PMR Signalling Processor
CMX881
AC Parameters (cont.)
Notes
Min.
Typ.
Max.
Unit
Receiver Signal Type Identification
Probability of correctly identifying signal
type
(SNR = 12dB)
>>99.9
%
CTCSS Detector
Sensitivity
(Pure Tone)
51
52
-26
140
210
160
dB
ms
ms
ms
Hz
Response Time
De-response Time
Dropout immunity
Frequency Range
(Composite Signal)
250
260
(Composite Signal) 52, 55
55
60
SELCALL Detector
Sensitivity
(Pure Tone)
53
-26
35
dB
ms
ms
ms
Hz
Response Time
De-response Time
Dropout immunity
Frequency Range
(Good Signal)
(Good Signal)
45
20
(Selcall)
400
58
3000
DCS Decoder
Sensitivity
51
mVp-p
edges
Bit-Rate Sync Time
2
FFSK/MSK Decoder
Signal Input Dynamic Range
Bit Error Rate
54
54
100
800
mVrms
10-8
(SNR = 20dB)
(SNR = 12dB)
<1
Receiver Synchronisation
Probability of bit 16 being correct
>99.9
%
51
52
Sub-Audio Detection Level threshold set to 16mV.
Notes:
Composite signal = 308mV rms at 1kHz + 75mV rms Noise + 31mV rms Sub-
Audio signal. Noise bandwidth = 5kHz Band Limited Gaussian.
Selcall Tone Detection Level threshold set to 16mV.
53
54
VDD (A) = 3.0V, for a “101010101 ... 01” pattern measured at the input amplifier
feedback pin (12). Signal level scales with VDD (A). See
Figure 15 for variation of BER with SNR.
55
With sub-audio dropout time (P2.4) set to ≥120ms. The typical dropout immunity
is approximately 40ms more than the programmed dropout immunity. The typical
de-response time is approximately 90ms longer than the programmed dropout
immunity. See section 1.6.20.3, P2.4
2004 CML Microsystems Plc
53
D/881/7
CMLMICRO [ CML MICROCIRCUITS ]
