Apparatus for conveying information in a portable communication device

A portable communication device (100) includes a radio (102) and RF memory key (104) that allows both RF and baseband signals to be transported over the radio antenna port. A single wire memory device (134) is embedded into RF memory key (104) along with frequency diplexing circuitry (116) to transport single wire bus communications between the radio (102) and RF memory key (104) while RF is passed from the radio (102) to an antenna (150).

RELATED APPLICATIONS

The invention is related to U.S. Publication No. 20050049020 entitled “System and Method for Antenna Identification and Control”, published on Mar. 3, 2005 and U.S. Pat. No. 7,149,554 entitled “Access Control Method Utilizing a Key Battery”, granted on Dec. 12, 2006, commonly assigned to Motorola, Inc.

FIELD OF THE INVENTION

The present invention relates generally to two-way portable communication devices and more particularly to a means for conveying user identity, radio and access control information in such devices.

BACKGROUND

Portable communication devices, such as hand-held two-way radios, are often shared by multiple users. Certain aspects of radio operation are identity-dependent and thus associated with the actual user of the radio. For example, a user wishing to make a radio-to-radio private call needs to have his or her identity known by the radio and/or the radio system. However, a radio identifier is not sufficient if the radios are shared amongst multiple users. Additionally, certain user configuration information or operational preferences may be associated with the individual user.

It is desirable for such user and configuration information to be able to move with the individual, regardless of the actual radio being used. It is undesirable to reprogram the radio when a user changes radios, because such operation is inconvenient and programming equipment may not be readily available. Having the user enter the data can also be prone to error, tampering, and is limited by the amount of information a user can remember. While it is reasonable for a user to remember a user ID, it is unlikely that a user will recall system or frequency information and be capable of manually entering this information each time a new radio is used.

For certain radio environments, such as the public safety environment, it may also be desirable to restrict access to certain features or capabilities of the radio. For example, certain features or capabilities may only be appropriate for users with special training or having a certain level authority. It is impractical to control access to special features of each device by configuring each device differently as this requires a personal computer (PC), software, and customized cables. As can be easily recognized, this process is both time-consuming and inconvenient.

The need to easily enable or disable special functionality in the field is very important. An example of such need is a two-way radio with front panel programming (FPP) capability. Such a radio is capable of being programmed directly using the radio's own keypad and display. Since a commercial two-way radio is capable of transmitting on a large number of frequencies, including those used by police and public safety agencies, it is desirable to restrict access to the front panel programmable feature to minimize the impact of a malicious user.

The enabling/disabling functionality can be implemented via password protection and/or a hardware key. While combining a hardware key with a password scheme offers enhanced security it also has a number of disadvantages. These disadvantages include: 1) altering the form factor of the device and/or increasing its size, potentially making it less comfortable to use; 2) changes in industrial design or electrical interface in successive products may preclude the re-use of the hardware key; and 3) the key requires the addition of a connector on the radio, or the key occupies an existing connector that can no longer be used for other purposes while the key is present.

Accordingly, there is a need for an improved way of moving user identity information and/or radio configuration information from one radio to another without the use of programming equipment. It is further desirable to have an access control mechanism to control access to restricted functionality of a portable communications device. Such access control mechanism should be inexpensive to design and manufacture, minimally impact the form factor of the communication device, and yet provide secure access.

DETAILED DESCRIPTION

In accordance with the present invention, there is provided herein an apparatus that provides an unambiguous means for a portable communication device, such as a handheld two-way radio, to read information via a radio frequency (RF) memory key attached to an antenna port of the portable device. User identity information and/or radio configuration information associated with a specific radio user can now be easily conveyed to the radio by simply having the user attach the RF memory key to the antenna port. Additionally, the RF memory key of the present invention can further provide access control to restricted local radio functionality, thus providing a hardware security key that can be used on a variety of radio form factors. While the present invention will be described in terms of a portable two-way radio, other portable communication devices having removable antennas can also derive benefit from the apparatus of the present invention.

FIG. 1is a portable communication device100, such as a portable two-way radio, andFIG. 2is a corresponding electrical block diagram200in accordance with the present invention. Portable communication device100and electrical block diagram200provide information conveyance and RF transport between a radio102and RF memory key104formed in accordance with the present invention. Referring to bothFIGS. 1 and 2, RF memory key104couples radio102to removable antenna150. RF memory key104includes a single wire bus interconnect for coupling to radio102. In accordance with the present invention, single wire bus communication circuitry is incorporated into RF memory key104including one or more single wire memory devices134,135. In accordance with the present invention, at least one memory device134includes information such as user identity information, radio configuration information, and/or access control information to access local device functionality.

In accordance with the present invention, the single wire bus circuitry interconnects a single bus master, provided by microcontroller160in radio102, to one or more slaves provided by single wire memory devices134,135in RF memory key104. The single wire bus has a single line in addition to ground and each device on the bus is able to drive it at the appropriate time. One wire systems, such as available from Dallas Semiconductor, can be incorporated into the configuration of the present invention.

