The PCM signal generator is designed for testing CCITT-recommended 30-channel PCM systems(Recommendation G.732-2048 kbit/s) when the exchange is out of service. Testing is performed at different levels of the exchange hierarchy using different codes. The PCM signal generator supplies frame and multi-frame alignment signals together with signals in the telephone channels. Alarm signals and error signals can be simulated by the instrument.
The PCM signal generator generates the 2048-kbit/s frame and multiframe structure according to CCITT recommendation G.732. The following parameters can be set by the instrument:
Line parameters
Telephone channel parameters
Error signal parameters
Individual (user-programmable)patterns
LINE PARAMETERS
The line parameters can be programmed by the user in accordance with individual requirements. The line parameters consist of :
Jitter(if this option is included)
Loss of signal
Code errors
Bit rate
Internal or external clock
Pulse width
Line code
Cable attenuation (if this option is included).
TELEPHONE CHANNEL
The telephone channel signal can be applied to any of the 30 telephone channels,and the others are set at an ‘idle’condition. The tollowing signals can be applied:
Tone(variable in frequency and level)
Digital milliwatt
Noise(variable in level)
Idle channel signal with alternating sign
8-bit signal word(programmable)
8-bit pattern for the 29 other telephone channels
External input signal(analog or digital)
64-kbit/s output(if this option is included)
4-bit signalling word (programmable0
4-bit pattern for the 29 other telephone channels
External signalling
ERROR SIGNAL PARAMETES
The error signal simulates error conditions in the digital signal.The following error signals may be applied:
AIS
User-programmable pattern for FAS and non-Fas words
Loss of frame alignment (according to G.732)
Frame alignment signal errors(equally distributed or in bursts)
AIS64
User-programmable pattern for MFAS word
Loss of multiframe alignment (according to G.732)
Octet slip.
INDIVIDUAL PATTERNS
Multiframe pattern:In this mode the user can specify a multiframe byte by byte.(512bytes)
User-programmable 16-bit pattern:In this mode the 16 bits bill be transmited continuously.
