All DOCSIS cable modems require that the RF signals fall within a very specific range to be an acceptable level for the modem to operate properly. Â These levels apply to all SURFboard cable modems and cable modem/gateways. Â This document describes how to verify the cable signal levels.
To Verify Signal Levels
- Obtain the Username and Password on the black label on the side of the SBG6782. They will be used for accessing the GUI.
- Launch a web browser, such as Internet Explorer, Firefox, or Safari. Enter http://192.168.0.1 into the address box.
NOTE: By default the LAN IP address is 192.168.0.1. If the default address has been changed, enter the custom address in the address box.
 - Enter the username and password in the appropriate fields, and click the Login button. The Status page appears.
 - In the Downstream Bonded Channels section, verify Power levels are within the acceptable range of - 15 dBmV to + 15 dBmV for each downstream channel.Â
- In the Downstream Bonded Channels section, identify the Modulation and Power to find verify SNR levels are within the acceptable range for each downstream channel.Â
Acceptable SNR Levels (dB):Â
If QAM64, SNR should be 23.5 dBmV or greater.Â
If QAM256 and DPL( -6 dBmV to +15 dBmV) SNR should be 30 dBmV or greater.Â
If QAM256 and DPL(-15 dBmV to -6 dBmV) SNR should be 33 dBmV or greater.  Â
 - In the Upstream Bonded Channels section, identify the number of Channels, Type, Symbolic Rate to find verify Upstream Power levels are within the acceptable range for each upstream channel.Â
Acceptable Upstream Power Levels (dBmV):
Â
Upstream Transmit Power Level |
Channel | US Channel Type | Symbol Rate | Acceptable US Power Level |
 Single | TDMA | 1280 Ksym/sec | +61 dBmV to 45 dBmV |
ATDMA | 2560 Ksym/sec | +58 dBmV to 45 dBmV |
5120 Ksym/sec | +57 dBmV to 45 dBmV |
  Two | TDMA | 1280 Ksym/sec | +58 dBmV to 45 dBmV |
ATDMA | 2560 Ksym/sec | +55 dBmV to 45 dBmV |
5120 Ksym/sec | +54 dBmV to 45 dBmV |
 Three or more | TDMA | 1280 Ksym/sec | +55 dBmV to 45 dBmV |
   ATDMA |  2560 Ksym/sec | +52 dBmV to 45 dBmV |
 5120 Ksym/sec | +51 dBmV to 45 dBmV |
- Refresh the page at least twice to identify variations in SNR, Downstream Power, and Upstream Power.  Â
NOTE: If the either of the signal levels are outside of the acceptable range, power cycle or factory reset the modem.Â
 - Contact the cable provider to adjust the signal level to the acceptable level range.
Acceptable Signal Levels
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Downstream Power Level (DPL) |
+15 to -15dBmV |
Downstream Signal to Noise Ratio (SNR): |
Modulation | Downstream Power Level | Acceptable DS SNR |
64 QAM | n/a | 23.5 dB or greater |
256 QAM | -6 dBmV to +15 BmV | 30 dB or greater |
-6 dBmV to -15 dBmV | 33 dB or greater |
Upstream Transmit Power Level |
Channel | US Channel Type | Symbol Rate | Acceptable US Power Level |
 Single | TDMA | 1280 Ksym/sec | +61 dBmV to 45 dBmV |
ATDMA | 2560 Ksym/sec | +58 dBmV to 45 dBmV |
5120 Ksym/sec | +57 dBmV to 45 dBmV |
  Two | TDMA | 1280 Ksym/sec | +58 dBmV to 45 dBmV |
ATDMA | 2560 Ksym/sec | +55 dBmV to 45 dBmV |
5120 Ksym/sec | +54 dBmV to 45 dBmV |
 Three or more | TDMA | 1280 Ksym/sec | +55 dBmV to 45 dBmV |
   ATDMA |  2560 Ksym/sec | +52 dBmV to 45 dBmV |
 5120 Ksym/sec | +51 dBmV to 45 dBmV |