General Technical Description - Lectrosonics SR Series Instruction Manual

General Technical Description

RF PCB Block Diagram
RF amp
SAW
filter
Receiver 1
Splitter
Phase
switch
Phase
switch
Receiver 2 Splitter
SAW
filter
RF amp
Audio PCB Block Diagram
LCD
display
Keypad
µP DSP
To both PLL
Memory
To phase switches
+3.3V
Audio 1
(from RF PCB)
Audio 2
V Reg
–5V
+5V
On/O
Fuse
DC-DC
Camera
conv
power in
The SRa5P and SRa consists of two separate receivers
built into a single, ultra compact housing with inter-
changeable adapters for video camera wireless receiver
slots and stand-alone use. Digital Hybrid Wireless
technology provides superb, compandor-free audio
quality and compatibility with other wireless systems.
The RF performance is extremely stable over a very
wide temperature range, making the receiver perfectly
suited to the rough environmental conditions found 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, and in the case of
the SRa5P, on the front panel through a 5-pin TA Series
connector.
A built-in spectrum analyzer scans across the tuning
range of the receiver to locate RF signals in the vicinity
to simplify finding clear operating frequencies.
Rio Rancho, NM
IF IF
243.950 MHz
Mixer
amp amp
SAW
filter
µP
1st
VCO
High side
injection
PLL
Ref. Osc
PLL
High side
injection
1st
VCO
µP
SAW
filter
IF IF
Mixer 248.450 MHz
amp amp
Ref xtal Audio amps
DAC
Codec
+3.3
DC-DC
conv
Osc
sync
+1.6V
DC-DC
conv
Osc
sync
243.950 MHz
250 kHz
SAW Pulse
Rx IC
filter detector
2nd
VCO
244.200 MHz
RSSI
SR Dual Receiver RF Board
RSSI
248.800 MHz
2nd
VCO
Pulse
SAW
Rx IC
detector
filter
350 kHz
248.450 MHz
+5V
50
5k
+5V
5k
50
+5V
50
5k
+5V
5k
50
Diode
µP
protected
digital
outputs
atten
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 phase switching, and the optimum antenna
phase. The system also employs "opportunistic switch-
ing" 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 1
Window
detect
Window
detect
Audio 2
+
Hi
Com
–
Lo
3
2
1
4 5
+
Hi
Com
–
Lo
allows each receiver to run indepen-
™
®
5