the address below (make checkspayable to SPELEONICS). If you have a ham-radiocallsign or NSSmembership number, please includethem when subscribing.

Foreign subscription can be paid in U.S. .paper"dollars in the mail. An international money-ordermay cost as much as the subscription; many peoplehave sent cash without problems.

f~'~ ~.~'-.r/ SPELEONICS ~

P. O. Box 5283 ~t~l.l..Bloomington. Indiana ~USA 47402-5283

Editorship rotates among the officers. Volunteerindividuals or groups are encouraged to guest-editor produce an issue. A technical session,followed by election of officers, is an annualevent held during the NSS Convention.

Complimentary copies of SPELEONICS are mailed toNSS offices and sections, the U.S. Bureau ofMines, U.S. Geological Survey, and the LongwaveClub of America.

Chain8an (and editorof the next issue):I an Drummond5619 Dalwood Way NWCalgary, AlbertaCANADA T3A IS6

Secretary:Frank Reid, W9MKVPO Box 5283Bloomington, IN 47402-5283

Treasurer (and editorof this issue):

Joe Giddens, N510ZPO Box 170274

Arlington, TX 76003

Publisher:Diana E. George, N9DEJ

1869 Trevilian WayLouisville, KY 40205

Bulk RateU. S. Postage

PAIDBloomington, INPermit No. 202