Minutes of the 2004 Annual Meeting of the
Communications & Electronics Section of the NSS

Brian Pease, Secretary/Treasurer
July 12, 2004, 1:00 PM

Attendance:

37 people put their names on the sign-in list either at the luncheon/business meeting or at the program session. This compares with 33 last year and 37 the year before. We now have a total of 76 "official" members with 19 known hams and only 2 people who did not list an email address. The NSS requires us to maintain a list of members, so we simply defined our membership as consisting of all of the people who have signed in at the annual meeting sometime within the last 5 years. The only officers present were Bart Rowlett and Brian Pease.

Minutes from 2003:

Brian read the 2003 minutes, which were unanimously approved.

Treasurer's Report:

Brian Pease (Sec/Treasurer) reported that we have $1512.28 as of 7/1/04 in the Section's money market account. Last year we had $1525.07. The only expense was $22 for our NSS web space.

Old Business:

Due to the difficulties involved in tracking down the people on the old membership list, which consisted of people who had paid in advance for paper issues of Speleonics, Brian has decided to deal with refunds on a case-by-case basis.

Henry Schneiker scanned and converted issues 1 & 2 of Speleonics to PDF and cleaned them up to very high quality.

David Larson found a way to quickly convert the remaining back issues (3-21) to PDF with minimal cleanup. The quality is more than adequate.

Gary Bush, our Communications Chair, recently discovered that his free web space had been drastically increased to 100 MB. He has uploaded the back issues to his web space with links from our NSS Website http://www.caves.org/section/commelect . All Speleonics issues are now on the web, including an index to the (formally) paper issues.

Bart Rowlett, who operates the Speleonics email list, explained how to subscribe. Send an email to speleonics-request@altadena.net with "subscription" in the subject line and "subscribe your email address" on the first line of the body. An alternate way to subscribe or get info on the list is to visit http://www.altadena.net/mailman/listinfo/speleonics . He said that due to the current volume of spam, he may not catch legitimate messages that were automatically rejected for some reason such as not being sent from the subscriber's normal email address.

New Business:

Brian Pease brought up the fact that we were not having the in-cave workshop at this years convention that we talked about last year. We decided to start planning for one in Alabama next year. I suggested that we have the workshop on Sunday when the only conflict would be the Hydrology Field Trip. I suggested taking some photos above and below ground. The results can be organized Sunday night and presented/discussed during the Session on Monday.

Doug Strait volunteered to find a place for the workshop next year. We need a cave close to the convention with adequate parking close to the entrance. It should have an easy entrance to a walking passage that goes under a rising hillside that will allow tests through 200 ft (and maybe 300 ft) of overburden. It should take only a short time (say 15 minutes) to walk from the test site in the cave to the point on the surface directly overhead.

Bill Franz said that he will coordinate with the Survey & Cartography Section.

On the surface, we would like to demonstrate the measurement of conductivity with a radiolocation set and also with a Wenner electrode array. We may demonstrate the simple measurement of earth current impedance. We will also use the radiolocation set to demonstrate tracking and to locate points on the surface directly over the underground location(s) and estimate the depth(s). We will attempt two-way communication between cave and surface by several methods at one or two depths:

    1. Brian's 185 KHz transverters with 1 m2 loop antennas at the deepest depth.
    2. Possibly test the transverters with earth-current dipoles.
    3. 2-way digital text comms using Ray Cole's PSK-31 radios.
    4. Brian's 27 MHz CB handhelds (at a shallower depth).
    5. HF radio at one or two frequencies (voice and/or cw) with fixed antennas (at the deepest depth) or mobile antennas shallower.
    6. We will measure in-cave comms range in curving passages using the HF radios; the CB radios; 2-meter handhelds; FRS radios.
    7. Demonstrate Ted Lapin's light-sensitive caver counter.
    8. Measurement of water conductivity with pocket meter.
    9. Possible coordination with the Survey & Cartography Section showing use of radiolocation to check cave map accuracy and align remote parts of cave on the topo map using radio/GPS. Radiolocation accuracy could be checked by surveying between two radiolocated points both on the surface and underground.

 

Presentation:

Brian Pease gave a presentation on his new Hi-Power 3496 Hz Radiolocation Beacon.

Abstract

An improved high power 3496 Hz beacon transmitter has been designed, built, and tested in the field.

