Lectrosonics SRC5P Data Sheet

SRc5P and SRc

Camera Slot Dual UHF Receiver

TECHNICAL DATA

• Fits camera “slots,” Lectrosonics Duopack
adapter and Octopack multicoupler, and
operates stand-alone with various adapters

• Tunes over a 76 MHz range* (3 blocks)

• Dual receiver design for two channels with
phase switched diversity or single channel
with ratio diversity operation

• Digital Hybrid Wireless® with compatibility
modes for use with earlier transmitters

The SRc5P and SRc design includes two separate
receivers built into a single, ultra compact housing with
adapters for video camera receiver slots and for stand­alone 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.

DSP compatibility modes allow the receiver to be used
with a variety of Lectrosonics systems, other brands of
wireless systems and with Lectrosonics IFB transmitters.

Digital Hybrid Wireless

that combines digital audio with an analog FM radio
link to provide both outstanding audio quality and
exemplary, noise-free RF performance.

Using a patented algorithm to encode 24-bit digital
audio information in the transmitter into an analog
format, the encoded signal is then transmitted over an
analog FM wireless link.

®

is a revolutionary design

• Tracking front-end filters for high
performance in tough RF environments

• LCD with RF spectrum scanning

• SmartSquelch

TM

DSP-controlled, noise based

filtering and squelch

• DSP-based pilot tone for squelch control

• IR sync port for quick transmitter setup

• SmartTune

TM

operation for quick and

confident frequency selection

The front panel features a menu-driven LCD interface
and four membrane switches which are used to view
and alter settings. The main LCD window displays the
pilot tone indicator, diversity activity, RF level, audio level
and transmitter battery status for both receivers. To find
clear operating frequencies, a built-in spectrum analyzer
scans across the tuning range of the receiver and dis­plays a histogram of RF activity across the band. Areas
with little or no RF activity are easily recognizable.

The two internal receivers can be operated separately,
each using switching, antenna combining diversity, or in
tandem with ratio diversity reception. The audio outputs
of the receivers can be mixed internally, or left separated
for discrete recording tracks or external mixing.

A variety of output adapters and mounting options are
available for camera slot operation. The receivers are
powered from an external 7 to 18 volt DC source. The
SRC5P model provides a 5-pin connector next to the
control panel with audio output from both channels in ad­dition to the camera slot outputs.

At the receiver, the signal is then decoded to restore
the original digital audio. This process eliminates
compandor artifacts and produces an audio
frequency response flat to 20 kHz.

(US Patent 7,225,135)

*Tuning range varies slightly in different bands

Rio Rancho, NM, USA
www.lectrosonics.com

Three Block Tuning Range

TUNING RANGE

The SRC & SRC5P receivers tune across a range of
over 76 MHz. This tuning range covers three standard
Lectrosonics frequency blocks.

BLOCK

BLOCK

BLOCK

IF (Intermediate Frequency) Filters

Following the front-end, the incoming RF signal in each
receiver is mixed down to a lower frequency for addition­al filtering with two SAW (surface acoustic wave) filters.
The use of two filters significantly increases the depth
of filtering while preserving sharp skirts, constant group
delay, and wide bandwidth.

Tuning ranges are available covering standard blocks
as follows:

Band Blocks Covered Freq. (MHz)

A1 470, 19, 20 470.100 - 537.575

B1 21, 22 23 537.600 - 614.375

B2 22, 23, 24 563.200 - 639.975

Block
606

C1 24, 25, 26 614.400 - 691.175

C2 25, 26, 27 640.000 - 716.775

23, 24

606.000 - 631.500

RF Front-End with Tracking Filter

A wide tuning range is helpful in finding clear frequen­cies for operation, however, it also allows a greater range
of interfering frequencies to enter the receiver. The UHF
frequency band, where almost all wireless microphone
systems operate, is heavily populated by high power TV
transmissions. The TV signals are immensely more pow­erful than a wireless microphone transmitter signal and
will enter the receiver even when they are on significantly
different frequencies than the wireless system. This pow­erful energy appears as noise to the receiver, and has
the same effect as the noise that occurs with extreme
operating range of the wireless system (noise bursts and
dropouts). To alleviate this interference, front-end filters
are needed in the receiver to suppress RF energy below
and above the operating frequency.

Each receiver employs a variable frequency, tracking
filter in the front-end section (the first circuit stage follow­ing the antenna). As the operating frequency is changed,
the filters re-tune to stay centered over the selected car­rier frequency.

BLOCK

In the front-end circuitry, a tuned tracking filter is followed
by an amplifier and then another tuned tracking filter to
provide the selectivity needed to suppress interference,
yet provide a wide tuning range and retain the sensitivity
needed for extended operating range.

BLOCK

BLOCK

Digital Pulse Counting Detector

Following the IF section, the receiver uses an elegantly
simple, yet highly effective digital pulse counting detec­tor to demodulate the FM signal to generate the audio,
rather than a conventional quadrature detector. This
unusual design eliminates thermal drift, improves AM
rejection, and provides very low audio distortion.

DSP-Based Pilot Tone

The Digital Hybrid system design uses a DSP generated
ultrasonic pilot tone to reliably mute the audio when no
RF carrier is present. The pilot tone must be present in
conjunction with a usable RF signal before the audio out­put will be enabled. 256 pilot tone frequencies are used
across each 25.6 MHz block within the tuning range of
the system. This alleviates erroneous squelch activity in
multichannel systems where a pilot tone signal can ap­pear in the wrong receiver via IM (intermodulation).

Automatic Power State Restoration

The firmware “remembers” whether it was turned on or
off when power is disconnected and returns to that state
when power is restored.

SmartSquelch

A DSP-based algorithm named SmartSquelchTM optimizes
the receiver performance in very weak signal conditions.
The RF level and supersonic noise in the audio are con­tinuously monitored to determine the appropriate noise
reduction needed and the point at which squelch (complete
muting of the audio) is necessary.

™

SmartTune™ Frequency Selection

SmartTune™ simplifies setup by scanning the tuning range
of the receiver or a selected frequency block, and auto­matically setting a channel to the best available frequency.
A prompt appears, reminding the user to use IR sync or
manual settings to tune the transmitter to the selected
frequency, then turn it on so the receiver sees it. Then, a
prompt asks if the process should continue for the second
channel. This process allows very quick and accurate tun­ing, whatever the RF environment.