QRX

What is QRX?

QRX is a passive APRS message safety net. It monitors APRS-IS for messages addressed to your callsign, watches for acknowledgment, and stores any unacknowledged messages for later retrieval.

When you come back online (detected via position beacon), QRX notifies you of missed messages. Think of it as voicemail for APRS.

QRX never ACKs on your behalf, never retransmits messages, and never injects itself into the delivery path. It is purely an observer that catches what falls through the cracks.

How It Works

1. Someone sends you an APRS message while your radio is off
2. QRX sees the message on APRS-IS, waits 90 seconds for your ACK
3. No ACK observed — QRX stores the message
4. You turn your radio on and beacon a position
5. QRX sees your beacon and sends you a notification
6. You send R to read messages one by one, like voicemail

Commands

Send as standard APRS messages to QRX. Single-letter shortcuts work.

Example Session

Details

Message retention: Unread messages are held for 7 days. Max 20 per station. When your inbox is full, QRX notifies you and oldest messages roll off.

Notification throttle: One notification per 30 minutes, even if you beacon frequently.

Beacon detection: A beacon from your registered SSID triggers notification for that SSID.

Sender notifications: When QRX stores a missed message, it notifies the sender that the message was saved and will be delivered when you're back online.

Read receipts: After reading a message, send A to notify the original sender that you've read their message.

Privacy: QRX only observes. It never ACKs on your behalf and never retransmits your messages.

SSID matching: REG registers your specific SSID. REG ALL monitors all SSIDs of your base callsign.

Bot filtering: Messages from known service bots are not stored in your inbox. Filtered callsigns: EMAIL, EMAIL-2, SMSGTE, WXBOT, WXYO, WXNOW, REPEAT, WHO-IS, ANSRVR, APRSPH, SOTA, POTA, MYANET, WLNK-1, WINLINK, CQSRVR, NTSGTE, JOKE, IRC, SMS, WTSAPP, WXCAN, WXSVR-AU, SHUB, MPAD, ODALRT-1, QUIZME, APSPOT, FIND, MAIL, DAGA, MTHOOD, 4FUN, WHO-15.

Maintenance & Contact

QRX has a nightly maintenance window from 0300-0500 UTC. The service remains running but there may be brief periods of unavailability.

Found a bug or have a suggestion? Email qrx@forkum.net.

Changelog

v1.1.4 — 2026-03-31

• Fixed: READ no longer deletes messages from inbox — previously, reading a message marked it as read and removed it permanently. Messages now stay until you explicitly delete with D or CLR.
• UNREG ALL — removes all SSIDs of your base callsign, symmetric with REG ALL
• Exponential backoff retransmission — 30s, 60s, 120s, 240s, 480s (APRS standard decay algorithm, 5 retries over ~15 min)
• Expanded bot filter — 38 known service callsigns blocked, hot-reloadable via config
• Flexible position parser — catches non-standard beacon formats for notification
• Follow-up commands (A, D) work immediately after reading

v1.1.3 — 2026-03-30

• Reliable message delivery — READ responses are now tracked for delivery confirmation. QRX waits for your radio to ACK each message. If no ACK within 30 seconds, QRX retransmits up to 3 times (4 total attempts over 2 minutes). Cursor only advances after confirmed delivery. If all retries fail, your next R re-delivers the same message so nothing is lost. (Thanks KB1GQZ for the feedback)

v1.1.2 — 2026-03-30

• Persistent message dedup — if your radio queues retries then powers off, those stale retransmissions won't create duplicate messages when it comes back online hours later
• Automatic health checks — QRX stays green on the service registry

v1.1.1 — 2026-03-30

• Bot message filtering — WXBOT, WLNK-1, and other service messages no longer stored in your inbox
• SIGHUP hot-reload — config changes applied without restart or downtime

v1.1.0 — 2026-03-30

• WHO command (W) — see who messaged you, grouped by callsign
• ACK command (A) — send read receipt to original sender
• Sender notifications — senders are told their message was stored
• STATS command — system-wide statistics with all-time counters
• Bulletin announcements — periodic BLN advertising QRX
• Bot loop protection — known bots are silently ignored
• Persistent stats — all-time message and registration counters
• Inbox full notification — alerts when oldest messages start dropping
• Max 5,000 registered stations

v1.0.0 — 2026-03-29

• Initial release with voicemail-style message playback
• Dynamic APRS-IS filtering, MIC-E beacon detection
• Single-letter command aliases (I, R, D, S, H)
• Registered on aprs.hemna.com service registry