Vital railway signal link
First Claim
1. A vital railway signal link for transmitting information from a link electrical input at a first terminal location to a link electrical output at a second terminal location, said link comprising:
- a transmitter at said first terminal location including an oscillator operable upon application of a DC input signal at said link electrical input to produce a periodic electrical signal of a preselected frequency;
said transmitter further having photo-emission means responsive to said periodic electrical signal for emitting a light signal modulated at said preselected frequency;
an optical conductor receiving said light signal from said transmitter and extending to said second terminal location;
a receiver at said second terminal location including a photo-sensitive input means for receiving said light signal from said optical conductor and producing an analogous electrical signal periodic at said preselected frequency;
said receiver farther having a bandpass filter electrically connected to said photo-sensitive input means to receive said analogous electrical signal, said bandpass filter tuned to produce a filtered electrical signal upon application of an electrical signal at said preselected frequency and otherwise producing essentially no electrical signal; and
said receiver further having output means electrically connected to receive said filtered electrical signal for producing a DC output signal at said electrical output.
1 Assignment
0 Petitions
Accused Products
Abstract
A vital railway signal link for passing DC signals between a first terminal location and a second terminal location. A transmitter at the first terminal location receives a DC input signal and responsively produces a light signal modulated at a preselected frequency. The light signal is conducted through an optical fiber to the second terminal location. There, a receiver detects the light signal and produces a DC output signal. The receiver contains discriminator circuitry preferably including a bandpass filter to prevent light signals other than those modulated at the preselected frequency from giving an output signal.
32 Citations
25 Claims
-
1. A vital railway signal link for transmitting information from a link electrical input at a first terminal location to a link electrical output at a second terminal location, said link comprising:
-
a transmitter at said first terminal location including an oscillator operable upon application of a DC input signal at said link electrical input to produce a periodic electrical signal of a preselected frequency; said transmitter further having photo-emission means responsive to said periodic electrical signal for emitting a light signal modulated at said preselected frequency; an optical conductor receiving said light signal from said transmitter and extending to said second terminal location; a receiver at said second terminal location including a photo-sensitive input means for receiving said light signal from said optical conductor and producing an analogous electrical signal periodic at said preselected frequency; said receiver farther having a bandpass filter electrically connected to said photo-sensitive input means to receive said analogous electrical signal, said bandpass filter tuned to produce a filtered electrical signal upon application of an electrical signal at said preselected frequency and otherwise producing essentially no electrical signal; and said receiver further having output means electrically connected to receive said filtered electrical signal for producing a DC output signal at said electrical output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A bidirectional vital railway signal link for transmitting information between a first terminal location and a second terminal location, said link comprising:
-
a first terminal location transmitter operable to receive a first DC input signal at a first link electrical input and produce a first light signal modulated at a first preselected frequency; a second terminal location transmitter operable to receive a second DC input signal at a second link electrical input and produce a second light signal modulated at a second preselected frequency; a first fiber optic conductor receiving said first light signal from said first terminal location transmitter and extending to said second terminal location; a second fiber optic conductor receiving said second light signal from said second terminal location transmitter and extending to said first terminal location; a second terminal location receiver operable to receive said first light signal from said first fiber optic conductor and produce a first DC output signal at a first link electrical output; said second terminal location receiver having first discriminator means for giving essentially no signal at said first link electrical output upon receipt of other than a light signal modulated at said first preselected frequency; a first terminal location receiver operable to receive said second light signal from said second fiber optic conductor and produce a second DC output signal at a second link electrical output; and said first terminal location receiver having second discriminator means for giving essentially no signal at said second link electrical output upon receipt of other than a light signal modulated at said second preselected frequency. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
-
18. A vital railway signal link for transmitting information from a link electrical terminal input at a first terminal location to a link electrical output at a second terminal location, said link comprising:
-
transmitting means at said first terminal location for receiving a DC signal at said link electrical input and emitting in response thereto a light signal modulated at a preselected frequency; a fiber optic conductor receiving said light signal from said transmitting means and extending to said second terminal location; and a receiver at said second location responsive to said light signal to produce a DC output signal at said link electrical output, said receiver having a discriminator circuit including an electrical isolation coupler giving essentially no output signal at said link electrical output upon receipt of other than a light signal modulated at said preselected frequency. - View Dependent Claims (19, 20, 21, 22, 23)
-
-
24. A method of transmitting railway signal information from a first location to a second location comprising the steps of:
-
(a) detecting at said first location a DC input signal; (b) producing in response to said DC input signal a periodic electrical signal of a preselected frequency; (c) emitting in response to said periodic electrical signal a light signal modulated at said preselected frequency; (d) applying said light signal to an optical conductor extending from said first location to said second location; (e) detecting said light signal at said second location and producing in response thereto an analogous electrical signal; (f) applying said analogous electrical signal to a vital bandpass filter circuit tuned to said preselected frequency; and (g) rectifying an output of said vital bandpass filter to produce a DC output signal at said second location. - View Dependent Claims (25)
-
Specification