1
Frequencies and Classes of
Emission
1.1 The radiotelephone and DSC transmitter should
be capable of transmitting on a number of frequencies in the bands
between 1,605 kHz and 4,000 kHz considered by the Administration as
adequate for the operation of the ship, but at least on the frequencies
2,182 kHz and 2,187.5 kHz.
1.2 Radiotelephone frequencies are designated
in terms of the carrier frequency; DSC frequencies are designated
in terms of the assigned (centre) frequency. When DSC signals are
transmitted using a transmitter in J2B mode, the (suppressed) carrier
frequency should be adjusted so as to have the DSC signal transmitted
on the assigned DSC frequency. The selected transmitter frequency
should be clearly identifiable on the control panel of the equipment.
1.3 The transmitter should be capable of transmitting
(upper side band signals, where appropriate) using classes of emission
J3E, H3E and either J2B or F1B.
1.3.1 When switching to the preset distress frequency
2,182 kHz, the appropriate class of emission in accordance with the
Radio Regulations should be selected automaticallyfootnote
1.3.2 When switching to the preset distress frequency
2,187.5 kHz, the class of emission J2B or F1B should be selected automatically.footnote
1.4 It should be possible to change the transmitter
from any class of emission to another for which it is designed to
operate by means of not more than one control.
1.5 It should be possible for the user to select
transmission frequencies independent of any receiver setting. This
does not preclude the use of transceivers.
1.6 It should be possible to change the transmitter
quickly from operation on any frequency to operation on any other
frequency, and in any event within a period not exceeding 15 s. The
equipment should not be able to transmit during channel switching
operations.
1.7 Means should be provided to prevent over-modulation
automatically.
2
Frequency Stability And Accuracy
The transmitter frequency should remain within 10 Hz of
the required frequency at all times following the warming-up period.
3.1 During normal modulation, the peak envelope
power in the case of J3E or H3E emissions, or the mean power in the
case of J2B or F1B emissions, should be at least 60 W at any frequency
within the specified frequency range.
3.2 If the rated output power exceeds 400 W, provision
should be made for reducing the output to 400 W or less.
4
Permissible Warming-Up Period
The equipment should be capable of operating on 2,182 kHz
and 2,187.5 kHz within 1 min after switching on.
Continuous operation should be possible when the transmitter
is adjusted to its rated power.
6
Controls and Indicators
6.1 Provision should be made for indicating the
antenna current or power delivered to the antenna. Failure of the
indicating system should not interrupt the antenna circuit.
6.2 Manually tuned equipment should be fitted
with a sufficient number of indicators to permit accurate and rapid
tuning.
6.3 Operation of the transmit/receive control
should not cause unwanted emissions.
6.4 All adjustments and controls necessary for
switching the transmitter to operate on 2,182 kHz and 2,187.5 kHz
should be clearly marked, in order that these operations may be performed
readily.
The equipment should be so designed and constructed that,
when the transmitter is providing power to the antenna, the transmitter
is protected against damage resulting from disconnection of the antenna
or short-circuiting of antenna terminals. If this protection is provided
by means of a safety device, that device should automatically be reset
following removal of the antenna open-circuit or short-circuit conditions.
8.1 If it is necessary to delay the application
of voltage, for example anode voltage, to any part of the transmitter
after switching on, this delay should be provided automatically.
8.2 If the transmitter includes parts which are
required to be heated in order to operate correctly, for example crystal
ovens, the power supplies to the heating circuits should be so arranged
that they can remain operative when other supplies to or within the
equipment are switched off. If a special switch for the heating circuits
is provided, its function should be clearly indicated; it shall normally
be in the "on" position and be protected against inadvertent operation.
The correct operating temperature should be reached within a period
of 30 min after the application of power.