Abstract:
A remote radio frequency (RF) power sensing unit includes a first module and a second module. The first module may be configured to generate an analog signal representative of a power level of a radio frequency (RF) signal. The second module may be configured to (i) receive a particular frequency of a plurality of frequencies over a wireless communication channel from a device, (ii) generate a value conveying a magnitude of said power level of said RF signal in response to said analog signal, (iii) convert said value into a digital signal communicating said power level based on said particular frequency indexed into a table, and (iv) transmit said digital signal communicating said power level and information identifying said radio frequency power sensing unit over said wireless communication channel to said device.

Description:
[0001]    This application relates to U.S. Ser. No. 15/137,482, filed Apr. 25, 2016, and U.S. Ser. No. 13/310,000, filed Dec. 2, 2011, now U.S. Pat. No. 9,347,796, issued May 25, 2016, each of which are incorporated by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to the test and measurement field generally and, more particularly, to a method and/or architecture for a wireless remote sensing power meter. 
       BACKGROUND OF THE INVENTION 
       [0003]    Power meters are used by maintenance engineers employed by major telecommunications companies. The current instrumentation market is mainly populated by stationary power meters designed for laboratory countertops, as well as portable power meters that tend to be rather large and bulky. Neither of these options proves to be convenient or practical for outdoor use by installation and maintenance engineers. 
         [0004]    It would be desirable to implement a system that allows remote placement of monitors for measurement of power using a handheld device and that matches the level of accuracy of a countertop meter, but without being physically connected to the monitor. 
       SUMMARY OF THE INVENTION 
       [0005]    The invention concerns a remote radio frequency (RF) power sensing unit including a first module and a second module. The first module may be configured to generate an analog signal representative of a power level of a radio frequency (RF) signal. The second module may be configured to (i) receive a particular frequency of a plurality of frequencies over a wireless communication channel from a device, (ii) generate a value conveying a magnitude of said power level of said RF signal in response to said analog signal, (iii) convert said value into a digital signal communicating said power level based on said particular frequency indexed into a table, and (iv) transmit said digital signal communicating said power level and information identifying said radio frequency power sensing unit over said wireless communication channel to said device. 
         [0006]    The objects, features and advantages of the invention include providing a wireless remote sensing power meter that may (i) allow remotely monitoring devices wirelessly, (ii) allow remotely controlling devices wirelessly, (iii) include GPS capability, (iv) allow taking measurements from multiple locations, (v) be easily updated as needed, (vi) allow monitoring of distribution networks from a single (or central) location, and/or (vii) provide separate sensor and reader units. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These and other objects, features and advantages of the invention will be apparent from the following detailed description and the appended claims and drawings in which: 
           [0008]      FIG. 1  is a diagram illustrating an example of a system in accordance with an example embodiment of the invention; 
           [0009]      FIG. 2  is a diagram illustrating an example operation of a sensor in accordance with an embodiment of the invention; 
           [0010]      FIG. 3  is a diagram illustrating an example implementation of a sensor of  FIG. 1 ; 
           [0011]      FIG. 4  is a diagram illustrating an example RF detector module of  FIG. 3 ; 
           [0012]      FIG. 5  is a diagram illustrating an example substrate attenuator and associated components of  FIG. 4 ; 
           [0013]      FIG. 6  is a diagram illustrating an example implementation of a application specific integrated circuit of  FIG. 3 ; 
           [0014]      FIG. 7  is a diagram illustrating another example implementation of a sensor module of  FIG. 1 ; 
           [0015]      FIG. 8  is a diagram illustrating a bottom surface of a printed circuit board of  FIG. 7 ; 
           [0016]      FIG. 9  is a diagram illustrating an example implementation of the sensor module of  FIG. 7  in accordance with an embodiment of the invention; 
           [0017]      FIG. 10  is a diagram illustrating an example look up table in accordance with an embodiment of the invention; 
           [0018]      FIG. 11  is a graph illustrating example power transfer curves for the RF detector of  FIG. 4 ; 
           [0019]      FIG. 12  is a diagram illustrating a carrying case for components of a system in accordance with an embodiment of the invention; 
           [0020]      FIG. 13  is a flow diagram illustrating an example process in accordance with an embodiment of the invention; 
           [0021]      FIG. 14  is a diagram illustrating a remote power sensing system in accordance with an example embodiment of the invention; and 
           [0022]      FIG. 15  is a diagram illustrating a CATV distribution system in accordance with an example embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    Referring to  FIG. 1 , a diagram is shown illustrating a system  100  in accordance with a preferred embodiment of the present invention. In one example, the system  100  may include a portable power meter comprising handheld reader and remote sensor units that use wireless technology to transmit measurement data from one unit to the other. Instead of building a read-out display into a main power head which contributes to the bulk of conventional portable power meters, the power meter, in accordance with an embodiment of the present invention, is split up into the remote sensor (or power head) unit and the handheld reader (or display) unit that communicate using a wireless protocol (e.g., Bluetooth®, WLAN, ZigBee®, etc.). Both components may be stored in and kept constantly charged by a carrying case that contains an internal rechargeable battery (described below in connection with  FIG. 12 ). The power meter implemented in accordance with an embodiment of the present invention may achieve the same level of accuracy of conventional countertop models. The accuracy and portability of the system  100  generally guarantee ease-of-use, for example, in a laboratory setting or atop a radio tower. 