It uses the well-known shunt-capacitor series tuned class-E power amplifier circuit with two inductors and two capacitors. This new beacon has several advantages over the classic design that has been used for many years, which is properly called a class-E tuned power amplifier with one inductor and one capacitor. The old design used narrow pulses to drive the loop, which induce large voltage transients on the power MOSFET and large current transients in the DC supply. The maximum output (Magnetic Moment) was about 50 Amp-turns-m2 for 5 Watts input. Any attempt to increase the output resulted in larger transients, reduced efficiency, and DC supply problems. The new circuit can be easily be trimmed for high or low power with various DC supply voltages. It was easy to trim the new circuit for 21 Watts output and 106 Amp-turns-m2 with a 15 V supply. The new beacon was field tested at ~600 ft (180m) depth in Belize. It worked reliably and the signal on the surface was more than adequate.

Show and Tell:

    1. Brian Pease showed his version of Ian Drummond's CB/185 KHz transverter. The block diagram and schematic are at http://Radiolocation.tripod.com. I altered the circuit to improve receiver sensitivity and dynamic range. He mentioned two other voice radios: the British Heyphone ( http://www.heyphone.org )and the French Nicola II (http://naylorgr.perso.cegetel.net/cave_radio/) .
    2. Brian Pease mentioned that he still has a few circuit boards for his Radiolocation receiver and beacon. He sold 3 boards and has 3 left.
    3. Brian Pease explained how large flat plate electrodes can be used with "earth-current" dipoles in place of the ground stakes. He showed a foil-backed building insulation that will make a rugged lightweight electrode. The material, called Reflectix, is basically bubble wrap with aluminum foil bonded on both sides. It can double as a camp mat and equipment padding. Home Depot has it, at least in the NE.
    4. Brian Pease showed a 2 Watt 27 MHz CB AM handheld radio with a 4 ft center-loaded whip that he has used for thru-the-earth voice comms. It will easily penetrate 60 ft of ordinary limestone, and 200-300 ft of low conductivity metamorphic rock (marble, dolomite). These radios cost him less than $5.00 each at a radio auction.
    5. Ray Cole showed his 24 LED headlamp with switching current regulator and variable brightness. It will work on 3-6 volts, which lets it work on 2,3, or4 AA alkalines, 3 or 4 NiCad or NiMH cells, or a single 3V lithium. He explained that many lamps have been built and that he has circuit boards for the surface-mount circuit. See http://members.cox.net/k4gaa/caving.htm
    6. Ray mentioned that he is making progress on 2-way text comms using PSK-31. He persuaded Peter Martinez, who originated the software, to removing the "windowing" that limits the bandwidth to 31 Hz. Without the windowing, the transmitter can operate in a simple and efficient saturated mode. He gave a demo of the transmitted sound at 3496Hz. He expects to be able to demo it next year.
    7. Doug Strait built a very compact 874 Hz pulsed beacon to help locate a new entrance to a 400 ft deep cave with 7 drops near the Suwanee, TN NSS Convention site called Suwanee Plunge. A tight 1500-3000 ft crawl between 2 of the drops seemed to be near the surface at the far end. He built the entire beacon, including loop antenna and battery into a flat Otter box. He said battery drain was 4 Watts with a Magnetic Moment of 2 A-T-m2. With his receiver, the limit of detection was about 300 ft. Explorers set up the beacon on their way in, and he had located it and had dug the entrance open enough to talk to them when they retrieved the beacon on their way out.
    8. Doug talked about the Candlepower Forum website. He got involved in a project to build a 1 cubic inch flashlight using a 3 Watt Luxeon white LED chip. He used a Texas Instruments low dropout linear regulator operating in its current-limiting mode as a 1-component current regulator for the high-power mode. The TPS-73101 limits at ~250 mA, the TPS-73201 at ~425 mA, and the TPS-73601 at ~ 650 mA. He used a "digital transistor", a PNP device with built-in base series resistor, as a current limiter for the low-power mode. The emitter connected to B+, the base to Negative, and the LED to the collector.

Elections:

Joe Hruska ran the elections. The Existing officers were reelected by acclimation, Bart Rowlett as Executive Chair, Brian Pease as Sec-Treasurer, Gary Bush as Communications Chair (Website), and Paul Jorgenson as Publications Chair.

 


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