Sage Digital ENDEC — Protocol & Behavior Reference

Source document: Sage Alerting Systems — Emergency Alert System Encoder/Decoder, Model 3644 (Sage Digital ENDEC), User's Guide and Reference Manual, Rev 1.0e1 (firmware v95), FCC ID V2W3644. sagealertingsystems.com/docs/digital_endec_1_0.pdf

EAS Station implementation referenced below: app_utils/eas_fsk.py, app_utils/eas.py, app_utils/eas_decode.py, app_core/audio/auto_forward.py, app_core/audio/eas_monitor.py.

Related: SAME.md (our on-air signalling), ../NRSC4B_SAME_STANDARD.md (the underlying standard).

The Sage Digital ENDEC is the commercial encoder/decoder appliance EAS Station™ is built to be an open, auditable alternative to. Its manual is the most complete public description of how a Part-11-certified box behaves on the wire and at its integration ports. This document distills the parts that matter for our implementation — the SAME wire format as Sage states it, the serial/network device protocols it exposes, and its incoming-alert filtering and priority model — and ends with a gap analysis (§5) measuring EAS Station against it.

This is a clean-room behavioral reference compiled from the published manual. It is not Sage firmware, contains no proprietary code, and the trademarks (Sage®, MHz Sub-Alert™, Chyron CODI™, VDS840EAS™) belong to their owners.

Contents

1. On-air wire format
2. Serial / network device protocols
3. Incoming-alert filtering & priority model
4. Operational notes worth keeping
5. Gap analysis — EAS Station vs. Sage
6. Sources, attribution & IP basis

1. On-air wire format (as documented by Sage)

Sage's description of the EAS alert (manual §2.4) matches FCC 47 CFR §11.31 / NRSC-4-B §4 and is consistent with our own SAME.md. Capturing it here gives us an independent second source to validate the encoder against.

The on-air timeline (manual Figure 2-1):

Header anatomy (manual §2.4, "Parts of an EAS Header"):

ZCZC-ORG-EEE-PSSCCC-PSSCCC…+TTTT-JJJHHMM-LLLLLLLL-

• Originators (ORG): Broadcast/Cable (EAS), Civil Authorities (CIV), National Weather Service (WXR), Primary Entry Point (PEP), Emergency Action Notification Network (EAN). The last two relay Presidential messages.
• Locations: up to 31 per header; "about 3300" predefined FIPS land codes plus marine codes (manual §18). The relayed ID is the station that relayed to you, not the originator.
• One header repetition takes 1–4 s depending on location count; all three copies plus pauses run 6–16 s.

1.1 Event codes (manual Table 5-1)

Sage ships 53 predefined event codes, each with an English and Spanish plain-language phrase. The full table (abbreviated to code → English phrase):

The manual predates NWSI 10-1712 (April 2022); EAS Station already tracks the newer EWW, SSW, SSA, BLU codes in app_utils/event_codes.py. The Spanish phrase column is the gap (see §5).

2. Serial / network device protocols

The ENDEC has a "computer" front port plus COM ports; each is assigned a device type (manual §12.50). These are simple, well-specified wire formats that any modern integration (or our REST/Socket.IO/Redis stack) can emit as a compatibility shim. Serial ports are PC-wired (pin 2 RxD, pin 3 TxD, pin 5 GND, pin 9 = +9 V accessory), use a null-modem cable (swap 2/3), and have a configurable baud rate (manual §13.1, §12.49).

2.1 Device-type catalog (manual §12.50)

2.2 Raw EAS — "Encoder" device (manual §9.1)

Same protocol as Part-11 synchronous EAS data, but async, one stop bit. The sync byte 0xAB (shown as +) is expected on input and emitted on output. Bytes fed in are interpreted exactly as FSK heard on an audio port; if they trigger an alert, the ENDEC pulls audio from its Encoder Audio In. Bytes sent out mirror everything the ENDEC transmits. Sample output:

++++++++++++++++ZCZC-EAS-RWT-006013+0015-1020624-SAGE-
++++++++++++++++ZCZC-EAS-RWT-006013+0015-1020624-SAGE-
++++++++++++++++ZCZC-EAS-RWT-006013+0015-1020624-SAGE-
++++++++++++++++NNNN++++++++++++++++NNNN++++++++++++++++NNNN

(16 sync bytes precede each of the three headers and each of the three EOMs.)

2.3 EAS decoder status — "Decoder" device (manual §9.1)

Emits decoder state whenever a message is received or sent:

<type>:<zczc string>
<expanded plain-language text>

Example:

local:ZCZC-EAS-RWT-006013+0015-1020638-SAGE-
A Broadcast station or cable system has issued a Required Weekly Test for
Contra Costa, CA beginning at 02:38 am and ending at 02:53 am (SAGE)

2.4 Generic Character Generator (manual §9.3)

<STX><sev><text><ETX>

2.5 News Feed (manual §9.4)

Each message is wrapped so newsroom software can find boundaries:

<ENDECSTART>
Local Alert sent at 02/07/97 22:52:55
The National Weather Service has issued a Severe Thunderstorm Watch for
Aleutian Islands, AK beginning at 10:52 pm and ending at 11:07 pm (SAGE)
ZCZC-WXR-SVA-002010+0015-0390352-SAGE-
<ENDECEND>

2.6 Network interfaces (manual §6, §12.62, §12.70)

• Web server (HTTP config UI).
• Automation interface — a TCP port at portbase (MENU.NETWORK.PORT BASE), enabled by MENU.NETWORK.AUTOMATION.
• ENDEC PRO/DJ LAN interface.
• ENDECSETD — config save/restore, over LAN or a serial port.

