The GPS page
The satellite receiver's view of the sky at /gnss (the navigation tab reads GNSS). Lightning locating works by comparing arrival times between stations, so the station's clock is as important as its antenna — this page is where you check both.
The satellite readings refresh every two seconds; the uptime and connection dot are checked every ten seconds. The line under the title shows the clock (locked, unlocked or nofix — pulses are locked but the second is not yet named) and the station's uptime; the dot beside the station name turns red when the page cannot reach the station. The dot turns red only after three failed status reads in a row, and the clock reads unknown while the page has no current reading. A note above the cards then says why: No GNSS update received (none since the page opened), GNSS values are stale (last update n s ago), or Last observation; current reception and timing unknown. The values shown are the last ones received, and the reception verdict reads unknown until fresh data arrives. The links at the bottom open the same data as JSON (/api/gnss, /api/status).
1. The summary cards
| Card | What it shows |
|---|---|
| Fix | FIX or no-fix, the fix type (none, 2D or 3D), the number of satellites used and the horizontal dilution of precision (HDOP). |
| Antenna | The receiver's own report on its antenna connection: OK, open, SHORT or unknown (section 6). |
| Time (UTC) | The time and date the receiver reports. |
| Position | Latitude and longitude, and the altitude once there is a 3D fix. |
2. The reception verdict card
The page opens with a reception verdict card — the station's own answer to “is my satellite antenna installed well?”. It gives a state word (healthy, degraded or unknown), a one-line verdict, What this means and What to do in plain words, the evidence behind it (which of the listed satellites are heard, from where, and whether the timing is locked), and a sky view coloured by signal strength, compared with an example of good reception. The possible verdicts:
| Verdict | What it means and what to do |
|---|---|
| Reception is good | Strong signals from many directions. Nothing to do. |
| Blocked sky likely towards the … | Signals from the open sky are strong, but satellites towards that direction are not heard. Check what stands in that direction — a wall, roof, mast or tree — and move the antenna clear of it. |
| Weak reception — antenna or mounting likely | Signals are weak in several directions; interference and a single blocked direction are ruled out. Check the antenna, its mounting direction, its clearance from metal and its cable. |
| Weak reception — cause not yet determined | Signals are weak in several directions, and interference is not ruled out yet because the receiver's interference check has no clean result. Check the antenna, its mounting and its cable, and also look for transmitters or noisy electronics near the antenna. |
| Radio interference likely | Reception is poor and the receiver reports signs of interference. Look for a transmitter or noisy electronics near the antenna and move it away from them. |
| Reception is poor — cause unclear | Many listed satellites are not heard, with no single direction to blame. Check the antenna, its mounting and its view of the sky. |
| Antenna connection fault | The receiver reports a fault on the antenna connector — a short, or an open connector with an active antenna configured. Check the antenna plug and cable (section 6). |
| No satellites heard | The receiver listened for two minutes and heard nothing. Check the antenna and its view of the sky. |
| Reception is limited | Some satellites are heard, but fewer or weaker than at a good installation. If you can, give the antenna a clearer view of the sky. |
| Still listening… | Not judged yet. “What this means” says which of the following it is waiting for, and the card judges by itself. Check back in a few minutes. |
While the card reads Still listening…, “What this means” says which of these it is waiting for:
| The card says | Meaning |
|---|---|
| “No complete satellite report has arrived yet.” | Normal right after a start. |
| “n of the 9 ten-second satellite reports it needs have arrived; a judgement follows once 8 of its last 12 ten-second readings agree (at least s s from now).” | The receiver needs 9 reports, one every ten seconds, and then waits until 8 of its last 12 ten-second readings agree. The card gives the earliest time left, in seconds. |
| “All 9 satellite reports it needs are in; it now waits until 8 of its last 12 ten-second readings agree (at least 70 s, longer while reception keeps changing).” | At least 70 seconds more, longer while the reception keeps changing. |
| “Satellite reports stopped arriving n s ago; judging resumes when they return.” (or “over 4 minutes ago”) | The receiver has stopped reporting; judging resumes when it reports again. |
| “Receiver settings changed recently; judging restarts within 2 minutes.” | Normal after the station has set up its satellite receiver. |
The card also labels each satellite in its sky view, adds a sats used column to its satellite details, and ends with a Signal bands section: a count Listed … · Heard …, then every satellite signal with its band, frequency and strength, or listed, not heard (no per-band data yet while the receiver reports none).
