Patent Publication Number: US-11386761-B2

Title: Methods and apparatuses for detecting an unauthorized RF device

Description:
BACKGROUND 
     In an retail environment, lost, stolen, or misplaced merchandises may result in loss revenue for the retail store. As a counter measure, the retail store may place security tags on merchandises to prevent loss. The retail store may use one or more authorized radio frequency (RF) scanners to locate the security tags in order to track the merchandises. If a potential shoplifter attempts to remove a merchandise from the retail store without purchasing the merchandise, the one or more authorized RF scanners may detect the security tag (associated with the stolen merchandise) leaving the retail store. In response, the one or more authorized RF scanners may trigger a notification or alarm. 
     However, the potential shoplifter may utilize an authorized RF device to disrupt the operation of the one or more authorized RF scanners. Therefore, improvements in security system may be desirable. 
     SUMMARY 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the DETAILED DESCRIPTION. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     Aspects of the present disclosure include methods, systems, and non-transitory computer readable media for identifying one or more authorized signal characteristic associated with at least one authorized RF signal, receiving at least one incoming RF signal having one or more incoming signal characteristic, identifying the one or more incoming signal characteristic, determining a presence of the unauthorized RF device based on at least one of the one or more authorized signal characteristic or the one or more incoming signal characteristic, and activating an alarm in response to determining the presence of the unauthorized RF device. 
     An aspect of the present disclosure includes a method including identifying one or more authorized signal characteristic associated with at least one authorized RF signal, receiving at least one incoming RF signal having one or more incoming signal characteristic, identifying the one or more incoming signal characteristic, determining a presence of the unauthorized RF device based on at least one of the one or more authorized signal characteristic or the one or more incoming signal characteristic, and activating an alarm in response to determining the presence of the unauthorized RF device. 
     Aspects of the present disclosure includes a radio frequency identification (RFID) scanner including a RFID driver, a memory that stores instructions, and a processor configured to execute the instructions to identify one or more authorized signal characteristic associated with at least one authorized RF signal, cause the RFID driver to receive at least one incoming RF signal having one or more incoming signal characteristic, identify the one or more incoming signal characteristic, determine a presence of the unauthorized RF device based on at least one of the one or more authorized signal characteristic or the one or more incoming signal characteristic, and activate an alarm in response to determining the presence of the unauthorized RF device. 
     Certain aspects of the present disclosure includes a non-transitory computer readable medium having instructions stored therein that, when executed by a processor, cause the processor to identify one or more authorized signal characteristic associated with at least one authorized RF signal, cause the RFID driver to receive at least one incoming RF signal having one or more incoming signal characteristic, identify the one or more incoming signal characteristic, determine a presence of the unauthorized RF device based on at least one of the one or more authorized signal characteristic or the one or more incoming signal characteristic, and activate an alarm in response to determining the presence of the unauthorized RF device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features believed to be characteristic of aspects of the disclosure are set forth in the appended claims. In the description that follows, like parts are marked throughout the specification and drawings with the same numerals, respectively. The drawing figures are not necessarily drawn to scale and certain figures may be shown in exaggerated or generalized form in the interest of clarity and conciseness. The disclosure itself, however, as well as a preferred mode of use, further objects and advantages thereof, will be best understood by reference to the following detailed description of illustrative aspects of the disclosure when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  illustrates an example of an environment for determining the presence of an unauthorized RF device in accordance with aspects of the present disclosure; 
         FIG. 2  illustrates an example of a radio frequency identification (RFID) scanner and a security tag in accordance with aspects of the present disclosure; 
         FIG. 3  illustrates an example of a method for determining the presence of an unauthorized RF device in accordance with aspects of the present disclosure; 
         FIG. 4  illustrates an example of a computer system in accordance with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following includes definitions of selected terms employed herein. The definitions include various examples and/or forms of components that fall within the scope of a term and that may be used for implementation. The examples are not intended to be limiting. 
