Single Frequency Interference; Impulse Noise Waveform Representation; Displays; Setup - HP 4935A Operating And Service Manual

Operation

3-48 SINGLE FREQUENCY INTERFERENCE

frequency interference refers to unwanted steady tones which may appear in lines.
particularly narrowband signals which are multiplexed onto a voiceband channel.
selective volt meter or spectrum analyzer must be used. Single frequency interference during a C-message
filter n~c~asurrmcnt occurs if the signal is 3 dB or less below the (:-message
3-52. IMPULSE NOISE
Impulse noise is that component of the received noise signal which is much greater in amplitude
than the normal peaks of the message circuit noise. It occurs as short duration spikes and/or bursts of
than one millisecond, and that all significant effects of the noise spike disappear within four milliseconds.
Waveform (h) in Figure :i-l:i illustrates a received holding tone (or test signal) that includes interfering
impulse ncjiscs spikes. The impulse noise measurement counts the number of noise spikes above a selected
threshold level during a specified time period.
TRANSMITTED
HOLDING
RECEIVED
HOLDING
WITH IMPULSE
NOISE SPIKES
TONE
TONE
Figure 3-13. Impulse Noise Waveform Representation
usually detect this interf'erencc, since tonesexceeding
noise limits.
TIME
Model 49:EA
operator listensforany