Security note (manual §6.1): all network services — web server, automation interface, PRO/DJ — ship disabled by default. The box is opt-in over the network. A useful posture to mirror.

3. Incoming-alert filtering & priority model (manual §5.4)

This is the richest part of the manual for our purposes. Sage's relay logic is a filter list, evaluated against each decoded alert.

A filter matches when: the alert's originator is in the filter's originator list AND the event is in its event list AND at least one of the alert's locations is in its location list.

Each matched filter carries an action, a priority (0–63), an attention-tone duration, and a hold time.

3.1 Action codes (manual Table 5-2)

3.2 Factory-default filters (manual Table 5-3)

Key takeaways: the highest-priority matching filter wins; the Presidential filter relays instantly with no hold; weekly tests are logged but never put on air; everything unmatched falls through to a low-priority timed-ignore.

3.3 Override / hold-off (manual §9.5, §9.6)

• Commercial tally / Hold Off — a relay input lets station automation defer a pending alert (max 15 minutes) so it doesn't interrupt a commercial break. The ENDEC can also close a relay to tell automation an alert is pending (a two-step handshake).
• MIN OVERRIDE PRIO — filters above this priority ignore the hold-off. EAN/EAT always ignore it.
• Hold Off Night — for daytime-only stations: overnight RMTs are held (exempt from the 15-minute cap) and relayed in the morning.

4. Operational notes worth keeping

• Three config surfaces, one state: front panel, web browser, and serial (ENDECSETD) all mutate the same parameter store. Good consistency model.
• Explicit volatility contract (manual §3.3): the box documents exactly what survives a reboot and what doesn't.
• Blink error codes (manual §14.1): a small, documented diagnostic vocabulary mapping LED patterns to fault classes.
• TTS fallback: for CAP alerts without attached audio, the ENDEC text-to-speech-renders the CAP text (manual §2.4) — the same strategy EAS Station uses.

5. Gap analysis — EAS Station vs. Sage Digital ENDEC

Measured against the codebase as of this writing. ✅ = parity/better, ⚠️ = partial/different, ❌ = not implemented.

5.1 On-air wire format — full parity ✅

EAS Station additionally supports the 1050 Hz NWR single tone (eas.py:2699, :3092), which the Sage manual does not document on the broadcast path.

5.2 Two-tone-on-RWT suppression — parity ✅ (and stricter)

Sage says the two-tone is not required for weekly tests. EAS Station goes further and prohibits it: RWT relay forces relay_tone_profile = 'none' (auto_forward.py:960-963, citing FCC §11.61), and RWT is suppressed from forwarding entirely unless the operator opts in via forwarded_event_codes (auto_forward.py:579, :846).

5.3 Filtering — present, but a different model ⚠️

5.4 Hold-off / commercial tally / day-night — not implemented ❌

No commercial-tally relay gate, no MIN OVERRIDE PRIO, no Hold-Off-Night for overnight RMT retention. RWT/relay paths fire immediately or not at all. This is the clearest operational feature gap for broadcaster parity.

5.5 Integration output formats — implemented ✅

All four Sage device-feed formats are now emitted over TCP by the ENDEC Device Feeds subsystem (configure under Admin → ENDEC Device Feeds):

Architecture: the detection/forwarding pipeline publishes a feed event to Redis (eas:endec_feed) at four points — match/nomatch in eas_monitor.py and dup/local in auto_forward.py — via endec_feed_publisher.py. The services.endec_feeds daemon subscribes, renders each event into every configured feed's wire format, and fans the bytes out to connected TCP clients (one listener per feed/port). Saving the admin form hot-reloads the daemon over a Redis control channel. Unlike Sage's RS-232 ports, the transport is TCP (connect with a character generator, newsroom system, or nc <host> <port>). The pre-existing structured JSON to Redis (eas:alerts:received) and webhooks (alert_forwarding.py) remain available alongside these byte-stream feeds.

5.6 Plain-language text — English yes, Spanish no ⚠️

build_plain_language_summary() (eas_decode.py:207) produces readable English. There is no Spanish generator or bilingual event-phrase table, which Sage carries for all 53 codes (manual Table 5-1).

5.7 Summary of actionable gaps

Items 1 and 5 shipped as the ENDEC Device Feeds subsystem. Items 3 and 4 remain the substantive operational/architectural deltas if full appliance parity is a goal.

6. Sources, attribution & IP basis

This document and the endec_feeds implementation are clean-room interoperability work built only from Sage's publicly published support manual:

• Facts, not expression. What is reproduced here are functional facts — wire formats, framing bytes, baud rates, event-code lists, configuration values — which are not protected by copyright. The manual's prose is paraphrased, not copied; only short functional snippets (format strings, sample headers) are quoted.
• Mostly a federal standard. The SAME signalling itself is mandated by FCC 47 CFR §11.31 and NWS Instruction 10-1712; it is not Sage's proprietary invention.
• No proprietary code. No Sage firmware or source was accessed or used. Every line in app_utils/endec_feeds.py and services/endec_feeds/ is original to EAS Station.
• Trademarks (Sage®, Chyron CODI™, VDS840EAS™, MHz Sub-Alert™) belong to their owners and are referenced only descriptively; EAS Station does not imply endorsement by or affiliation with Sage Alerting Systems, Inc.

This mirrors standard compatibility practice ("works with X"). It is not legal advice; patent questions are out of scope of a manual review.