Methods and equipment for reducing power loss in cellular systems
Methods of powering a radio that is mounted on a tower of a cellular base station are provided in which a direct current (“DC”) power signal is provided to the radio over a power cable and a voltage level of the output of the power supply is adjusted so as to provide a substantially constant voltage at a first end of the power cable that is remote from the power supply. Related cellular base stations and programmable power supplies are also provided.
1. A method of powering a radio, the method comprising:
obtaining a resistance of power conductors between a power supply and the radio;
outputting a direct current (DC) power signal from the power supply and supplying the DC power signal that is output from the power supply to the radio over the power conductors;
measuring a current level of the DC power signal; and
automatically adjusting a voltage level of the DC power signal in response to changes in the measured current level of the DC power signal, wherein the voltage level of the DC power signal that is output from the power supply is adjusted so that a voltage, of the DC power signal at radio ends of the power conductors adjacent the radio, is maintained within a predetermined margin and below a maximum voltage of the radio notwithstanding variation in the current level of the DC power signal that is output from the power supply.
2. The method of claim 1 , wherein obtaining the resistance of the power conductors comprises receiving a feedback signal from a voltage sensor located at the radio ends of the power conductors.
3. The method of claim 2 , wherein the feedback signal comprises a voltage level that is measured at the radio ends of the power conductors.
4. The method of claim 1 , wherein obtaining the resistance of the power conductors comprises transmitting at least two alternating current (AC) power signals having different frequencies over the power conductors and measuring an amplitude and phase shift of each of the at least two AC power signals at the radio ends of the power conductors.
5. The method of claim 1 , wherein obtaining the resistance of the power conductors comprises transmitting at least two DC power signals having different voltages over the power conductors and measuring a current of each of the at least two DC power signals at the power supply.
6. The method of claim 1 , wherein obtaining the resistance of the power conductors comprises measuring an impedance of the power conductors.
7. The method of claim 1 , wherein the predetermined margin is a substantially constant voltage.
8. The method of claim 1 , wherein the resistance is determined at periodic intervals.
9. A power system comprising:
a power supply configured to automatically adjust a voltage level of a direct current (DC) power signal output by the power supply in response to changes in a measured current level of the DC power signal, wherein the voltage level of the DC power signal that is output from the power supply is adjusted so that a voltage, of the DC power signal at radio ends of power conductors between the power supply and a radio, is maintained within a predetermined margin and below a maximum input voltage of the radio notwithstanding variation in the measured current level of the DC power signal that is output from the power supply.
10. The power system of claim 9 , further comprising a shunt capacitance unit provided between first and second conductors of the power conductors and configured to dampen increases in voltage that result from changes in current drawn by the radio.
11. The power system of claim 10 , wherein the shunt capacitance unit comprises two or more capacitors coupled in series between the first and second conductors of the power conductors.
12. The power system of claim 10 , wherein the shunt capacitance unit provided between the first and second conductors of the power conductors is configured to dampen increases in voltage where a dampened, increased voltage does not exceed the maximum input voltage of the radio.
13. The power system of claim 10 , wherein the power conductors comprise a trunk cable and a jumper cable, and wherein the shunt capacitance unit is provided in the jumper cable.
14. The power system of claim 9 , wherein the power supply further comprises a resistance measurement circuit configured to determine a resistance of the power conductors.
15. The power system of claim 14 , wherein the resistance measurement circuit is configured to determine the resistance of the power conductors based on current measurements of at least two DC power signals having different voltages transmitted over the power conductors.
16. The power system of claim 15 , wherein the resistance measurement circuit is configured to determine the resistance of the power conductors based on a measured impedance of the power conductors.
17. A power system comprising:
a power supply configured to automatically adjust a voltage level of a direct current (DC) power signal output by the power supply in response to changes in a measured current level of the DC power signal, wherein the voltage level of the DC power signal that is output from the power supply is adjusted so that a voltage, of the DC power signal at a radio ends of power conductors between the power supply and a radio, is maintained within a predetermined margin and below a maximum input voltage of the radio notwithstanding variation in the measured current level of the DC power signal that is output from the power supply; and
a voltage sensor located at the radio ends of the power conductors and configured to provide a feedback signal to the power supply.
18. The power system of claim 17 , wherein the feedback signal comprises a voltage that is measured at the radio ends of the power conductors.
19. The power system of claim 17 , wherein the predetermined margin is a substantially constant voltage.
20. The power system of claim 17 , further comprising a shunt capacitance unit provided between first and second conductors of the power conductors and configured to dampen increases in voltage that result from changes in current drawn by the radio.
21. The method of claim 1 , wherein a voltage level at the radio ends of the power conductors exceeds a nominal DC voltage level of the radio.
22. The method of claim 21 , wherein the voltage level at the radio ends of the power conductors is within four volts of a maximum DC voltage level of the radio.
23. The power system of claim 9 , wherein the voltage at the radio ends of the power conductors exceeds a nominal DC voltage level of the radio.
24. The power system of claim 23 , wherein the voltage at the radio ends of the power conductors is within four volts of a maximum DC voltage level of the radio.
25. The power system of claim 17 , wherein the voltage at the radio ends of the power conductors exceeds a nominal DC voltage level of the radio.
26. The power system of claim 25 , wherein the voltage at the radio ends is within four volts of a maximum DC voltage level of the radio.