     In some aspects of the present disclosure, a radio frequency identification (RFID) scanner may be configured to detect an unauthorized radio frequency (RF) device. For example, a retail store may use the RFID scanner, with RFID security tags attached to merchandises, to track and/or inventory the merchandises. Specifically, the RFID scanner may identify any merchandise being removed by a shoplifter from the retail store without proper payment. To counter this, the shoplifter may deploy an unauthorized RF device to interfere with the operation of the RFID scanner by “jamming” the RFID scanner. 
     In one aspect of the present disclosure, the RFID scanner may be configured to distinguish RF signals from an authorized device and the RF signals from an unauthorized device. If the RFID scanner detects unauthorized RF signals, the RFID scanner may activate an alarm to alert the security personnel and/or clerks associated with the retail store. For example, the RFID scanner (or another RFID scanner associated with the retail store) may transmit one or more authorized RF signals intended for the RFID security tags associated with the retail store. The shoplifter may deploy the unauthorized RF device to attempt to jam the RFID scanner by transmitting one or more unauthorized RF signals. The RFID scanner may receive the one or more unauthorized RF signals as one or more incoming RF signals. The RFID scanner may compare the characteristics (e.g., frequency, amplitude, time, duration, waveform shape, phase, etc.) of the one or more authorized RF signals with the characteristics of the one or more incoming RF signals. If the characteristics of the one or more authorized RF signals are different than the characteristics of the one or more incoming RF signals, the RF scanner may determine the presence of the unauthorized RF device, and activate an alarm. 
       FIG. 1  illustrates an example of an environment  100  (e.g., a retail store) for detecting an unauthorized RF device according to aspects of the present disclosure. The environment  100  may include a merchandise  102  having a security tag  104  attached to the merchandise  102 . The security tag  104  may be locked (e.g., unable to be removed from the merchandise  102  without damaging the merchandise  102 ) to the merchandise  102 . The security tag  104  may include a RFID device  240  configured to transmit and/or receive RFID signals. 
     In certain implementations, the environment  100  may include a RFID scanner  112  configured to detect the presence of an unauthorized RF device  120 . The RFID scanner  112  may include a communication component  142  configured to transmit and/or receive RF signals. The RFID scanner  112  may include an identification component  144  configured to identify one or more characteristics associated with RF signals. The RFID scanner  112  may include a determination component  146  configured to determine the presence of the unauthorized RF device  120  based on the characteristics of authorized RF signals (e.g., configured to be transmitted by the RFID scanner  112  or by an optional RF transmitter  114 ) and the characteristics of unauthorized RF signals. The RFID scanner  112  may include an alarm component  148  that activates an alarm when detecting the unauthorized RF device  120 . 
     In some aspects, the environment  100  may optionally include a control RFID tag  106 . The control RFID tag  106  may receive RF signals from the RFID scanner  112  (or the optional RF transmitter  114 ), and transmit a control RF signal in response. 
     During operation, in certain implementations, the RFID scanner  112  may transmit at least one source RF signal  134 . The at least one source RF signal  134  may be intended for the security tag  104 . The at least one source RF signal  134  may be transmitted or be scheduled to be transmitted by the RFID scanner  112  and/or the optional RF transmitter  114 . In response to receiving the at least one source RF signal  134 , the security tag  104  may transmit at least one response RF signal  132  to the RFID scanner  112 . The at least one response RF signal  132  may indicate the location of the security tag  104 , merchandise information associated with the merchandise  102 , etc. 
     In some instances, a shoplifter (not shown) may utilize the unauthorized RF device  120  to transmit at least one unauthorized RF signal  122  to disrupt the operations of the RFID scanner  112  and/or the security tag  104 . For example, the unauthorized RF device  120  may transmit the at least one unauthorized RF signal  122  at a power level significantly higher than the power level of the at least one response RF signal  132 . As a result, the at least one unauthorized RF signal  122  may prevent the RFID scanner  112  from properly receiving and/or detecting the at least one response RF signal  132 . In another example, the unauthorized RF device  120  may transmit the at least one unauthorized RF signal  122  to prevent the security tag  104  from properly receiving the one or more source RF signals  134 . As a result, the security tag  104  may not be able to transmit the at least one response RF signal  132 . 
