Answer | Cable signal levels for all DOCSIS cable modems need to be at acceptable levels for the modem to operate properly. The three signal levels that need to be within the acceptable level are Downstream Power, SNR (Signal to Noise Ratio), and Upstream Power. Downstream Power refers to the line signal sent from the cable provider to cable modem.  Downstream SNR (Signal to Noise Ratio) refers to the signal being sent in relation to the noise on the line.  Upstream Power refers to the line signal from the cable modem to transmit data back to the cable provider.  This document describes how to check the three signal levels to determine if they are within the acceptable level for the modem operate properly.Â
Checking Signal Levels
- Launch a web browser, such as Internet Explorer, Firefox, or Safari.  Enter http://192.168.100.1 into the address box, and press the Enter key.  The Login page will appear.
NOTE 1: A security or private risk alert may appear on the web browser advising users to proceed with caution when accessing the Web Manager. There is no risk in proceeding to the Web Manager. For instructions to by-pass the alert screen, refer to article # 18181 - Alert Message for Web Manager Access. NOTE 2: A login page may appear to access the Web Manager. Enter the default username admin in the Username field and enter the default password password in the Password field. It may be required to set a unique password to proceed to the Web Manager. For assistance with Web Manager Access, refer to article # 18739 – SBG7600AC2: First Time Accessing the Status Page.  - On the Login page, enter admin in the Username field.
 - Enter password or a customized password in the Password field then click the Send button. The Status page will appear.Â
 - In the Downstream section, verify Power levels are within the acceptable range of - 15 dBmV to + 15 dBmV for each downstream channel.Â
 - In the Downstream section, identify the Modulation and Power to verify SNR levels are within the acceptable range for each downstream channel.Â
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Downstream Signal To Noise Ratio (SNR) | Modulation | Power | Acceptable SNR | 64QAM | -15 to 15 dBmV | 23.5 dB or greater | 256QAM | -6 to 15 dBmv | 30 dB or greater | -15 to -6 dBmV | 33 dB or greater |
 - In the Upstream section, identify the number of Upstream Channels, Channel Type, and Symbolic Rate to verify the Power levels are within the acceptable range for each upstream channel.Â
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Upstream Transmit Power Level | Channel | US Channel Type | Symbol Rate | Acceptable Upstream Power Levels | Single   | TDMA | 1280 Ksym/sec | 45 dBmV to 61 dBmV | ATDMA | 2560 Ksym/sec | 45 dBmV to 58 dBmV | 5120 Ksym/sec | 45 dBmV to 57 dBmV | Two | TDMA | 1280 Ksym/sec | 45 dBmV to 58 dBmV | ATDMA | 2560 Ksym/sec | 45 dBmV to 55 dBmV | 5120 Ksym/sec | 45 dBmV to 54 dBmV | Three or more | TDMA | 1280 Ksym/sec | 45 dBmV to 55 dBmV | ATDMA | 2560 Ksym/sec | 45 dBmV to 52 dBmV | 5120 Ksym/sec | 45 dBmV to 51 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. Factory resetting the modem will eliminate any customized settings.  - Contact the cable provider to adjust the signal level to the acceptable level range.
Acceptable Signal LevelsÂ
Acceptable Downstream Power Level | -15 dBmV to +15 dBmV | Downstream Signal to Noise Ratio (SNR) | Modulation | Downstream Power | Acceptable Downstream 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 Upstream Power Levels | Single (1) | TDMA | 1280 Ksym/sec | 45 dBmV to 61 dBmV | ATDMA | 2560 Ksym/sec | 45 dBmV to 58 dBmV | 5120 Ksym/sec | 45 dBmV to 57 dBmV | Two (2) | TDMA | 1280 Ksym/sec | 45 dBmV to 58 dBmV | ATDMA | 2560 Ksym/sec | 45 dBmV to 55 dBmV | 5120 Ksym/sec | 45 dBmV to 54 dBmV | Three or more (>=3) | TDMA | 1280 Ksym/sec | 45 dBmV to 55 dBmV | ATDMA | 2560 Ksym/sec | 45 dBmV to 52 dBmV | 5120 Ksym/sec | 45 dBmV to 51 dBmV |
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