Abstract:
A test device to isolate and locate problems in a wireless transmission antenna system by selectively inducing multiple faults in an independent integral configuration. The test device is used in conjunction with test analysis equipment allowing a technician to induce independent multiple faults system test configurations to detect, isolate and locate feed line and antenna system problems. By selectively connecting the test device at different points along the transmission path dependent on the test analysis outcome, the exact physical location of the problem can be determined within the transmission circuit.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This invention relates to the use of transmission line testing equipment used for the site testing of wireless transmission systems at the tower site. A variety of transmission line problems can occur at the transmission tower site which can create, for example, wireless phone users symptoms such as poor receiver signals and increase drop out call rates. Such problems can occur in a variety of situations such a rainwater penetration, condensation, and bullet holes, for example. Also improper installation situations such as feed line clamps being over tightened or for example, crimped or smashed cable and improper or loose connections during installation, etc. 
     Determining the nature and most importantly the location of the problem along the transmission line is critical to the proper repair and replacement of the affected element in the field. 
     2. Description of Prior Art 
     Prior art testing analysis devices have been developed to test transmission lines and analyze antennas used in the cellular telephone industry. Typically, such testing devices will determine the nature of the problem and attempt to isolate and thus indicate the location of the problem within the system. Such testing equipment utilizes a variety of specific testing procedures such as frequency domain reflectometer (FDR) to cover the required frequencies or range of frequencies. Time domain reflectomoter (TDR) test instrument uses a pulse which is able to detect system faults that may lead to a system failure. Other tests will perform a variety of RF measurements such as return loss and SWR measurements, well known and understood by those within the art. 
     Such test as return loss, cable loss and distant to fault can be performed by such testing equipment. Specific samples of testing equipment are manufactured by Anritsu under the brand name such as Site Master, Model Series 51134 and 5331-2C. It is important to note that with the use of the existing testing equipment, it is very difficult to determine the exact physical location of the problem in the transmission line given that often the actual feed line length is not known to the technician at the location. Present testing equipment may indicate a problem at some point along the feed line and antenna, but often does not relate physically where that problem i.e. fault is actually located. 
     SUMMARY OF THE INVENTION 
     A multi-feature testing device for use on wireless transmission towers that can induce a number of testing criteria or faults to the cell tower transmission circuit. The device has multiple testing features including an open short, a short induced by grounding and interchangeable loads and connectors. The induced loads can be selectively changed by the use of interchangeable load circuits, well known and available within the art. An interchangeable connector is provided to accommodate a variety of connector configurations encountered in the field. The testing device allows a technician to easily perform multiple fault location tests at selective locations on the tower to isolate the fault area so that associated testing equipment can determine the nature and the exact location of the problem within the section isolated. 
    
    
     DESCRIPTION OF THE INVENTION 
     FIG. 1 is a partial cross-sectional view of the testing device of the invention; 
     FIG. 2 is an enlarged top plan view of a contact engagement portion of the testing device; 
     FIG. 3 is an enlarged side elevational view of the contact engagement portion shown in FIG. 2; 
     FIG. 4 is an enlarged cross-sectional view on lines  4 — 4  of FIG. 3; 
     FIG. 5 is an enlarged partial cross-sectional view of the ground inducing short activation elements; 
     FIG. 6 is an enlarged partial side elevational view of the open induced short activation elements; 
     FIG. 7 is a graphic representation of a cellular antenna tower installation illustrating placement of test equipment and the testing device; 
     FIG. 8 is a block flow diagram of the induced testing elements by the testing device within the antenna circuit; and 
     FIG. 9 is a cross-section on lines  9 — 9  of FIG.  1 ; 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1 of the drawings, a testing device  10  of the invention can be seen having a generally rectangular main housing  11  with a top  12 , bottom  13  and oppositely disposed ends  14  and  15 . A mounting bore at  16  extends longitudinally through the main housing  11  defining oppositely disposed access openings  17  and  18  in the respective ends  14  and  15 . The access opening  17  is internally threaded at  19  to accept a load inducer element  20  therein as will be disclosed in greater detail hereinafter. 
     A pair of spaced parallel vertically oriented activation openings  21  and  22  extend from the top surface  12  and are in communication with the mounting bore  16 . A first annular insulator mount  23  is positioned within the bore  16  abutting the threaded portion  19 . The insulator mount  23  has a notched portion at  24  with a central aperture  25  extending therethrough to receive and support a first conductive pin  26  extending from the load inducer  20 . 
     The load inducer  20  is available in different wattages to simulated loads such as  50  ohm and has the conductive pin  26  used for the testing device  10  of the invention attached thereto. A second annular insulator mount  27  is positioned within the mounting bore  16  inwardly of the opposite access opening  18  in the end  15  of the main housing  11  as hereinbefore described. The second insulator mount  27  is centrally apertured at  28 . 
     A connector fitting  29  is mounted within the opening  18  in the end  15  of the main housing  11  by fasteners F and in this example chosen for illustration is a type N male as will be understood by those skilled in the art. 
     A second conductive pin  30  is attached to and extends from the conductor fitting  29  through the aperture  28  in the second insulator mount  27  having a contact  31  attached to and extending from its free end in spaced relation to the insulator mount  27 . 
     The contact  31  is contoured for partial surface attachment with the conductive pin  30  and selective engagement with the first conductive pin  26  as best seen in FIGS. 2,  3  and  4  of the drawings. 
