Patent Description:
Telecommunication cables are manufactured in factories and need to be tested. Radio frequency (RF) coaxial cables are used in cell-towers, in-building systems, cable TV systems, satellite communication base station systems, and the like.

When cables are terminated (sometimes referred to as "connectorized"), RF tests are conducted with specialized equipment, such as Vector Network Analyzers (VNAs). A VNA typically includes a plurality of ports, such as two ports, with a first port used to generate a signal and a second, different, port to provide various terminations such as open, short, or load.

In a laboratory environment, the use of a two-port VNA is suitable, however in the field environment, the use of two-port VNA is not feasible for practical reasons. For example, the cables are sometimes more than one hundred feet long and the ends may be on different floors in a building or at the top of a vertical tower. Moreover, the thickness of the cables is often greater than one inch, rendering their bend radius difficult to perform two-port VNA testing. That is, the cables cannot be readily bent to attach to the VNA as the cables have a minimum bend radius which must not be exceeded.

In the field, a one-port VNA may be used. One end of the network analyzer can be connected to the VNA and the other end to a termination such as an RF open, RF short or an RF load. The three terminations are usually available in one physical unit called an Open-Short-Load (OSL). The OSL may be referred to as an OSLT when it also has a through port. Sometimes the OSL is referred to as a T-load due to the shape of the OSL in the form of the letter 'T'. A through port can allow for normal operation of the telecommunication system, since it routes the RF to its destination-typically an antenna.

The one-port test of an RF cable typically involves using a one-port VNA connected to the cable under test using a phase-stable cable on one end and the OSL on the other end. The OSL is switched from open to short to load, manually, depending on the type of the RF test that is being performed. For an RF cable test, it is common to see tests for multiple frequency bands and multiple terminations such as open or short or load. For example, a return-loss (RL) test can be performed with the OSL connected as a load, a Distance-to-Fault (DTF) measurement can be performed with a short and an insertion loss/cable loss (CL) can be performed with an open. These cables are hundreds of feet in length and may span between different floors of a building.

The testing is usually performed with two technicians, one on each end of the cable. The technicians communicate using a wireless communication system (such as, e.g., a walkie talkie). A first technician on the end of the cable having the VNA can change between two or more frequencies. The first technician can also change between test modes (such as RL, DTF, CL). The first technician can instruct a second technician on the other end of the cable to connect the correct termination (such as open, load or short) based on the particular test plan being implemented. The same test process is sometimes followed for RF components as well. This process can be laborious, time-consuming and prone to human error, specifically when performed in the field.

RF cable installation technicians continue to demand more efficient, easier means to handle RF cable installation. Prior art documents <CIT> and <CIT> describe relevant examples of approaches for characterising cables in telecommunication systems.

Aspects and advantages of the invention in accordance with the present disclosure will be set forth in part in the following description.

The invention is defined by a testing system for testing radio frequency RF cables in a telecommunication system according to claim <NUM> and the associated method according to claim <NUM>. Further embodiments are defined by the corresponding dependent claims.

A full and enabling disclosure of the present invention, including the best mode of making and using the present systems and methods, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:.

Reference now will be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the drawings. Moreover, each example is provided by way of explanation, rather than limitation of, the technology. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present technology without departing from the scope of the claimed technology. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims.

The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. For example, a process, method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus.

Terms of approximation, such as "about," "generally," "approximately," or "substantially," include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, "generally vertical" includes directions within ten degrees of vertical in any direction, e.g., clockwise or counter-clockwise.

Benefits, other advantages, and solutions to problems are described below with regard to specific embodiments.

In general, embodiments in accordance with the present disclosure allow for testing of cables in telecommunication systems using a remotely controlled termination device. In this regard, testing can be performed quicker, easier, and more efficiently. Whereas traditional testing systems and methods require operators on both ends of the cable under test, systems and methods described in embodiments herein allow for testing by a single operator. Moreover, where testing requires placement of a termination device at a dangerous location, e.g., at an antenna located on top of a large structure, systems and methods described herein can reduce risk by eliminating the need for the testing operator to remain at the dangerous location during testing.

