TDA7705 Electrical specifications
Doc ID 15938 Rev 9 29/42
3.5.5 WX overall system performance
Antenna level equivalence: 0 dBµV = 1 µV
rms
(Antenna terminal voltage with 50 source).
Figure 14. WX input set-up
Input level referred to signal generator loaded with 50 (V
rf
, node 'A'); no antenna dummy;
AM input not connected. F
rf
=162.475 MHz, V
rf
= 60 dBµV, mono modulation, f
dev
= 3 kHz,
f
audio
=400 Hz. De-emphasis = 75 µs. Application: WX using mixer input 2, in conjunction
with FM narrow-band. Unless otherwise specified.
Table 21. WX overall system performance
Parameter Test condition Min Typ Max Units
Sensitivity S/N = 26 dB - -7 - dBµV
Ultimate S/N @ 60 dBµV - 81 - dB
Distortion Deviation= 4.5 kHz - 0.8 - %
Max deviation THD = 3 % - > 5 kHz - kHz
Adjacent channel Selectivity
F= 25 kHz, SINAD = 30 dB
desired 40 dBµV,
dev =2.0 kHz, 400 Hz
undesired. dev= 3 kHz, 1 kHz
-70-dB
Alternate Channel Selectivity
F=50kHz, SINAD=30dB
desired 40 dBµV,
dev=2.0kHz, 400Hz
undesired. dev=2.0kHz, 1kHz
-70-dB
V
rf
+ 6dB
PCB
UNDER
TEST
50Ω
V
rf
+ 6dB
V
rf
50Ω
50Ω
A
