🌐 Eesti — Community translation View in English

Kuidas Meshtastic signaalimõõtur töötab

Meshtastici signaalimõõtur – rakenduses tuttavad tulbad või olekuvärv – arvutatakse väga erinevalt traditsioonilise mobiiltelefoni või WiFi-ruuteri „tulpadest”.

Most consumer devices simply measure how “loud” a signal is. Kuna Meshtastic kasutab LoRa (Long Range) tehnoloogiat, mõõdab selle signaalimõõtja signaali selgust võrreldes sinu võrgu konkreetsete sätetega.

1. The Two Metrics: “Loudness” vs. “Clarity”

Every time the LoRa radio chip receives a message, it reports two measurements:

  • RSSI (Received Signal Strength Indicator): The loudness of the raw power hitting your antenna.
  • SNR (Signal-to-Noise Ratio): The clarity of the signal compared to the background static.

💡 Vihje: Siin on analoogia – kujuta ette, et sa üritad kuulda sõpra sinuga rääkimas.

  • RSSI is how loud their voice is.
  • The Noise Floor is the background noise in the room (air conditioning, other people talking, traffic).
  • SNR is how easily you can distinguish your friend’s voice from the background noise.

Kui su sõber karjub sulle kõrvulukustava rokkkontserdi ajal, on signaal uskumatult vali (kõrge RSSI), aga sa ei saa temast ikkagi aru, sest taustamüra on valjem (halb signaali-müra suhe). Conversely, if your friend whispers to you in a dead-silent library, the signal is very weak (Low RSSI), but you can understand them perfectly (Great SNR).

2. The Magic of LoRa: Hearing “Below the Noise Floor”

For standard radios (like FM or WiFi), if the background noise is louder than the signal (a negative SNR), the receiver just hears static.

LoRa is special. It uses “Spread Spectrum” modulation, which allows the radio to mathematically pull a signal out of the air even when it is buried deep underneath the background noise. Seepärast näed Meshtasticus sageli negatiivseid SNR numbreid (nt -10 dB, mis tähendab, et signaal on 10 detsibelli nõrgem kui taustamüra).

Sõltuvalt sellest, millist Meshtastic eelhäälestust kasutad (nt PikkKauge vs. LühikeKiire), on raadiol kindel SNR-i piirang – absoluutne maksimaalne müra hulk, mida see talub enne, kui sõnum staatilise müra tõttu täielikult kaob.

3. How the Signal Meter Calculates Quality

The app rates your signal quality (None, Bad, Fair, or Good) from SNR alone, measured relative to the preset’s SNR Limit — the demodulation floor described above. It deliberately does not factor RSSI into the rating: without the local noise floor, RSSI cannot tell you whether a signal is actually decodable, so SNR-versus-the-preset-limit is the meaningful measure. (RSSI is still displayed to you elsewhere.)

Kuna hinnang on eelseadistatud piirangu suhtes suhteline, võib sama signaali-müra suhe erinevatel eelseadistustel olla erinev – „-15 dB” on „LongSlow” puhul kasutatav, kuid „ShortFast” puhul mittekasutatav. Letting limit be the active preset’s SNR Limit, here is how the app picks the bars (or color):

Level Bars Criteria Meaning
Hea 3 SNR above the preset’s limit Signal is comfortably above the demodulation floor — healthy connection.
Rahuldav 2 less than 5.5 dB below the limit Decodable, but getting close to the floor.
Halb 1 5.5 dB to 7.5 dB below the limit At the very edge of what the preset can recover.
Puudub 0 more than 7.5 dB below the limit Below the floor — transmission lost to noise.

Märkus: Fikseeritud SNR lävesid, mida võisid mujal näha (-7 dB / -15 dB), kasutatakse nüüd ainult üksikute hüpete rõhutamiseks traceroute’i tulemustes – mitte siin kirjeldatud sõlmepõhise signaalimõõtja jaoks.

4. What This Means for You

Kuna Meshtasticu mõõdik toimib “selguse mõõturina”, käitub see erinevalt sellest, mida enamik inimesi ootab:

💡 Vihje: Ära paanitse madala RSSI pärast. You might see a seemingly terrible RSSI value like -118 dBm. On a cell phone, you would have zero bars. Aga kui sinu seadme signaali-müra suhe on +2 dB, näitab Meshtastic ikkagi tugevat signaali! The library is quiet, so the whisper is heard perfectly.

⚠️ Warning: Watch out for local noise. If you hook up a massive antenna and see a great RSSI (e.g., -90 dBm) but your signal meter is only showing 1 Bar (Bad), you have a problem. It means you have local interference — perhaps a cheap power supply, a noisy computer, or a nearby radio tower — creating so much static that it is drowning out your mesh.

Where Signal Information Appears

In the app, signal data is shown in several places:

  • Node list — signal bars icon next to each node
  • Node detail — SNR, RSSI, and signal quality in the device metrics section
  • Traceroute — iga vahendussõlme signaali kvaliteet hüppe kohta
  • Signal metrics — historical SNR and RSSI data in the metrics charts

Node entry showing SNR, RSSI values and colored signal bars