Referring now to the drawings, <FIG> illustrates a schematic view of a testing system <NUM> for testing radio frequency (RF) in cables of telecommunications systems in accordance with an embodiment. By way of example, the telecommunications system can include a coaxial network including one or more coaxial cables and supporting structure, such as cell-towers, in-building systems, cable TV systems, satellite communication base station systems, and the like. The system <NUM> can be implemented with one or more cables under test <NUM> to determine one or more operating parameters of the cable(s) under test <NUM>. The cable under test <NUM> can generally include a proximal end <NUM> and a distal end <NUM>. In certain instances, the proximal and distal ends <NUM> and <NUM> can correspond with transmission ends of the cable under test <NUM>. In other embodiments, the proximal and distal ends <NUM> and <NUM> can correspond with portions of the cable under test <NUM> located near the ends of the cable under test <NUM>. That is, the system disclosed herein may be implemented at locations spaced apart from the transmission ends of the cable where the signal is fed and received.

The testing system <NUM> can include a termination element <NUM> configured to be coupled to the distal end <NUM> of the cable under test <NUM>. The termination element <NUM> can include, for example, an open-short-load (OSL) termination device. In an embodiment, the termination element <NUM> can include a single physical unit. The OSL can be used to test the one or more operating parameters of the cable under test <NUM>. In an embodiment, the OSL can include a through port which allows for passage of the signals traveling through the cable. Thus, the OSL can route the signal to its final destination, e.g., when the OSL is not used for active testing purposes. OSL devices with through ports may be referred to herein as OSLTs.

The termination element <NUM> can be switchable between two or more termination states. Each termination state can be used for performing a different test on the cable under test <NUM>. By way of non-limiting example, these termination states may include any one or more of an open termination state, a short termination state, or a load termination state. In certain instances, a return-loss (RL) test can be performed with the termination element <NUM> connected as a load. In other instances, a distance-to-fault (DTF) measurement can be performed with the termination element <NUM> connected as a short. In yet other instances, an insertion loss/cable loss (CL) can be performed with the termination element <NUM> connected as an open. During testing, an operator may switch between these termination states to test the cable under test <NUM> in accordance with a desired testing protocol.

<FIG> depicts a schematic view of the termination element <NUM> in accordance with an embodiment. Referring to <FIG>, the termination element <NUM> can include an RF switch <NUM>, an RF power sensor <NUM>, a processor <NUM>, and a power source <NUM>. The RF switch <NUM> can be coupled with an RF connector <NUM>. The RF connector <NUM> can be an external connector to which the cable under test <NUM> (<FIG>) can be connected, e.g., during testing or permanently. The processor <NUM> can be coupled with the RF switch <NUM>. The power source <NUM> can include, for example, a battery and a charging circuit. The power source <NUM> can be coupled with the processor <NUM>. The RF power sensor <NUM> can be coupled with the RF switch <NUM> and the processor <NUM>.

The termination element <NUM> can further include open, short, load, through (OSLT) terminations <NUM> and a bias generator <NUM> coupled with a bias voltage at a bias voltage connection port <NUM>. By way of non-limiting example, the bias voltage may control, e.g., turn on, one or more amplifiers coupled downstream from the termination element <NUM>. The termination element <NUM> may be configured to pass the bias voltage through when the bias is generated by the test instrument. In another embodiment, the termination element <NUM> can provide a bias voltage to an amplifier (such as, e.g., a Tower Mounted Amplifier - TMA) through its bias voltage connection port <NUM> so as to turn the TMA ON or OFF remotely to perform certain RF tests.

The terminations <NUM> can be coupled with an RF connector <NUM> which can be coupled downstream of the termination element <NUM>, e.g., to an antenna. The termination <NUM> can be disposed between the RF switch <NUM> and the RF connector <NUM>. In this regard, inputs received at the RF connector <NUM> can pass through the RF switch <NUM> and the terminations <NUM> prior to passing through the termination element <NUM> at the RF connector <NUM>.

In certain instances, the termination element <NUM> can further include a user interface which allows the operator to operate the termination element <NUM>. The user interface can include, for example, one or more pushbuttons <NUM>. The pushbuttons <NUM> may be exposed from a body of the termination element <NUM> to allow the operator ready access thereto. In certain instances, the termination element <NUM> can further include one or more visual indicators <NUM> to allow the operator to see a status or operating parameter of the termination element <NUM>. By way of non-limiting example, the visual indicator(s) <NUM> can include light emitting diodes (LEDs). An audible indicator <NUM> can be further included to alert the operator of a particular status or operating parameter of the termination element <NUM>. By way of non-limiting example, the audible indicator <NUM> can include a buzzer.

