in the following detailed description , reference is made to the accompanying drawings , which form a part hereof and show by way of illustration specific embodiments in which embodiments of the present invention may be practiced . these embodiments are described in sufficient detail to enable those skilled in the art to practice them , and it is to be understood that other embodiments may be utilized , and that structural , logical , processing , and electrical changes may be made . the progression of processing steps described is an example ; however , the sequence of steps is not limited to that set forth herein and may be changed as is known in the art , with the exception of steps necessarily occurring in a certain order . now referring to the figures , where like numerals designate like elements , fig1 is a schematic diagram of a bpl system 100 constructed in accordance with an embodiment described herein . bpl system 100 includes first , second , and third utility poles 105 , 110 , 115 ; a medium - voltage power line 120 ; a low - voltage power line 121 ; first , second , and third bpl regenerators 125 , 130 , 135 ; and a customer site 140 connected to the low - voltage power line 121 near the second regenerator 130 for receiving the broadband signal . first through sixth bpl couplers 145 - 150 are connected between the bpl regenerators 125 , 130 , 135 and the medium - voltage power line 120 . bpl system 100 further includes components 160 , 165 , 170 , 175 , which can be any other typical components found in a power grid and connected to any part of the grid , e . g ., transformers , arresters , reclosers , and taps . each utility pole 105 , 110 , 115 connected to a respective regenerator 125 , 130 , 135 is a node a , b , c . each node has two couplers 145 - 150 connected to it , one for receiving the bpl signal at a first frequency , and the other for transmitting the bpl signal at a second frequency . it should be noted that every utility pole in a power grid may not have a bpl regenerator . the medium - voltage power line 120 may be a single - phase or multi - phase power line , such as a three - phase power line . fig2 is a block diagram of an apparatus 200 for measuring voltage or voltage phase angle on a power line constructed in accordance with an embodiment described herein . apparatus 200 includes a first load 210 having a first predetermined impedance z 1 . apparatus 200 further includes a second load 220 having a second predetermined impedance z 2 . the first and second loads 210 , 220 are connected to each other at node d . the apparatus 200 is connected between the medium - voltage power line 120 and neutral wire 121 , and forms a voltage divider at node d . the neutral wire 121 may also be a ground wire . the phase angle can be measured at the node d of the voltage divider . the voltage v m at the medium - voltage power line 120 can be calculated according to : where v m is the voltage at the medium - voltage power line , v d is the voltage measured across the second load 220 at node d , and z 1 and z 2 are the respective impedances of the first and second loads 210 , 220 . fig3 illustrates a further embodiment of an apparatus 300 for measuring voltage and voltage phase angle on a power line in a bpl system constructed in accordance with an embodiment described herein . the apparatus includes a voltage divider built into one of the bpl couplers 145 - 150 , the coupler being represented in this case by capacitor - based bpl coupler 301 . the first load 310 is the predetermined native capacitance of the capacitor - based bpl coupler 301 . the second load 320 may be a resistor or other resistive device . the second load 320 is built into the bpl coupler 301 . the apparatus 300 forms a voltage divider at node d . the apparatus 300 is connected between the medium - voltage power line 120 and the low - voltage power line 121 . the voltage v m at the medium - voltage power line 120 can be calculated according to : where v m is the voltage at the medium - voltage power line , v d is the voltage measured across the second load 320 at node d , z c is the capacitance 310 of the capacitor - based bpl coupler 301 , and z 2 is the impedance of the second load 320 . another exemplary method of measuring the phase angle of a medium - voltage power line 120 is to isolate a 60 hz frequency from the rf bpl signal and measure the 60 hz frequency . adding a shift capacitor to the sensor shifts the voltage phase angles by 90 °, which should be taken into account when comparing phase angles from multiple medium - voltage power lines . a shift resistor may also be used in place of the shift capacitor ; however it may increase the capacitance , and this affects the rf bpl signal . fig4 illustrates a schematic diagram of a system 400 for measuring voltage phase angle on a bpl system on a multi - phase power line . medium - voltage power lines 422 , 423 , 424 each have an apparatus 401 , 402 , 403 for measuring their respective phase angles , consistent with an embodiment of the present invention . ideally , the phase angles of each phase in the multi - phase power line system are equal . the respective phase angles of the medium - voltage power lines 422 , 423 , 424 are then communicated to a phase angle comparing device 450 . phase angle comparing device 450 may be a processor configured to receive phase angle measurements , or a circuit configured to receive values ( such as voltages ) representing the detected phase angles , and output another value ( such as another voltage ) representing a difference between the detected phase angles . it should be understood that several methods of comparing measured phase angles are known in the art , and the phase angle comparing device 450 is not limited to the above - described embodiments . the respective phase angles are compared to each other , and if they are not equal , or not within a predetermined tolerance , correction may be required . the voltage phase angles and the comparison results may be reported automatically to a remote location ( not shown ) such as a power station or office , for instance by a data collection device ( not shown ). the result may be the comparison alone or a warning that correction is needed . in both fig2 and 3 , the power on the medium - voltage power line 120 can also be calculated according to : where p is the power , v m is the voltage at the medium - voltage power line , and i is a current measured at the medium - voltage power line 120 . the determined voltage and voltage phase angle at the medium - voltage power line v m and power p may be reported automatically to a remote location such as a power station or office , for instance by a data collection device . the processes and devices in the above description and drawings illustrate examples of methods and devices of many that could be used and produced to achieve the objects , features , and advantages of embodiments described herein . for example , embodiments include receiving and transmitting the same signal frequency at each node a - c while still avoiding interference . thus , the embodiments are not to be seen as limited by the foregoing description of the embodiments , but only limited by the appended claims .