The reception cause panel
Reception cause explains what the available evidence can say about poor reception. It complements the reception verdict: preliminary (not yet used for the verdict) means the cause assessment is still preliminary. The panel shows its Confidence, Evidence span and when it was Updated, followed by the evidence in words.
| Shown | How to read it |
|---|---|
| Interference | The evidence points to radio interference. |
| Frequency loss · Band missing | The evidence points to weaker reception at a frequency, or to a missing signal band. It does not identify the faulty part. |
| Sector blockage | Reception is weaker in part of the sky. Read the directional evidence before changing the installation. |
| Uniform / pattern weakness | The weakness is spread across the sky or follows a pattern. |
| Healthy | The cause assessment supports healthy reception over its stated evidence span. |
| Cause not determined yet — the evidence below is not enough to tell interference, antenna detuning and blockage apart | The cause is still unknown. The evidence below the heading says what is available and what is missing. |
Support lists the possible causes as unsupported, possible, supported or not measured. Signal loss against the expected level and By direction show the comparisons behind the assessment; a span marked historical is older evidence. Receiver data quality lists accepted, empty and rejected satellite reports. What would change this opinion names the evidence still needed. not measured means there is no measurement to judge, not that a test failed.
If no cause can be shown, the panel says why: No cause evidence received from the board yet., Cause opinion withheld: the GNSS data stopped updating. It returns with the next update. or Cause evidence arrived incomplete or inconsistent; waiting for the next update. Let fresh reports arrive before drawing a conclusion.
3. The sky plot and the signal bars
The separate Sky plot (az / el) card below appears only while the reception verdict card is not shown; otherwise the card's own sky view and its Signal bands section take its place. The signal bar chart is always shown.
- The sky plot looks straight up: north at the top, the horizon at the edge, the zenith at the centre, with rings at 30° and 60° elevation. Filled markers are satellites used in the position solution; outlined markers are received but not used; a small grey dot is a satellite in view with no signal. Colour names the constellation, and each marker carries the satellite's number.
- A banner at the bottom counts satellites that are tracked but have no known position yet (tracked, position unknown (no almanac yet)) — normal right after power-on, before the receiver has collected its almanac.
- The bar chart sorts every satellite by signal strength (C/N₀, in dB-Hz), with the value on each bar; bars of satellites not used in the solution are faded. The reception verdict calls a signal fair from 32 dB-Hz and strong from 38 dB-Hz. Judge the installation from the reception verdict and its evidence, rather than one bar alone.
- The Satellites table lists each one with its constellation, elevation, azimuth, signal strength and whether it is used in the solution.
4. The Receiver card: the numbers that matter
| Reading | Meaning |
|---|---|
| Fix, Satellites, Position | The fix quality, satellites used of those in view, and — when there is a position but no height — the reason: no fix yet, needs 4 satellites or 2D fix. A height needs a 3D fix, at least four satellites; until then the page says why rather than inventing an altitude. The 3D fix also gates the station's registration with the lightning network (chapter 6). |
| DOP (PDOP/HDOP/VDOP) | Dilution of precision: how good the satellite geometry is. Lower is better; a station that sees only a corner of the sky reads high. |
| 1PPS | locked means the receiver's one-pulse-per-second time signal is disciplining the station's clock. This is the lock the GPS LED reports in the classic LED mode, and the foundation of every timestamp the station sends. second named means the receiver has also told the station which second each pulse marks. |
| Timebase | The station counts its own timer against the 1PPS signal and shows the difference from nominal in ppm — that is the crystal's error, measured rather than assumed. |
| PPS rejected / mismatched · Stamped captures | Pulses the station did not trust, and how many captures received a satellite-disciplined timestamp. |
| Receiver · GSV per system · Sentences seen | The serial speed and how many messages the receiver has sent, with errors; which constellations it reports satellites for. Useful when a receiver seems silent. |
| AGC / noise | The receiver's signal and interference readings. AGC above 7000 of 8191 is labelled (near maximum — very little signal); it does not by itself identify the cause. A reported jamming figure of 50 or more is labelled (interference). If the receiver reports no jamming figure, the row says not measured. |
5. Receiver identity and constellations
Blue boards do not all carry the same satellite receiver, and the different makes in the field share no configuration protocol. The station identifies the receiver before applying settings supported by that receiver. A receiver that never identifies itself is left unchanged. The Module row shows the identity it found and the firmware the receiver runs, and Supported shows what it can track and how many systems at once.
