Applicable for undergroundlight railroadspeedwayshipmineMain features of product:1Cabinetaluminum alloy diecastinghigh anti-violent, able to glisten, convenient for looking for ( optional).2Door coverorient automatically and good selfclosingconvenient for use.(Note that the power of open:50Kg)3Handlemade of special engineering plastichigh anti-knock resistancehigh tensile strength resistance and high anti-violent.4All of the components including handle telephone receiver and transmitterkeypadbuzzercircuit board and cabinet are designed to be multilayer waterproof and dustproof which is up to Class III grade. The whole machine is up to national standard GB4208-93 IP 66 .5Phone is provided with high stabilityhigh anti-jamming capabilityand it is up to national standard GB/T 15279-94.Main technical indexes1Applicable for various types of SPC exchangedispatching exchange and dispatching exchange system with feeding voltage of 48-69V.2Ambient temperature:-30~60 Relative humidity:10%~95%Atmospheric pressure: 86~106Kpa Circumstance noise: 60dBA3Sound level of ringing70dBA.4Standard frequencylow frequency group697770852941Hz,high frequency group120913361477Hz, frequency deviation?1.5%If service line is a 3Km signallevelStandard frequencylow frequency group-9dB?3dBhigh frequency group-7dB?3dBlevel difference between low and high frequency of compound signal2?1dBthe total distortion caused by intermodulation of harmonic wave is lower than the basic level by at least 20dB.5Call transmission index(5Km)SLR12,RLR-1,STMR10, output impedance is 600.6Super strong function is available for dialing of 12 groups of numbers stored in the memory maximum length of each number is16 digits