         [0024]    In one example, the system  100  may comprise one or more handheld units  102   a - 102   n  and one or more remote sensor units (or monitors)  104   a - 104   n . In one example, a handheld unit  102   a  may be implemented as a dedicated reader. In another example, handheld units  102   b , . . . ,  102   n  may be implemented as a personal computing device (e.g., cellular telephone, smart phone, tablet, PDA, etc.) configured through software (e.g., an application program or “APP”) to perform as a reader. In an example, the handheld units  102   a - 102   n  may include, but are not limited to Android® and/or iPhone® devices. 
         [0025]    In one example, the remote sensor units  104   a - 104   n  may be configured for connection to various types of communication equipment. For example, one or more of the remote sensor units  104   a - 104   n  may be implemented with a type “N” male adapter  106 . In another example, one or more of the remote sensor units  104   a - 104   n  may be implemented with a type SMA female adapter  108 . However, any other appropriate adapters for connecting to a particular system to be monitored may be implemented accordingly to meet the design criteria of a particular implementation. The remote sensor units  104   a - 104   n  are generally implemented as self-contained, calibrated sensor/processor/wireless transceiver modules. 
         [0026]    In one example, the handheld unit  102   a  may comprise a display  110  and a number of controls (e.g., switches, buttons, etc.)  112 - 120 . In one example, the control  112  may be centered beneath the display  110 . In one example, the control  112  may be configured as a power button. In another example, the control  112  may be configured to initiate a read operation. However, other functions may be implemented to meet the design criteria of a particular implementation. The controls  114  and  116  may be placed adjacent to one another and configured to provide complementary actions (e.g., scroll up, scroll down, etc.). The controls  118  and  120  may also be located adjacent to one another and similarly assigned complementary functions (e.g., scroll left, scroll right, etc.). The controls  114 - 120  may also be configured for selecting remote sensor units to be read by the handheld unit  102   a . In another example, the display  110  and controls  112 - 120  may also be realized as areas of a touch screen  122  of the devices  102   b - 102   n.    
         [0027]    The system  100  may implement a wireless interface between the remote sensor units  104   a - 104   n  and the handheld (or display) units  102   a - 102   n . The remote sensor units  104   a - 104   n  may be configured to transmit to any receiver compliant with the wireless protocol implemented by the sensor units. In one example, each remote sensor unit  104   a - 104   n  may have an individual MAC ID that may be used to identify the source of power readings and provide secure communications. In one example, the handheld units  102   a - 102   n  may be configured to maintain communications with multiple sensor units. For example, the controls on the handheld units  102   a - 102   n  may be used to switch between multiple remote sensor units. 
         [0028]    In one example, the handheld units  102   a - 102   n  may be configured to scan and pair to any available remote sensor units  104   a - 104   n . Pairing to the remote sensor units  104   a - 104   n  may be performed one sensor at a time. In one example, the handheld units  102   a - 102   n  may be configured to display only a predetermined number of nearer remote sensor units. The remote sensor units  104   a - 104   n  may incorporate, in one example, a GPS (global positioning system) puck to provide location and time reference information (e.g., useful in cloud monitoring). In one example, the handheld units  102   a - 102   n  may be configured to display readings in alphanumeric format. However, other formats (e.g., graphic, oscilloscope, etc.) may be implemented to meet the design criteria of a particular implementation. 
