Signal strength

Who it’s for

Anyone diagnosing connectivity on remote devices — a fleet of cellular trackers, Wi-Fi sensors in a building, gateways on a site. The question is whether a device that is reporting badly has a radio problem, and RSSI in dBm answers it once it is drawn as bars anyone can read.

What it does

The Signal strength widget draws an RSSI reading as a set of signal bars, in either Wi-Fi or cellular form. An rssi value in dBm lights the bars proportionally in green, dimming to gray where the signal does not reach, and a value at or below the configured no-signal threshold leaves every bar inactive.

• RSSI drawn the way phones draw it — a number in dBm means nothing to most readers, and bars mean the same thing to everyone.
• Two layouts, Wi-Fi arcs or cellular bars, so the tile matches the radio the device actually uses.
• The no-signal threshold is explicit, so a device sitting at the floor of the scale is visibly disconnected rather than merely weak.
• The active bar color can follow the value, so a marginal link is a different color from a good one.
• A tooltip carries the exact dBm value and the time it was read, keeping the precise figure available without cluttering the tile.
• The date line can be shown on the card itself, which distinguishes a weak signal from a stale reading.
• The Signal strength widget shows one current reading: signal over time belongs on a chart, which is where an intermittent link is actually diagnosed.

How to set up

Data keys

The Signal strength widget takes one datasource, one entity and one data key.

Key	Role	Type	Description
rssi	The signal level the bars are drawn from	Timeseries	Numeric, in dBm, normally negative. An attribute works equally well.

Signal

Setting	Default	Effect
Layout	Wi-Fi	Draws Wi-Fi arcs or cellular bars
”No signal” rssi value	-100	At or below this, every bar is inactive
Active signal bars color	Green, range-capable	The lit bars; accepts ranges so a marginal link differs from a good one
Inactive signal bars color	Light gray	The unlit bars
Date	Off	Shows the reading’s timestamp on the card

Set the no-signal threshold to the floor your radio actually reports. A modem that bottoms out at −113 will never show a fully empty tile while the threshold sits at −100, and every disconnected device looks merely weak.

How to customize

• To match the radio — set Layout to Wi-Fi or Cellular bar.
• To mark a marginal link — set Active signal bars color to a range, so bars change color before they run out.
• To make the floor of the scale correct — set the “No signal” rssi value to the lowest figure the device reports.
• To show staleness on the card — turn on Date and set its format, font and color.
• To change what the tooltip reports — turn its Value or Date off, and set their fonts, colors and the tooltip background and blur.
• To fit a dark dashboard — set the Inactive signal bars color and the card background so the unlit bars stay visible.

Tips

• Turn the date on for battery and cellular devices. A tile showing two bars is read as a weak signal, when for a device that last reported yesterday the actual finding is that it stopped.
• Set the active bar color to a range with a boundary at the level your radio starts retrying. Full bars and no bars are both easy; the reason connectivity dashboards exist is the marginal middle, and only a color boundary makes that visible.