Radios, meteors and the Morrow Project

[robj3]

How does the wakeup signal get to a bolthole, anyway?

The problem is comparable with communicating with submarines at sea;
ground penetration of radio waves is limited by soil and rock moisture and electrolyte content. High electrical conductivity causes attenuation of the signal.

The transmitter needs to have a wide range and also be relatively easy to disguise.

Transmission should not depend on satellites for propagation, given the limited usable lifetime of satellites. Not needing certain atmospheric conditions for signal propagation would be useful, but this limits the available range of frequencies.

On the receiving end, above ground antennae also have to be limited in height and size otherwise concealment becomes difficult. Buried antennae need to be larger to compensate for the attenuating effects of the ground. This would require large amounts of land, especially in the case of lower frequencies/longer wavelengths (see below).


* Meteor Burst Communications
Meteors continually enter the Earth's atmosphere; as they burn up they ionise the surrounding air. This enables radio transmissions to be bounced off these ionisation trails, which typically occur at an altitude of 50-75 miles (80-121km).
Stations can be up to 1,243 miles (2,000km) apart.

Low frequency (30-300kHz) transmissions can propagate this far, but large antennae are required (up to 200+m in height) e.g. the LORAN (long range navigation) network.

Frequencies in the VHF band over the 30-100MHz range can be used. The optimum for maximum range is 40-50MHz.

A master station transmits a probe signal into the upper atmosphere. Remote stations wait to receive the probe signal reflected off a meteor trail. They then transmit a message back to the master station that a communication channel is open. The master then acknowledges the remote station and communications begin.

Another option is that the master repeatedly transmits to an array of remote stations.
The remotes are in a receive mode only. Given enough time a channel will open to all the remotes.

The main problem is a relatively low bandwidth due to the fleeting (~0.5 second) and random nature of meteor trails (varies with time of day and year; delays of several minutes are possible, but usual wait times are less than 90 seconds).
Despite needing to send information in short bursts, transmission rates of over four kilobits per second are possible.

Transmitters and receivers can be small: 10.6" x 4" x 2.42" (26.9 x 10.2 x 13.5 cm).

Antennae are relatively small: 2-3m (7-10ft) for portable systems, 10-15m (30-50ft) for large base stations. Transmission power ranges from 100W to 1kW (the maximum transmitter power for a civilian AM radio station today in North America is 50kW).

The best known meteor-burst communication system is used by SNOTEL (snow telemetry).
It has been operated by the USDA since 1977 and measures and transmits snowpack and precipitation data from over 700 locations across the Western United States, including Alaska.

COMET was a military system used by NATO from 1965 with stations in the Netherlands, France, Italy West Germany, Norway and the United Kingdom. Data rate was 115-310 bits per second.

Meteor burst systems look like a good modality for longer-range Project communications.
They are portable, secure and offer over the horizon capability without the need for satellites or other relays.

* Shortwave
Also known as high frequency (3-30MHz). It is possible to communicate around the world over this band, provided atmospheric conditions are suitable; the radio waves are refracted by the ionosphere.

Time of day, season and solar activity affect the ionosphere and thus the maximum range obtainable.

Frequencies above 12MHz propagate better during the day; at night, the converse is true.

Solar activity (especially flares) reduces shortwave range.

In the short term after a nuclear exchange, widespread atmospheric ionisation will also adversely affect range; a much smaller interference effect can be seen with thunderstorms.

Shortwave antennae can be quite small, on the order of a foot (0.3m); longer range transmitters and receivers require larger systems (the extreme case being several hundred yards [metres] for a buried antenna with intercontinental range).


* What about ELF?
Extremely Low Frequency (ELF) radio uses frequencies between 30 and 300Hz; the problem is that extremely large antennae are required for transmitters.

In addition there are severe geological restrictions - access to large areas of
low-conductivity rock is needed.

The original plan for the U.S. ELF transmitter, Project Sanguine, would have used an area equivalent to 2/5 of the state of Wisconsin (~21,992 sq. miles or 56,960 km^2).
Three locations were considered: Nevada (Nellis AFB, Nevada Test Site); New Mexico (White Sands/Fort Bliss); and the upper peninsula of Michigan.

This would have used the Laurentian granite bedrock of the Lake Superior region as a giant antenna. 6,000 miles (9,650km) of cable would be tunneled through the rock to form an antenna grid.

The proposal was vetoed because of potential biological effects. Enormous quantities of power would be required to energise the antenna.

A smaller version, Project ELF, became operational in 1989. It was dismantled in 2004.
There were two antennae, one near Clam Lake, WI, and the other near Republic, MI.

The Wisconsin antenna was made up of two 14 mile (22.53km) lines, the Michigan three lines - two 14 miles (22.53km) long, and one 28 (45.06km) long. The antennae were mounted on 40ft (12m) telegraph poles and had a cruciform arrangement.
The attendant transmitter facilities were six (MI) and two (WI) acres (2.4 and 0.8 ha) in size. They were connected by a 165 mile (265.5km) cable.

