On Mon, 25 Aug 2003 00:26:46 +0000, "Uncle StoatWarbler"
wrote:

On Sun, 24 Aug 2003 19:35:16 +1200, Barry Lennox wrote:

The 406MHz COSPAS/SARSAT ones are much more accurate, typically about
200-300metres just from a satellite fix, but they are also much more
expensive. Depends on how much you are worth!

It won't be long before the new generation combines a gps fix with the
distress squawk.

They already exist right now, and have done for about 6 years, but
they are expensive, and that won't come down too much. The problem is
the 121.5/243 MHz ones cannot support embeddded data, and
COSPAS/SARSAT plans to stop monitoring these freqs in 2006 (I think,
maybe 2008) because of this limitation and the VERY high rate of false
alarms, over 90% in most countries, inc NZ.

The 406 MHz ones certainly support embedded data, but you pay a lot
for them. The big cost driver is the very stable oscillator required,
plus the many thousands required for certification.

On Mon, 25 Aug 2003 18:16:47 +0000, "Uncle StoatWarbler"
wrote:

On Mon, 25 Aug 2003 19:38:13 +1200, Barry Lennox wrote:

It won't be long before the new generation combines a gps fix with the
distress squawk.

They already exist right now, and have done for about 6 years, but
they are expensive, and that won't come down too much.

Wanna bet? There are moves afoot to push the devices into all sorts of
transport equipment which don't currently have 'em (and arguably don't
need 'em in most parts of the world)

I would, but whatever happens does happen, This has not been discussed
at COSPAS/SARSAT meetings I have minutes for. I think you may be
confused with some other beacons.


The problem is
the 121.5/243 MHz ones cannot support embeddded data, and
COSPAS/SARSAT plans to stop monitoring these freqs in 2006 (I think,
maybe 2008) because of this limitation and the VERY high rate of false
alarms, over 90% in most countries, inc NZ.

That and the satellites are already way past their use-by date, plus there
are the usual interference issues. Txing on 121.5 is awkward (airband)
anyway.

Use-by date? They do get replaced ! "Interference issues"? Like
what, In every ITU region and WARC these frequencies are very
agressively protected. The UWB case is an excellent example.

"Txing on 121.5 is awkward" WTF?! Quite a few A/C carry either a D/F
or homing system that lets them localise the beacon source. In
addition, early every decent A/C Comm Rx has a "Guard" Rx on 121.5 to
detect a beacon. That is the whole point of it, and how the SAR and
aviation infrastructure has grown in the past 50+ years.

The 406 MHz ones certainly support embedded data, but you pay a lot
for them. The big cost driver is the very stable oscillator required,
plus the many thousands required for certification.

This will come down rapidly. The oscillators can be selftweaking off GPS
clocking information, providing ongoing accuracy feedback and
substantially reducing setup costs.

Hmmm, none of the 3 beacon manufacturers I have dealt with over the
past 4 years would agree. The certification costs can only go up.

On Tue, 26 Aug 2003 09:33:53 +1200, "Fred"
wrote:


In practical terms, what do you suggest that conscientious Kiwi trampers
should take with them when they spend a few days in the bush?

A few first aid bits.
All the other safety stuff, pocket knife, strong cord, razor blades,
pen, paper, etc, etc
A very loud whistle
A CD (signal mirror)
A cellphone (If you are remotely near coverage)
Perhaps a day/night flare
A space blanket (Aluminized mylar)
Several options for fire-lighting, don't rely on just one. A fire is
one of the greatest life-savers. Not only does it give you warmth, but
it's also a signaling mechanism, as well as keeping your spirits
up.Just be careful not to set off the greatest bush fire ever known!
Some sort of beacon or MRS set, see below.


Are these
locator beacons available in NZ and for what price?

Yes, anywhere from about $350-400 upwards

Who sells them?

Most of the safety/camping/map shops

Do
these beacons put out a strong signal?