Removable antenna150includes a connector, such as a coaxial connector, having an antenna center conductor146and antenna ground147which normally couple to radio102via a standard radio antenna port formed of radio center conductor120and radio ground122. In accordance with an embodiment of the invention, however, antenna150couples to RF memory key104via first interconnect145. First interconnect145is formed of the antenna center conductor146and antenna ground147on the antenna side and RF memory key center conductor148and RF memory key ground142on the RF memory key side. RF memory key104couples to radio102via second interconnect108. Second interconnect108is formed of a second RF memory key center conductor110and a second RF memory key ground112on the RF memory key side and the radio center conductor120and the radio ground122on the radio side. First interconnect145thus provides a first coaxial connection coupling the removable antenna150to the RF memory key104while second interconnect108provides a second coaxial connection coupling the RF memory key104to the radio102. First and second interconnects145,108thus provide a pass-through for RF from the radio through the RF memory key104to removable antenna150. Alternatively, the RF memory key104can be integrated within the removable antenna150.

In accordance with the present invention, radio102includes electronic circuitry114for diplexing RF and baseband signals, and RF memory key104includes electronic circuitry116for diplexing the RF and baseband signals. In accordance with the present invention, the RF memory key104provides a transport for RF signals and access to memory devices134,135by baseband signals. The RF signals are used for regular transmit and receive radio operation, and the baseband signals which generated from the single wire bus124are used for accessing user identity, radio and/or access control information stored in the memory devices134,135.

The electronic circuitry which accomplishes the frequency division filtering is implemented as follows. On the radio side102, a radio frequency (RF) signal126is capacitively coupled, through capacitor118, to the radio center conductor120. The capacitive connection is designed to pass, with high efficiency, the high frequency RF signals while blocking baseband signals. The single wire bus124is DC coupled to the connector center conductor120through an RF blocking inductor, L1,142. Inductor142has negligible impedance to the frequency of single wire bus signals, but provides very high impedance at RF frequencies to prevent loading of the RF path. Capacitor, C2,128further prevents any residual RF from entering the single wire bus124by providing a low impedance short to RF signals while not substantially loading the low frequency baseband signals. This frequency division filtering for interconnection is commonly known as diplexing.

On the RF memory key side, the RF and baseband signals are separated once again using a means similar to the intermixing done in radio102. Inductor L2,140prevents RF from entering single wire bus node130by presenting a high impedance at RF frequencies, while at the low single wire baseband frequencies, inductor L2140allows the baseband signals to pass. Capacitor C3132removes residual RF from the single wire bus node130without substantial loading of the single wire bus signals.

The result, in accordance with the present invention, is transport of both the RF signal and the single wire bus signal across the same single interconnect108normally used for the antenna feed. RF signal136is transported to interconnect145, which provides connection to antenna150. In accordance with the present invention, interconnect145provides RF connectivity to antenna150through RF memory key104and filtering of RF memory key104prevents the single wire baseband frequencies from passing to antenna150. Again, one or more single wire memory devices134,135are used to store information to be accessed by microcontroller160. Other components, such as other RF bypass capacitors, may be included as well depending on the antenna design.

In an alternative embodiment, a plurality of stacked RF memory keys104can be stacked in between the removable antenna150and radio102. In these types of applications, the baseband signals would be allowed to pass through RF memory key104to interconnect145to allow access to the memory devices contained in the additional keys.

In accordance with an embodiment of the invention, at least one of the single wire memory devices134,135is manipulatable by the radio102, via microcontroller160. Also, at least one of the single wire memory devices134,135can be used to manipulate operation of the radio102.

Incorporation of single wire bus communications into the radio102allows the single wire memory device134, such as an EEPROM, to be contained within the RF memory key104. In accordance with a first embodiment of the invention, single wire memory device134may be programmed with user identity information, user configuration information, and/or user preferences. In this embodiment, some portion of the information is logically associated with a specific radio user.

In the first embodiment, the single wire memory device134in RF memory key104contains user identity information, user configuration information, and/or user preferences. This information would likely include a user identification number for identifying a user for selective calling or paging, identifying a user for radio system access, and/or identifying a user for phone interconnect. Those skilled in the art will recognize there are additional usage cases for establishing a unique user identity for usage in a two-way radio. Additionally, the single wire memory device134may contain additional configuration information, such as radio system information, radio personality information, conventional channel information, channel assignments, scan lists, etc. User preference information may also be included, such as programmable scan lists, phone lists, backlight timers, keypress beep enable, etc. The user identity information, the user configuration information, and the user preferences, if present and used in aggregate, may be recognized to be a complete radio “codeplug”. In this first embodiment, the information stored in single wire memory device134may represent a complete radio codeplug or simply a portion thereof.

