System Architecture

Digital voice modes connect to XLX690 Module A, the central audio matrix and multi-protocol distribution bridge. Connecting to one of the targets below provides a path to the other linked modes and the local VA3ODC RF repeater.

Mode	Network target	Connection details	Description
D-Star	XLX690 A	Link to XLX690 A, DCS690 A, or REF690 A	Native D-Star reflector linking to the local VA3ODC RF repeater.
DMR	TG 3027496	BrandMeister master 3021, Slot 2, TG 3027496	BrandMeister VA3ODC connection bridged into XLX Module A.
System Fusion (YSF)	YSF04200	Select YSF04200 (CA XLX690)	System Fusion room linked into XLX690 using hardware AMBE transcoding.
P25	TG 690	Select talkgroup 690 on reflector P25-690 / 00690	APCO Project 25 talkgroup bridged into Module A; activity is shown on the dashboard.

Connecting from a radio or hotspot

• D-Star: Link your radio gateway or hotspot (Pi-Star / openSPOT) to XLX690 A, DCS690 A, or REF690 A.
• DMR: Use BrandMeister talkgroup 3027496 on Slot 2.
• System Fusion: Select YSF04200 (CA XLX690) in your reflector list or hotspot menu.
• P25: Select talkgroup 690 on reflector P25-690 / 00690. View activity on the P25 Live Dashboard.

The system is distributed across a cloud instance and a local hardware cluster hosting the AMBE gateway and PBX.

Architecture diagram supplied by VA3ODC. Embedded as a data URI so the source image is included in this HTML file. Some email clients block data-URI images; for broad email delivery, attach the JPEG and use a CID image or host it publicly.

VA3ODC / XLX690 System Architecture

The transcoding engine: dedicated hardware AMBE

XLX deployments require audio transcoding between digital voice codecs, including D-Star AMBE and DMR AMBE+2. This design uses a dedicated multi-channel hardware AMBE server on the local cluster rather than relying solely on software emulation. Actual audio quality and latency depend on codec paths, configuration, and network conditions.

The gateway is designed to connect to an on-site Grandstream UCM6102 IP-PBX over a private SIP trunk on port 5060. Four extensions provide different telephone access modes:

1300	Listen-only repeater monitor Allows callers to monitor repeater traffic. Concurrent-call capacity depends on PBX and gateway configuration.
1301	Manual toggle PTT Callers listen and use the phone keypad's # key to key up and speak over RF, with courtesy confirmation tones.
1302	Smart VOX patch Uses VOX and a pre-roll buffer (specified as 480 ms) to reduce clipping at the start of speech.
1303	PSTN autopatch Bridges an inbound telephone call to XLX690 Module A and can play a courtesy chime and announcement.

Hands-free “Call Finished” hangup

The proposed speech-control feature monitors audio for the phrase “Call Finished”. When recognized, it terminates the telephone connection and plays a courtesy tone. Recognition reliability depends on the active speech engine and audio conditions.

The design includes an on-demand voice assistant intended to run on local hardware, avoiding external cloud dependencies for its core functions.

IMAGE_PLACEHOLDER_2: Insert the voice assistant / Mermaid diagram here.

Supported command examples

Time check	“What time is it?” or “Time check” — reports local 12-hour time and UTC/Zulu time. Example display: TIME 0230Z.
Weather report	“What is the weather in [City]?” — intended to report current temperature, conditions, high/low, and wind speed in metric. Example display: WX: CHATHAM 8C.
Severe weather	“Weather alerts [City]” — checks for active alerts from Environment Canada and/or NOAA, depending on location.
Repeater status	“Repeater status” or “Status check” — checks the configured XLX, P25, DMR, YSF, transcription, and telephony subsystems.
Help guide	“Help”, “Help Weather”, or “Help Status” — provides guidance for available commands and query formats.

Audio processing

A proposed in-memory filter chain shapes assistant speech before encoding for radio transmission:

• 3,500 Hz low-pass filter: reduces high-frequency content.
• 180 Hz high-pass filter: reduces low-frequency rumble.
• 2,200 Hz presence EQ: emphasizes speech articulation.
• Peak limiter: helps prevent clipping and excessive level.

A background watchdog is designed to run every 15 minutes and check the configured network services:

• XLX reflector
• P25 system
• DMR bridge
• System Fusion
• Voice transcription engine
• SIP telephony

Edge-triggered and silent: when all services are operating normally, the watchdog should make no radio transmissions. If a service fails or recovers, the system can wait for a clear channel before announcing an advisory.

“Repeater Advisory: P25 System has gone offline.” ALERT: P25 OFF “Repeater Advisory: P25 System has been restored.” P25 RESTORED

The network's public monitoring hub is available at repeater.solosoft.ca.

• Live talker metadata and audio: stream information may include callsign, name, protocol, and module.
• Speech transcription: a live text feed of on-air transmissions, where enabled.
• Assistant control panel: command history, simulator, listening-window settings, and voice-output gain controls, where available.
• P25 live activity: link status and talkgroup activity at xlx690.solosoft.ca/p25.

Live audio & text	https://repeater.solosoft.ca
APRS maps & i-Gate coverage	https://aprs.solosoft.ca
XLX690 reflector	https://xlx690.solosoft.ca
P25 status	https://xlx690.solosoft.ca/p25

VA3ODC / XLX690 — Bridging amateur radio digital voice with modern open-source tools.