 |
 |
 |
| The award-winning monthly publication of The Baltimore Radio Amateur Television Society P.O.Box 5915 Baltimore, MD 21282-5915 |
| |
|
|
| The award-winning monthly publication of The Baltimore Radio Amateur Television Society P.O.Box 5915 Baltimore, MD 21282-5915 |
French radio amateurs bounce laser signals off a rain cloud
That Amateur Radio is a hobby with variety and challenge was illustrated this week when two French radio
amateurs made a one way contact over a distance of 40 km scattering laser signals from rain clouds. The
flash pulses were at times 12 dB above the noise at 40 km which seem to indicate that under the right
conditions a distance of 150 km could be covered. Laser communication systems are wireless connections
through the atmosphere. They work similarly to fibre optic links, except that the beam is transmitted through
free space. While generally speaking the transmitter and receiver must require line-of-sight conditions, they
have the benefit of eliminating the need for broadcast rights and buried cables. Laser communication
systems can be easily deployed since they are inexpensive, small, low power and do not require any radio
interference studies. The carrier used for the transmission signal is typically generated by a laser diode.
Two parallel beams are needed, one for transmission and one for reception.
Laser communication have been a hot topic lately, as solutions for how to satisfy ever increasing bandwidth
needs are in high demand. Some have suggested that bandwidth could be distributed in neighbourhoods
by putting laser communication systems on top of homes and pointing them towards a common transceiver
with a fast link to the Internet. With possible transmit speeds of up to a gigabit per second, this is an exciting
area. Other applications for this technology include temporary connectivity needs (e.g. sporting events,
disaster scenes, or conventions), or space based communications. The French team proved that laser
signals can be scattered from clouds thus proving that the notion that laser communication can only be line
of sight, is wrong.
Source: The South African Radio League
Virginia radio amateur not prosecuted on radio-related felony charges
Dennis Alford, KC4VGA, of Wythe County, Virginia, is breathing a bit more easily now that he's no longer facing
a felony charge of possessing an unlawful communication device. According to a news report in The Wytheville Enterprise, a misdemeanor charge of unlawful interfering with a two-way radio was taken under advisement.
It will be dismissed after a year if no similar charges are brought against Alford, a 60-year-old longtime radio
amateur. The newspaper says a Wythe County General District Court judge accepted an agreement worked
out by Alford, his attorneys and a local prosecutor. A disabled truck plant worker who had been employed as a
Wal-Mart greeter, Alford still must forfeit three of the radios police confiscated last March. One of Alford's
attorneys told the court that Alford had bought the confiscated radios used and didn't realize they'd been
modified. Following his August 31 court appearance, authorities returned other confiscated radio equipment to
Alford. Police had searched Alford's home after the Wytheville Police Department in January reported extensive interference on its dispatching system that was traced to Alford's transmissions. Police subsequently arrested
him at work and confiscated several pieces of his radio equipment as well as a computer that since had been
returned to him. He had been on bond pending the hearing. Alford denied making any illegal transmissions
and said afterward he was satisfied with the resolution of his case to this story
| October, 2006 |  |
Page 1 Next > |