Why it matters
- Faster first solution: No need to wait for satellites to send their own ephemeris pages (which can take minutes).
- Reliable cold starts: Essential for rovers that power-cycle or move between job sites frequently.
- Unified delivery: Uses the same NTRIP connection as the main correction stream—no additional sockets or SDKs required.
Broadcast behavior
| Parameter | Value |
|---|---|
| Interval | Every 5 seconds |
| Trigger | Begins immediately after connect; stops when first valid NMEA GGA is received |
| Constellations | GPS (1019), GLONASS (1020), BeiDou (1042), Galileo (1046) |
| Format | Standard RTCM 3.x binary frames |
| Transport | Shared with the primary TraceRouter mount; enabled by default for every TraceNav session |
If your rover supports assisted positioning metadata, configure it to store the latest ephemerides. This avoids re-requesting data after short drops.
Typical startup timeline
Rover responsibilities
- Parse & cache: Store incoming ephemerides until a fix is achieved; most SDKs do this automatically.
- Send GGA: Transmit NMEA GGA sentences every 1–5 seconds once position estimates become available.
- Validate fallbacks: If GGA stops, TraceRouter can resume ephemeris mode (depending on configuration).
Monitoring
Within the TraceNav dashboard:- Open the device session detail to view Ephemeris Mode duration.
- Verify message counts—ephemeris bursts appear as spikes in message 1019/1020/1042/1046 graphs.
Related docs
- TraceNav VRTK – differential corrections after first fix
- TraceRouter – orchestrates the hand-off between ephemeris and VRTK
- RTCM message map – decode the ephemeris message content