         [0029]    In one example, the remote sensor units  104   a - 104   n  may be calibrated using a 50 MHz power reference. Each of the remote sensor units  104   a - 104   n  generally stores a respective calibration table in non-volatile memory (e.g., Flash, EEPROM, etc.). Each of the remote sensor units  104   a - 104   n  may be re-calibrated and the table updated as needed (e.g., yearly, after repair due to damage, etc.). A threshold may be implemented for each of the remote sensor units  104   a - 104   n  to monitor a condition (e.g., impedance) of an integrated RF (radio frequency) detector (e.g., diode). Each of the remote sensor units  104   a - 104   n  may be configured to recommend re-calibration based on the threshold. 
         [0030]    The system  100  may have many applications, including but not limited to testing cellular infrastructure equipment and WLAN (wireless local area network) devices, and allowing for the easy installation and maintenance of business communication systems. For example, the remote sensor units  104   a - 104   n  may be connected to the communication systems in hard to reach areas (e.g., on a cell tower, in a closed cabinet, etc.). The readings may be taken remotely (e.g., on the ground, outside the cabinet, at a central location, etc.) from the remote sensors  104   a - 104   n  using one of the handheld units  102   a - 102   n.    
         [0031]    Referring to  FIG. 2 , a diagram is shown illustrating an example operation of the system  100 . In one example, a remote sensor unit  104   i  may comprise a block (or circuit)  150 , a block (or circuit)  152 , a block (or circuit)  154 , a block (or circuit)  156 , a block (or circuit)  158 , a block (or circuit)  160 , and a block (or circuit)  162 . The block  150  may be implemented as a peak detector. The block  152  may be implemented as a diode device. The block  154  may be implemented as an analog-to-digital converter (ADC). The block  156  may be implemented as a processor. The block  158  may be implemented as a temperature module. The block  160  may be implemented as a memory. The block  162  may be implemented as a transceiver (TX/RX) module. In one example, the blocks  150 - 154  may be implemented as a first (analog) module and the blocks  156 - 162  may be implemented as a second (digital) module. The blocks  150 - 162  may be connected using conventional techniques. 
         [0032]    In one example, a microwave or millimeter wave (GHz) signal  180  may be sent through the remote sensor unit  104   i . The microwave signal  180  may initially be passed through the peak detector  150 . An output of the peak detector  150  generally presents a signal representing the high frequency peak power (W) of the microwave signal  180 . The output of the peak detector  150  may be presented to a first terminal (or input) of the diode device  152 . A second terminal (or output) of the diode device  152  may present a signal to the analog-to-digital converter  154 . The analog-to-digital converter  154  may convert the output of the diode device  152  to the digital domain so that the processor  156  may transmit information (e.g., power level, etc.) regarding the digitized microwave signal via a wireless link  190  to the handheld display unit  102 , a central office  192  or some other device (e.g., cloud resources), where a user may read the information (e.g., power measurement, etc.). In an example, the handheld unit  102  may allow the user to take local readings to check remote readings (e.g., at the central office, cloud, etc.) for interference. 
         [0033]    The processor  156  is generally configured (e.g., through software, firmware, microcode, hardwiring, etc.) to generate the information regarding the digitized microwave signal. In one example, the processor  156  may generate the information using, for example, data for temperature compensation from the temperature module  158  and conversion (or calibration) tables stored in the memory  160 . The information regarding the digitized microwave signal may be transmitted via the wireless link  190  to the handheld unit  102  or central office (facility)  192  using the transceiver module  162 . In one example, the memory  160  may be configured to store a three-dimensional lookup table containing calibration information for the particular remote sensor (or power head) unit  104   i . The information (e.g, tables) in the memory  160  and/or software, firmware etc. of the processor  156  may be updated (programmed) via the wireless link  190 . 
         [0034]    Referring to  FIG. 3 , a diagram of remote sensor unit  104  is shown illustrating an example implementation of a remote sensor unit of  FIG. 1 . In one example, the remote sensor unit may comprise an RF detector module  200  and a signal processing module  202 . An output of the RF detector module  200  may be connected to the signal processing module  202  using conventional techniques (e.g., soldering, a connector, surface mounting, etc.). The RF signal to be measured may be presented to the RF detector  200  through a connector attached to an input of the RF detector module  200 . 
