Tele Systems EC-4543 Echo Canceller W/SF Bypass Telecom Card Module 107690-0015

Tele Systems EC-4543 Echo Canceller W/SF Bypass Telecom Card Module 107690-0015

The Tele Systems EC-4543 is an echo canceller card module with Single Frequency (SF) bypass capability, designed for use in voice telecommunications circuits. Echo cancellers of this type are inserted into voice paths to detect and remove the acoustic or hybrid echo that degrades call quality on long-delay circuits — particularly satellite links and long-haul terrestrial routes where round-trip propagation delay makes echo audible and disruptive. The SF bypass function allows the card to detect single-frequency tones (such as those used in in-band signaling) and disable echo cancellation during those tones to prevent interference with signaling protocols.

Specifications & What's Included

• Model: EC-4543
• Description: Echo Canceller with SF (Single Frequency) Bypass
• PCB Part Number: 107690-0015
• PCB Revision: Rev B (Work Order 02326)
• Form Factor: Plug-in card / chassis module
• RX OUT interface: terminal block connector (front panel)
• TX IN interface: terminal block connector (front panel)
• Front-panel indicators: Disabled, Disable, Normal/No Adaptation LEDs
• Manufacturer: Tele Systems (Tele Systems Inc.), USA
• Included: Card module only — no chassis, no external cables

Applications

Echo cancellers like the EC-4543 are standard components in voice telecommunications infrastructure where long circuit delays cause audible echo. They are used in satellite communication ground stations, long-haul carrier circuits, and international voice gateway equipment — anywhere the one-way propagation delay exceeds roughly 25–30 milliseconds, which is the threshold at which echo becomes perceptible to callers. The SF bypass feature makes this card suitable for circuits that carry in-band single-frequency signaling, such as those found in older carrier and toll networks, where disabling echo cancellation during signaling tones is required for proper operation. Cards of this type were typically installed in multi-card chassis frames that aggregated multiple voice channels, making them a modular, per-channel solution for echo control in telecom switching and transmission facilities. This particular design dates from the era of analog and early digital carrier telephony, when chassis-based modular echo cancellers were the standard approach before DSP integration moved echo cancellation into larger platform hardware.