|
Looks like a second ex RO Dreamer band
, 4 Khz with EU hams getting 100 Hz data mode ?
Firstly all the coast is covered
by VHF to 30 + miles out , linked aprs and
radar plots give position and ship date , gps has
replaced console & MF beacons , secondly, Imarsat and
auto-hf have replaced the Radio operators , and nav-text
relays endless data on channel buoys with lights
out , rig moves , and no go areas for gunnery practice ,
with the odd gale warning oh and the odd bit of
cargo adrift , on its way to Cornwall
So what on earth is the system
going to relay, that the existing system (systems)
is/are not doing at the moment , and at
300/400 miles range who cares , the ship will more
likely be tied up at the destination port and
the crew ashore in the pub ..
And 2 slots as well simplex
broadcast only ... what nonsense ... Just a 'dead dog' data system with
rigamortis ...
G.
Sent: Friday, November 05, 2010 6:14 PM
Subject: RE: IMO SYNOPTIC was Re: LF: The Wideband
Noise
"The estimated coverage area from shore is approximately
320 nautical miles with a radiated power of 1 kW and 400 nautical miles with a
radiated power of 5 kW."
This seems a very conservative estimation to me.
I can hear the stronger G-stations (ERP 1-10W)
day and night with solid copy at similar distances (with a partly land
path).
73, Rik ON7YD - OR7T
PS: the "bubbles" arround 500kHz are good copy
here, but the signal seems to appear/disappear all the tile
________________________________________
Van:
[email protected] [[email protected]] namens
Terry GW0EZY [[email protected]]
Verzonden: vrijdag 5 november 2010
18:41
Aan: [email protected]
Onderwerp: RE: IMO SYNOPTIC was
Re: LF: The Wideband Noise
I guess these tests relate to a proposed new
system being discussed in ITU
Working Party 5B:
PROPOSED MODIFICATIONS
TO PRELIMINARY DRAFT NEW
REPORT ITU-R M.[500 kHz]
Utilization of the
495-505 kHz band by the maritime mobile
service for the digital broadcasting
(from shore-to-ships)
of information related to safety and
security
The draft new report has contributions from France and USA. Some
extracts
from the documents:
This preliminary draft Report provides
information on a digital broadcasting
system working in the 500 kHz band.
This system is intended to be used to
broadcast from shore to ships
information related to navigational and
meteorological warnings, urgent
information and other information related to
safety and security. The system
will utilize the band 495-505 kHz and have
the same coverage area as the
current NAVTEX system operating at 490 kHz and
518 kHz. New digital
technology provides a greatly improved data throughput
from that provided by
the current NAVTEX system. It also provides protection
to the incumbent
NAVTEX system.
This system will operate in a manner similar to the
current NAVTEX system.
The coast stations will be spaced along the coast
approximately [500]
nautical miles apart. All the transmitters on a coast
will share the 10 kHz
channel by transmitting in a specific time slot. An
example of time slot
allocations for a network of 500 kHz broadcast
transmitters for the Atlantic
coast of Europe is based on 3-minute slots of a
60 minute cycle. There is
also discussion on using 495-500 kHz and 500 - 505
kHz as two slots for a
"permanent mode"
The radiated power from the
regional coast station transmitter should be
what is sufficient to cover the
intended service area of that coast station.
The power would be decreased at
night during periods of better r.f.
propagation. The estimated coverage area
from shore is approximately 320
nautical miles with a radiated power of 1 kW
and 400 nautical miles with a
radiated power of 5 kW. The modulation is of
type OFDM with N-QAM. An
example of 64-QAM @ 47.4 kbps.system has a data rate
of 100 bit/second with
a 300 Hz channel. This system would have a data rate
of up to 47 400
bits/second with a 10 kHz channel.
A transmitter site
in France is mentioned in the report: Pointe de Corsen
coordinates: 48.414444
N, 4.794444 W. Google Earth shows some sort of
installation there.
73
Terry GW0EZY
| 