Chapter 3 · Applies to firmware v390 and later · Updated 2026-09-24

Settings and automatic tuning

Where each setting's value comes from, which values the station tunes by itself, and what every setting does. You do not need to change anything for the station to work: it starts with values chosen for it and adjusts the important ones itself.

1. Where a value comes from

A setting can be given a value in five places. They are applied in this order:

Source	When it is applied	After a restart
1. Firmware default	Built into the firmware; used from power-on.	Restored. Changes only with a firmware update.
2. Station profile	Stations carry a profile in the firmware that holds some values. On current hardware it always holds the health-check noise limits; some stations also hold others, for example the detection method, the filter band or the timing correction. The station re-applies these every second, so a change you make to most of them is undone within a second. For the filter settings it usually waits 15 minutes after your change. A few held settings (`ampk`, `cfarmin`, `selmin`, `deadveto`) keep your value until the next restart, except that automatic tuning may still adjust `ampk` (section 2).	Restored.
3. Remote configuration from Denko	Downloaded 30 seconds after start and then every 2 minutes. It can hold values for all stations and for one station. A value is applied when it first appears or when Denko changes it.	Applied again about 30 seconds after every start. If Denko removes a value, the station keeps it until its next restart.
4. Automatic tuning	A few values are adjusted by the station itself while it runs (section 2).	Starts again from the default, about 30 seconds after start.
5. Your changes	The controls in the web interface and `/set?` addresses. Applied immediately.	Lost. A restart happens at least once a day, after every firmware update and after a power cut.

A later source does not always win: a value held by the station profile comes back within a second, and the remote configuration is applied again at every start. The only lasting changes are firmware updates and Denko's remote configuration. Ask Denko if you need a value to stay.

2. What the station tunes by itself

Nothing needs to be started: automatic tuning is on by default. It begins about 30 seconds after start, once the station has measured its trigger rate.

Value	How it is tuned	How to stop it
`khi` slope threshold	Used by the default (slope) detection method. Every 30 seconds the station looks at how often the detector triggered: more than 20 per second raises the threshold by 2, more than 8 per second by 1, and fewer than 1 per second lowers it by 1, but only if a lower value would not flood the station with noise. Range 4–48, starting at 12. If the antenna appears dead, it returns to 12 and waits.	`khiauto=0`, or set `khi` yourself (tuning then stays off until the next restart).
`ampkq` amplitude threshold	Used by the amplitude and envelope methods. Every 60 seconds the station looks at how many signals it reported: more than 3 per second raises the threshold by 4 at once, and more than 1.5 per second in five checks in a row raises it by 1. It never lowers the threshold because the sky is quiet, since a quiet sky and a too-strict threshold look the same. Range 68–160: after any manual change it waits 15 minutes, and then also brings a value outside this range back inside it (so a hand-set `ampk` above 10 returns to 10).	`ampkauto=0`.
`cfarmin` contrast minimum	Only on stations whose profile sets it. At most once per start, after an hour and 10,000 triggers, if the minimum never let a detection through it is lowered once.	Set `cfarmin` yourself.
Health check	Judged every 5 seconds; decides whether reports are held back (chapter 2).	`hgate=0` (not recommended).
`caprank`, `pbf`	Adapt themselves while switched on. Both are off by default.	Set them to 0.
100 Hz mode	Switching `lfmode` on sets three filters together (`hpfhz`, `drechz`, `hpfrac`); switching it off sets both high-pass filters back to 4 kHz and restores `hpfrac`.	`lfmode=0`.

3. Every setting

Kept after restart: “Remote” means the value survives a restart only when Denko sets it in the remote configuration; a value you set yourself is always lost at restart. Changed automatically: what else can change the value (section 1 and 2). Advice: “In the web interface” — you may use the control as described in chapter 1; “Leave” — leave it to the station and Denko; “Service only” — factory and diagnostic use, do not use.

Further settings exist for factory testing and service. They are deliberately not listed here: do not use any setting that is not in this chapter.

Startup antenna measurement

Setting	What it does	Default	Range	Kept after restart	Changed automatically	Advice
`sweepboot`	Starts enabled at each boot: measures for 30 seconds from acquisition start instead of detecting lightning. 0 cancels an unfinished startup measurement; 1 does not start another. Remote configuration arrives too late to reliably prevent the next startup measurement. Capturing the physical test signal depends on power-on timing and is not yet verified.	1	0/1	Remote	Reset to 1 at restart; remote value applied later	Service only

