MX589 Consumer Microcircuits Limited, MX589 Datasheet - Page 10

• Manufacturer Part Number: MX589
• Description: Mx589 High Speed Gmsk Modem
• Manufacturer: Consumer Microcircuits Limited

High Speed GMSK Modem 4k to 64kbps
4.2.5
The RX S/N Detector system classifies the incoming zero-crossings as GOOD or BAD depending upon the
time when each crossing actually occurs with respect to its expected time as determined by the Clock
Extraction PLL. This information is then processed to provide a logic level output at the RX S/N pin. A high
level indicates a series of GOOD crossings; a low level indicates a BAD crossing.
By averaging this output, it is possible to derive a measure of the Signal-to-Noise-Ratio and hence the Bit-
Error-Rate of the received signal.
4.2.6
The effect of input Rx Signal quality on the Rx S/N output is shown in Figure 7.
©2001 MX-COM, Inc.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
BER
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Rx S/N Detection
Rx Signal Quality
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-6
-1
% High Time
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0
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BT = 1.0 (Theoretical)
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Figure 7: Typical Rx S/N Output High time (%) vs. Input S/N
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www.mxcom.com tel: [phone] 744 5050 fax: [phone]
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Figure 6: Typical Bit-Error-Rate Performance
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S/N (dB) [Noise Bandwidth = Bit Rate]
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MX589 BT = 0.5
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All trademarks and service marks are held by their respective companies.
S/N (dB)
MX589 BT = 0.3
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BT = 0.5
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BT = 0.3
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Doc. # 204800103.011
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MX589