Справочник Пользователя для Lectrosonics Inc D4T

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General Technical Description

D4T Transmitter

The transmitter can accept up to four inputs from digi-

tal or analog sources. Inputs 1 and 2 are selectable be-

tween two digital channels each or 1 balanced analog

channel each and inputs 3 and 4 can each accept a 

single balanced analog signal.
The inputs can be configured as follows:

•  Four balanced analog inputs using all four jacks
•  Two digital channels using jack 1 and two bal-

anced analog inputs using jacks 3 and 4

•  Four digital channels using jacks 1 and 2

The input connectors are TA3 “mini XLR” types with 

the same pin numbering and configuration as standard 

XLR connectors for AES-EBU and balanced line level 

analog signals.
Input preamp circuits use a special balanced amplifier 

with very high common mode rejection to minimize

hum and noise.

Analog input signals are sampled at 48kHz and con-

verted to 24-bit digital audio and fed into the FPGA 

for further processing. The FPGA applies a spreading 

algorithm to expand the bandwidth of each channel 

to 4,2 MHz to improve immunity to interference and 

noise. The baseband signal is then delivered to the 

D-A to generate the I and Q signals for final output.
The modulated signal is filtered before and after the 

RF amp to suppress out of band noise and spurious 

signals. A circulator/isolator is used in the final RF 

output to minimize IM that can occur when external 

signals enter the output stage through the antenna. 

The isolator passes the transmitter output signal to the 

antenna but shunts returning signals to ground.
A USB port is provided to simplify firmware updates.

POWER 
AMP

OSC

900 MHz

RF

DEMOD

DIGITAL 

BASEBAND 

ENCODER

24-bit D/A

(analog)

AES/EBU 

OUT

(digital)

24-bit D/A

(analog)

AES/EBU 

OUT

(digital)

24-bit D/A

(analog)

24-bit D/A

(analog)

TA3F 

INPUTS

CIRCULATOR

ISOLATOR

FILTER

1

2

3

4