Detection threshold

Setting	What it does	Default	Range	Kept after restart	Changed automatically	Advice
`amp`	Detection method: 0 = slope (rate of change), 1 = amplitude, 2 = envelope. Decides which threshold below is in use.	0	0–2	Remote	Station profile	Leave
`khi`	Threshold of the slope method, in multiples of the background variation. Higher = less sensitive.	12	1–64	Remote	Automatic tuning (section 2)	Leave
`khiauto`	Automatic tuning of khi: 1 = on, 0 = off.	1	0/1	Remote	Station profile	Leave
`ampk`	Threshold of the amplitude and envelope methods, in whole multiples of the noise floor. Sets ampkq to 16 × ampk.	8	2–64	Remote	Station profile; automatic tuning via ampkq	Leave
`ampkq`	The same threshold in steps of 1/16.	128	32–1024	Remote	Automatic tuning (section 2); station profile via ampk	Leave
`ampkauto`	Automatic tightening of ampkq: 1 = on, 0 = off.	1	0/1	Remote	—	Leave
`devmin`	Smallest background variation the slope method assumes, so the threshold cannot collapse on a very quiet input.	2	1–1024	Remote	—	Leave
`nfslow`	Amplitude methods: use the 12-minute minimum noise floor instead of the running one.	0	0/1	No	—	Leave
`thrabs`	Fixed threshold in raw converter units, replacing the relative one. 0 = off.	0	0–16777216	Remote	—	Leave
`thrfloor`	Lower limit for the threshold, in raw converter units. 0 = off.	0	0–16777216	Remote	—	Leave
`statdec`	Updates the slow statistics less often to save processing time. 0 = off.	0	0–4	No	—	Service only
`slopeavg`	Averaged slope estimate (diagnostic).	0	0/1	No	—	Service only

Re-arming after a detection

Setting	What it does	Default	Range	Kept after restart	Changed automatically	Advice
`refovr`	Lets the detector trigger again during its re-arm time if a new signal is more than refovr/16 times the previous peak. 0 = off.	24	0 or 16–255	Remote	—	Leave
`envshift`	Release time of the envelope follower (10 = 2 ms).	10	4–10	Remote	—	Leave
`deadus`	Fixed pause after each capture, in µs.	2000	0–50000	Remote	—	Leave
`deadveto`	Shorter pause (0.25 ms instead of 2 ms) after a candidate that was rejected.	0	0/1	No	Station profile	Leave
`refmax`	Longest allowed re-arm time, in samples (51200 = 100 ms).	51200	16–51200	Remote	—	Leave

Additional detection stages

Setting	What it does	Range	Kept after restart	Changed automatically	Advice
`cfararm`	Additional trigger based on contrast with the signal just before it. 0 = off.	0–4096	Remote	—	Leave
`cfar2`	A second, guarded version of the contrast trigger. 0 = off.	0–4096	Remote	—	Leave
`sbcfar`	Contrast trigger on weighted frequency sub-bands. 0 = off.	0–65535	Remote	—	Leave
`cfarmin`	Minimum contrast a detection must have to be reported. 0 = measure only.	0–65535	Remote	Station profile; lowered once (section 2)	Leave

Selecting what is reported

Setting	What it does	Default	Range	Kept after restart	Changed automatically	Advice
`selmin`	Minimum contrast score for the selector. 0 = off.	0	0–20000	Remote	Station profile	Leave
`selgap`	Pause after a selected report, in µs.	200000	0–2000000	Remote	—	Leave
`durmin`	Minimum number of samples above the threshold within 125 µs. 0 = off.	0	0–64	Remote	—	Leave
`caprank`	When the limit of 50 reports per second is reached, send the strongest candidates rather than the first ones.	0	0/1	Remote	Adapts itself when on	Leave
`imp`	Minimum impulsiveness of a signal, per mille. 1000 = off.	1000	1–1000	Remote	—	Leave
`magmin`	Minimum signal strength (0–7, the white-bar scale) for a signal to be detected and reported. 0 = all. The detect ≥ selector on the History tab.	0	0–7	Remote	—	In the web interface
`magdb0`	Where the strength scale starts, in dB (slope method). With magmin above 0 it also moves the detection limit.	18	0–60	No	—	Leave
`hpfrac`	Minimum share of a signal's energy above 4 kHz, in %, for it to count as lightning.	3	0–100	Remote	100 Hz mode sets it to 0	Leave
`pbf`	Blocks signals whose energy keeps falling in the same narrow band (interference). 0 = off.	0	0–9	Remote	Adapts itself when on	Leave
`net`	Threshold of the learned confirmation stage. 0 = off. Switching it on also widens the filters.	0	integer	No	Station profile	Service only
`dense`	Experimental detector, scoring only.	0	0/1	No	—	Service only
`densethr`	Threshold of the experimental detector; non-zero also switches it on.	0	±2^30	No	—	Service only
`txblank`	Blocks triggering for this many µs after each Wi-Fi transmission.	0	0–20000	Remote	—	Leave

