System and method for detecting a device requiring power
View Patent ↗A system and technique for detecting a device that requires power is implemented with a power detection station. The power detection system includes a detector having an output and a return which are coupled together by the device when the device requires power. The detector includes a word generator for generating test pulses for transmission to the device via the detector output, and a comparator for comparing the detector output with the detector return. The power detection station has a wide variety of applications, including by way of example, a switch or hub.
1. A detecting station having an output and a return coupled to a two-way transmission line, comprising:
a word generator operable to generate a test word that is transniitted on the detection station output;
a comparator to compare the detecting station output with the detecting station return; and
a controller operable to determine whether a device requiring power is coupled to the transmission line based on the comparison;
wherein the test word comprises an address of the controller.
2. The detecting station of claim 1 wherein the word generator comprises a free running timer.
3. The detecting station of claim 1 further comprising a pulse shaping device coupled between the word generator and the detecting station output.
4. The detecting station of claim 3 wherein the pulse shaping device is progranirnaNe by the controller.
5. A detector having an output and a return coupled to a two-way transmission line, comprising:
a word generator operable to generate a test word that is transmitted on the detector output;
a register coupled between the word generator and the detector output and operable to latch a word generator output in response to a trigger;
a timer enabled by the trigger for a predetermined time thereafter;
a comparator operable to compare the detector output with the detector return, the comparator being enabled only while the timer is enabled; and
a controller operable to determine whether a device requiring power is coupled to the transmission line based on the comparison.
6. The detector of claim 5 wherein the word generator comprises a free running timer.
7. The detector of claim 5 further comprising a pulse shaping device coupled between the word generator and the detector output.
8. The detector of claim 7 wherein the pulse shaping device is programmable.
9. The detector of claim 8 wherein the pulse shaping device is programmed to output a first pulse having a first pulse width and a second pulse having a second pulse width different from the first pulse width.