A possible Plan for NPOTA at Mammoth Cave (draft-a)
Bob Bruninga, PE
US Naval Academy
last name at usna dot edu
This page suggests a possible plan for the NPOTA event starting from the simplest
to the more adventurous. The amount of complexity is measured with respect to the
amount of possible NPS manpower support that might be needed. From practically
none with some setups to a dedicated escort for the most ambitious (with research value).
Please refer to the NPOTA background on this initiative.
National Parks on the Air: NPOTA is an event organized by the ARRL
(National Foundation for Amateur Radio) to give exposure to the National
Parks during this years 100th centennial. The idea is simple, to use hams
throughout the country (chasers) to make contacts with hams (activators) at
all the National Parks. There are over 800 such parks and properties so
this can be a very exciting event indeed. The local Kentucky HAM clubs are
already supporting NPOTA from Mammoth during some weekend events, but this
particular idea for Mammoth Cave hopes to make a unique approach to highlight
the unique feature of the park, and that is to operate from underground!
Setup #1, Main Station:
This station, something like a table and radio as shown above, would have a
pair of operators sitting in a public area with one person making radio
contacts to other NPOTA stations at any of the other 800 national parks or
service areas. The second person interacts with the public and explains
what is going on. Posters promote the 100th NP Centenial. Other than
permissions and pre-planning, routine NPS manpower is not required.
Setup #2, Cave Station HF:
The Cave Station sets up at a card-table off to the distant side of the cave
Rotunda below the parking lot in the orange circle area as shown below. This
location is ideal because other amateur radio mobiles can drive through the
parking lot and make contact without disrupting traffic or needing any other
NPS manpower support. These mobiles are unique with high power HF transceivers
and large antennas on their cars. The involvement of Park Personnel would be
limited to simply allowing access and insuring the Operator is properly setup
in the approved location. The public can observe this strange operating table
and public Ham Radio outreach during the tours as part of the 100th Centennial.
Setup #3, Cave Station VHF:
This setup is identical to the Setup #2 and just adds another operator and
radio at the card table under the parking lot. This operator operates on VHF
which may or may not work depending on the circumstances. This link will
appear the same function as the HF link above, but will be beneficial research
to see if the VHF band can pentrate the rock with the 50W power and beam
antennas. Hopefully the rock is thin enough at this location so that contacts
can also be made with topside amateur radio operators with nothing but handheld
handi-talkies (HT's). Both FM voice and possibly APRS data exchange will be
tested.
Setup #4, Cave Station, Antenna Topside:
This station sets up anywhere in the cave where there is an easy conduit to the
surface for a coax run. The station below ground operates at his assigned card-table
location but uses an antenna topside. This station can make nationwide contacts just
like the public station #1. Ideally this station would also be in a public area
such as in the food court near the elevator where a conduit may exist. Again, no
NPS manpower required other than inintial escort.
As an added option, this station could have a solar panel topside and the power
from the solar panel could power the station. This would be a unique demonstration
of clean renewable energy as supported by the NPS.
Setup #4, The Hams on-TOUR setup:
The TOUR method, shown above, involves one operator topside (in a parking space in the parking
lot with with a powerful VHF station and beam pointing down into the ground to make contacts
with ten or more radio operators as they walk underneath him on existing tours. This method
requires no special NPS manpower. The radio operators just join a tour with their handheld
equipment And try to make contact dsicretely from the back of the tour group. No special
NPS manpower support is needed as the contacts can be made at walking speed and remain with
the tour group.
Setup #5, UHF link-test and Research data collect:
The LEAP-FROG method is simpilar to the 2013 test and uses ten or more cavers with HT's
below ground spreading out in a chain and maintaining contact and then the end unit passes
by all other operators to the front of the line making contacts as he goes. This leap-frog
is necessary because "radio relay" does not count for the NPOTA statistics. This method
appears trivial from an RF lionk perspective, but actually offers the most research potential
because in effect, it is re-testing the link-by-link method of communication used in the
2013 cave link test but without all the data-packet complexity.
It is much eaiser to find the best link-by-link distances using UHF walkie talkies and voice
contact than it was by waiting for the once every 20 second test packets. This method would
require dedicated NPS or NSS guides/monitors in a non-public part of the cave.
Ten operators can probably spread out as much as a mile in Cleveland Avenue as the scale map
below shows. This is a copy of the approximate location of the UHF digipeaters and the lengths
of each link used in the 2013 test.
Handheld Antenna Performance:
The antenna shown above can be used for added gain at UHF or VHF for making contacts under
weak signal conditions. It is composed of threaded aluminum arrows which can be disassembled
and carried in a small mailing tube about 2 feet long. It has the advantage of being able to
be hand directed and optimized for the best angle of arrival and polarity of the topside signal.
So, depending on the perimssions of the NPS and the number of Ham Radio volunteers that we
get signed up, and the dates chosen for the event, we can really put Mammoth Cave on the map
for public visibility of the 100th NPS Centenial.
Link back to the original Mammoth Cave NPOTA ideas page
Bob Bruninga, WB4APR
US Naval Academy
lastname at usna dot edu