Clear-Com PTX-3 - Manual (Page 8)

Vitec Group Communications
PTX-3 UHF Digital Hybrid IFB Transmitter
1 - 2
DIGITAL HYBRID TECHNOLOGY
The PTX-3 features Digital Hybrid Wireless* technology for
compatibility with some other brands of receivers. The Digital Hybrid
system in the PTX-3 overcomes channel noise and compandor
artifacts in a dramatically new way, digitally encoding the audio in the
transmitter and decoding it in the receiver, yet still sending the
encoded information via an analog FM wireless link. This proprietary
algorithm is not a digital implementation of an analog compandor, but a
technique which can be accomplished only in the digital domain.
Figure 1-2: PTX-3 Block Diagram
AUDIO INPUT INTERFACE
The standard 3 pin XLR connector on the rear panel handles all audio
inputs. The four DIP switches allow setting the input sensitivity for low
levels, such as microphone inputs, or for high levels, such as line
inputs, balanced or unbalanced. The switches also offer special
settings to provide the proper input configurations to match to Clear
Com, RTS1, and RTS2 intercom systems. Pin 1 of the XLR input
connector is normally connected to ground but an internal jumper can
be moved if a floating input is desired.
While the XLR input does not offer phantom power, it is fully
compatible with standard 48 Volt phantom power. Phantom supplied
microphones may be connected to the PTX-3 without the need for DC
isolation.
A user-selectable low frequency roll-off can be set for 35 Hz or 50 Hz.
The recommended 50 Hz default setting helps to remove wind and
traffic noise, air conditioner rumble, and other sources of undesired low
frequency audio. The 35 Hz setting offers a fuller range of sound in the
absence of adverse conditions.