1
Frequencies and Classes of
Emission
1.1 The receiver should be capable of being tuned
throughout the bands between 1,605 kHz and 27.5 MHz. Tuning should
be either continuous, or by incremental steps, or by the selection
of a number of spot frequencies considered by the Administration as
adequate for the operation of the ship, or by any combination of these
methods. As a minimum, the following frequencies should be readily
accessible to the operator: the carrier frequencies 2,182, 4,125,
6,215, 8,291, 12,290 and 16,420 kHz for radiotelephony; the NBDP frequencies
2,174.5, 4,177.5, 6,268, 8,376.5, 12,520 and 16,695 kHz; and the DSC
frequencies 2,187.5, 4,207.5, 6,312, 8,414.5, 12,577 and 16,804.5
kHz.
1.2 Radiotelephone frequencies should be designated
in terms of the carrier frequency; NBDP and DSC frequencies should
be designated in terms of the assigned (centre) frequency. The selected
receiver frequency should be clearly identifiable on the control panel
of the equipment.
1.3 The receiver should be capable of receiving
upper sideband signals as appropriate for classes of emission J3E,
H3E, J2B and F1B.
1.4 The class of emission should be selectable
by not more than one control.
1.5 It should be possible for the user to select
reception frequencies independent of any transmitter setting. This
does not preclude the use of transceivers.
1.6 The receiver should be capable of being tuned
to different frequencies quickly, and in any event within a period
not exceeding 15 s.
2
Frequency Stability and Accuracy
The receiver frequency should at all times remain within
10 Hz of the required frequency following the warming-up period.
For classes of emission J3E and F1B the sensitivity of the
receiver should be equal to or better than 6 μV e.m.f. at the receiver
input for a signal-to-noise ratio of 20 dB. For NBDP and DSC an output
character error rate of 10-2 or less should be obtained
for a signal-to-noise ratio of 12 dB.
4.1 For the reception of voice signals, the receiver
should be suitable for use with a loudspeaker and a telephone handset
and should be capable of providing power of at least 2 W to the loudspeaker
and at least 1 mW to the handset.
4.2 An output should be provided for NBDP and
DSC signals if the corresponding facility is not integrated.
5
Permissible Warming-up Period
The equipment should be capable of operating within 1 min
after switching on.
6
Immunity to Interference
The immunity to interference of the receiver should be such
that the wanted signal is not seriously affected by unwanted signals.
The receiver should be provided with automatic gain control.
If the receiver 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 should 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.