         [0035]    In an example, the signal processing module  202  may comprise a block (or circuit)  204 , a block (or circuit)  206 , and a block (or circuit)  208 . The circuit  204  may implement an amplifier (e.g., a video amplifier). In an example, the amplifier  204  may include auto ranging. The circuit  206  may be implemented, in an example, as an application specific integrated circuit (ASIC). In various embodiments, the circuit  206  may be implemented including an IEEE 802.15.4/ZigBee® planar inverted F antenna (PIFA) module. However, other signal processing and wireless transceiver modules may be implemented accordingly to meet the design criteria of a particular implementation. In one example, the circuit  206  may be implemented using an MD100A ZigBee® PIFA module available from Aveslink Technology, Inc. of San Jose, Calif. The circuit  208  may implement an extended memory for the circuit  206 . The signal processing module  202  may also include a USB connector (not shown), which may be used to communicate with the circuit  206  and/or charge batteries associated with the remote sensor  104 . 
         [0036]    Referring to  FIG. 4 , a diagram is shown illustrating a circuit diagram (a), a top view (b), and a side view (c) of an example implementation of the RF detector module  200  of  FIG. 3 . In an example, a zero bias Schottky diode detector (e.g., part number EZM0126PM1 manufactured by Eclipse Microwave of San Jose, Calif.) may be used to implement the RF detector module  200 . In an example, the RF detector module  200  may comprise an input pin (or lead)  210 , an output pin (or lead)  212 , a match attenuator  214 , and a capacitor  216 . The pin  210  may be connected to an input of the match attenuator  214  using, in one example, a gold mesh. An output of the match attenuator  214  may be connected to a first terminal of the capacitor  216  using, in one example, a 0.7 mil gold wire. A second terminal of the capacitor  216  may be connected to the output pin  212  using, in one example, a 0.7 mil gold wire. The wire between the second terminal of the capacitor  216  and the output pin  212  may be held in place using a non-conductive epoxy stake  218 . 
         [0037]    In one example, a detector circuit of RF detector module  200  may comprise a first resistor (R 1 ), a second resistor (R 2 ), a third resistor (R 3 ), a first capacitor (C 1 ), a second capacitor (C 2 ), and the zero bias Schottky diode (D 1 ). The components may be implemented as part of the match attenuator  214 . In another example, an optional second diode (D 2 ) and third capacitor (C 3 ) may also be implemented. In an example, an anode of the diode D 2  may be connected to a cathode of the diode D 1 . 
         [0038]    Referring to  FIG. 5 , a diagram of the match attenuator  214  of  FIG. 4  is shown illustrating an example implementation. In one example, the match attenuator  214  may comprise a substrate attenuator and associated components implementing the detector circuit of  FIG. 4 . In one example, the substrate attenuator may be implemented comprising a first metal portion  220 , a second metal portion  222 , a third metal portion  224 , a fourth metal portion  226 , and a fifth metal portion  228 . The metal portions  220  and  222  may be connect to a second substrate (e.g., a ground plane) using plated-through vias  230  and  232 , respectively. The metal portion  224  may be connected to the metal portion  220  (e.g., through a resistor R 4  and a 0.7 mil gold wire). The metal portion  224  may also be connected to the metal portion  222  (e.g., through a resistor R 5  and a 0.7 mil gold wire). The metal portion  224  may be further connected to the metal portion  226  (e.g., through a capacitor  240  and a gold wire mesh). The metal portion  226  may also be connected to (i) the metal portion  220  (e.g., through a resistor R 6  and a 0.7 mil gold wire), (ii) the metal portion  222  (e.g., through a resistor R 7  and a 0.7 mil gold wire), and (iii) the metal portion  228  (e.g., through a resistor R 8 ). The metal portion  228  may be connected to the metal portion  222  (e.g., through a diode D 1  and a capacitor  242 ). 