In an embodiment, the termination element <NUM>, or components thereof, can be integrated into one or more printed circuit boards (PCBs). In another embodiment, the termination element <NUM> can be constructed from discrete components in electrical communication with one another.

Referring again to <FIG>, the system <NUM> can further include a controller <NUM> in communication with the termination element <NUM>. The controller <NUM> can be in wireless communication with the termination element <NUM>. By way of non-limiting example, wireless communication can occur through Bluetooth, over WiFi, through cellular signal, or a mesh network interface. In certain instances, the controller <NUM> can include a remote. In other instances, the controller <NUM> can be integrated into an existing smart device, such as a smart phone. The controller <NUM> can include, for example, a software application executable by the smart device to instruct the termination element <NUM> to perform a particular operation, such as to switch between two or more termination states.

The controller <NUM> can be movable with respect to the termination element <NUM>. In this regard, the operator performing the test can maneuver within the environment associated with the cable under test <NUM> without having to remain at the termination element <NUM> while maintaining the ability to control the termination element <NUM>. By way of example, the operator can control the termination element <NUM> using the controller <NUM> when the operator is located at the proximal end <NUM> of the cable under test <NUM>. In this regard, the operator can be located at a position associated with injection of the signal into the cable under test <NUM> while affecting the termination element <NUM> to a desired termination state. This may be particularly suitable for situations where the termination element <NUM> is in a hard to reach or dangerous location, such as on a rooftop, a tower, or the like. Using the controller <NUM>, the operator can repeatedly affect the termination element <NUM> without having to expose themselves to increased risk of bodily harm.

The controller <NUM> can have a communication element <NUM> which can wirelessly communicate with a wireless interface <NUM> of the termination element <NUM> (<FIG>). In certain instances, the termination element <NUM> may also, or alternatively, include a wired interface <NUM> which can be connected to the communication element <NUM> through a wired interface, such as a cable.

Referring still to <FIG>, the system <NUM> can further include a test instrument <NUM> configured to execute one or more tests to be performed on the cable under test <NUM>. The test instrument <NUM> can be disposed at the proximal end <NUM> of the cable under test <NUM>. For instance, the proximal end <NUM> of the cable under test <NUM> can be connected to a port of the test instrument <NUM>. By way of non-limiting example, the test instrument <NUM> can include a vector network analyzer (VNA). The VNA can include a plurality of ports with at least one port configured to provide signals along the cable under test <NUM>.

In a particular test of the system <NUM>, the test instrument <NUM> can inject a signal into the cable under test <NUM> which can be measured by the power sensor <NUM> of the termination element <NUM>. The power sensor <NUM> can communicate the sensed power to the processor <NUM> which can relay information associated with the sensed power to the wireless interface <NUM> or the wired interface <NUM> to communicate the information to the operator.

<FIG> depicts an embodiment of the system <NUM> in accordance with another embodiment. As depicted, the system <NUM> further includes an injector module <NUM> coupled between the test instrument <NUM> and the cable under test <NUM>. The injector module <NUM> can perform at least one of the following functions during testing of the cable under test <NUM>. The injector module <NUM> can provide power, e.g., direct current, to the termination element <NUM>, e.g., through the cable under test <NUM>. The injector module <NUM> can receive power, e.g., direct current, from the test instrument <NUM>, e.g., through a USB or other dedicated power connection. The injector module <NUM> can pass commands from the test instrument <NUM>, controller <NUM>, or another element to the termination element <NUM>, e.g., through the cable under test <NUM>. The injector module <NUM> can receive responses from the termination element <NUM>, e.g., through the cable under test <NUM>. The injector module <NUM> may further transmit the received responses to the test instrument <NUM>, the controller <NUM>, or another element associated with the system. The injector module <NUM> can provide feedback to the operator through responses to commands, LEDs, buzzers, or the like.

