HCD28P/TSD low-leakage telephone is a government-specialized telephone focusing on simplicity and practicality, classified as a commonly used wired communication terminal. It is mainly used for equipping military agencies and local party and government private networks. Suitable for program-controlled, automatic, and common battery telephone exchanges, it features good voice transmission quality, high reliability, lightning protection, and low electromagnetic leakage.
Main Functions
Compatible with FSK/DTMF caller ID standards;
Outgoing calls: up to 16 groups of 8 digits, dynamically stored internally, with a maximum storage length of 32 digits;
Incoming calls: up to 52 groups of 8 digits, fully dynamically stored with single key and automatic IP;
Three groups of 32-digit direct storage memory;
Intelligent backlight;
Incoming calls can be set as VIP function, deletion-proof, with special ringtone for incoming calls;
24 diverse style ringtones, selectable ringtone volume;
5-digit area code, 1-digit exit code, incoming call filtering;
32-digit pre-dial and correction;
Incoming and outgoing call callback;
Automatic redial function;
Hands-free volume adjustment;
Music hold function;
Incoming/outgoing numbers can be transferred to direct storage memory;
Date, clock, and call timing functions;
LCD brightness adjustment;
32-digit last number redial;
Number sending pause function;
Flash function.
Main Performance Indicators
Operating Conditions
Ambient temperature: -10℃ to 40℃
Relative humidity: 10% to 95%
Atmospheric pressure: 86kPa to 106kPa
Ambient noise: ≤60dB(A)
Main Technical Parameters
Electroacoustic parameters (5km): Sending loudness rating (SLR) ≤15dB
Receiving loudness rating (RLR) ≤2dB
Sidetone masking rating (STMR) ≥12dB
Stable balance return loss (2km): ≥15dB
Echo balance return loss (2km): ≥17dB
Sending and receiving nonlinear distortion: ≤7%
DC resistance: ≤350Ω
Ringing sound level: ≥70dB(A)
Connection resistance: ≤350Ω
Dual-tone multi-frequency signal level: Low frequency component -9dBm±3dB
High frequency component -7dBm±3dB
High frequency component level is 2dB ±1dB higher than low frequency component level
Receiving caller ID information FSK signal:
“0”=2200Hz±1% level is -37dBm to -6dBm
“1”=1200Hz±1% level is -32dBm to -6dBm
Level difference: ±10dB
Mean Time Between Failures (MTBF): ≥5000h
Power source: 3 AA batteries
Dimensions: 228mm×180mm×105mm
