Sonifex HY02 DIGITAL, User Handbook Manual

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Page 2-4 Circuit Description & Controls
HY02 Digital TBU User's Guide
2.2.5. Line Balancing Electronics
The DHY 02 is designed to achieve the best possible audio performance available
from a telephone line. To this end, a high quality 16 bit dual codec is used. The equipment ensures that
the dynamic range is as large, and the distortion and noise are as small as possible.
The send audio signal from the codec is processed via the DSP before being sent to
the telephone line. The send signal is checked for excess level and the input analogue signal is limited
as above if the signal is found to be overloading. The signal is then high-pass filtered, and, if enabled,
acoustic cancellation is implemented.
2.2.5.1 Duplex Control
Transmit/receive path level locking :
Off position :
No processing.
Low position : +12dB dynamic levelling.
High position : +24dB dynamic levelling.
Attack and release time 1dB per 5msec. Hysteresis 8dB for no processing.
2.2.5.2 Adaption System
Network cancellation of 28ms. Double-talk detection and normalised adaptive FIR
system used with pink noise cancellation
2.2.5.3 Send Circuit
Transmit set to low :
Maximum output (soft limited)
0dBM
Sensitivity for max output : +6dB
Maximum input level : +20dB
Distortion at -1dBM to line : 0.1%
Output noise to line : -71dB
Tx LED sensitivity :
-14dB on, -17dB off
Frequency response : -3dB at 250Hz, flat until
3.5kHz
Dynamic control profile as below :
Input
Output
+20dB
0dB
+10dB 0dB
0dB 0dB
-10dB -10dB
-20dB -22dB
30dB -41dB
40dB -57dB
50dB -66dB
Attack: 125mS, decay, 1dB per 5mS
Transmit set to medium :
As above, but input 0dB for 0dBM to line.
Transmit set to high :