<FIG> depicts an exemplary schematic view of the injector module <NUM> in accordance with an embodiment. As depicted, the injector module <NUM> can include similar elements as compared to the termination element <NUM>, such as for example, an RF switch <NUM>, a power sensor <NUM>, a processor <NUM>, a power source <NUM>, terminations <NUM>, a bias generator <NUM>, and the like. The injector module <NUM> can further include a de-modulator <NUM> and a modulator <NUM>. The de-modulator <NUM> and modulator <NUM> can include RF/LF modulator/demodulators.

As previously described, the termination element <NUM> can be an OSL device, and more particularly, an OSLT. In an embodiment, the injector module <NUM> can also be an OSL device. Specifically, the injector module <NUM> should be an OSLT. In certain instances, the termination element <NUM> and the injector module <NUM> can be essentially similar devices, including similar, or same, structures and operating protocols.

Using the injector module <NUM>, the operator can affect the termination element <NUM> which can respond to commands by switching to an appropriate termination state (e.g., open, short or load). Using this technique, testing efficiency can be drastically increased as the operator can remain at the proximal end <NUM> of the cable under test <NUM> while affecting the termination element <NUM> disposed at the distal end <NUM> of the cable under test <NUM>. Communication to the termination element <NUM> can come from, e.g., the injector module <NUM>. The communication can include, e.g., voltage signals (e.g., DC voltage signals) for various modes or frequency modulated messages in the form of frequency-shift keying (FSK) modulation or phase-shift keying (PSK) modulation.

In an embodiment, messages coded in low frequency pulses or RF modulated signals can be used to communicate between the injector module <NUM> and the termination element <NUM>. Sophisticated two-way communication mechanisms can also be implemented.

In an embodiment, the termination element <NUM> can be commanded to measure RF power of a signal received from the test instrument <NUM> through the cable under test <NUM> using the RF power sensor <NUM>. The termination element <NUM> can report the power back to the operator through the test instrument <NUM>, the smart device, or the like.

In an embodiment, one of the injector module <NUM> and termination element <NUM> can be controlled using a first device, such as a smart device running a software application. The other of the injector module <NUM> and termination element <NUM> can be controlled using a second device, different from the first device. By way of non-limiting example, the second device can be another smart device running the same or different software application. In certain instances, the first and second devices can operate on a common communication protocol, such as on a same network. In other instances, the first and second devices can operate on different communication protocols. For example, the first device can operate using Bluetooth and the second device can operate using WiFi. Alternatively, the first and second devices can utilize the same type of network but different available protocols available in the network. In an embodiment, both the injector module <NUM> and the termination element <NUM> can be controlled using the same device, such as using a software application installed on a single smart device.

In certain applications, at least one of the termination element <NUM> and the injector module <NUM> can be operable using a third-party software. The third-party software may also control the test instrument <NUM>. In this regard, the operational efficiency can be further improved by reducing the number of components required to test the cable under test <NUM> and the system <NUM>.

In accordance with an embodiment, the termination element <NUM> can be left in place in-line on a network of RF components, e.g., to monitor performance. Referring to the exemplary embodiment depicted in <FIG>, two termination elements 108A and 108B are depicted in-line between a signal distribution network <NUM>, including for example a splitter, cables, amplifiers and the like, and antennas 152A and 152B. A splitter or coupler <NUM> is disposed between the termination element 108B and the antenna 152B.

<FIG> illustrates a system <NUM> including a plurality of cables <NUM> arranged in an exemplary manner. Each of the cables <NUM> is depicted extending between two nodes. The nodes can include, for example, antennas <NUM>, splitters or couplers <NUM>, and the like. Testing can be performed on each of the cables <NUM> individually or together to measure operational characteristics of each cable <NUM>, a plurality of cables <NUM>, or the overall system <NUM>. In an embodiment, the system <NUM> can be tested from a single, first testing location <NUM>. In another embodiment, the system <NUM> can be tested from a plurality of locations including the first testing location <NUM> and a second testing location <NUM>.

The termination element <NUM> described above can be implemented within the system <NUM>, e.g., at the antennas <NUM>, adjacent to the splitters or couplers <NUM>, or the like. The termination element <NUM> can be controlled, e.g., by the controller <NUM>. In an embodiment, the termination element <NUM> can be remotely controlled by the controller <NUM>. In an embodiment, a plurality of termination elements can be implemented within the system <NUM> to test different cable pathways. The plurality of termination elements can be operated using a common controller or different controllers.

