Automated in situ testing of railroad telemetry radios

Details Automated in situ testing of railroad telemetry radios Automated in situ testing of railroad telemetry radios

1998-10-23

2001-04-10

Shah, Kamini (Department: 2857)

Data processing: measuring, calibrating, or testing

Testing system

Of circuit

C375S224000, C246S18700R

Reexamination Certificate

active

06216095

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to testing of railroad telemetry radios used in intra-train communications and, more particularly, to an automated on-locomotive testing of Locomotive Control Unit (LCU) radios and End of Train (EOT) radios. The LCU and the EOT are complementary devices which communicate with each other as part of a complete information and control system required by the Federal Railroad Administration (FRA) to be used on freight trains with few exceptions.
2. Background Description
End of Train (EOT) signaling and monitoring equipment, now widely used in place of cabooses, and a Locomotive Control Unit (LCU) installed in the locomotive are used as part of an intra-train digital telemetry communications system. The EOT is typically mounted on the last car of the train and monitors brake pipe air pressure, train movement, battery condition, etc., and transmits this information as digital data over the radio frequency (RF) telemetry link to the LCU. The information monitored by the EOT and transmitted to the LCU is displayed to the crew in the locomotive. The EOT also receives RF transmissions from the LCU to control an air valve in the train's brake pipe to initiate emergency, and in some cases, service braking.
Since the proper operation of EOTs and LCUs in intra-train communications is critical, the systems are tested before each use by the railroads. Thus, after a train has been “made-up” in the rail yard and the LCU and EOT installed, a functional test is performed to verify the overall operation of both devices. This is done as part of the normal linking and arming sequence and verifies the functional operability of the system, i.e., LCU and EOT as a linked pair.
Note that this test does not check the performance limits of the LCU and EOT radios. To check radio performance, the LCU and EOT must normally be brought to a radio shop where the proper equipment is available, and requires opening the LCU and EOT enclosures to gain access to the radios. However, as described and explained herein, the subject invention permits full radio performance testing to be performed at a convenient regular interval, in situ, such as when locomotives are “shopped”.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an in situ test of railroad telemetry radios;
It is another object of the invention to provide an on-locomotive test capability for the LCU radio installed on the locomotive.
It is a further object of the invention to provide an in situ test capability for the EOT radio separate from a central radio shop.
According to the invention, there is provided a multi-function test set to automate testing of the LCU without the need to remove the LCU or to open its cover. The radio module inside of the LCU contains both a transmitter and a receiver. Both are individually tested to verify proper performance. Receiver sensitivity testing of the LCU radio is tested by a bit error rate (BER) measurement with LCU test software and a dedicated BER modulator modulating the test set. The BER modulator and test set generate a known low amplitude message comprised of a short, continuously repeated pseudorandom pattern which is demodulated by the radio receiver. The test software processes the received data and counts the number of errorless messages received over a specific period of time. The receiver sensitivity is known to be acceptable if the number of correct messages received is higher than a predetermined minimum value. The transmitter performance is tested by measuring radio frequency (RF) carrier frequency, modulation frequency, deviation and RF output power. The test set is programmed to automatically measure these parameters, determine whether they meet minimum requirements, and prompt the technician as to pass/fail status.
The automated test set and procedure of this invention have significant advantages. Only those LCUs requiring adjustment and maintenance are removed, resulting in less downtime for locomotives. The procedures used for testing LCU radios are easily adapted to in situ testing of EOT radios in those situations where railroads use a central radio shop for repair and calibration, and EOTs would otherwise have to be sent to this central location for radio testing.


REFERENCES:
patent: 4100531 (1978-07-01), Kobayask
patent: 5685707 (1997-11-01), Horst et al.
patent: 5757291 (1998-05-01), Kull
patent: 6137830 (2000-10-01), Schnelder

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