         [0039]    In one example, the capacitor  240  may be implemented as a 100 pf surface mount capacitor. In one example, the capacitor  242  may be implemented as a 470 pf surface mount capacitor. The resistors R 4 , R 5 , R 6 , and R 7  may be implemented, in one example, as 100 ohm, 5% tolerance surface mount resistors. The resistor R 8  may be implemented, in one example, as a 50 ohm, 5% tolerance surface mount resistor. The resistors R 4  and R 5  generally correspond with the resistor R 1  of  FIG. 4 . The resistors R 6  and R 7  generally correspond to the resistor R 2  of  FIG. 4 . The resistor R 8  generally corresponds to the resistor R 3  of  FIG. 4 . The capacitors  240  and  242  generally correspond to the capacitors C 1  and C 2 , respectively, of  FIG. 4 . In one example, the substrate attenuator may be formed on a 0.015 inch thick polished alumina substrate comprising 99.6% Al 2 O 3 . In one example, the substrate attenuator may have a finish of 250±50 angstroms TiW and 100UIN type Gold on both sides. 
         [0040]    Referring to  FIG. 6 , a diagram is shown illustrating an example implementation of the module  206  of  FIG. 3 . In one example, the module  206  may comprise a circuit (or module)  250  and a circuit (or module)  252 . The circuit  250  may be implemented, in one example, as a processing module. In one example, the circuit  250  may be implemented using a JN5139 chip available from Aveslink Technology, Inc. of San Jose, Calif. The circuit  252  may be implemented, in one example, as a serial flash memory. The module  250  may also include a crystal  254  and PIFA module  256 . Optionally, the PIFA module  256  may be replaced with an interface to an external antenna. In one example, the optional interface may comprise a connector and a balun. In another example, the interface may also include a power amplifier (PA) and/or low noise amplifier (LNA). 
         [0041]    In one example, the circuit  250  may comprise a processor (e.g., a RISC CPU), memory (e.g., random access memory (RAM), read only memory (ROM), etc.), a radio transceiver (e.g., 2.4 GHz), a modem (e.g., O-QPSK, etc.), an IEEE 802.15.4 MAC accelerator, an encryption accelerator (e.g., 128-bit AES, etc.), a serial peripheral interface (SPI), a vector network analyzer, and a 2-wire serial interface (e.g., USB). The circuit  250  may also comprise one or more timers, one or more universal asynchronous receiver transmitters (UARTs), one or more 12-bit analog-to-digital converters (ADCs) and comparators, one or more 11-bit digital-to-analog converters (DACs), and a temperature sensor. The components of the circuit  250  may be connected by one or more busses. The circuit  250  may also comprise power management circuitry. 
         [0042]    Referring to  FIG. 7 , a diagram is shown illustrating another example implementation of a sensor module of  FIG. 1 . In one example, the sensor module  104  may comprise a circuit (or module)  260 . In an example, the circuit  260  may be implement on a double sided printed circuit board (PCB). In an example embodiment, the circuit  260  may comprise a circuit (or module)  261 , a circuit (or module)  263 , a circuit (or module)  265 , a USB connector  267 , and a power indicator (e.g., a light emitting diode)  269 . The circuit  251  may be implemented, in one example, as a microprocessor or microcontroller chip. The circuit  263  may be implemented, in one example, with an IEEE 802.15.4/ZigBee® planar inverted F antenna (PIFA) module. In another example, the circuit  263  may be implemented using an MD100A ZigBee PIFA module available from Aveslink Technology, Inc. of San Jose, Calif. However, other signal processing and wireless transceiver modules may be implemented accordingly to meet the design criteria of a particular implementation. 
         [0043]    The circuit  265  may implement a removable media socket. In an example, the circuit  265  may be configured to allow the circuit  260  to use a removable memory card (e.g., a micro SD card, etc.) as extended memory. The USB connector  267  may be used to communicate with the circuit  260  and/or charge batteries associated with the remote sensor  104 . The indicator  269  may be configured to provide a visual indication whether the remote sensor module  104  is turned on, turned off, charged, and/or charging. 
         [0044]    Referring to  FIG. 8 , a diagram is shown illustrating an example implementation of a bottom surface of the circuit board  260  of  FIG. 7 . In an example, the bottom surface of the circuit board  260  may provide connections for a block (or circuit)  262  and a block (or circuit)  264 . The circuit  262  may implement an impedance bridge. The circuit  264  may implement a signal generator and/or reference source. In an example, the circuit  264  may implement a 50 MHz 1 milliwatt calibrated reference source. 
