CMX589AP4 View Datasheet(PDF) - MX-COM Inc
Part Name
Description
MFG CO.
'CMX589AP4' PDF : 21 Pages View PDF
High Speed GMSK Modem
11
CMX589A PRELIMINARY INFORMATION
4.2.5 Rx S/N Detection
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.
10-1
10-2
10-3
BER
10-4
CMX589A BT = 0.3
BT = 1.0 (Theoretical)
10-5
CMX589A BT = 0.5
10-6
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
S/N (dB) [Noise Bandwidth = Bit Rate]
Figure 6: Typical Bit-Error-Rate Performance
Note: Figure 6 indicates typical performance, independent of bit rate (although the applied noise bandwidth is
considered to match the bit rate used), radio performance (e.g. IF filter distortion), supply voltage (higher bit
rates require VDD 4.5V), and other ‘real world’ factors.”
1998 MX-COM, Inc.
www.mxcom.com Tele: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480183.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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