Abstract: An FSK demodulator is provided comprising means for receiving and digitizing an FSK signal (such as a signal comprising two frequencies f1 and f2 in which first and second logic states are represented by first and second periods of different durations). First, second, third and fourth consecutive transitions of the signal are identified and the times of said transitions are identified. A first period between the first and third transitions is calculated, as is a second period between the second and fourth transitions. A change of frequency in the signal is indicated when the first and second periods lie on opposite sides of a first threshold period (.tau.) and no change of frequency is indicated when the first and second periods lie on the same side of the threshold period (.tau.). In a further aspect of the invention, a transition is rejected as illegal when two consecutive transitions occur within a predetermined period of time.

Abstract: An intersystem communication path (20, 67) can be established on an as needed basis. Already established paths are fully utilized before new paths are established. Already established paths can be automatically disconnected when no longer needed, or when existing calls can be merged on to fewer lines. Dial up lines can be mixed with dedicated lines. If desired, excess capacity can be guaranteed to accommodate high traffic conditions and/or other conditions that precipitate a likely need for communication services between systems.

Abstract: A method is disclosed which automatically establishes a communication path between at least two devices (106, 110, 118, 120, 128). Each device has a unique identification (ID), and is coupled to a switching center (132-137) of a Public Switched Telephone Network (PSTN, 130). The PSTN (130) has a facility access center (FAC, 140) for coupling the switching centers (132-137) to a storage facility controller (SFC, 146), which provides access to a central storage facility (148). The method includes the steps of determining (306) an ID of a first device and then selecting (318) a portion of the central storage facility (148) associated with that ID. Then, after ascertaining a second ID of a second device, an element associated with the second ID is retrieved (322) from that portion of the central storage facility (148). Lastly, a communication path is created (327, 328) between the first device (106, 110, 118) and the second device (108, 112, 128).

Abstract: Co-channel user (129) interference on trunked radio communication systems cannot be compensated for in the same way as conventional radio systems because the communication unit does not know what frequency it will be assigned to until it begins transmitting. Placing an additional receiver (119) in the coverage area (125) of the co-channel user (129) and sending information of recent co-channel usage to the controller (101) allows the controller (101) to decide which channel has the least likelihood of co-channel interference so that it may be assigned.

Abstract: A method of collapsing a communication path among at least two communication units (104-107) reduces the number of sites normally required to provide a communication. Each of a plurality of site controllers (103) in a radio communications system has a corresponding coverage area (100, 101), and at least some of the coverage areas (710-712) overlap one another. The method includes the step of determining (402) whether the communication units are currently being serviced by different sites, and then determining (405) whether they can be serviced by a common site. When the communication units are serviceable by a common site, the call might be established (406) through the common site, resulting in a reduced number of sites required to complete a call.

Abstract: A bulletin board communication resource provides a message to communication units regarding available communication systems in a particular geographic area. The bulletin board resource also supports registration of the communication unit with one or more of these systems as selected by the communication unit.

Abstract: A radio communication system controller embodies the present invention by providing extended use (306) of a communication resource (106) to a plurality of communication units. The inventive method includes the steps of assigning (402) a first communication resource to a first communication unit, and then temporarily configuring (406) the assigned communication resource as a reserved resource. The controller then receives (408), from a second communication unit, a request to transmit a second communication on the assigned communication resource. Lastly, the controller re-configures (412) the assigned communication resource to allow transmission of the second communication on the assigned communication resource.

Abstract: A communication resource is subdivided as a function of time into a plurality of time slots (210), which may then be further subdivided on a non-periodic basis into a number of sub-slots (220). In a slot or sub-slot, communication units (101) may utilize the communication resource according to a specific set of access methods defined for that slot or sub-slot. In one embodiment the time slots are subdivided on a non-periodic basis into a least two random access sub-slots, during which communication units may either request one or more reserved time slots, or send unreserved data packets (240). In response to requests for reserved time slots from a requesting communication unit, one or more reserved time slots are provided for the use of the requesting communication unit.

Abstract: Power consumption in a portable communication unit (101) is reduced by first transmitting at a first time, a message (701) at a first transmit power level to a repeater (103) on a first communication channel. At a second time the message (701) is repeated (903) by the repeater on a second communication channel, thereby transmitting a delayed message (703). The portable communication unit (101) tunes (807) to the second communication channel after transmitting all of the message (701), so as to receive at least part of the delayed message (703). The repeater (103) establishes a receive quality metric (705) for the message (701) and transmits (909) the receive quality metric after all of the delayed message (703) is transmitted. The portable communication unit receives and stores (809) the receive quality metric (705), and determines a second transmit power level for transmitting another message using the receive quality metric.