         [0045]    The circuit  264  may be used to determine whether the power sensor module  104  is still operating within a desired accuracy. When power sensors are calibrated, the calibration is performed against a particular reference source. The check is not of the diode itself, but instead makes sure the diode is detecting the correct power level. The industry typically calibrates to a 1 milliwatt, 50 MHz source provided by the National Bureau of Standards. In an example, the circuit  264  may be configured (calibrated) to generate a 50 MHz, 1 milliwatt signal similar to the National Bureau of Standards signal. The signal generated by the circuit  264  may be utilized to check for drift in the power measurements performed by the circuit  260  using the diode detector  200 . The circuit  264  may be calibrated prior to the sensor  104  being placed out in the field. 
         [0046]    Referring to  FIG. 9 , a diagram is shown illustrating an example implementation of the sensor module of  FIG. 7  in accordance with an embodiment of the invention. In an example, the circuit (or module)  260  may comprise a block (or circuit)  261 , a block (or circuit)  263 , a block (or circuit)  270 , a block (or circuit)  271 , a block (or circuit)  272 , a block (or circuit)  273 , a block (or circuit)  274 , a block (or circuit)  275 , a block (or circuit)  276 , a block (or circuit)  278 , a block (or circuit)  279 , a block (or circuit)  280 , a block (or circuit)  281 , and a block (or circuit)  282 . An input of the circuit  260  may be coupled to an output of the RF detector  200 . The circuit  260  also may be connected to the removable media socket  265 . The removable media socket  265  may allow the circuit  260  to use a removable memory card (e.g., micro SD, etc.) as an extended memory. 
         [0047]    The circuit  261  may be implemented as a processor. The circuit  263  may be implemented as a Bluetooth circuit. In one example, the circuit  263  may be implemented using an MD100A ZigBee® PIFA module available from Aveslink Technology, Inc. of San Jose, Calif. However, other signal processing and wireless transceiver modules may be implemented accordingly to meet the design criteria of a particular implementation. The circuit  270  may be implemented as one or more low noise precision amplifiers. The output of the RF detector  200  is generally presented to an input of the circuit  270 . The circuit  271  may implement a temperature compensation circuit. In an example, the circuit  271  may be configured to provide temperature compensation for the low noise amplifiers (LNAs) of the circuit  270 . 
         [0048]    The circuits  272  and  273  may be implemented as analog-to-digital converter (ADC) circuits. The circuit  274  may implement a solid state random access memory (e.g., SRAM). The circuit  275  may implement a nonvolatile memory (e.g., Flash, etc.). The circuit  275  may be configured to store firmware (e.g., instruction code executed by and controlling operation of the processor  261 ) and/or calibration tables. The circuit  276  may implement a self check circuit. The circuit  278  may implement a serial memory interface circuit. The circuit  278  may be configured to connect to the removable media slot  265  to the processor  261 . The circuit  278  also may be configured to provide power to the removable media slot  265 . 
         [0049]    The circuit  279  may implement a universal serial bus (e.g., USB 2.0, etc.) interface circuit. The circuit  279  may connect signals to and from the processor  261  from and to the USB connector  267 . The circuit  280  may implement a power supply control circuit. The power supply control circuit  280  may provide power supplied by a rechargeable battery to various modules of the sensor unit  104 . The circuit  280  may also be configured to charge the battery when an external power supply is available (e.g., via the USB connector). The circuit  281  may implement a buck/boost power supply circuit. The circuit  282  may implement a shake detector. The various blocks in the circuit  260  may be connected together by various traces, buses and/or protocols. 
         [0050]    Referring to  FIG. 10 , a diagram of a table  290  is shown illustrating an example power lookup table (LUT) in accordance with an embodiment of the present invention. In one example, the table  290  may comprise a number of frequency data points F 0 , . . . , FN, a number of voltage data points V 0 , . . . , VN for each frequency F 0 , . . . FN, and a number of power data points P 0 , . . . , PN for each frequency F 0 , . . . , FN. The table  290  may be configured to relate a voltage reading to a respective power reading for every frequency Fi. The size of the table  290  is generally only limited by the amount of memory (e.g., Flash, etc.) available. 
