General Technical Description - Lectrosonics SRc5P-941 Instruction Manual

General Technical Description

SRC-941 DUAL RECEIVER
Ant 1
SAW
LNA
BPF
RECEIVER 1
Ant 2
RECEIVER 2
SAW
LNA
BPF
Keypad
To both PLL
To phase switches
+3.3V
V Reg
Fuse
Power
The design consists of two separate receivers built into
a single, ultra compact housing with interchangeable
adapters for video camera wireless receiver slots and
stand-alone use. Digital Hybrid Wireless
provides superb, compandor-free audio quality and
compatibility with other wireless systems. The RF per-
formance is extremely stable over a very wide tempera-
ture range, making the receiver perfectly suited to the
rough environmental conditions in field production.
The front panel features a menu-driven LCD interface
and four membrane switches used to view and alter set-
tings. Audio outputs are provided on the rear panel for
camera slots or other audio devices.
A built-in spectrum analyzer scans across the tuning
range of the receiver to simplify finding clear operating
frequencies.
The dual receiver architecture allows two different types
of diversity reception:
Rio Rancho, NM
RF BLOCK DIAGRAM
Mixer
Splitter
Phase
Shifter
µP
Splitter
Phase
Shifter
Mixer
LCD
display
Ref xtal
µP
DSP
Memory
Codec
Audio 1
(from RF PCB)
Audio 2
–5V
+5V
On/O
DC-DC
conv
Osc
sync
technology
®
248.450 MHz
IF Amp
SAW SAW
BPF BPF
248.800 MHz
1st 2nd
VCO VCO
High Side
High Side
Injection
Injection
PLL
12 MHz
Ref.
µP
Osc.
PLL
High Side High Side
Injection Injection
2nd
1st
VCO
VCO
244.200 MHz
SAW SAW
BPF BPF
IF Amp
243.950 MHz
SRC-941 DUAL RECEIVER
AUDIO BLOCK DIAGRAM
Audio amps
DAC
µP
digital
atten
+3.3V
DC-DC
conv
+30V
DC-DC
Osc
conv
sync
+1.6V
DC-DC
conv
SmartDiversity
dently to provide two separate audio channels. The
algorithm analyzes both the incoming RF level and the
rate of change in RF level to determine the optimum
timing for antenna phase switching. The system also
employs "opportunistic switching" to analyze and then
latch the phase in the best position during brief squelch
activity.
Ratio Diversity blends the audio outputs of both receiv-
ers in a seamless manner to produce a single audio
output. A panning circuit blends more signal from the re-
ceiver with the stronger RF signal over a wide RF level
range to anticipate and eliminate dropouts long before
they occur. When a good RF signal is present at both
receivers and the audio is blended equally, the signal-
to-noise ratio is increased by 3 dB.
UHF Digital Hybrid Wireless
Audio
Rx IC
Pulse
Amp &
350 kHz
Detector
Filter
BPF
Audio
Rx IC
Pulse
Amp &
250 kHz
Detector
Filter
BPF
+5V
50
+
Hi
5k
Com
+5V
5k
–
Lo
50
µP
2
1
polarity
4
+5V
50
+
Hi
5k
Com
+5V
5k
–
Lo
50
Diode
protected
outputs
allows each receiver to run indepen-
™
®
Audio 1
Window
Detector
RSSI
RSSI
Window
Detector
Audio 2
3
5
3