     In some aspects of the present disclosure, the RFID scanner  112  may identify, via the identification component  144 , the one or more authorized signal characteristic of the at least one authorized RF signal  130 . The one or more authorized signal characteristic may include the amplitude, the frequency, the power level (average or instantaneous), duty cycle, transmission time, period, on/off duration, wavelengths, and/or other characteristics of the at least one authorized RF signal  130 . The at least one authorized RF signal  130  may include portions or all of the at least one source RF signal  134 , the at least one response RF signal  132 , and/or at least one control RF signal  138  (described below). 
     In some aspects, the RFID scanner  112  may utilize hardware and/or software to identify the one or more authorized signal characteristic. For example, the RFID scanner  112  may include a frequency counter and/or a resonant circuit (not shown) to determine the frequency of the at least one authorized RF signal  130 . In another example, the RFID scanner  112  may include a wattmeter to measure the power level of the at least one authorized RF signal  130 . 
     In certain implementations, the RFID scanner  112  may receive, via the communication component  142 , at least one incoming RF signal  136  having one or more incoming signal characteristic. The at least one incoming RF signal  136  may be the at least one unauthorized RF signal  122  or the at least one authorized RF signal  130 . The RFID scanner  112  may be unable to distinguish the at least one unauthorized RF signal  122  and the at least one authorized RF signal  130  until identifying the one or more incoming signal characteristic of the at least one incoming RF signal  136 . 
     In an aspect of the present disclosure, the RFID scanner  112  may identify, via the identification component  144 , the one or more incoming signal characteristic of the at least one incoming RF signal  136 . The one or more incoming signal characteristic may include the amplitude, the frequency, the power level (average or instantaneous), duty cycle, transmission time, period, on/off duration, wavelengths, and/or other characteristics of the at least one incoming RF signal  136 . 
     In some aspect, the RFID scanner  112  may determine, via the determination component  146 , a presence of the unauthorized RF device  120  based on at least one of the one or more authorized signal characteristic of the at least one authorized RF signal  130  or the one or more incoming signal characteristic of the at least one incoming RF signal  136  (e.g., the at least one unauthorized RF signal  122 ). The determination may be performed over a specific duration of time. 
     For example, the RFID scanner  112  may determine the presence of the unauthorized RF device  120  based on the frequency of the at least one authorized RF signal  130  being different than the frequency of the at least one unauthorized RF signal  122 . 
     In another example, the RFID scanner  112  may determine the presence of the unauthorized RF device  120  based on the frequency and/or power level of the at least one authorized RF signal  130  being within the regulatory limit while the frequency and/or power level of the at least one unauthorized RF signal  122  being beyond the regulatory limit. The at least one unauthorized RF signal  122  may be transmitted at a power level above the regulatory threshold and the at least one authorized RF signal  130  may be transmitted at a power level below the regulatory threshold. The at least one unauthorized RF signal  122  may be transmitted at a frequency beyond the regulatory range and the at least one authorized RF signal  130  may be transmitted at a frequency within the regulatory range. 
     In other examples, the RFID scanner  112  may determine the presence of the unauthorized RF device  120  based on the transmission time of the at least one authorized RF signal  130  being different than the transmission time of the at least one unauthorized RF signal  122 . The at least one authorized RF signal  130  may be transmitted between the time of t=0 to t=50 milliseconds (ms), and t=100 ms to t=150 ms, and may not be transmitted between the time of t=51 ms to t=99 ms. At least a portion of the at least one unauthorized RF signal  122  may be transmitted (by the unauthorized RF device  120 ) during the time of t=51 ms to t=99 ms. The RFID scanner  112  may determine the presence of the unauthorized RF device  120  based on at least a portion of the at least one unauthorized RF signal  122  being transmitted during the time of t=51 ms to t=99 ms. 
     In one aspect of the present disclosure, the RFID scanner  112  and/or the optional RF transmitter  114  may transmit the at least one source RF signal  134  to the control RFID tag  106 . The control RFID tag  106  may respond with the at least one control RF signal  138  to the RFID scanner  112 . If the unauthorized RF device  120  transmits the at least one unauthorized RF signal  122 , the control RFID tag  106  may be unable to properly receive the at least one source RF signal  134 , and/or transmit the at least one control RF signal  138 . The RFID scanner  112  may determine the presence of the unauthorized RF device  120  based on the RFID scanner  112  being unable to detect the at least one control RF signal  138  after transmitting the at least one source RF signal  134 . 
