CM820A/NA: Cable Signal Levels

Checking Signal Levels

1. 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 Status page will appear.
    
2. In the Downstream section, verify Power levels are within the acceptable range of - 15 dBmV to + 15 dBmV for each downstream channel. 
   
   
    
3. In the Downstream section, identify the Modulation and Power to 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.   
   
   
    
4. In the Upstream section, identify the number of Upstream Channels, Channel Type, and Symbolic Rate to verify thePower levels are within the acceptable range for each upstream channel. 
   
   Acceptable Upstream Power Levels (dBmV):
   
   
    

   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

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.  Factory resetting the modem will eliminate any customized settings.
    
6. Contact the cable provider to adjust the signal level to the acceptable level range.