Internet Movie Radio Database:Current events

From Internet Movie Radio Database

Ham radio saves the day

By Jill McNeil, Channel 6 news
April 6, 2010

Sat-nav devices face big errors as solar activity rises

By Jason Palmer Science and technology reporter, BBC News
February 10th, 2010

Researchers say the Sun is awakening after a period of low activity, which does not bode well for a world ever more dependent on satellite navigation.

The Sun's irregular activity can wreak havoc with the weak sat-nav signals we use.

The last time the Sun reached a peak in activity, satellite navigation was barely a consumer product.

But the Sun is on its way to another solar maximum, which could generate large and unpredictable sat-nav errors.

It is not just car sat-nav devices that make use of the satellite signals; accurate and dependable sat-nav signals have, since the last solar maximum, quietly become a necessity for modern infrastructure.

Military operations worldwide depend on them, although they use far more sophisticated equipment.

Sat-nav devices now form a key part of emergency vehicles' arsenals. They are used for high-precision surveying, docking ships and they may soon be used to automatically land commercial aircraft.

Closer to home, more and more trains depend on a firm location fix before their doors will open.

Simple geometry

The satellite navigation concept is embodied currently by the US GPS system and Russia's Glonass network, with contenders to come in the form of Europe's Galileo constellation and China's Compass system.

It depends on what is - at its root - a simple triangulation calculation.

A fleet of satellites circling the Earth are constantly beaming a radio signal with two bits of exceptionally precise information: where exactly they are, and at exactly what time.

A sat-nav receiver on Earth - or on a ship or plane - collects the time and position signals from the satellites that happen to be in its line of sight.

It then works out, based on how long it took those signals to arrive, how far it is from each of those satellites. Some simple geometry yields its position.

• 1. Satellites advertise their exact position, and the precise time at which they are sending it
  
• 2. The signal travels through the outer atmosphere, the ionosphere; its speed depends on how much the Sun's radiation and particle winds are affecting the ionosphere's composition
  
• 3. A receiver on Earth determines how long the signals took to arrive from a number of satellites, calculating the position from the time differences
  

But those signals are incredibly weak and, as researchers have only recently begun to learn, sensitive to the activity on the Sun.

Solar flares - vast exhalations of magnetic energy from the Sun's surface - spray out radiation across the electromagnetic spectrum, from low-energy radio waves through to high-energy gamma-rays, along with bursts of high-energy particles toward the Earth.

The radiation or waves that come from the Sun can make sat-nav receivers unable to pick out the weak signal from satellites from the solar flare's aftermath.

There is little that current technology can do to mitigate this problem, with the exception of complex directional antennas used in military applications.

Sat-nav receivers will be blinded for tens of minutes, probably a few times a year at the solar maximum.

Charged up

A further complication comes from the nature of the outermost layer of the Earth's atmosphere, the ionosphere.

That is composed in part of particles that have ionised, or been ripped apart by radiation from the Sun, with the composition dependent on how much radiation is coming from the Sun at a given time.

The problem comes about because sat-nav technology assumes that signals pass through at a constant speed - which in the ionosphere isn't necessarily the case.

"The key point is how fast the signals actually travelled," said Cathryn Mitchell of the University of Bath.

"When they come through the ionosphere, they slow down by an amount that is actually quite variable, and that adds an error into the system when you do the calculations for your position," Professor Mitchell told BBC News.

The amount of solar activity runs on many cycles; the ionisation will be different on the sun-lit side of the Earth from the night side, and different between summer and winter; each of these cycles imparts a small error to a sat-nav's position.

Professor Louise Hara from University College London explains how the SDO will look at the Sun's magentic field(Solar images: Hinode/Jaxa/Nasa)

But the disruption caused by solar flares is significantly higher.

The increased radiation will ionise more molecules, and the bursts of particles can become trapped in the ionosphere as the Earth's magnetic field drags them in.

The effects that sat-nav users will face, however, are difficult to predict.

"We can look at the measurements from the last solar maximum," Professor Mitchell said.

"If we project those forward, it varies quite a lot across the Earth; looking at the UK it will be about 10-metre errors in the positioning."

The errors would be much more long-lasting than the "blindness" problem, lasting hours or even days.