Transmission power was on the order of 5 megawatts.

A road mobile system with 30 miles of cable (lay grid out on road) was investigated.

On the receiving end, a submarine deploys a wire antenna several hundred yards (metres) long. ELF waves will penetrate several hundred yards (metres) of seawater.

The data transmission rate is slow, on the order of 1 bit every 1-10,000 seconds.
As a result, a submarine usually ascends to a depth where faster communications are possible.


* What about VLF?
Very Low Frequency (3-30 kHz) signals are also used to communicate with submarines.
They can penetrate sea water up to 40m deep, depending on frequency and salinity.

Transmission and reception antennae also need to be quite large.
For the TACAMO system, aircraft deployed a 5 mile (8km) wire antenna to transmit to submarines. The receiving antennae were similar in length to the ELF system.

Terrestrial transmitters occupy several acres. Transmitter power 1-3MW.

The following sites formed the U.S. strategic VLF communications network:
- Northwest Cape, Exmouth, Western Australia
- Yosemi, Japan
- Rugby, UK
- Anthorn, UK
- Wahiawa, Hawaii
- Annapolis, MD
- Cutler, ME
- Jim Creek, WA


* Maintaining communications after nuclear attack: GWEN
The Ground Wave Emergency Network (GWEN) was built in the 1980s to provide a secure communication infrastructure for U.S. strategic forces. It was designed to be resistant to electromagnetic pulse and have the ability to route data packets around damaged nodes like the Internet (packet switching).

Transmission would not rely on bouncing off the ionosphere for range
(low frequency at 150-175kHz).

58 290ft (88m) transmission towers were built across CONUS. 49 access terminals were distributed.

GWEN was defunded in 1998. Its functions were covered by the existing Survivable Low Frequency Communications System (SLFCS) operated by SAC/STRATCOM and the Minimum Essential Emergency Communications Network (MEECN). SLFCS/MEECN were also connected into the Navy's VLF/ELF system.

SLFCS transmitted from four locations:
- Silver Creek, Nebraska
- Hawes AFS, California
- Post Attack Command and Control System aircraft (5 on alert in the northern U.S.)
- The National Emergency Airborne Command Post (National Airborne Operations Centre)

Terrestrial (VLF/LF) antennae were buried, increasing their survivability.

Messages were relayed to bombers via the GREEN PINE stations in Alaska and Canada.

Ground based receiving stations were at the bomber and ICBM bases.

MEECN replaced SLFCS in 2005. This has satellite uplink capacity to the Milstar constellation as well as the low frequency (14-60kHz) bands used by SLFCS.


Rob

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* References
http://en.wikipedia.org/wiki/Radio_propagation

Underground and underwater(!) antennae from the early days of radio:
http://www.rexresearch.com/rogers/1rogers.htm

= Meteor Burst Communications
http://en.wikipedia.org/wiki/Meteor_...communications
http://en.wikipedia.org/wiki/SNOTEL
http://www.meteorcomm.com/technologies/tech_burst.aspx
Cohen D., Grant W., and Steele F.NTIA Report 89-241. Meteor Burst System Communications
Compatibility. U.S. Department of Commerce, March 1989.
Haakinson E.J. NTIA Report 83-116. Meteor Burst Communications Model. U.S. Department
of Commerce, February 1983.
http://en.wikipedia.org/wiki/LORAN-C

= Shortwave
http://en.wikipedia.org/wiki/Shortwave

= ELF
http://en.wikipedia.org/wiki/Extremely_low_frequency
http://en.wikipedia.org/wiki/Communi...ith_submarines
http://enterprise.spawar.navy.mil/Up...ke_elf2003.pdf
http://www.plrc.org/docs/941005B.pdf
Schwartz S., et al. Atomic Audit: the costs and consequences of U.S. nuclear weapons
since 1940. The Brookings Institution, 1998. p.215

= VLF
http://en.wikipedia.org/wiki/Very_Low_Frequency
http://www.globalsecurity.org/wmd/systems/e-6.htm
Schwartz S., et al. Atomic Audit: the costs and consequences of U.S. nuclear weapons
since 1940. The Brookings Institution, 1998. p.209, 214-215

= GWEN
Foster N. Citizens jam nuclear radio network. Bulletin of the Atomic Scientists
44:9 (Nov 1988). p.21-26
http://en.wikipedia.org/wiki/Ground_...rgency_Network
http://en.wikipedia.org/wiki/SLFCS
http://en.wikipedia.org/wiki/MEECN
http://www.globalsecurity.org/wmd/systems/gwen.htm
http://www.globalsecurity.org/wmd/systems/slfcs.htm
http://www.globalsecurity.org/wmd/systems/meecn.htm