     It will be evident to one skilled in the art that the conductive pins  26  and  30  and the contact  31  must be of a highly conductive nature and therefore would be preferable plated with gold as is the standard within the industry. 
     A pair of test activation fault assemblies  32  and  33  are positioned from the top  12  of the main housing  11  having respective rubber weather engagement caps  32 A and  33 A and associated springs  32 B and  33 B as will be described in greater detail hereinafter. 
     The fault activation assembly  32  has a conductive activation rod  32 C extending through the access opening  21  for selective engagement with the first conductive pin  26  in the notched end portion  24  of the insulator  23 , best seen in FIGS. 1 and 5 of the drawings. The fault activation assembly  33  has a non-conductive activation rod  33 C, preferably plated with gold, extending through the respective access opening  22  for selective engagement with the second conductive pin  30  which is in communication with the first conductive pin  26  via the contact  31  as hereinbefore described. It will be evident from the above description that both the respective activation rods  32 C and  33 C are held in non-activation position by engagement of their respective springs  32 B and  33 B thereon within the respective weather caps  32 A and  33 A. 
     Referring to FIG. 7 of the drawings, an illustrative wireless transmission circuit  34  is shown having an antenna  35  with an antenna jumper  36  connected by a top connector  37  and bottom connector  38  to a feed line  39 . Correspondingly, at the opposite end of the feed line  39  a feed line jumper  40  has a bottom connector  41  for connection with the associated test analysis equipment generally indicated at  42 . 
     This type of testing analysis equipment  42  is typically referred to as transmission line and antenna analyzer devices which are currently used within the industry to detect and locate fault problems within the antenna system. 
     In use, the testing device  10  of the invention is used in conjunction with the testing equipment  42  which will allow an onsite technician (not shown) to easily pinpoint the fault problem. 
     The type of test analysis equipment  42  used is a FDR (Frequency Domain Reflectometer) an example of which is manufactured by Anrtisu, model no.  331  B. A TDR (Time Domain Reflectomotor) an example manufactured by Bird, model no. 2500A and a network analyzer example, manufactured by Marconi, no. 6200A or similar such devices. 
     The testing device  10  of the invention uses its load inducer  20  to simulate the antenna system being tested in a new condition. Once the testing device  10  is connected into the transmission system, a “short” can be induced by use of the first fault activation assembly  32  by depressing the weather guard  32 A and advancing the conductive rod  32 B against the spring  33 B into contact with the conductive pin  26  extending from the load inducer  20 . The conductive pin  26  effectively shorts the conductive rod  32 B with the housing  11  which will validate the position of the testing device  10  in the circuit by using the test equipment “distance to fault” mode as hereinbefore described. 
     Alternately, by depressing the second fault activation assembly  33  the non-conductive rod  33 B will be advanced against the spring  33 B engaging the second conductive pin  30  displacing it by deflection so as to displace the contact  31  with the conductive pin  26  as best seen in FIG. 6 of the drawings. This imparts a “open short” defining a “open circuit” which also confirms the physical location of the tester  10  within the system and serves to isolate the open end of the feed line  39  from the inner band RF test signal which will disrupt the readings on the test equipment. 
     The following test procedure is used when the test analysis equipment  42  indicates initially that the problem i.e. fault is off the ground. In this situation, the testing device  10  of the invention is installed first on the upper jumper connection  37  illustrated in FIG. 7 of the drawings. If the fault is no longer present as indicated by the test analysis equipment  42 , the problem is then determined to be within the antenna  35  and can be replaced. 
     If the problem i.e. fault is still indicated, the user will activate the testing device  10  “sending” a short which will identify on the test analysis equipment  42  the testing device  10  location and is appropriately noted. The test analysis equipment  42  will then determine (by use of distant to fault feature) how far the problem i.e. fault is from the tester  10  and record same by placement of a marker in the test analysis equipment indicating where the fault is. Accordingly the difference of the distance from the marker to the test device  10  becomes the actual distance to the problem i.e. fault. This distance is then physically measured on the tower from the test device  10  which will provide an actual physical location of the problem i.e. fault in the transmission line. 
     In an example in which the fault measurement is at the feed line connector then it will be necessary to open up this connection and connect the testing device  10  to the feed line  39 . Accordingly, if the problem is no longer present, then it can be determined that the problem is in the antenna jumper  36 . 
     If the problem still exist and the technician determines the fault lies just below the testing device  10 , the fault may be in the top feed line connector  38 , for example. After repairs are made, a final confirmation test is performed by the test analysis equipment  42  to confirm proper operation of the antenna system. 
     It will be evident from the above description that the testing device  10  of the invention provides for a simple compact mobile device that can easily be used by a technician on a wireless transmission tower to determine the exact location of a fault within the antenna transmission system working in conjunction with currently available testing analysis equipment  42  operated by a technician on the ground. The testing device  10  of the invention provides for isolation of sections of the antenna transmission system and can be identified within the transmission line accurately by inducing an open short or a ground short which is then used to determine in conjunction with the distance to fault indicator of the test analysis equipment  42 , the actual physical distance from the testing device  10  to the problem i.e. fault within the antenna system. 
     It will thus be seen that a new and useful testing device has been illustrated and described and it will be apparent to those skilled in the art that various changes and modifications may be made therein within departing from the spirit of the invention.