     In some aspects of the present disclosure, the RFID scanner  112  may periodically receive background signals, including one or more of the at least one authorized RF signal  130 , and/or signals from other transmitters in the environment  100  (e.g., cellular phones belonging to customers in the retail store). The RFID scanner  112  may determine a background power level associated with the background signals. If the unauthorized RF device  120  transmits the at least one unauthorized RF signal  122 , the RFID scanner  112  may receive the at least one unauthorized RF signal  122  as the at least one incoming RF signal  136 . The RFID scanner  112  may determine that the power level associated with the at least one incoming RF signal  136  exceeds the background power level. In response, the RFID scanner  112  may determine the presence of the unauthorized RF device  120 . 
     In some aspect, the RFID scanner  112  may activate an alarm  124 , via the alarm component  148 , in response to determining the presence of the unauthorized RF device  120 . In some examples, the RFID scanner  112  may send an alarm signal  126  to an optional alarm system (not shown) in the RFID scanner  112  to activate the alarm system (e.g., audio siren and/or visual light). In another example, the RFID scanner  112  may transmit an indication signal (e.g., the alarm signal  126 ) to an external alarm system (e.g., the alarm  124 ) to activate the external alarm system. The alarm system (optional and/or external) may alert personnel associated with the environment  100  (e.g., retail store clerk, security, etc.) regarding the presence of the unauthorized RF device  120 . 
     Referring to  FIGS. 1 and 2 , an example of the RFID scanner  112  may be configured to transmit the at least one source RF signal  134  and/or receive the at least one incoming RF signal  136 . The RFID scanner  112  may include a processor  210  that executes instructions stored in a memory  212  for detecting the unauthorized RF device  120  described herein. 
     The term “processor,” as used herein, can refer to a device that processes signals and performs general computing and arithmetic functions. Signals processed by the processor can include digital signals, data signals, computer instructions, processor instructions, messages, a bit, a bit stream, or other computing that can be received, transmitted and/or detected. A processor, for example, can include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described herein. The term “memory,” as used herein, can include volatile memory and/or nonvolatile memory. Non-volatile memory can include, for example, ROM (read only memory), PROM (programmable read only memory), EPROM (erasable PROM) and EEPROM (electrically erasable PROM). Volatile memory can include, for example, RAM (random access memory), synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), and direct RAM bus RAM (DRRAM). 
     The term “memory,” as used herein, can include volatile memory and/or nonvolatile memory. Non-volatile memory can include, for example, ROM (read only memory), PROM (programmable read only memory), EPROM (erasable PROM) and EEPROM (electrically erasable PROM). Volatile memory can include, for example, RAM (random access memory), synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), and direct RAM bus RAM (DRRAM). 
     In some implementations, the RFID scanner  112  may include the memory  212 . The RFID scanner  112  may include a RFID driver  220  configured to transmit and/or receive RF signals via a scanner coil  222 . The RFID driver  220  may energize the scanner coil  222  to transmit the RF signals. The scanner coil  222  may include one or more inductors that transmit or receive electromagnetic signals. Additionally, in some non-limiting examples, the security tag  104  may include the RFID device  240  that transmits and/or receives RF signals via a tag coil  242 . 
     During operation, in some implementations, the processor  210 , the memory  212 , and/or the identification component  144  of the RFID scanner  112  may identify the one or more authorized signal characteristic associated with one or more authorized RF signal. For example, the processor  210 , the memory  212 , and/or the identification component  144  of the RFID scanner  112  may identify the one or more authorized signal characteristic of the at least one authorized RF signal  130 . The at least one authorized RF signal  130  may be transmitted by the RFID scanner  112  the optional RF transmitter  114 , the security tag  104 , the control RFID tag  106 , and/or other authorized RF devices in the environment  100 . 