         [0051]    Referring to  FIG. 11 , a graph  300  is shown illustrating example power transfer curves  302 . In an example, the processor  156  of  FIG. 2  may be configured to generate additional data values using the table stored in the remote sensor unit. For example, if a measurement from the ADC  154  falls between two frequency data points, the processor  156  may be configured to determined the correct frequency using, for example, straight-line interpolation or extrapolation. Similarly, if a voltage measurement falls between two points in the power table, the processor may be configured to take a slope of a corresponding one of the power transfer curves  302  to calculate the correct power measurement. Thus, the processor  156  may create a pseudo table for in-between frequencies based on the table stored in the remote sensor unit (e.g., in the memory  160 ). The power transfer curves  302  for the diode device are generally very predictable, so a lot of points are not necessary. In one example, 40 points may be used to calibrate the remote sensor unit  104   i  (e.g., 1 dB steps from −30 to +10 dBm). In one example, the points may be calculated using one of the curves  302  and the following equations: 
         [0000]        P 2− P 1=10 log [ V 2/ V 1],below −17 dBm;
 
         [0000]    and 18 log to 20 log above −17 dBm. 
         [0052]    Referring to  FIG. 12 , a diagram is shown illustrating various components of a power meter system in accordance with an example embodiment of the present invention. In one example, a carrying case  400  may be configured to house the system  100  when the system  100  is not in use. In one example, the carrying case may provide space for the handheld unit  102 , a number of remote sensor units  104   a - 104   n , a power reference  402  for calibrating the remote sensor units  104   a - 104   n , a USB charger  404 , and a battery pack  406 . The handheld unit  102  and the remote sensor units  104   a - 104   n  may be implemented with rechargeable batteries. The rechargeable batteries of the handheld unit  102  and the remote sensor units  104   a - 104   n  may be maintained in a charged condition using the USB charger  404  and/or the battery pack  406  in the carrying case  400 . In one example, the internal battery pack  406  may be implemented as a 6-hour USB rechargeable battery, keeping both batteries of each separate unit constantly charged. The carrying case  400  may also include a shoulder or belt strap  408  for ease of carrying. 
         [0053]    Referring to  FIG. 13 , a flow diagram is shown illustrating a power reading process  500  in accordance with another example embodiment of the present invention. In one example, the process (or method)  500  may comprise a step (or state)  502 , a step (or state)  504 , a step (or state)  506 , a step (or state)  508 , a step (or state)  510 , a step (or state)  512 , a step (or state)  514 , a step (or state)  516 , a step (or state)  518 , a step (or state)  520 , and a step (or state)  522 . In the step  502 , a frequency at which the measurement is being made may be input. In one example, the particular frequency may be entered by the user. For example, the handheld unit may implement a user interface that allows the user to scroll through and select frequencies at which measurements are made. 
         [0054]    When the frequency has been input, the process  500  may move to the step  504  where a frequency table is checked for the frequency that was input. The process  500  then moves to the step  506 . In the step  506 , a determination is made whether the frequency that was input in the step  502  is in the table checked in the step  504 . When the frequency is not in the table, the process  500  moves to the step  508  and generates a frequency data point using two known frequency data points and library formulas  510 . In one example, the process  500  may generate the new data point through straight-line interpolation or extrapolation. When the new frequency data has been generated or the frequency that was input in the step  502  is in the table, the process  500  moves to the step  512 . 
         [0055]    In the step  512 , the process  500  may measure the voltage representing the microwave power level (e.g., reading the output of the ADC  154 ). When the voltage level has been measured, the process  500  may move to the step  514 , where a power table is checked for the voltage that was measured. The process  500  then moves to the step  516 . In the step  516 , a determination is made whether the voltage that was measured in the step  512  is in the power table checked in the step  514 . When the voltage is not in the power table, the process  500  moves to the step  518  and generates a power data point using two known power data points and library formulas  520 . In one example, the process  500  may generate the new power data point through straight-line interpolation or extrapolation. When the new power data point has been generated or the voltage that was measured in the step  512  is in the power table, the process  500  moves to the step  522 . In the step  522 , the power is read and displayed or transmitted. 
         [0056]    Referring to  FIG. 14 , a diagram is shown illustrating a remote power sensing system in accordance with an example embodiment of the invention. In various embodiments, a system  600  may comprise a number of resources implemented in the form of a computing cloud  602  and a number of remote locations  604   a - 604   n . Remote power sensing may be performed at the remote location  604   a - 604   n  by connecting sensor modules  104  to devices located at the remote locations (e.g., base stations, relay stations, hubs, nodes, etc.). The sensor modules at the location  604   a - 604   n  may wirelessly transmit measurements to cloud resources  602 . In an example, a central office or monitoring station (not shown) may monitor the remote locations  604   a - 604   n  through the cloud based infrastructure. The system  600  generally provides the ability for devices connected to the cloud  602  to measure power levels at each of the locations  604   a - 604   n  without having to send a technician out to those remote locations. The measurements may be made numerous times in a day while minimizing the amount of overhead needed to maintain the distribution system. 
