Detail of GB/T 42724-2023

Introduction of GB/T 42724-2023

Ships and marine technology - Navigation and ship operations - Guidelines for onboard telephone equipment 1 Scope This document provides general and specific recommendations related to the quality of communication, connectivity, installation, performance and maintenance of onboard telephone equipment, including automatic telephones, common battery telephones, battery-less telephones and sound-powered telephones. It also specifies requirements for the related performance tests (shop tests and onsite tests) and for the maintenance tests. The scope of application of this document is shown in Table 1. It is not applicable to digital telephones, LAN (VoIP) telephones, and wireless telephones. Table 1 further illustrates the applicability of this document. 2 Normative references There are no normative references in this document. 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 Types of telephones 3.1.1 automatic telephone telephone commanded under an automatic telephone exchanger (3.3) Note 1: Automatic telephones can be classified into four types - desk, wall-mounted, flush-mounted and portable - based on their structural appearance. Note 2: Automatic analog telephones are called "automatic telephones" in this document. 3.1.2 common battery telephone telephone powered by a power supply (24V) Note 1: ommon battery telephones are classiied into two types - “selective” and “direct” - based on their connectivity. Note 2: ommon battery telephones can be classiied into four types - desk, wall-mounted, lush-mounted, and portable - based on their structural appearance. 3.1.3 battery-less telephone telephone itted with a hand crank generator for communicating by voice, ampliied by self- generated power Note 1: attery-less telephones areclassiied into twotypes- “selective” and“direct” -based on their connectivity. Note 2: attery-less telephones can be classiied into four types - desk, wall-mounted, lush-mounted, and portable - based on their structuralappearance. 3.1.4 sound-powered telephone battery-less telephone (3.1.3) not requiring an external power sourcefor conversation (talk circuit) Note 1: handcrank generator is only used for signalling actions. Note 2: Sound-powered telephones can be classiied into four types - desk, wall-mounted, lush-mounted, and portable - based on their structural appearance. 3.2 automatic telephone equipment system that connects automatic telephones (3.1.1) to an automatic telephone exchanger (3.3), thereby enabling telephonic ringing and telephonic conversation between any two automatic telephones through selection signals (such as push button or dial pulse dialling) 3.3 automatic telephone exchanger telephone exchanger that uses automatic telephones (3.1.1), made durable to withstand typical shipboard vibration and environments Note: This is also available for public announcements by way of a P system. Through this, the automatic telephone is able to communicate with land telephones via STOM or INMRST, etc. 3.4 howling unpleasant noise caused by audio feedback due to repeated ampliication by the ampliier of the voice input, that impedes intelligible conversation 4 General characteristics 4.1 General The classiication and connectionof telephones areshown in Table 2and Figure 1. The onboard telephone equipment includes automatic telephones, automatic telephone exchanger, common battery telephones, battery-less telephones and sound-powered telephones. The equipment should ensure accurate transmission and reproduction of the caller voice signals. 4.2 Automatic telephones The automatic telephone equipment enables calling between onboard and outboard telephone equipment by connecting to outboard communication systems (such as INMARSAT, VSAT, cellular phones, and landline telephones). It also enables paging broadcasts from the telephone equipment by coupling with a public addresser. The automatic telephone exchanger should be able to withstand typical vibration and swinging motions (pitch and roll) for use in a shipboard environment. The automatic telephone exchanger should comply with ISO 19847 and ISO 16425. Electric source for the automatic telephones should be supplied by both AC power and DC power (DC24V). In case the AC power is lost, the telephones can switch to the DC power supply automatically. 4.3 Common battery telephones Selective common battery telephones permit telephonic ringing and telephonic conversation between any two devices. Direct common battery telephones only permit telephonic ringing and telephonic conversation between parent and child telephones (such as 1:1, 1:2, and 1:3 conigurations).parent and child telephones (such as 1:1, 1:2, and 1:3 conigurations). A DC power supply (24V) is required forcommon battery telephones. 4.4 Battery-less telephones Battery-less telephones are able to use their built-in generator to call other telephones, even if power is not supplied from an externalsource. If a complete power failure occurs on a ship, the battery-less telephone (or sound-powered telephone) may be the only emergency system available for communication. 4.5 Sound-powered telephones In high noise environments, the hand crank generator may also power a latching circuit at a remote station that augments the hand crank generator powered signalling circuit withan externally powered audible or visual signalling device. The hand crank generator powers the signaling circuit to notify another station. Sound-powered telephones use “common talk”(everyone hears the conversation) for all stations on the circuit. Sound-powered telephones are classiied as direct call and selective call. If a complete power failure occurs on a ship, the sound-powered telephone (or the battery-less telephone) maybe the only emergency system available for communication.

Contents of GB/T 42724-2023