Reference Values

Reference Values

DOCSight Thresholds

DOCSight uses modulation-aware thresholds based on the official Vodafone Kabel Deutschland (VFKD) service guidelines. Each channel is assessed individually based on its actual modulation.

Since v2026-02-28.6, thresholds are managed as modules — the built-in VFKD profile is active by default, and community members can contribute regional profiles for other ISPs.

Downstream Power Level (dBmV)

Tier	64QAM	256QAM	1024QAM	4096QAM (OFDM)
✅ Good	-9.9 to 7.0	-3.9 to 13.0	-1.9 to 15.0	-1.9 to 15.0
⚠️ Warning	-11.9 to -10.0 / 7.1 to 12.0	-5.9 to -4.0 / 13.1 to 18.0	-3.9 to -2.0 / 15.1 to 20.0	-3.9 to -2.0 / 15.1 to 20.0
🔴 Critical	< -14.0 / > 14.0	< -8.0 / > 20.0	< -6.0 / > 22.0	< -6.0 / > 22.0

SC-QAM vs OFDM: 64QAM and 256QAM are SC-QAM channels (DOCSIS 3.0, 8 MHz each). 1024QAM and 4096QAM are typically OFDM channels (DOCSIS 3.1, up to 192 MHz). Power thresholds for 4096QAM are the same as 1024QAM since OFDM power measurement follows the same per-subcarrier rules.

Upstream Power Level (dBmV)

Tier	SC-QAM (EuroDOCSIS 3.0)	OFDMA (DOCSIS 3.1)
✅ Good	41.1 to 47.0	44.1 to 47.0
⚠️ Warning	37.1 to 41.0 / 47.1 to 51.0	40.1 to 44.0 / 47.1 to 48.0
🔴 Critical	< 35.0 / > 53.0	< 38.0 / > 50.0

⚠️ Fritz!Box DOCSIS 3.1 Upstream Bug: Fritz!Box displays DOCSIS 3.1 upstream power 6 dB lower than the actual value. DOCSight's FritzBox driver automatically compensates for this (+6 dB) so that the same real VFKD thresholds work correctly for all modems.

SNR / MER (dB)

Tier	64QAM	256QAM	1024QAM	4096QAM (OFDM)
✅ Good	> 27.0	> 33.0	> 39.0	> 40.0
⚠️ Warning	25.0 to 27.0	31.0 to 33.0	37.0 to 39.0	38.0 to 40.0
🔴 Critical	< 24.0	< 30.0	< 36.0	< 36.0

Note: Fritz!Box shows MSE as negative values. DOCSight uses the absolute value for comparison.

4096QAM SNR: The CableLabs DOCSIS 3.1 PHY specification (Table 46) defines a minimum MER of 39 dB for 4096-QAM. DOCSight uses 40 dB as the "good" threshold to provide a comfortable operating margin above the spec minimum.

Regional Threshold Profiles

Since v2026-02-28.6, thresholds are managed through the module system. The built-in VFKD profile ships as docsight.thresholds_vfkd and is active by default. You can switch profiles in Settings > Modules.

Using a different profile:

1. Download or create a threshold module (see TEMPLATE-THRESHOLDS)
2. Mount it into DOCSight: -v ./your-profile:/modules/your-profile
3. Restart and enable it in Settings > Modules — the previous profile is auto-disabled

Only one threshold profile can be active at a time. The active profile shows an "Active Profile" badge in Settings > Modules.

Contributing regional profiles: If your ISP uses different thresholds (e.g., Vodafone NRW/BW, Comcast, Virgin Media), consider contributing a profile to the Community Module Registry. See #121 for ongoing discussion about regional values.

If no threshold module is loaded, DOCSight falls back to hardcoded VFKD defaults.

Where Do These Values Come From?

DOCSight's thresholds are based on the Vodafone Kabel Deutschland (VFKD) service guidelines, as documented in the Inoffizielles Vodafone-Kabel-Forum FAQ. These are the same thresholds Vodafone technicians use to evaluate cable connections.

The VFKD guidelines are consistent with (but more specific than) the CableLabs EuroDOCSIS specifications:

• EuroDOCSIS 3.0 Physical Layer Specification (CM-SP-PHYv3.0-I12-150305)
• DOCSIS 3.1 Physical Layer Specification

Modulation Quality

Higher modulation = more data per signal = more speed. Downgrades indicate signal problems.

Modulation	Typical Use	Quality
4096QAM	DOCSIS 3.1 OFDM	Excellent
1024QAM	DOCSIS 3.1	Very good
256QAM	DOCSIS 3.0 DS standard	Good
64QAM	DOCSIS 3.0 US standard	Normal (upstream)
16QAM	Fallback	Degraded
4QAM / QPSK	Emergency fallback	Critical

Community Resources

The Inoffizielles Vodafone-Kabel-Forum is the go-to community for cable internet questions in Germany. Key threads:

• FAQ zur Interpretation der Pegelwerte — Complete guide to reading modem signal values
• Übersicht Modemwerte — Community-collected modem values for comparison