Frequency band and filters

Setting	What it does	Default	Range	Kept after restart	Changed automatically	Advice
`fc`	Upper edge of the measurement band (low-pass), in kHz. 0 or 250 and above = full width. The filter buttons and field on the Live Scope tab.	24	1–243	Remote	Station profile (usually after 15 min)	In the web interface
`hp`	Lower edge of a band-pass in the measurement filter, in kHz. Leave at 0: at the default upper edge of 24 kHz the station refuses it, and a large value can move the upper edge (fc) far outside the lightning band.	0	0–128	Remote	Station profile	Leave
`hpf`	High-pass filter of the detector, in kHz. Removes mains and other low-frequency noise. 0 = off. It cannot go above 80 % of fc (19.2 kHz at the default).	4	0–200, max 80 % of fc	Remote	Station profile; 100 Hz mode	Leave
`hpfhz`	The same filter, in Hz. 0 = off.	4000	0 or 10–115200, max 80 % of fc	Remote	Station profile; 100 Hz mode	Leave
`drechz`	High-pass of the recording used for the noise figures and for waveform retrieval, in Hz.	4000	5–25600	Remote	100 Hz mode	Leave
`lfmode`	100 Hz mode: sets the detector and recording high-pass to 100 Hz and turns the 4 kHz check off. 0 sets lightning mode: both high-pass filters are set back to 4 kHz, even if the station was not in 100 Hz mode. The mode switch on the Live Scope tab. On stations whose profile sets the detector high-pass, the profile puts that part back within a second.	0	0/1	Remote	Station profile (partly, within 1 s)	In the web interface
`inotch1`	Notch filter 1 for fixed-frequency interference: centre frequency in Hz. 0 = off.	0	0 or 1000–115200	No	—	Leave
`inotch2`	Notch filter 2: centre frequency in Hz. 0 = off.	0	0 or 1000–115200	No	—	Leave
`inotchq`	Sharpness (Q × 10) of both notch filters.	580	10–5000	No	—	Leave
`notch`	Notch in the measurement filter: centre frequency in Hz. 0 = off.	0	0 or 1000–30000	Remote	—	Leave
`notchbw`	Width of that notch, in Hz.	2000	250–6000	Remote	—	Leave

Mains interference

Setting	What it does	Range	Kept after restart	Changed automatically	Advice
`comb`	Mains comb filter: delay in samples. 0 = off.	0 or 7314–12799	Remote	—	Leave
`mains`	Satellite-timed tracker of the 50 Hz mains wave.	0/1	No	Station profile	Leave
`msub`	Subtracts the tracked mains wave from the signal (needs mains = 1).	0/1	No	—	Leave

Timing and reporting

Setting	What it does	Default	Range	Kept after restart	Changed automatically	Advice
`toa`	Timing correction in ns, subtracted from every reported time. Set per station by Denko.	53000	±2000000	Remote	Station profile	Leave
`netenable`	Which networks your detections are reported to: 1 = Blitzortung only, 2 = Denko only, 3 = both, 0 = neither. Switching a network off also ends the registration that keeps the station known there; switching it back on re-registers from scratch. Values outside 0–3 are refused. Firmware v407 and later.	3	0–3	Remote	—	Leave
`detail`	Reports to Denko's own server: 1 = detailed 16-bit, 0 = compatible 8-bit.	1	0/1	No	—	Leave

Health check

Setting	What it does	Default	Range	Kept after restart	Changed automatically	Advice
`hgate`	Holds back reports while the health check fails (chapter 2). 0 = information only.	1	0/1	Remote	Station profile	Leave
`nbndmin`	Lowest background noise level a healthy station should show, in raw units.	100 (current hardware: 200)	0–20000	Remote	Station profile (within 1 s)	Leave
`nbndmax`	Highest background noise level for a healthy station. 0 = no limit. Set by Denko only; not available locally.	8000 (current hardware: 40000)	≥ 0	Remote	Station profile (within 1 s)	Leave
`nbndreset`	Starts a new site survey (use nbndreset=1). The Start a new survey button on the Status tab.	—	1	No	—	In the web interface
`gnssant`	Type of satellite antenna, used only to judge its antenna fault report: 0 unspecified, 1 active, 2 passive. Denko sets it for your hardware; if the GNSS tab shows "unspecified", reporting is not affected.	0	0/1/2	Remote	—	Leave

4. Changing a setting, and undoing it

Open http://<IP address>/set?<name>=<value>. Several settings can be changed at once: /set?fc=24&magmin=0. The change applies immediately.
Out-of-range values are limited to the range, some limits depend on other settings (the high-pass, for example, cannot exceed 80 % of fc), and a few values are ignored. The exception is netenable: an out-of-range value is refused and the previous value stays in force. For most settings the reply is just {"ok":1}, whatever happened; check the result on the Status tab or in /status.json. Changes to fc or hp reply with the values actually applied.
To undo every change you made, restart the station (switch it off and on). It returns to its defaults, its profile and Denko's remote configuration.
If a change is undone by itself within a second, the setting is held by the station profile. If it is undone after about 15 minutes, it is a filter setting held by the profile. If it creeps back up over minutes, automatic tuning is adjusting it. A change that stays until restart can still be a profile setting: ampk, cfarmin, selmin and deadveto keep your value until then (ampk subject to automatic tuning).

The station works best on its own settings. Change a setting only if you know what it does, and restart the station if a change made things worse.