NSK70721PE.C2 Intel, NSK70721PE.C2 Datasheet - Page 60

• Manufacturer Part Number: NSK70721PE.C2
• Manufacturer: Intel

Specifications of NSK70721PE.C2

• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (min): 4.75V
• Operating Supply Voltage (max): 5.25V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 28
• Lead Free Status / RoHS Status: Supplier Unconfirmed

SK70725/SK70721 — Enhanced Multi-Rate DSL Data Pump Chip Set
3.3.4
60
Loop Loss and SNR
In software control mode, EMDP provides information to compute approximate loop loss and
SNR. The approximate loop loss (LL) can be calculated as follows:
LL = 20*log
Where:
The value of DAGC and AAGC are calculated as shown in the description of register RD6. See
Table
The value of AGC tap is calculated as shown in the description of register RD1. See
The signal levels inside the EDSP are dependent on both the line attenuation, and the circuit
components outside the EMDP chip set. System manufacturers should calibrate the line attenuation
reading using a null loop and other test arrangements with known attenuation and introduce a
correction factor (modify k) appropriate for each system implementation. Note that the EDSP relies
most heavily on peak pulse amplitude attenuation in performing this calculation. This attenuation is
not the same as the attenuation measured at any particular frequency. In most applications and on
most loops, attenuation measurements at 20% of the bit rate (157 kHz for a 784 kbps line rate) give
a good approximation of the pulse attenuation.
The SNR is computed as follows:
SNR = Noise Margin + 21.5 dB; when WR9 is set to 00h, indicating that receiver gain is set to 0 dB
(default).
SNR = Noise Margin + 15.5 dB; when WR9 is set to 0Fh, indicating that receiver gain is set to 6
dB.
Error propagation in the DFE and descrambler may introduce some fractional errors in this
formula. The relationship between the SNR and the noise margin remains valid as long as the noise
is White Gaussian noise.
Since the period of the noise margin calculation is very short (64 bauds), it is recommended that
1000 samples be averaged for evaluating the operating SNR.
20.
k = 24 dB if 6 dB receiver gain is disabled.
k = 30 dB if 6 dB receiver gain is enabled.
10
(DAGC
*
AGC tap) + AAGC + k dB.
Table
Datasheet
16.