"Ten metres out is probably going to be OK for a sat-nav system in a car, but if you're using the system for something safety-critical like ships coming into harbour for navigation or possibly in the future landing aircraft, you're looking for much greater accuracy and more importantly, much greater reliability."

Bob Cockshott, a director of the government-funded Digital Systems Knowledge Transfer Network, said that for most consumer applications such as sat-nav for cars, the problem will be more troublesome than dangerous.

"You might find for a number of hours or even a day or two you couldn't go out surveying or be able to dock your oil tanker at the deep-ocean oil well," he told BBC News.

"It's more at the annoyance level than something that's going to bankrupt your business."

A number of schemes have been proposed to do real-time corrections to the signals as the atmosphere changes, allowing for local adjustments that are broadcast to receivers by other means such as the mobile phone network.

However, Mr Cockshott said that it remains unclear whether such a correction makes sense economically for manufacturers of sat-nav-enabled technology.

So as the Sun builds up to its peak in a few years' time, be aware that your sat-nav may for a time give some strange results - or for a short while none at all.
BBC News

Haiti help ask a ham radio operator see bands also below

iReport
January 13, 2010
Earthquake net frequencies - 7045, 3720 kHz - Please keep clear

All radio amateurs are requested to keep 7045 kHz and 3720 kHz clear for possible emergency traffic related to today's major earthquake in Haiti.

International Amateur Radio Union (IARU) Region II Area C Emergency Coordinator Arnie Coro, CO2KK, reports that as of 0245 UTC on January 13, nothing had been heard from radio amateurs in Haiti, but that the above frequencies were being kept active in case any Haitian hams manage to get on the air, and in case of other related events in surrounding areas, including aftershocks and a possible tsunami.

The following is from an e-mail from CO2KK:

A few minutes after the earthquake was felt in eastern Cuba's cities, the Cuban Federation of Radio Amateurs Emergency Net was activated, with net control stations CO8WM and CO8RP located in the city of Santiago de Cuba, and in permanent contact with the National Seismology Center of Cuba located in that city.

Stations in the city of Baracoa, in Guantanamo province, were also activated immediately as the earth movements were felt even stronger there, due to its proximity to Haiti. CO8AZ and CO8AW went on the air immediately, with CM8WAL following. At the early phase of the emergency, the population of the city of Baracoa was evacuated far away from the coast, as there was a primary alert of a possible tsunami event or of a heavy wave trains sequence impacting the coast line at the city's sea wall ...

Baracoa could not contact Santiago de Cuba stations on 40 meters due to long skip after 5 PM local time, so several stations in western Cuba and one in the US State of Florida provided relays. CO2KK as IARU Region II Area C Emergency Coordinator, helped to organize the nets, on 7045 kHz and also on 3720 kHz, while local nets in Santiago de Cuba and Baracoa operated on 2 meters.

As late as 9,45 PM local time 0245 UTC we have not been able to contact any amateur or emergency services stations in Haiti.

Amateurs from the Dominican Republic, Puerto Rico, Venezuela were monitoring the 40 meter band frequency, that I notified to the IARU Region II executive Ramon Santoyo XE1KK as in use for the emergency, requesting that 7045 kHz be kept as clear as possible..

We are still keeping watch on 7045 kHz hoping that someone in Haiti may have access to a transceiver and at least a car battery to run it.

All information that has so far come from the Cuban seismologists tell us of a very intense earthquake, and also of the possibility of other events following.

Following the advice of the geophysicists, we are keeping the 7045 and 3720 kiloHertz frequencies active until further notice.
CNN International

Ham radio operator helped in Logan Canyon emergency

Associated Press
December 7th, 2009

A North Logan man is being credited for his help after a truck crashed in a remote part of Logan Canyon.

Although there was no cell phone reception for miles, Brent Yeates had a hand-held amateur "ham" radio with him. Yeates called out for help after the dairy truck crashed and another ham operator heard it, then contacted emergency dispatchers.

The Utah Highway Patrol originally thought the call came from someone who had to drive to get a cell phone signal after the accident last week.

Yeates says once he waded through the cold water of the Logan River and helped the driver get out of the cab, he was able to make the call on his radio.
KSL