         [0057]    Referring to  FIG. 15 , a diagram is shown illustrating a CATV (or other RF) distribution system  700  in accordance with an embodiment of the present invention. In various embodiments, the distribution system  700  may be implemented in a community, in a building (e.g., different floors), in a plane, from one end to another end of a train, etc. The system  700  may comprise a signal (power) source  702  and a number of ports  704   a - 704   n . The ports  704   a - 704   n  may be distributed across multiple legs (or branches) of the system  700 . The branches may be formed by a number of splitters  706   a - 706   n . Signals may be measured at the various ports  704   a - 704   n  in the system  700  using a plurality of sensor modules  104   a - 104   n . In an example, power levels at each port  704   a - 704   n  may be measured and loss(es) from one port to another or from the source  702  to any port  704   a - 704   n  may be determined remotely. 
         [0058]    The functions illustrated by the diagram of  FIG. 13  may be implemented using one or more of a conventional general purpose processor, digital computer, microprocessor, microcontroller, RISC (reduced instruction set computer) processor, CISC (complex instruction set computer) processor, SIMD (single instruction multiple data) processor, signal processor, central processing unit (CPU), arithmetic logic unit (ALU), video digital signal processor (VDSP) and/or similar computational machines, programmed according to the teachings of the present specification, as will be apparent to those skilled in the relevant art(s). Appropriate software, firmware, coding, routines, instructions, opcodes, microcode, and/or program modules may readily be prepared by skilled programmers based on the teachings of the present disclosure, as will also be apparent to those skilled in the relevant art(s). The software is generally executed from a medium or several media by one or more of the processors of the machine implementation. 
         [0059]    The present invention may also be implemented by the preparation of ASICs (application specific integrated circuits), Platform ASICs, FPGAs (field programmable gate arrays), PLDs (programmable logic devices), CPLDs (complex programmable logic device), sea-of-gates, RFICs (radio frequency integrated circuits), ASSPs (application specific standard products), one or more monolithic integrated circuits, one or more chips or die arranged as flip-chip modules and/or multi-chip modules or by interconnecting an appropriate network of conventional component circuits, as is described herein, modifications of which will be readily apparent to those skilled in the art(s). 
         [0060]    The present invention thus may also include a computer product which may be a storage medium or media and/or a transmission medium or media including instructions which may be used to program a machine to perform one or more processes or methods in accordance with the present invention. Execution of instructions contained in the computer product by the machine, along with operations of surrounding circuitry, may transform input data into one or more files on the storage medium and/or one or more output signals representative of a physical object or substance, such as an audio and/or visual depiction. The storage medium may include, but is not limited to, any type of disk including floppy disk, hard drive, magnetic disk, optical disk, CD-ROM, DVD and magneto-optical disks and circuits such as ROMs (read-only memories), RAMs (random access memories), EPROMs (erasable programmable ROMs), EEPROMs (electrically erasable programmable ROMs), UVPROM (ultra-violet erasable programmable ROMs), Flash memory, magnetic cards, optical cards, and/or any type of media suitable for storing electronic instructions. 
         [0061]    The elements of the invention may form part or all of one or more devices, units, components, systems, machines and/or apparatuses. The devices may include, but are not limited to, servers, workstations, storage array controllers, storage systems, personal computers, laptop computers, notebook computers, palm computers, personal digital assistants, portable electronic devices, battery powered devices, set-top boxes, encoders, decoders, transcoders, compressors, decompressors, pre-processors, post-processors, transmitters, receivers, transceivers, cipher circuits, cellular telephones, digital cameras, positioning and/or navigation systems, medical equipment, heads-up displays, wireless devices, audio recording, audio storage and/or audio playback devices, video recording, video storage and/or video playback devices, game platforms, peripherals and/or multi-chip modules. Those skilled in the relevant art(s) would understand that the elements of the invention may be implemented in other types of devices to meet the criteria of a particular application. 
         [0062]    While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the scope of the invention.