     In an implementation, the processor  210 , the memory  212 , and/or the communication component  142  of the RFID scanner  121  may receive the at least one incoming RF signal  136 . For example, the processor  210 , the memory  212 , and/or the communication component  142  of the RFID scanner  112  may receive the at least one incoming RF signal  136 . The at least one incoming RF signal  136  may be a portion or all of the at least one unauthorized RF signal  122 . 
     In certain aspects, the processor  210 , the memory  212 , and/or the identification component  144  of the RFID scanner  112  may identify the one or more incoming signal characteristic of the at least one incoming RF signal  136 . For example, the processor  210 , the memory  212 , and/or the identification component  144  of the RFID scanner  112  may identify the amplitude, the frequency, the power level (average or instantaneous), duty cycle, transmission time, period, on/off duration, wavelengths, and/or other characteristics of the at least one incoming RF signal  136 . 
     In some aspects of the present disclosure, the memory  212 , and/or the determination component  146  of the RFID scanner  112  may determine a presence of the unauthorized RF device  120  based on at least one of the one or more authorized signal characteristic and/or the one or more incoming signal characteristic as described above. 
     In one aspect of the present disclosure, the processor  210 , the memory  212 , and/or the alarm component  148  may activate an alarm system in response to determining the presence of the unauthorized RF device  120  as described above. 
     Turning to  FIG. 3 , an example of a method  300  for determining the presence of an unauthorized RF device may be performed by one or more of the communication component  142 , the identification component  144 , the determination component  146 , the alarm component  148 , the processor  210 , the memory  212 , the RFID driver  220 , and/or the scanner coil  222  of the RFID scanner  112 . 
     At block  302 , the method  300  may identify one or more authorized signal characteristic associated with one or more authorized RF signal. For example, the processor  210 , the memory  212 , and/or the identification component  144  may identify one or more authorized signal characteristic associated with the one or more authorized RF signal  130  as described above. The processor  210 , the memory  212 , and/or the identification component  144  may be configured to and/or define means for identifying one or more authorized signal characteristic associated with one or more authorized RF signal. 
     At block  304 , the method  300  may receive at least one incoming RF signal having one or more incoming signal characteristic. For example, the processor  210 , the memory  212 , the communication component  142 , the RFID driver  220 , and/or the scanner coil  222  may receive the at least one incoming RF signal  136  having one or more incoming signal characteristic as described above. The processor  210 , the memory  212 , the communication component  142 , the RFID driver  220 , and/or the scanner coil  222  may be configured to and/or define means for receiving at least one incoming RF signal having one or more incoming signal characteristic. 
     At block  306 , the method  300  may identify the one or more incoming signal characteristic. For example, the processor  210 , the memory  212 , and/or the identification component  144  may identify the one or more incoming signal characteristic as described above. The processor  210 , the memory  212 , and/or the identification component  144  may be configured to and/or define means for identifying the one or more incoming signal characteristic. 
     At block  308 , the method  300  may determine a presence of the unauthorized RF device based on at least one of the one or more authorized signal characteristic or the one or more incoming signal characteristic. For example, the processor  210 , the memory  212 , and/or the determination component  146  may determine a presence of the unauthorized RF device  120  based on at least one of the one or more authorized signal characteristic or the one or more incoming signal characteristic as described above. The processor  210 , the memory  212 , and/or the determination component  146  may be configured to and/or define means for determining a presence of the unauthorized RF device based on at least one of the one or more authorized signal characteristic or the one or more incoming signal characteristic. 
     At block  310 , the method  300  may activate an alarm in response to determining the presence of the unauthorized RF device. For example, the processor  210 , the memory  212 , and/or the alarm component  148  may activate the alarm  124  in response to determining the presence of the unauthorized RF device  120 . The processor  210 , the memory  212 , and/or the alarm component  148  may be configured to and/or define means for transmitting a wireless signal to the wireless device to enable the RFID device to receive a RFID signal used to unlock the security tag from the merchandise. 
