Chairman and delegate discussion units of the Relacart WDC-903 system
A conference discussion system is the chain of chairman units, delegate units and a central host that controls who may speak, amplifies every seat and feeds the audio to recording, streaming or interpretation equipment. It is the standard audio setup wherever many people take turns addressing one room formally - councils, hearings, assemblies, university boards.
This guide defines each part in plain language, using the two Relacart systems most often quoted in recent tenders: the wired CS-302 and the wireless WDC-903.
The Three Building Blocks
Delegate units are the microphones each participant uses. A delegate presses a speak key; a ring indicator lights while speaking and goes dark when closed. Chairman units add a priority key that lets the chair mute a speaking delegate, and in request mode the chairman approves or rejects requests to speak.
The host (central controller) is the brain. It sets the meeting mode, limits how many units may open at once, powers the chain and routes audio onward. In the CS-302 system the CS-302M host supports up to 110 conference units with an expander and carries four video inputs plus one video output for SDI-based tracking.
The Four Meeting Modes
Discussion systems differ less in hardware than in how they ration the floor. Both Relacart systems offer the same four modes, chosen in the host:
Voice-activation mode opens the microphone when someone simply speaks into it - no button at all. This is the mode the Philippine Charity Sweepstakes Office chose, precisely because attendees of different backgrounds and ages should not have to struggle with settings. Time-limit mode closes each speech after a set 1-60 minutes. FIFO (first-in-first-out) mode replaces the oldest open unit when the limit is reached. Request mode holds speeches until the chairman approves them.
CS-302C delegate unit: speak key, priority ring indicator and built-in speaker
How the Units Connect: Wired Chain vs Wireless Link
The wireless numbers are not theoretical. At a Buddhist university in Myanmar, a WDC-903 system serves a 23-seat U-shaped table in a room that also hosts other campus purposes - and the LoRa control signaling is rated as strongly immune to interference from computers, mobile phones and Bluetooth devices.
The same vocabulary applies to both connection styles
| Aspect | Wired hand-in-hand | Wireless (LoRa + UHF) |
|---|
| Connection | Units daisy-chain on one cable | Control at 433 MHz LoRa, audio in UHF band |
| Power | 24 V DC from the host, expanders as repeaters | Batteries; units can power on automatically from a host command |
| Capacity | Up to 110 units (CS-302M with EXP-124) | Up to 255 units, 5 speaking simultaneously |
| Add-on audio | Dante interface | Dante interface |
Camera Tracking: What It Is and What It Needs
Camera tracking makes the video camera follow whoever is speaking. When a discussion unit switches its microphone on, a tracking system aims the camera at that seat and shows the speaker on the display. The Relacart VTS-2000 pairs with any Relacart conference system equipped with camera tracking, and a frame-freeze function smooths the picture between speakers.
In the wired CS-302, tracking is built into the host: it controls up to four cameras over RS-232 or RS-422 serial protocols, compatible with VISCA, PELCO-D and PELCO-P code protocols.
VTS-2000 automatic video tracking system
FAQ
What is the difference between a conference discussion system and a conference microphone?
A conference microphone is one device. A conference discussion system is the controlled set: delegate and chairman units plus a host that decides who speaks, in which mode, with what audio routing. Buying microphones without the control layer is the most common first-time-buyer mistake.
How many delegate units can one system support?
The wired CS-302M supports up to 110 conference units with the EXP-124 expander; the wireless WDC-903 supports up to 255 units with a maximum of 5 speaking simultaneously.
Can a discussion system feed remote or hybrid participants?
Yes. Both the CS-302 and WDC-903 have Dante interfaces, so their audio can be routed into any Dante-enabled DSP, codec or recorder over the network - the standard path for hybrid meeting rooms.
Do delegate units need batteries?
Wired units draw 24 V DC from the host over the hand-in-hand cable and never need batteries. Wireless units carry their own power and can switch on automatically when the host sends the start command.
