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PDF CMX264 Data sheet ( Hoja de datos )
| Número de pieza | CMX264 | |
| Descripción | Frequency Domain Split Band Scrambler | |
| Fabricantes | Consumer Microcircuits Limited | |
| Logotipo |  |
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CMX264
Frequency Domain
Split Band Scrambler
D/CMX264/1 August 1999
1.0 Features
• Ensures Privacy
• Full Duplex
• High Quality Recovered Audio
• Low Height, Surface Mount Package
• 3.0V, Low Power Operation
Advance Information
• Fixed or Rolling Code
• Standby Mode
• Uses Split Band Inversion
• Low Current, Low Voltage
• 4.433619MHz Operation
1.1 Brief Description
The CMX264 is a frequency domain scrambler for use in analogue cellular phone systems. It contains
separate Tx and Rx paths for full duplex operation and operates under µProcessor control via a simple serial
interface.
In the Tx path, scrambling is achieved by splitting the audio band into two parts, or sub-bands, and frequency
inverting each one. The frequency at which the signal is split, the “split-point”, can be either fixed or rolling
between four possible settings resulting in a transmitted audio signal which is unintelligible to eavesdroppers.
Descrambling is achieved by a receive device set to the same split point as the remote transmitter. Thus if the
Tx and Rx devices are synchronously cycled through the same sequence of split points, a clear recovered
signal will emerge at the output of the receiver.
A 4.433619MHz crystal is used allowing up to four split points to be programmed. The device is designed to
be compatible with existing cellphone circuitry.
© 1999 Consumer Microcircuits Limited
http://www.Datasheet4U.com
1 page  
Frequency Domain Split Band Scrambler
1.3 Signal List (continued)
CMX264
Package
D5
Signal
Pin No.
Name
15 -
16 MUTERX
17 EXTO
18 -
19 RECO
20 -
21 CSN
22 SCLOCK
23 SDATA
24 VDD
Description
Type
- This pin should be left unconnected.
I/P A logic input which when high (VDD) immediately
de-activates the two Rx outputs (RECO and
EXTO), overriding the serial data previously
loaded. When this input is low (VSS), the Rx
outputs are controlled by the serial data port.
O/P One of two Rx outputs. This is used for routeing
the recovered audio to external devices, e.g. a
speakerphone. This output may be
independently activated or de-activated by
selecting the appropriate internal state. When
de-activated, either by the serial data or by the
MUTERX pin, the output is set to VBIAS.
- This pin should be left unconnected.
O/P The other Rx output. This is used for routeing
the recovered audio to the telephone
loudspeaker. This output may be independently
activated or de-activated by selecting the
appropriate internal state. When de-activated,
either by the serial data or by the MUTERX pin,
the output is set to VBIAS.
- This pin should be left unconnected.
I/P )The serial port input pins. Data applied here
I/P )sets up the internal state of the device, e.g. split
I/P )point, scramble/clear, etc. See Figure 10.
POWER
The positive supply rail. This pin must be
decoupled to VSS by a capacitor mounted close
to the device.
Notes: I/P = Input
O/P = Output
BI = Bidirectional
© 1999 Consumer Microcircuits Limited
5
D/CMX264/1
5 Page 
Frequency Domain Split Band Scrambler
1.5.3.4 Output Select (D8, D7, D6)
CMX264
D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 MICO RECO EXTO
0 0000
Pre/De-Emphasis
Split Point
Bias Bias
001
Select/Bypass
Select
Bias
Active
010
Active
Bias
011
Active
100
Bias Bias
101
Active
Active
110
Active
Bias
111
Active
10 0 0
Pre/De-Emphasis
Scrambler
Bias Bias
001
Blocks all Powersaved
Bypassed
Bias
Active
010
and Bypassed
Active
Bias
0 1 1 X X X X XX
Active
100
Bias Bias
101
Active
Active
110
Active
Bias
111
Active
Table 5
Bits D8, D7, D6 activate or de-activate the audio outputs in both clear (D9 = 1) and scramble
(D9 = 0) modes:
Bit D8 controls the Tx output MICO.
Bit D7 controls the Rx output RECO.
Bit D6 controls the Rx output EXTO.
In all cases, the output is activated by setting the relevant data bit to logic 1 and is de-activated
by setting the bit to logic 0. The Rx outputs (RECO and EXTO) can also be de-activated by the
MUTERX pin, which asynchronously overrides bits D6 and D7.
When activated, the signal output at an output pin is determined by the internal state of the device,
e.g. in clear mode (D9 = 1), the MICO pin will output the signal from the MICIN pin. In scramble mode,
when the Tx de-emphasis circuit is selected, the MICO pin will carry the signal from the de-emphasis
output, and so on.
When de-activated, an output is pulled to VBIAS by means of an internal high impedance.
1.5.3.5 Pre/De-Emphasis Select (D5, D4, D3, D2)
D10
0
D9 D8
D7 D6 D5 D4 D3 D2 D1 D0
0 MICO
RECO
EXTO
Output Control Output Control Output Control
Pre/De-Emphasis
Select/Bypass
(See Text)
Split Point
Select
Table 6
Bits D5, D4, D3, D2 have an effect in scramble mode only and are used to select or bypass the pre-
emphasis and de-emphasis blocks.
© 1999 Consumer Microcircuits Limited
11
D/CMX264/1
11 Page | ||
| Páginas | Total 25 Páginas | |
| PDF Descargar | [ Datasheet CMX264.PDF ] | |
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