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
