AN2832 Freescale Semiconductor / Motorola, AN2832 Datasheet - Page 10

• Manufacturer Part Number: AN2832
• Description: Packet Telephony Remote Diagnostics on the StarCore SC140 Core
• Manufacturer: Freescale Semiconductor / Motorola

Remote Diagnostic Architecture
The training signal is composed of M = 100 periods of 128 ms frames at a sampling rate of 8 KHz (that is, N = 128
× 8 = 1024 samples). Two estimates of echo return loss enhancement (ERLE) are also computed, both indicating an
ERLE of about 44 dB. Figure 7 illustrates similar results, but with noise injected to simulate an SNR = 0 dB.
Notice that the intrusive method can achieve at least 6 bits of precision and an ERLE of about 20 dB under this
high noise condition. Similar performance would be difficult to achieve with non-intrusive standard methods, such
as NLMS-based channel estimation techniques.
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Figure 6. Example of Estimated Multi-Window Impulse Response Under SNR = 30 dB
Figure 7. Example of Estimated Multi-Window Impulse Response Under SNR = 0 dB
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Packet Telephony Remote Diagnostics on the StarCore SC140 Core, Rev. 1
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ERLE = 20.18 (20.25) dB, Precision = 6 Bits
ERLE = 43.99 (43.98) dB, Precision = 9 Bits
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