CML Microcircuits CMX7031 Application Note page 18

Application Note
4.7.3 MSK and Inband Signal Detection Threshold Calculations
The MSK and Inband tone detection threshold level is determined by the value loaded into
Programming Block P1.1. The programmed value corresponding to 50mV
determined as follows:
Bit resolution = 3.99mV
Desired threshold level = 50mV
Number of bits for desired threshold level = 50mV
13d = 0xD
The value of 0xD is then loaded into b9..4 of P1.1.
5 Operating States
There are several possible operating states for the CMX7031 in this application. The following state
flow diagram illustrates the possible transitions between the various operating states.
ST AT E 0
Power Up
ST AT E 1
Load Function
data message
complete
FFSK/MSK Rx
data transmission
complete
© 2007 CML Microsystems PLC
/ bit (at V
RMS
Image™
ST AT E 2
Setup
ST AT E 3
Sleep
RSSI > threshold
ST AT E 4
Rx Startup
MSK
detected
ST AT E 7
data
transmission FFSK/MSK T x
required
voice transmission
complete
Figure 6: CMX7031 Application State Flow Diagram
CMX7031
: An Example Core Design for a Complete Family Radio
= 3.3V)
DD
RMS
RMS
release "Monitor"
button
wait
press any
radio button
error
ST AT E 5
Ring T one T x
CT CSS
detected
data
transmission
required
voice
transmission
ST AT E 8
required
ST AT E 9
Voice T x
18 of 28
(MSK threshold) can be
RMS
/ bit) ≅ 13 bits
/ (3.99mV
RMS
ST AT E 10
Monitor
press "Monitor"
button
voice message
complete
CT CSS
detected
ST AT E 6
Voice Rx
AN/2WR/7031/FRS/3 July 2007