     Aspects of the present disclosures may be implemented using hardware, software, or a combination thereof and may be implemented in one or more computer systems or other processing systems. In an aspect of the present disclosures, features are directed toward one or more computer systems capable of carrying out the functionality described herein. An example of such the computer system  400  is shown in  FIG. 4 . In some examples, the RFID scanner  112  may be implemented as the computer system  400  shown in  FIG. 4 . The RFID scanner  112  may include some or all of the components of the computer system  400 . 
     The computer system  400  includes one or more processors, such as processor  404 . The processor  404  is connected with a communication infrastructure  406  (e.g., a communications bus, cross-over bar, or network). Various software aspects are described in terms of this example computer system. After reading this description, it will become apparent to a person skilled in the relevant art(s) how to implement aspects of the disclosures using other computer systems and/or architectures. 
     The computer system  400  may include a display interface  402  that forwards graphics, text, and other data from the communication infrastructure  406  (or from a frame buffer not shown) for display on a display unit  450 . Computer system  400  also includes a main memory  408 , preferably random access memory (RAM), and may also include a secondary memory  410 . The secondary memory  410  may include, for example, a hard disk drive  412 , and/or a removable storage drive  414 , representing a floppy disk drive, a magnetic tape drive, an optical disk drive, a universal serial bus (USB) flash drive, etc. The removable storage drive  414  reads from and/or writes to a removable storage unit  418  in a well-known manner. Removable storage unit  418  represents a floppy disk, magnetic tape, optical disk, USB flash drive etc., which is read by and written to removable storage drive  414 . As will be appreciated, the removable storage unit  418  includes a computer usable storage medium having stored therein computer software and/or data. In some examples, one or more of the main memory  408 , the secondary memory  410 , the removable storage unit  418 , and/or the removable storage unit  422  may be a non-transitory memory. 
     Alternative aspects of the present disclosures may include secondary memory  410  and may include other similar devices for allowing computer programs or other instructions to be loaded into computer system  400 . Such devices may include, for example, a removable storage unit  422  and an interface  420 . Examples of such may include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an erasable programmable read only memory (EPROM), or programmable read only memory (PROM)) and associated socket, and the removable storage unit  422  and the interface  420 , which allow software and data to be transferred from the removable storage unit  422  to computer system  400 . 
     Computer system  400  may also include a communications circuit  424 . The communications circuit  424  may allow software and data to be transferred between computer system  400  and external devices. Examples of the communications circuit  424  may include a modem, a network interface (such as an Ethernet card), a communications port, a Personal Computer Memory Card International Association (PCMCIA) slot and card, etc. Software and data transferred via the communications circuit  424  are in the form of signals  428 , which may be electronic, electromagnetic, optical or other signals capable of being received by the communications circuit  424 . These signals  428  are provided to the communications circuit  424  via a communications path (e.g., channel)  426 . This path  426  carries signals  428  and may be implemented using wire or cable, fiber optics, a telephone line, a cellular link, an RF link and/or other communications channels. In this document, the terms “computer program medium” and “computer usable medium” are used to refer generally to media such as the removable storage unit  418 , a hard disk installed in hard disk drive  412 , and signals  428 . These computer program products provide software to the computer system  400 . Aspects of the present disclosures are directed to such computer program products. 
     Computer programs (also referred to as computer control logic) are stored in main memory  408  and/or secondary memory  410 . Computer programs may also be received via communications circuit  424 . Such computer programs, when executed, enable the computer system  400  to perform the features in accordance with aspects of the present disclosures, as discussed herein. In particular, the computer programs, when executed, enable the processor  404  to perform the features in accordance with aspects of the present disclosures. Accordingly, such computer programs represent controllers of the computer system  400 . 
     In an aspect of the present disclosures where the method is implemented using software, the software may be stored in a computer program product and loaded into computer system  400  using removable storage drive  414 , hard disk drive  412 , or the interface  420 . The control logic (software), when executed by the processor  404 , causes the processor  404  to perform the functions described herein. In another aspect of the present disclosures, the system is implemented primarily in hardware using, for example, hardware components, such as application specific integrated circuits (ASICs). Implementation of the hardware state machine so as to perform the functions described herein will be apparent to persons skilled in the relevant art(s). 
     It will be appreciated that various implementations of the above-disclosed and other features and functions, or alternatives or varieties thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.