Train communication network
View Patent ↗An access point for a communication network is disclosed. The access point may have a communications processor configured to receive signals from a different access point of the communication network, and at least a first attenuator configured to selectively attenuate the signals before they are received by the communications processor. The access point may also have a voltage clamp configured to limit a strength of the signals before they are received by the at least a first attenuator, and a second attenuator configured to attenuate all signals before they are received by the voltage clamp.
1. An access point for a communication network, comprising:
a communications processor that receives signals from a different access point of the communication network;
at least a first attenuator that receives and selectively attenuates the signals before they are received by the communications processor;
a voltage clamp that receives and limits a strength of the signals before they are received by the at least a first attenuator; and
a second attenuator that receives and attenuates all signals before they are received by the voltage clamp.
2. The access point of claim 1 , wherein the at least a first attenuator includes:
an analog front end amplifier; and
an adjustable attenuator located upstream of the analog front end amplifier.
3. The access point of claim 2 , wherein the analog front end amplifier is configured to selectively attenuate the signals based on commands from the communications processor.
4. The access point of claim 3 , further including a gain controller in communication with the adjustable attenuator and configured to selectively adjust an amount of attenuation provided by the adjustable attenuator.
5. The access point of claim 4 , wherein:
the gain controller is configured to intercept the commands from the communications processor to the analog front end amplifier; and
the gain controller is configured to selectively adjust the amount of attenuation provided by the adjustable attenuator based on the commands.
6. The access point of claim 5 , wherein the adjustable attenuator is configured to adjust the signals to a desired voltage level that is reliably interpreted by the communications processor.
7. The access point of claim 6 , wherein the desired voltage level is about 3V.
8. The access point of claim 7 , wherein the voltage clamp is configured to limit the signals to a maximum of about 5V.
9. The access point of claim 8 , wherein the second attenuator is a passive attenuator configured to attenuate all signals by about ⅓ to ½.
10. The access point of claim 1 , further including a cable configured to conduct the signals to the communications processor of the access point and outgoing signals from the communications processor to the different access point, wherein the second attenuator is located downstream of a point at which the outgoing signals generated by the communications processor are directed onto the cable.
11. The access point of claim 10 , wherein the second attenuator is configured to isolate the voltage clamp, the at least a first attenuator, and the communications processor from the outgoing signals directed by the communications processor onto the cable.
12. A communication network, comprising:
a first access point having a first communications processor, at least a first attenuator, a first voltage clamp, and a second attenuator;
a second access point having a second communications processor, at least a third attenuator, a second voltage clamp, and a fourth attenuator; and
a cable connecting the first and second access points,
wherein:
the at least a first attenuator and the at least a third attenuator are connected to the cable at locations between the first and second communications processors;
the first and second voltage clamps are connected to the cable at locations between the at least a first and at least a third attenuators; and
the second and fourth attenuators are connected to the cable at locations between the at least a first and at least a third attenuators.
13. The communication network of claim 12 , wherein the at least a first attenuator and the at least a third attenuator each includes:
an analog front end amplifier configured to selectively attenuate signals based on commands from the corresponding one of the first and second communications processors; and
an adjustable attenuator located upstream of the analog front end amplifier.
14. The communication network of claim 13 , further including a gain controller in communication with the adjustable attenuator and configured to selectively adjust an amount of attenuation provided by the adjustable attenuator.
15. The communication network of claim 14 , wherein:
the gain controller is configured to intercept the commands from the corresponding one of the first and second communications processors to the analog front end amplifier; and
the gain controller is configured to selectively adjust the amount of attenuation provided by the adjustable attenuator based on the commands.
16. The communication network of claim 15 , wherein the adjustable attenuator is configured to adjust the signals to a desired voltage level of about 3V.
17. The communication network of claim 16 , wherein the first and second voltage clamps are configured to limit the signals to a maximum of about 5V.
18. The communication network of claim 17 , wherein the second attenuator is a passive attenuator configured to attenuate all signals by about ⅓ to ½.
19. The communication network of claim 12 , wherein the second and fourth attenuators are configured to isolate the first and second voltage clamps, the at least a first attenuator, the at least a third attenuator, the first communications processor, and the second communications processor from outgoing signals.
20. A train consist, comprising:
a first locomotive;
a second locomotive;
a tender car;
a first access point located on the first locomotive and being configured to control operations of the first locomotive;
a second access point located on one of the second locomotive and the tender car and being configured to control operations of the one of the second locomotive and the tender car; and
a cable connecting the first and second access points to communicate signals associated with coordinated control over operations of the first locomotive, the tender car, and/or the second locomotive,
wherein each of the first and second access points includes:
a communications processor configured to receive signals;
an analog front end amplifier located to receive and selectively attenuate the signals before the signals are received by the communications processor;
an adjustable attenuator located to receive and selectively attenuate the signals to about 3V before the signals are received by the analog front end amplifier;
a gain controller configured to affect adjustment of the adjustable attenuator;
a voltage clamp configured to selectively limit a strength of the signals to about 5V before the signals are received by the adjustable attenuator; and
a passive attenuator configured to attenuate all signals by about ⅓ to ½ before the signals are received by the voltage clamp.