The information stored in single wire memory device134of RF memory key104may be required for radio operation, meaning that the user identity, radio configuration information, and/or user preference information is required for radio operation. Hence, the absence of RF memory key104would render the radio inoperable or substantially limited in capability.

Alternately, the information stored in single wire memory device134of RF memory key104may be used to supplement the radio's codeplug. The radio would have a “default” configuration that allows basic operation without individual identity or with a default identity. Addition of the RF memory key104would provide the radio with additional information that would extend, enhance, or customize the default configuration according to the content of the user identity and configuration information. In one example, the RF memory key104may merely provide user identify information, which would be used to make a radio with a generic codeplug specific to an individual so long as the RF memory key104were attached. In another example, the RF memory key104may provide user identify information and add additional trunking systems, radio personalities, and/or conventional channels beyond what is specified in the generic radio codeplug. The present invention allows for the radio to alter the contents in single wire memory device134to store new user preferences or for reprogramming.

In accordance with a second embodiment of the invention, the single wire memory device134is programmed with access control information to enable access to local radio functionality. In this second embodiment, there is no logical association or coupling between a specific RF memory key and a specific user.

In the second embodiment of the invention, the RF memory key104is used to enable access to restricted, latent, and local radio functionality. The radio firmware contains a set of features or capabilities that are restricted and may only be accessed by means of a hardware key. On a radio without an RF memory key104attached, the set of restricted features are non-operable and their existence may even be hidden. On a radio with the RF memory key104attached, in accordance with this second embodiment, one or more of the set of restricted features may be authorized by data contained in the single wire memory device134contained in RF memory key104. The information contained within the memory device134contains one or more flags or security keys that enable access to latent radio functionality. A single key or flag may enable access to all restricted functionality, or there may be a separate key or flag associated with each specific capability. Those skilled in the art will recognize that it may be advantageous to encrypt or digitally sign the keys to increase security and thwart attempts to inappropriately activate the restricted functionality or to create imitation hardware keys.

The first embodiment of the invention thus includes or allows user identity information to be included in the data stored in the single wire memory device134. The second embodiment, in contrast, contains no user identity information whatsoever. A likely usage case of the second embodiment is to enable front panel programming (FPP) operation of a portable two-way radio.

To further illustrate this point, an analogy can be made to a set of identical deadbolt locks protecting multiple rooms and set of identical keys that operate all of the deadbolt locks. A set of authorized people need access to all of the rooms, and each of these people are given a key. The keys can be randomly assigned to each person, but each person will still be able access all the rooms. A restricted feature in each radio is analogous to a room, the access control mechanism is analogous to the deadbolt lock, and the RF memory key containing a flag or security key is analogous to the deadbolt key. Any radio user who physically possesses an RF memory key is permitted to access the restricted functionality on any radio to which it is attached. The individual's identity is not important; all that matters is whether the person possesses a key.

It is also possible to have the first and second embodiments combined such that user identity and radio configuration information is incorporated along with access control. In this third embodiment, only specific predetermined users with appropriate identification would be able to use the radio and even these specific users would have different levels of access to restricted functionality.

Though the single wire bus124is provided to allow communications with a single wire memory device134, such as an EEPROM, additional memory devices135can be used for additional storage space. Those skilled in the art will recognize that if a single memory device does not meet the storage needs of the particular application, that “n” memory devices can be used and mapped accordingly so that they appear as or are ultimately processed as a single contiguous bank of memory.

Today's communication devices are equipped with an antenna removably coupled to the radio's antenna port. The RF memory key of the present invention can take advantage of the existing antenna interconnect, be it coaxial or other type, along with circuitry within the radio and antenna to enable both RF and single wire bus communications via a single port, the radio antenna port.

Accordingly, there has been provided an RF memory key that provides an unambiguous means for a radio to retrieve and process user identity information, user configuration information, and user preference information stored in one or more memory devices of the RF memory key. The apparatus of the present invention provides increased operating versatility by providing a user a means to easily migrate personal information among a plurality of different radios, possibly including different radio form factors, without the need for specialized programming equipment. The RF memory key is small, unobtrusive, and its “pass through” nature avoids the consumption of a valuable radio interface port.

The RF memory key of the present invention can further provide an access control mechanism used to access restricted, local, latent radio functionality to authorized individuals who possess the RF memory key. This aspect of the invention meets Federal Government requirements for a hardware access control mechanism for the front panel programming capability of two-way radios.

The RF memory key of the present invention is inexpensive to design and manufacture, minimally impacts the form factor of the radio, and does not prevent the use of accessories or other capabilities. The user need not enter data or reprogram the radio each time a new radio is used. The portable radio is less prone to programming error or tampering by outsiders. The RF memory key does not require the addition of a connector on the radio as it is embodied as an extension to the removable antenna or can even be integrated within the removable antenna.