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Interference Frequency Signatures 
The 965DSP Spectrum Analyzer function provides 
a graphical display of the signals and noise on a line 
over a selected range of frequencies.  
The spectrum analyzer continuously analyzes the 
line and updates the screen as conditions change.  
The screen displays the average power of all signals 
and noise in the selected frequency span in dBm at 
the upper left.  The actual signal level at the cursor 
position is displayed in dB at the upper right. 
Interfering noise signals on a pair often occur as the 
result of crosstalk from other wideband services in 
the same cable. 
Each wideband service type has a unique frequency 
signature as shown in the following figures.  Use 
the spectrum analyzer to classify the source of 
the noise interference on the pair.  Following are 
some examples of the most common frequency 
signatures.
ISDN Interference
HDSL Interference
T1 Interference
ADSL Upstream Interference
ADSL Downstream Interference