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C H A P T E R
8 :
T E C H N I C A L
S P E C I F I C A T I O N S
Echo Algorithm
General:
Maximum echo delay:
Frame size:
Averaging window size:
1000 ms
16 ms at 8 kHz
800 ms at 8 kHz
Available Measurement Results:
•
Echo Return Loss (ERL)
•
Momentary attenuation of the highest echo peak (ERLmom)
•
Momentary delay of the highest echo peak (ERLmom Delay)
•
Attenuation of the highest echo peak during the whole measurement period (ERLpeak)
•
Delay of the highest echo peak during the whole measurement period (ERLpeak Delay)
8.2 Hardware
POTS Telephony Board
General:
Board Capacity:
4 analog 2 wire loop start interfaces.
Power / Environment:
Power requirements +5V/+12V/-12V:
Operating: temp / humidity (noncondensing):
Storage : temp / humidity (noncondensing):
0.8A (typ. 0.3A)/<0.1A/<0.1A
0°C/+50°C 5%/80%, non-condensing
-20°C/+70°C 5%/80%, non-condensing
Loop Parameters:
Impedance:
Country specific, linear (600Ω or 900Ω) or complex
(Europe: according to ETSI TBR 21)
Audio Signal Processing:
Receive Range:
-50 to +0 dBm (optional configurable AGC above
nominal -44 dBm).
Programmable (nominal –12 dBm).
Programmable (nominal –44 dBm).
8 ksamples/sec (telephone industry standard).
• 64 kbps µ-law or A-law per ITU-T G.711
• 16, 24, 32, 40 kbps ADPCM using ITU-T G.726
algorithm
• 16, 24, 32 kbps NMS compatible ADPCM
• 32 kbps VOX compatible ADPCM
• 8, 16 bit PCM 11, 22, 44 kHz
• 16 bit mono PCM 8 kHz
Transmit:
Silence Detection:
Sampling Rates:
Speech:
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