OVERVIEW
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1-4
SIG-00-22-02 JUNE 2022 (Revised September 2022)
Version: B.1
Configuration menus are available on the Display Module which provides field selectable
options such as:
•
PSO transmitter, receiver, and island frequencies
•
PSO transmit power
•
Up to five unique modulation address codes
•
Configurable inputs and outputs for an application
•
Configurable receiver, island, and input pickup delays
•
Drop Delay Timer, Internal Directional Stick Logic, and Stick Cancel Timer when
configured as a Crossing unit
•
Taking units Out of Service
•
Advance Preemption and Gate Down Logic
•
Configurable vital logic
•
Customer Defined Logic Equations
•
AND gates
•
OR gates
The PSO Module is functionally compatible with the PSO 4000 and PSO+ Modules, the PSO III
receiver and transmitter as well as the PSO II receiver and PSO II transmitter when using an A
or C address.
The Transmitter generates a modulated audio-frequency track signal. It sends a coded, 8-bit
address code through the rails using an audio frequency signal as a carrier. The rail
connections for the coupling unit delimit the other end of the track circuit. The modulated signal
is detected by the receiver where it is decoded and processed. The Receiver responds only to
signals of the proper frequency, address, and amplitude. The ability of the PSO Module to
differentiate between its operating signal and all other signals present on the track is due to the
nonsymmetrical coded modulation and receiver decoding techniques which ensure that the
system is immune to most foreign AM, FM, and beat signals. The receiver decodes the signal
and, if it qualifies the signal as valid, the receiver produces an output to energize a vital relay or
logic state. The receiver is connected to the track via a Tuned Receiver Coupler, which is a
separate piece of equipment.
No insulated joints are needed to confine the signal because the coupling units have low
impedance at the operating frequency of the track circuit, and high impedance at all other
frequencies. The PSO Module can also be used on the same track used for coded or non-coded
DC or AC track circuits, Grade Crossing Predictors (GCPs), motion detectors, and other audio
frequency track circuits.
The GCE application’s crossing functionality includes two receivers plus a combination
transmitter/receiver Island Track Circuit that is incorporated into the Module. In a crossing
application, the Module is capable of performing the Directional Stick Logic, drop delay, and
Stick Cancel functionality. The Module provides configurable receiver and island pickup delays.
The Module has the flexibility to use external inputs instead of or in addition to the internal PSO
receivers and island. For instance, if the installation already has a track circuit in place (e.g., a
DC track circuit), this could be used in place of one of the approach receivers. Either of the PSO
receivers and/or the Island may be enabled or disabled. The Island function supplies a limited
distance audio frequency track circuit with an effective range between 120 to 500 ft. (36.6 to
152.4 m). The island circuit performs a similar function as Siemens Rail’s Model 71150
Intelligent Processor Island Track Circuit (IPITC) and Intelligent Processor Island Track Circuit II