psf21911 ETC-unknow, psf21911 Datasheet - Page 63

• Manufacturer Part Number: psf21911
• Description: Isdn Echocancellation Circuit Terminal Applications Iec-q
• Manufacturer: ETC-unknow

Combinations of transition criteria are possible. Logical “AND” is indicated by “&” (TN &
DC), logical “OR” is written “or” and for a negation “/” is used. The start of a timer is
indicated with “TxS” (“x” being equivalent to the timer number). Timers are always
started when entering the new state. The action resulting after a timer has expired is
indicated by the path labelled “TxE”.
2.5.7
This chapter describes the activation and deactivation behavior of the IEC-Q TE. It
applies for both NT and TE mode.
2.5.7.1
Two types of start-up procedures are supported by the U-transceiver: cold starts and
warm starts.
Cold starts are performed after a reset and require all echo and equalizer coefficients to
be recalculated. This procedure typically is completed after 1-7 seconds depending on
the line characteristics. Cold starts are recommended for activations where the line
characteristics have changed considerably since the last deactivation.
A warm start procedure uses the coefficient set saved during the last deactivation. It is
therefore completed much faster (maximum 300 ms). Warm starts are however
restricted to activations where the line characteristics do not change significantly
between two activations.
Regarding the path in the transition diagram, cold starts have in particular that the U-
transceiver has entered the state ’Test’ (e.g. due to a reset) prior to an activation. The
activation procedure itself is then identical in both cases. Therefore, the following
sections apply to both warm and cold starts.
Semiconductor Group
State Machine
Cold and Warm Starts
63
U-Transceiver
PSB 21911
PSF 21911
11.97