HCD28P/TSD Low Radiation TelephoneA simple and practical government-only telephone, commonly used as a wired communication terminal. Mainly used for equipping military and local party and government special networks. Suitable for programmed, automatic, and common battery telephone exchanges, featuring good voice transmission quality, high reliability, lightning protection, and low electromagnetic leakage.
Features：
Primary Functions
Compliant with FSK/DTMF caller ID standards.
Phone Calls: Up to 16 groups of 8 digits, dynamically stored internally, with a maximum of 32 digits storage.
Call-in: Up to 52 groups of 8 digits, featuring full dynamic storage with single key and automatic IP.
Three sets of 32-bit direct storage memory
Intelligent Backlight
Callers can be set as VIP with anti-deletion feature, and special ringtones for incoming calls.
24 diverse ringtones available, with selectable ringtone sizes.
5-digit area code, 1-digit outgoing code, incoming call filtering
32-bit dialing ahead and error correction
Call forwarding, incoming and outgoing call return.
Automatic Call Back Feature
Hands-free volume control;
Music play function
Dialing/calling numbers can be saved to direct memory storage.
Date, clock, and call timer functions;
LCD Brightness Adjustment
Redial the last 32-digit number.
Feature to pause serial number issuance
Overcurrent protection function.
Key Performance Indicators (KPIs)
Terms of Use
Ambient Temperature: -10℃ to 40℃
Relative Humidity: 10% ~ 95%
Atmospheric Pressure: 86kPa ~ 106kPa
Environmental Noise: ≤60 dB(A)
Key Technical Parameters
Electro-acoustic Parameters (5km): Sound Level Rating (SLR) ≤ 15 dB
Received Loudness Rating (RLR) ≤ 2 dB
Side Tone Masking Rating (STMR) ≥ 12 dB
Stable Return Loss (2km): ≥15 dB
Echo Balance Return Loss (2km): ≥17dB
Transmission and reception of non-linear distortion: ≤7%
Direct Current Resistance: ≤350Ω
Ringing Sound Level: ≥70dB(A)
Wiring Resistance: ≤350Ω
Dual Tone Multi-Frequency (DTMF) Signal Level: Low Frequency Component -9dBm ± 3dB
High-frequency Component -7dBm±3dB
The high-frequency component level is 2dB ± 1dB higher than the low-frequency component level.
Receive FSK signal for caller ID information
"0" = 2200 Hz ± 1%, level -37 dBm to -6 dBm
"1" = 1200 Hz ± 1% with a level of -32 dBm to -6 dBm
Level difference: ±10 dB
Average Mean Time Between Failures (MTBF): ≥5000h
Power Source: 3 AA batteries
Dimensions: 228mm x 180mm x 105mm
