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SB6190: Cable Signal Levels

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Question
What are the acceptable Cable Signal levels for the SB6190 Modem?
Answer
Cable signal levels for all DOCSIS cable modems require to be within the acceptable level for the modem 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 be within the acceptable level for the modem operate properly. 

To Verify Cable Signal Levels

NOTE:
If the SB6190 is connected to a router, it is recommended to disconnect the router and connect the SB6190 directly to a computer with an Ethernet cable.
  1. Launch a web browser, such as Internet Explorer, Firefox, or Safari.  Enter http://192.168.100.1 into the address box.  The Status 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 or customized password in the Password field.  For additional information, refer to article # 16148 – SB6190 Web Manager Access.

     
  2. In the Downstream Bonded Channels section, verify Power levels are within the acceptable range of - 15 dBmV to + 15 dBmV for each downstream channel. 

    Right click on the image to save it to your computer.

     
  3. 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. 

    Acceptable SNR Levels (dB): 
    If QAM64, SNR should be 23.5 dB or greater. 
    If QAM256 and DPL( -6 dBmV to +15 dBmV) SNR should be 30 dB or greater. 
    If QAM256 and DPL(-15 dBmV to -6 dBmV) SNR should be 33 dB or greater.  

    Right click on the image to save it to your computer.

     
  4. 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. 

    Right click on the image to save it to your computer.

    Acceptable Upstream Power Levels (dBmV)

     
    Upstream Transmit Power Level
    ChannelUS Channel TypeSymbol RateAcceptable Upstream Power Levels
    SingleTDMA1280 Ksym/sec45 dBmv to 61 dBmV
    ATDMA2560 Ksym/sec45 dBmv to 58 dBmV
    5120 Ksym/sec45 dBmv to 57 dBmV
     TwoTDMA1280 Ksym/sec45 dBmv to 58 dBmV
    ATDMA2560 Ksym/sec45 dBmv to 55 dBmV
    5120 Ksym/sec45 dBmv to 54 dBmV
    Three or moreTDMA1280 Ksym/sec45 dBmv to 55 dBmV
    ATDMA 2560 Ksym/sec45 dBmv to 52 dBmV
     5120 Ksym/sec45 dBmv to 51 dBmV
  5. Refresh the page at least twice to identify variations in SNR, Downstream Power, and Upstream Power.   

    NOTE: If the either of the signal levels are outside of the acceptable range, power cycle or factory reset the modem. 

     
  6. Contact the cable provider to adjust the signal level to the acceptable level range.
     
Acceptable Signal Levels
 
Acceptable Downstream Power Level
-15 dBmV to +15 dBmV
Downstream Signal to Noise Ratio (SNR)
ModulationDownstream PowerAcceptable Downstream SNR
64 QAMn/a23.5 dB or greater
256 QAM
 
-6 dBmV to +15 BmV30 dB or greater
-6 dBmV to -15 dBmV33 dB or greater
Upstream Transmit Power Level
ChannelUS Channel TypeSymbol RateAcceptable Upstream Power Levels
Single (1)TDMA1280 Ksym/sec45 dBmv to 61 dBmV
ATDMA2560 Ksym/sec45 dBmv to 58 dBmV
5120 Ksym/sec45 dBmv to 57 dBmV
 Two (2)TDMA1280 Ksym/sec45 dBmv to 58 dBmV
ATDMA2560 Ksym/sec45 dBmv to 55 dBmV
5120 Ksym/sec45 dBmv to 54 dBmV
Three or more (>=3)TDMA1280 Ksym/sec45 dBmv to 55 dBmV
ATDMA 2560 Ksym/sec45 dBmv to 52 dBmV
 5120 Ksym/sec45 dBmv to 51 dBmV

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