Answer | Cable signal levels for all DOCSIS cable modems require to be within the acceptable level for the modem operate properly. Â The three signal levels that need to be within the acceptable level are Downstream Power, SNR (Signal to Noise Ratio), and Upstream Power. Â Downstream Power refers to the line signal sent from the cable provider to cable modem. Â Downstream SNR (Signal to Noise Ratio) refers to the signal being sent in relation to the noise on the line. Â Upstream Power refers to the line signal from the cable modem to transmit data back to the cable provider. Â This document describes how to check the three signal levels to be within the acceptable level for the modem operate properly.Â
Checking Signal Level​
- Launch a web browser, such as Internet Explorer, Firefox, or Safari. Enter http://10.0.0.1 into the address box, and press the Enter key. The Login page will appear.
 - On the Login page, enter admin in the Username field.
 - Enter password in the Password field then click the Login button.  The Gateway > At a Glance page will appear.
NOTE: A prompt to change the password appears when the SVG2482AC is using the default password. To change the password click the OK button or click the Cancel button to bypass it.
 - On the left hand-menu, click the Connection link then click the XFINITY Network link on the sub-menu.  The Gateway > Connection > XFINITY Network page will appear.
 - 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
| Downstream Signal To Noise Ratio (SNR) | | Modulation | Power | Acceptable Downstream SNR | | 64QAM | -15 dBmV to 15 dBmV | 23.5 dB or greater | | 256QAM | -6 dBmV to 15 dBmv | 30 dB or greater | | -15 dBmV to -6 dBmV | 33 dB or greater |
 - In the Upstream section, identify the Symbolic Rate to verify Upstream Power levels are within the acceptable range.
Â
| Upstream Transmit Power Level | | Channel | US Channel Type | Symbol Rate | Acceptable Upstream Power Levels | Â
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 | Â
Â
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 | Â
Three or more | TDMA | 1280 Ksym/sec | 45 dBmV to 55 dBmV | Â
Â
Â
ATDMA | Â 2560 Ksym/sec | 45 dBmV to 52 dBmV | | Â 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 gateway.Â
 - Contact the cable provider to adjust the signal level to the acceptable level range if the signal levels are outside of the acceptable 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 | | 64QAM | n/a | 23.5 dB or greater | 256QAM
 | -6 dBmV to 15 BmV | 30 dB or greater | | -15 dBmV to -6 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 |
|
|
|---|