Yes, quite strong enough.

What battery power do they require?

Sometimes a special pack, manufacturer provided, but some have 4 or 6
alkaline AA cells in a battery pack

How long does the beacon transmit for after it is turned on?

Varies with the battery type and temp, often 20-50 hours, with the
transmitted power falling off towards the end

Can the signal
from one of these beacons be obstructed by a heavy bush canopy in the
same way that GPS and cell phone signals can?

Yes, it can, but the satellites are well above you, so they have a
better chance.


Is the signal from a locator beacon monitored 24
hours a day?

Yes.

How is the information passed on to the authorities and by whom?

Through the COSPAS/SARSAT organisation. Bear in mind that it takes two
satellite passes to resolve the position ambiguity, and the
positioning accuracy is quite poor with the low-cost beacons, often
around 20Km, a huge area. The 406 MHz ones are much better, during
some trials, we managed to set one off accidentally. The first pass
put our position 67 miles out, the second pass was 380 feet.

Bear in mind that over 90% of all such beacon activations are false
alarms. If I was taking one out, I'd leave notice with friends, etc
that I would activate the beacon for say, 111 minutes, then turn it
off for exactly, say 47 minutes, then back on for 4 hours, or some
"coded sequence" like that. This is not an approved system or method,
but it would pretty much eliminate it as just another damm false
alarm. They would have to pass it on to police and the SAR center
after hearing of a beacon activation, or suspecting a problem.


Incidentally, I can't see why the signal from a 5-watt UHF radio
would not be picked up by someone listening to the emergency channel,
particularly when it was known that a person was lost. A helicopter search
for example would probably pick up such a signal, as would someone
on the top of a nearby high hill.

Sure they would, 5 watts will typically go 80-120 miles in an good
air-ground link. BUT, you must be transmitting on the same freq they
were receiving on. And how would they know you were lost in the first
place?

An MRS, Mountain Radio Set would also be a good option to hire, they
do require a bit of messing about to setup and some limited skill to
operate. The big thing about them, is there is a regular monitoring
watch with probably a large number of operators each night. So there
is a good chance you will get through to somebody, somewhere in NZ.

Best of luck, be careful.

On Wed, 27 Aug 2003 10:50:37 +1200, "Fred"
wrote:
Thanks very much Barry for a most informative reply. It concerns me that
some trampers / hikers think you are a bit paranoid or overanxious
Fred,

I have just found my "standard-minimum" hiking kit, and it's listed
below. You may find it useful, but I'll bet you get plenty of s******s
from those who have never been in a tricky situation.

Many, many, years ago, 3 of us did get a bit in the pooh. While we
were young and fit, as well as having plenty of survival training, we
had a tense day and night until we found our way out. The kit below
would have been a big help!

My list:

Matches, waterproof in a 35mm film cannister
candle stub
Bic butane lighter
Zippo lighter
several Band-Aids and a crepe bandage
2-3 safety pins
a dozen or so Disprin
magnifying glass
small bottle alcohol, about 75 mL.
Water purifying tablets
fish hooks and line
nylon parachute cord
Space blanket
A good solid pocket knife, or survival knife
2 x compass (one good, one standby cheapie)
Maps as required
A very loud whistle
2 x CDs
5 x single edged razor blades
pencil and paper
sunglasses
small roll of duct tape
LED flashlight and spare batteries
Plastic bags large and small
A 35 mm cannister holding cotton wool balls soaked in vaseline (a
great firestarter)
Waxed cardboard box to hold some of the above (secondary duty as
firestarter)


While it reads like a lot, it's all very compact and light.

While it's out of print, for sure, I often see used copies of an
excellent little book: "How to Survive in NZ" by Flt Lt B Hildreth.
It's worth a study, and I would generally carry it, depending on how
weight fussy I am. He used to teach survival techniques to RNZAF
airman cadets, and last I heard he was running a survival school in
the UK