(a) Narrow-band direct-printing (NB-DP) operating procedures.(1) When both terminals of the NB-DP circuit are satisfied that the circuit is in operable condition, the message preamble must be transmitted in the following format:
(i) One carriage return and one line feed,
(ii) Serial number or number of the message,
(iii) The name of the office of origin,
(iv) The number of words,
(v) The date of handing in of the message,
(vi) The time of handing in of the message, and
(vii) Any service instructions. (See The ITU “Manual for Use by the Maritime Mobile and Maritime Mobile-Satellite Services”.)
(2) Upon completion of transmission of the preamble, the address, text and signature must be transmitted as received from the sender.
(3) Upon completion of transmission of the signature the coast station must, following the signal “COL”, routinely repeat all service indications in the address and for figures or mixed groups of letters, figures or signs in the address, text or signature.
(4) In telegrams of more than 50 words, routine repetition must be given at the end of each page.
(5) Paragraphs (a) (1) through (4) of this section need not be followed when a direct connection is employed.
(6) In calling ship stations by narrow-band direct-printing, the coast station must use the ship station selective calling number (5 digits) and its assigned coast station identification number (4 digits). Calls to ship stations must employ the following format: Ship station selective call number, repeated twice; “DE”, sent once; and coast station identification number, repeated twice. When the ship station does not reply to a call sent three times at intervals of two minutes, the calling must cease and must not be renewed until after an interval of fifteen minutes.
(7) A public coast station authorized to use NB-DP frequencies between 4000 kHz and 27500 kHz may use class A1A emission on the “mark” frequency for station identification and for establishing communications with ship stations. The radio station license must reflect authority for this type of operation, and harmful interference must not be caused.
(b) Watch on ship calling frequencies.(1) Public coast stations using telegraphy must maintain a continuous watch during their working hours for calls from ship stations on frequencies in the same band(s) in which the coast station is licensed to operate. See subpart H of this part.
(2) Such station must employ receivers which are capable of being accurately set to any designated calling frequency in each band for which the receiver is intended to operate. The time required to set the receiver to a frequency must not exceed five seconds. The receiver must have a long term frequency stability of not more than 50 Hz and a minimum sensitivity of two microvolts across receiver input terminals of 50 ohms, or equivalent. The audio harmonic distortion must not exceed five percent at any rated output power.
(c) Radiotelegraph frequencies. Radiotelegraph frequencies available for assignment to public coast stations are contained in subpart H of this part.
Title 47 published on 2012-10-01
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