Technicians Handbook - Historic Naval Ships Association

Technicians Handbook - Historic Naval Ships Association Technicians Handbook - Historic Naval Ships Association

phy.davidson.edu
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Table 1-21.—New Style Military Fuse IdentificationTable 1-22.—Old Style Military Fuse Identification1-78

Commercial fuse identification and a fuse cross-reference can be found in NEETS, Module 3,Introduction to Circuit Protection, Control, and Measurement; and in Military Standard 1360A (MIL-STD-1360A). These will assist you in selecting or identifying fuses.Circuit breakers are too numerous to cover in this text. They are used in houses, vehicles, ships, andairplanes. Military Standard 1498 (MIL-STD-1498) contains information to help you select or identifycircuit breakers.Classification of Rf EmissionsThe system of designating rf emissions is arranged according to modulation type, mode, andsupplementary characteristics. For example: A3B indicates amplitude modulation, telephony, twoindependent sidebands, and a suppressed carrier. Table 1-23 will assist you in breaking down theemission classification code.EmissionTable 1-23.—Emission TypesTypeModulation TypesAmplitudeAFrequencyFPulsePModulation (Transmission Mode)None 0Telegraphy (keyed r-f carrier) 1Telegraphy (tone) 2Telephony 3Facsimile 4Television 5Four Channel Diplex Telegraphy 6Multichannel Voice Frequency Telegraphy Complex 7FormsSupplemental CharacteristicsDouble SidebandnoneSingle Sideband-reduced carrierA-full carrierH-suppressed carrierJTwo Independent Sidebands-suppressed carrierBVestigial Sideband PulseC-amplitude modulatedD-width modulatedE-phase modulatedF-code modulatedG*Capital or lower case letter**Commercial practice is to reduce carrier 20 dB, to provide sufficientcarrier for receiver afc lock-in, where afs receivers are used.Note: a number preceding the emission designation indicates thebandwidth in kilohertz.1-79

Commercial fuse identification and a fuse cross-reference can be found in NEETS, Module 3,Introduction to Circuit Protection, Control, and Measurement; and in Military Standard 1360A (MIL-STD-1360A). These will assist you in selecting or identifying fuses.Circuit breakers are too numerous to cover in this text. They are used in houses, vehicles, ships, andairplanes. Military Standard 1498 (MIL-STD-1498) contains information to help you select or identifycircuit breakers.Classification of Rf EmissionsThe system of designating rf emissions is arranged according to modulation type, mode, andsupplementary characteristics. For example: A3B indicates amplitude modulation, telephony, twoindependent sidebands, and a suppressed carrier. Table 1-23 will assist you in breaking down theemission classification code.EmissionTable 1-23.—Emission TypesTypeModulation TypesAmplitudeAFrequencyFPulsePModulation (Transmission Mode)None 0Telegraphy (keyed r-f carrier) 1Telegraphy (tone) 2Telephony 3Facsimile 4Television 5Four Channel Diplex Telegraphy 6Multichannel Voice Frequency Telegraphy Complex 7FormsSupplemental CharacteristicsDouble SidebandnoneSingle Sideband-reduced carrierA-full carrierH-suppressed carrierJTwo Independent Sidebands-suppressed carrierBVestigial Sideband PulseC-amplitude modulatedD-width modulatedE-phase modulatedF-code modulatedG*Capital or lower case letter**Commercial practice is to reduce carrier 20 dB, to provide sufficientcarrier for receiver afc lock-in, where afs receivers are used.Note: a number preceding the emission designation indicates thebandwidth in kilohertz.1-79

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