Abstract: A communications system provides subfleet calls for both voice and data communications using a secondary identification (301, 303, 305, 307, 309) incorporating a plurality of subfleets in a hierarchical arrangement. A message including the secondary identification (301, 303, 305, 307, 309) is transmitted to a communication unit (117) having a stored secondary identification (301, 303, 305, 307, 309). If the transmitted secondary identification sufficiently matches the stored secondary identification, the communication unit (117) responds to the instructions in the transmitted message.

Abstract: System configuration data required for use by various interfaces (102) can be obtained either directly via a data link (104) that couples the interfaces to other systems (109 or 111), or by a down link from a system data manager (106) configured as part of the interfaces' system (100).

Abstract: Multilevel angle modulated information is decoded through integral use of channel state information. In a Viterbi Algorithm Trellis Code Modulation decoder (213), channel state information indicating temporal reliability of received symbols is utilized, along with the received symbol information and the Trellis Coding rules themselves, to facilitate a most probable symbol determination. The channel state information may be received signal strength indication information. The latter can be additionally processed by, for example, time delay compensation (401), normalization (403), morphological erosion (404), linearization (406), and/or through static channel detection (408).

Abstract: In order to maintain low-splatter in a peak-to-average reduction for a linear communication system, a method of windowed-clipping is used. When a sample of input signal is determined to be above a predetermined threshold, a signal peak is found and an attenuating window is centered at the peak. The attenuating window is applied to the input signal.

Abstract: A communication resource allocator of a trunking communication system may more efficiently handle service requests during extremely busy times in the following manner. While receiving service requests from communication units, the communication resource allocator determines whether it can process the service request within a predetermined period of time. If the communication resource allocator cannot process the service request within a predetermined period it generates a global system busy which indicates that the communication resource allocator cannot individually process or acknowledge additional service requests. Having generated the global system busy signal, the communication resource allocator transmits it to the plurality of communication units. The communication units process the global system busy signal such that they will not transmit nonpriority service requests during the duration of the global system busy signal.

Abstract: A call box (201) provides vandal-resistant operation by using a concealed magnetic switch and magnet (179) and specially locked compartments (101 and 103) in a heavy duty structure. The concealed magnetic switch determines the position of a handset (119) within the call box (201). When the handset (119) is removed from its resting position, a radio (129) within the call box (201) responds when a pushbutton (127) within the call box (201) is pressed. When the pushbutton (127) is pressed, telephone service is provided via a radio (129) to a preprogrammed phone number, such as the highway patrol for a call box (201) located on a highway, to handle situations such as a malfunctioning vehicle.

Abstract: In a communication system network, the central controller may more efficient respond to group regrouping requests in the following manner. Once a console generates a dynamic group regrouping request which requests the regrouping of a set of communication groups into a super group, the central controller determines, for each communication system, whether at least one of the set of communication groups is registered in that communication system. When at least one of the set of communication groups is registered in the communication system, the central controller groups the at least one of the set of communication groups into a local super communication group. Having done this, the central controller then generates super communication group information and transmits it to the communication systems but only that portion that pertains to the local super communication group.

Abstract: A communication resource is subdivided as a function of time into a plurality of time slots (210). These time slots are further subdivided on a non-periodic basis into a least two random access sub-slots (220), during which communication units (101) may request one or more reserved time slots (240). In response to such requests for reserved time slots from a requesting communication unit during one of the random access sub-slots, one or more reserved time slots are provided for use by the requesting communication unit.

Abstract: In a communication system network that includes a processing multiplexer and a plurality of communication systems, wherein each of the communication systems includes a plurality of signal sources, a plurality of signal destinations, and a processing interface means and wherein the processing multiplexer includes system data database means that stores information pertaining to communication system configuration data, a method for maintaining the system data database is described. Maintaining the system data database means comprises querying the processing multiplexer interface means of at least one communication system for information pertaining to communication system configuration data. Upon receiving the information, allocating entries in the system data database means for the information pertaining to communication system configuration data and entering the information into the allocated entries.

Abstract: An originator of a communication (110) selects from among a set of candidate displayable source indicators, which displayable source indicators can include both a unit ID and alias IDs, and then attempts to initiate a communication with a recipient communication unit (111). The attempt to initiate communication includes transmission of information, including the selected displayable source indicator. This allows a transmitting communication unit to most appropriately identify itself to a receiving communication unit.