Справочник Пользователя для Moseley Associates Inc 08MUD1F
System Description
1-10
602-13729-01 Rev B
Expedio Digital Electronic News Gathering Radio
1.5.5 RF First Downconverter
S ingle D ow n-C onverter
M IC R O C O N TL R
R E F O S C
I6 M H Z
IN TE R N AL
D C
C O N V E R TE R S
B AC K P L AN E IN TE R F AC E
I2
+
12V
+5 V dc/
200 m A
200 m A
+10 V dc /
250 m A
P2
R F in p u t
-40 to -90 d B m
19 90 -21 10 M H z
24 50 -25 00 M H z
1: 2050 M Hz/
120 M Hz
2: 2475 M Hz/
50M Hz
48 0 M H z
U H F
O U T
S Y N TH
1.51 -1 .6 3 G H Z
1.97 -2 .0 2 G H Z
2 -2 .5 G H Z
C O N V E R T E R
480M H Z/
25M HZ
13dB
14dB
17dB
Figure 9: RF Downconverter Block Diagram
The receiver handles the traditional RF to UHF conversion from the carrier to 480 MHz.
Considerations are given to image rejection, intermodulation performance, dynamic range, agility,
and survivability. A separate AGC loop was assigned to the RF front end to prevent
intermodulation and saturation problems associated with reception of high level undesirable
interfering RF signals resulting from RF bandwidth that is much wider than the IF bandwidth.
Considerations are given to image rejection, intermodulation performance, dynamic range, agility,
and survivability. A separate AGC loop was assigned to the RF front end to prevent
intermodulation and saturation problems associated with reception of high level undesirable
interfering RF signals resulting from RF bandwidth that is much wider than the IF bandwidth.