Referring again to <FIG>, in certain instances, the termination element <NUM> can be controlled by a bias voltage generated at the test instrument <NUM>. Some test instruments <NUM> may be capable of inserting a fixed direct current (DC) voltage, known as a bias voltage, into the RF data channel using a device such as, e.g., a bias-tee. The bias-tee can include a plurality of ports, such as an RF input, and RF output, and an input for the bias voltage. The bias-tee can combine the incoming RF and the bias voltage together and drive the resultant DC/RF mix from the output.

<FIG> depicts an exemplary view of a bias-tee <NUM> receiving a bias voltage <NUM> from the test instrument <NUM>. The bias-tee <NUM> can further receive an RF input <NUM> and have an RF and bias voltage output <NUM>. In an embodiment, the bias-tee RF input <NUM> can be coupled to, e.g., directly coupled to, the test instrument <NUM>. In some instances, the RF and bias voltage output <NUM> can be injected directly into the cable under test <NUM>. In other instances, the RF and bias voltage output <NUM> can be injected into the cable under test <NUM> through an injector module (not depicted). The termination element <NUM> can decode the bias voltage on the cable under test to determine its behavior, selecting between open, short, load or through operation.

In an embodiment, the test instrument <NUM> can drive a plurality of bias voltage levels into the bias-tee. The termination element <NUM> can decode the bias voltage level and use the decoded information to configure its own behavior. For example, a first bias voltage level can cause the termination element <NUM> to turn on its load, a second bias voltage level can cause the termination element <NUM> to set its input to the open state, a third bias voltage level can cause engage the internal short of the termination element <NUM>, and a fourth bias voltage level can enable the through port of the termination element <NUM>. In certain instances, the termination element <NUM> can decode the absence of a bias voltage (e.g., that the bias voltage is zero) as a unique command. By way of non-limiting example, the absence of the bias voltage might enable the through port of the termination element <NUM>, which may correspond with its normal operating state, where incoming RF simply passes through the system.

RF equipment downstream of the termination element <NUM> can include a DC block to prevent DC voltage on the cable (e.g., the bias voltage inserted by the test equipment) from being propagated further downstream.

<FIG> illustrates a flow chart of a method <NUM> of testing RF cables in a telecommunication system including a cable under test. The method <NUM> can include a step <NUM> of installing a termination element to a distal end of the cable under test. The method <NUM> can further include a step <NUM> of communicating with the termination element from a test instrument coupled to a proximal end of the cable under test, the proximal end of the cable under test being opposite the distal end. The method <NUM> can further include a step <NUM> of controlling the termination element from the proximal end of the cable under test. In an embodiment, the step <NUM> of controlling the termination element can include switching the termination element between two or more termination states selected from the group consisting of an open termination state, a short termination state, and a load termination state. The step <NUM> can be performed, e.g., by a controller in wireless communication with the termination element. Alternatively, or in addition, the step <NUM> can be performed by a controller in wired communication with the termination element. The controller can include, e.g., a smart device such as a mobile device.

In an embodiment, the method <NUM> can further include measuring RF power through the cable under test using the termination element, and communicating the measured RF power to an operator located at a proximal end of the cable under test. The operator can remain at the proximal end of the cable under test during testing, relying on the controller to communicate with the termination element.

Further aspects of the invention are provided by one or more of the following embodiments:.

Claim 1:
A testing system (<NUM>) for testing radio frequency RF cables in a telecommunication system including a cable under test (<NUM>), the testing system (<NUM>) comprising:
a termination element (<NUM>) configured to be coupled to a distal end (<NUM>) of the cable under test (<NUM>);
a controller (<NUM>) in wireless communication with the termination element (<NUM>), wherein the controller (<NUM>) is adapted to wirelessly switch the termination element (<NUM>) between each of an open termination state, a short termination state, a load termination state, and a through state; and
a test instrument (<NUM>) configured to execute one or more tests of the cable under test (<NUM>), the test instrument (<NUM>) being disposed at a proximal end (<NUM>) of the cable under test (<NUM>), the proximal end (<NUM>) of the cable under test (<NUM>) being opposite the distal end (<NUM>).