Specifications | 248
DFXS Dual foreign exchange subscriber interface
General
Audio 64 kbit/s (PCM as per ITU G.711)
32, 24 and 16 kbit/s (ADPCM as per ITU G.726 and ANSI
TI.303)
Signalling Allocation 8-32 kbit/s allocated for CAS
Compression coding A-Law or µ-Law
Maximum line length 600 metres (2000 feet) on 0.4 mm / 26 AWG copper pair
Calling line ID (CLI) Support provided for ETSI: EN 300 659-1 & 2 and BT: SIN
227 and 242
Fax Conforms to G3 standard for 64 kbit/s PCM and 32 kbit/s
ADPCM compression
Analogue
Transmission performance
characteristics
ITU G.712 E2 for an operating level range of -6 dBr to +2.5
dBr
Input level range -9.0 dBr to +3.0 dBr in 0.5 dB steps
Output level range -9.5 dBr to +2.5 dBr in 0.5 dB steps
Default Input level +1.0 dBr
Default Output level -6.0 dBr
Maximum level +3.14 dBm0
Line impedance / Hybrid
balance impedance options
600
900
600 + 2.16 µF
900 + 2.16 µF
220 + (820 || 120 nF) (TN12)
270 + (750 || 150 nF) (TBR21)
370 + (620 || 310 nF) (BT3)
Return Loss better than 20 dB over the frequency range 200 - 3600 Hz
Trans hybrid loss better than 30 dB between 300 - 3400 Hz (with matched
external line and hybrid balance impedance)
Common mode rejection ratio better than 40 dB over the frequency range 50 - 3600 Hz
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