Minutes of the 2008 Annual Meeting of the
Communications & Electronics Section of the NSS
Lake City, FL

Brian Pease, Secretary/Treasurer
August 11, 2008

Meeting

The luncheon/meeting got underway at noon with only 10 people in attendance. The only officers present were Bart Rowlett and myself. Gary Bush was at the BOG meeting that took place at the same time. I read the minutes, which were accepted. I gave the treasurers report. Last year at this time we had $15.40.75. As of 8/05/08, we had $1550.91 in the Peoples Bank (CT) passbook account.

We discussed what to do for the International Congress of Speleology next year in Kerrville, Texas. Kirk MacGregor said than the normal business meetings of the NSS will be held at the ICS, but that they will typically be breakfast meetings which will not conflict with the crowded session schedule. We decided to look into what we would be able to do, then hold an ICS planning session on Friday in place of the Lighting session.

Bart decided to not hold elections this year due to the small number of officers and members in attendance. All 4 officers are willing to continue for another year:

    Bart Rowlett, Executive Chair
    Brian Pease, Sec/Treas Chair
    Paul Jorgenson, Publications Chair
    Gary Bush, Communications Chair
The meeting was over by 1 PM, so the next hour was an informal chat session.

Session

The informal Session got underway at 2 PM as scheduled, with no formal papers to be presented.

I talked about the use of Near Vertical Incidence Skywave HF communications in Belize this year. I explained how several people obtained Belize (and US) ham licenses. We first tested IC-703 SSB voice transceivers in March on 80 meters with full size dipoles only a few feet off the ground. The range was 45 miles between the jungle and our lodge, which does not mean much when the signals are bouncing off the ionosphere 100 miles (or greater) up. We had 2-way voice comms but with high manmade noise levels at the lodge. We operated during the day when there was no skip. When we returned in May, we had added PSK31 capability just in case, using a Dell Axim pocket PC at the cave. This multi-day backpack trip was to a large cave in the Chiquibul Forest Reserve about 40 miles from the lodge. At the cave, the horizontal antenna was at least 100 ft down in a huge sinkhole, which reduced our transmitted signal. As a result, we could receive voice clearly, but our voice was never heard in the steady S7 noise at the lodge. As a result, we used PSK31 to transmit information. We used a simple program called PocketDigi on both ends, which has a feature called Reed Solomon ID (RSID) that is sent at the start of each transmission to automatically tune the receiving program to the frequency of our upcoming transmission and even switch to the mode we will be using! This corrected any tuning errors and drift, allowing reception even if the operator had stepped away. It worked.

I demonstrated the program, including the RSID feature, using acoustic coupling between the Axim and a laptop.

Ray Cole demonstrated a semi-coherent CW program called “CW Lab” that operates at 10 baud, also using acoustic coupling between computers. It uses LabView, which is included. He intends to use it to key 3496 Hz beacons for 2-way comms during radiolocations. It looks promising. He described CW keying the beacon’s monostable multivibrator to hard limit the sound card audio output.

I described my class-E beacon circuit, showing the schematic, and explained the advantages of series tuning and high efficiency.

I showed my bicycle wheel shielded loop built for Bill Stone.

ICS Planning Meeting

The ICS planning meeting was held Friday at Noon. Only Bart, myself, Gene Melton, and Bill Franz attended. We decided to try to hold 3 events at the ICS:
  1. A breakfast business meeting, on Monday if possible.
     
  2. An informal meeting, open to all, for people to share what is going on around the world in caving electronics, with show and tell and informal presentations. This is allowed at the Congress and would probably fall under Tools and Techniques.
     
  3. A Wednesday Field Trip to a local wild cave, preferably dry horizontal with as much as 200-400 ft of overburden. We would probably demonstrate AF comms and radiolocation along with HF comms.
Anyone who wished to present a formal paper could do so at a formal session, preferably at a time that did not conflict with our meeting #2. The papers can be older work already published in Speleonics or elsewhere.

We decided to attempt to design, and I would construct, some simple 3496 Hz units that would be capable of radiolocation and two-way manual CW comms as stand along devices. They would use the same loop for both beacon and receive, with moderate range. It would be possible to connect a pocket PC or laptop to this basic unit to allow 2-way digital comms in modes such as PSK31 and MFSK16. A possible addition would be a small filter/matcher to allow the use of earth current antennas for longer range digital comms. Bart made up a tentative spec sheet. The idea would be to demonstrate this during the Field Trip.

 


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