Dual SPM Detector
Page 9 of 16
MX641 Preliminary Information
4.3.1.1
Controlled Sensitivity Setting Information
The sensitivity figures in Table 4 are based on the following:
1. The recommended amplifier components (see Figure 2) are used, providing an amplifier gain at 16kHz
of 19.8dB ±0.3dB or at 12kHz of 19.1dB ±0.3dB.
2. A comparator sensitivity of 1.6dB(ref.) ±1dB (the variation is due to filter gain error, filter output offset,
comparator input offset or a combination of all 3).
3. The applied V
DD
is 5.0 volts; 0dB (ref.) = 775mV
RMS
.
12kHz System
Bit D0 = ‘1’
Serial Data
Bits
D5 - D1
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
Bandpass
Filter Gain
(dB)
0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
23.0
24.0
25.0
26.0
27.0
Minimum
Sensitivity
dB(ref.)
-16.2
-17.2
-18.2
-19.2
-20.2
-21.2
-22.2
-23.2
-24.2
-25.2
-26.2
-27.2
-28.2
-29.2
-30.2
-31.2
-32.2
-33.2
-34.2
-35.2
-36.2
-37.2
-38.2
-39.2
-40.2
-41.2
-42.2
-43.2
Nominal
Sensitivit
y
dB(ref.)
-17.5
-18.5
-19.5
-20.5
-21.5
-22.5
-23.5
-24.5
-25.5
-26.5
-27.5
-28.5
-29.5
-30.5
-31.5
-32.5
-33.5
-34.5
-35.5
-36.5
-37.5
-38.5
-39.5
-40.5
-41.5
-42.5
-43.5
-44.5
Maximum
Sensitivity
dB(ref.)
-18.8
-19.8
-20.8
-21.8
-22.8
-23.8
-24.8
-25.8
-26.8
-27.8
-28.8
-29.8
-30.8
-31.8
-32.8
-33.8
-34.8
-35.8
-36.8
-37.8
-38.8
-39.8
-40.8
-41.8
-42.8
-43.8
-44.8
-45.8
Minimum
Sensitivity
dB(ref.)
-16.9
-17.9
-18.9
-19.9
-20.9
-21.9
-22.9
-23.9
-24.9
-25.9
-26.9
-27.9
-28.9
-29.9
-30.9
-31.9
-32.9
-33.9
-34.9
-35.9
-36.9
-37.9
-38.9
-39.9
-40.9
-41.9
-42.9
-43.9
16kHz System
Bit D0 = ‘0’
Nominal
Sensitivit
y
dB(ref.)
-18.2
-19.2
-20.2
-21.2
-22.2
-23.2
-24.2
-25.2
-26.2
-27.2
-28.2
-29.2
-30.2
-31.2
-32.2
-33.2
-34.2
-35.2
-36.2
-37.2
-38.2
-39.2
-40.2
-41.2
-42.2
-43.2
-44.2
-45.2
Maximum
Sensitivity
dB(ref.)
-19.5
-20.5
-21.5
-22.5
-23.5
-24.5
-25.5
-26.5
-27.5
-28.5
-29.5
-30.5
-31.5
-32.5
-33.5
-34.5
-35.5
-36.5
-37.5
-38.5
-39.5
-40.5
-41.5
-42.5
-43.5
-44.5
-45.5
-46.5
These states should never be used. If sensitivities of this order are required (e.g. the Swedish Rural
SPM specification), it is recommended that the Controlled Sensitivity setting be set to 20dB (10100)
and external components selected to set the Input Amp gain to a higher figure. This action will
prevent falsing by sub-harmonic frequencies.
Table 4: Controlled Sensitivity Setting Information
ã
2001 MX-COM, Inc.
www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054
Doc. # 20480115.004
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