Baseband Processor For Mixed Mode Land Mobile Radio
CMX880
AC Parameters (cont.)
Notes
Min.
Typ.
Max.
Units
Analogue Channel Audio Filtering
Pass-band (nominal bandwidth):
Received voice
71
72
73
300
300
300
3000
3000
2550
Hz
Hz
Hz
dB
dB
dB
dBp
12.5kHz channel transmitted voice
25kHz channel transmitted voice
Pass-band Gain (at 1.0kHz)
Pass-band Ripple (wrt gain at 1.0kHz)
Stop-band Attenuation
0
-2
33.0
+0.5
Residual Hum and Noise
78
-50
Pre-emphasis
De-emphasis
74
75
6
- 6
dB/oct
dB/oct
Digital (APCO 25) Channel Audio Filtering
Band Pass filtering (TX)
76
77
Voice from MIC input (nominal bw)
Pass-band Gain (at 1.0kHz)
Pass band ripple (wrt gain at 1kHz)
Low Pass filtering (RX)
200
- 2
0
3300
1
Hz
dB
dB
0
0
Voice to Audio output (nominal bw)
Pass-band Gain (at 1.0kHz)
Pass band ripple (wrt gain at 1.0kHz)
3300
2
Hz
dB
dB
- 1
Notes:
71.
The receiver voice filter complies with the characteristic shown in Figure 5. The
high pass filtering removes sub-audio components from the audio signal.
The 12.5kHz channel filter complies with the characteristic shown in Figure 13
The 25kHz channel filter complies with the characteristic shown in Figure 12
The pre-emphasis filter complies with the characteristic shown in Figure 14.
The de-emphasis filter complies with the characteristic shown in Figure 6.
The high pass filtering part of the band pass is implemented by the microphone
input filter components defined in section 1.4. The Tx voice filter complies with the
characteristic shown in Figure 17.
72.
73.
74.
75.
76.
77.
78.
The Rx voice filter complies with the characteristic shown in Figure 10.
dBp represents a psophometrically weighted measurement.
ã 2001 Consumer Microcircuits Limited
75
D/880/1
CMLMICRO [ CML MICROCIRCUITS ]