Which constellations are used is a request, not a command (gnss_sys: GPS, GLONASS, Galileo, BeiDou). The firmware clamps the request to what the receiver supports and to how many systems it can track at once; GPS is never dropped. The Constellations row shows what the receiver reports it is using, what the station asked for — which can differ from the configured value while the automatic weak-reception switch below is active — and the receiver's answer (accepted, refused, already set; nothing written, written, never answered or no write attempted yet). If the receiver cannot report its settings, the row says this receiver cannot report its own state; while a report is still due, it says waiting for the receiver to report. Both are requests, not confirmed readback. Two behaviours that are easy to misread:
- Some receivers, asked for GLONASS and BeiDou together, do not refuse — they acknowledge and enable only one. The station notices the disagreement, re-plans, and counts it in the Quietly dropped row. That is a different fault from Refused, and the page says which.
- Older receivers speak a message version that has no sentence type for Galileo or BeiDou: the satellites are received and used, but never named. The station raises the receiver's message version so they appear — a fix in the messages, not in the sky.
There is also an automatic answer to weak reception, on identified receivers that support GLONASS and can report their applied constellation plan. A station left on the fleet's default constellation plan watches its own sky: when fewer than 4 satellites stay at or above 32 dB-Hz for 10 minutes, it switches the plan to GPS+GLONASS by itself — the pair most likely to keep a position at a poor site. While the switch is active, the Constellations row reads GPS+GLONASS even though the configured value has not changed; that is the station helping itself, not a settings mistake. It returns to the configured plan only once both conditions hold: at least 6 hours on GPS+GLONASS and 2 hours of unambiguously good reception in one stretch — a fix, with at least 6 satellites at or above 38 dB-Hz. If reception turns weak again within a day of a return, the next wait doubles (up to 48 hours); it can return to the configured plan at most three times per restart. If it switches to GPS+GLONASS again after that, it stays there until a restart. Every restart begins from the configured plan again. A choice you make yourself always wins: set the constellations for your own station (chapter 6, section 4) and the switch — active or not — is dropped at once. Missing or silent satellite reports do not count as weak reception. If the receiver refuses GPS+GLONASS, or does not report that plan within 5 minutes, the station requests its configured plan again and does not retry the switch until a restart.
6. The antenna status
Receivers that support it watch their own antenna connection and report it. You see it in three places — the Antenna card and the Receiver card on this page, and the GNSS section of the Diagnostics page — together with whether the receiver's antenna supply is on:
| Status | Meaning |
|---|---|
| ok / OK | Nothing wrong was detected on the antenna connection. |
| open / OPEN | Normal with the standard passive antenna, which draws no current — it is not a fault. If you use an external antenna with an amplifier (active antenna), then it is not getting power: check its cable and connector. |
| SHORT | A fault. The antenna cable or connector is short-circuited. Check and replace the cable, connector or antenna. |
| unknown / initialising | The receiver has not reported its antenna yet, or this receiver cannot report it at all. |
Both cards say this themselves: an open connection reads open (grey on the Antenna card), followed by No current drawn — normal for a passive antenna. If your antenna has an amplifier (active antenna), it is not getting power: check its cable and connector. One more caveat, which the Diagnostics page states when it applies: detecting an open connection is off by default (ant_ocd), and with it off the receiver can only report a short, so “ok” then only means “not shorted”.
Telling the antenna apart from the sky is the point of this row: a SHORT is a cable or connector problem, while weak bars with an ok or open antenna point at the view of the sky.
7. What this page cannot fix
Enabling a constellation does not make it acquirable. Cold acquisition needs a reasonably strong signal to decode each satellite's data, and adding a system to a weak antenna adds messages, not satellites. Use the reception verdict, cause panel and signal bars to decide whether the antenna needs a clearer view of the sky. Adding constellations cannot compensate for an antenna that cannot hear them.