Communication and Electronics Section

Better Caving Through Electrical Stuff

2020 Annual Session Minutes

Provisional until approved by the CES membership at the 2021 Annual Meeting.

Communication & Electronics Session Minutes
2020 NSS Virtual Convention
Monday, July 27, 2020
Zoom Meeting
Brian Pease, Sec/Treas

The virtual C&E Session started just before 5PM Eastern time, directly following the C&E Meeting. The 3 presentations were made available on the NSS youtube channel all day Monday, but the decision was made to stream them directly after the meeting while everyone was present to ask and answer questions just like a regular session.

Sam Rowe talked briefly about the special event station, which this year consisted of several operators at their home stations, using the call K8V/x, where x is the call area they are actually located in. He made a certificate instead of a QSL card this year because several different stations were operating. He has applied for K6V for next year in Weed, CA.

Gene Harrison said that the C&E Club callsign K7NSS is available for use at conventions and expeditions by contacting him.

John Lyles gave an obituary of Bob Buecher, who died recently of complications following heart surgery. Bob was a presenter at the C&E Sessions for many years. He was involved with studies at Kartchner Caverns, AZ, the CRF, Carlsbad Caverns, NM, and Fort Stanton Cave, NM. He built an 874Hz Radiolocator that he used to double-check the theodolite survey before the elevator shaft was dug into Kartchner Caverns. He built Ian Drummond's 185kHz voice transverters and Brian Pease's DQ radiolocator gear for use in Fort Stanton Cave. He also build LIDAR gear that was used to image parts of Fort Stanton Cave, and altimeters used to check the vertical accuracy of the survey in this very flat long cave. Bob will be missed.

The first of the 3 pre-recorded presentations (all available on the NSS youtube channel) was by Brian Pease, entitled Data Transmission Through a Long Single Wire Phone Line. The entire talk in text format is available on Brian's new website He mentioned successful tests on Bill Stone's last Cheve expedition by Kristen Anderson. The need for good grounding was discussed. A model of the single wire line was created and used to predict performance of Kristen's baseband TTL system on very long lines. Another approach using audio tone modems was proposed that uses existing software (andFLmsg) and the audio in/out from the headset jack on the Android tablets used for Topodroid surveying. This was shown to be superior to the TTL approach for long ranges and poor cable conditions.

The second presentation, Real Time Carbon Dioxide Monitoring System at Edgewood Caverns, NM, was by John Lyles,who owns the single entrance to Edgewood Caverns in Santa Fe County, NM. The cave has high CO2 levels from natural non-organic sources that fluctuate with barometric pressure, 2% or more when the cave exhales and lower when it inhales. He showed various portable CO2 monitors he has used during exploration. He is currently constructing a housing for a permanent CO2 monitor for the entrance area that will be solar powered and tied to the cell network (for $5.00/month) to allow remote CO2 monitoring in real time to know in advance when conditions are safe for exploration. It remains to be seen how long the CO2 sensor will work in the cave environment.

John Lyles second talk was UHF Cave Data Communication Network for Fort Stanton Cave, NM. This 3 year effort, with Government funding for equipment, will use point-to-point battery powered UHF repeaters to send sensor data (CO2 and water level) to the surface. The initial network will reach 1 mile from the entrance to 20 steps, with an estimated 10 repeaters. The complete network will reach 2 miles to Turtle Junction, which will allow continuous monitoring of the water level in Snowy River. Among the challenges are high UHF attenuation in real passages, line of sight positioning, battery life, moisture, and passing UHF through 2 steel gates. A possible candidate network is Digimesh, that uses timers to occasionally turn on the repeaters and send data. There was some live discussion about using cheap, rugged, military surplus field phone line, hidden in the mud, instead of UHF, which could also power the sensors from the surface.