Panasonic UF-E1 Service Manual page 151

5. Pseudo Ring Back Tone (PRBT): Fax / Tel Mode
This 400Hz, modulated by 16Hz tone is generated by the Modem and has a 1 sec. On and 2.6 sec.
Off interval. The Off time of Pseudo Ring Back Tone requires at least 4 sec. to detect CNG.
(UK)
1sec 1sec 2sec
CML ON
(Other Countries)
CML ON
6. CNG Detection
The 1100Hz CNG signal is checked by the integration time of On-time and Off-time. If the On and Off
time of the detected signal is within a specified value, the signal is recognized as CNG. If it is not within
a specified value, the unit will re-start the CNG detection from the beginning.
Start CNG Tone
Detection
1100 Hz
300 to 600 msec.
4sec 1sec 1sec
1st OGM
1st OGM
Fig. 6.3.2.6
On OFF
2550 to 3450 msec.
Fig. 6.3.2.7
2.6sec 1sec
1st OGM
Complete CNG
Tone Detection
1100 Hz
300 to 600 msec.
147
2rd OGM
On
UF-E1