Abstract: A network audio feed source terminal, for coupling units of audio content from an audio source to a network. The feed terminal includes a source interface that receives audio content from the audio source and a content monitor that identifies audio content in accordance with monitoring criteria. The feed terminal also includes a means for capturing a selected portion of the identified audio content as units of audio content in accordance with capture criteria, and, a network interface that couples the units of audio content into the network.

Abstract: A system and method of communicating audio through a network. The method includes detecting audio content from an audio source by a first network terminal, sending a directory packet including a network address of the detected audio content to a second network terminal, and requesting the audio content through the network by the second audio terminal. The further step of storing the detected audio content in a buffer for audio packets identified by packet identities may be added. The sending a directory packet step may include sending a packet identity, and the requesting step may include specifying an audio packet according to the packet identity. A further step of sending a source packet including the network address of the detected audio content to a network directory server by the first network terminal may be added. The network directory server may execute the sending a directory packet step.

Abstract: A network audio receive terminal. A receive terminal includes a network interface that receives network packets and a network packet scanner coupled to the network interface that sequentially scans received network packets in accordance with scan criteria. A content selector is coupled to the network packet scanner, and selects network packets containing units of audio content from the scanned network packets based on selection criteria, including pertinence data. An audio content processor is coupled to the content selector, and processes the audio content in the selected network packets. The network packets may include directory packets containing audio content addresses, in which case, the content selector further selects directory packets based on selection criteria. An audio packet requestor requests audio packets through the network identified by the audio content addresses that correspond to the selected directory packets.

Abstract: The invention provides an apparatus and a method for determining the frequency of a radio frequency signal. The coherency of a received signal is determined and only the frequency of a coherent signal is determined. Zero amplitude transitions of coherent signals are counted in respective time periods. If the counts in each time period agree within a quantization error, the accumulated counts for a fixed time period are employed to determine a frequency. The frequency determining apparatus and method are particularly useful with a frequency agile radio receiver for detecting the presence of radio frequency signals from nearby mobile and stationary transmitters. Upon determination of the frequency of the nearby transmitter, the channel of transmission can be determined from a memory within the receiver and the receiver can be tuned to monitor the transmission. Additional tests to verify the frequency determination may be applied using squelch and window detector circuits of the radio receiver.

Abstract: A system and method of communicating audio through a network. The method includes detecting audio content from an audio source by a first network terminal, sending a directory packet including a network address of the detected audio content to a second network terminal, and requesting the audio content through the network by the second audio terminal. The further step of storing the detected audio content in a buffer for audio packets identified by packet identities may be added. The sending a directory packet step may include sending a packet identity, and the requesting step may include specifying an audio packet according to the packet identity. A further step of sending a source packet including the network address of the detected audio content to a network. directory server by the first network terminal may be added. The network directory server may execute the sending a directory packet step.

Abstract: A method and apparatus provide for monitoring radio frequency signals and, in conjunction with the monitoring, determining frequency of a received dominant radio frequency signal. Zero amplitude transitions of the signal are counted in primary and secondary sampling periods to determine frequency and frequency stability. The method and apparatus can be used to tune to radio frequency signals having frequencies in a list of frequencies to be monitored and detecting signals in the radio frequency spectrum on other frequencies. The monitoring and scanning may occur simultaneously, sequentially, or in any order or sequence. The frequencies of dominant signals received are determined and added to the list for monitoring. The receiver may be tuned to a frequency determined immediately upon determination of the frequency determined, after storage of the frequency determined, only after a signal on the currently monitored frequency terminates, or upon other conditions.

Abstract: A method and apparatus provide for monitoring radio frequency signals and, in conjunction with the monitoring, determining frequency of a received dominant radio frequency signal. Zero amplitude transitions of the signal are counted in primary and secondary sampling periods to determine frequency and frequency stability. The method and apparatus can be used to tune to radio frequency signals having frequencies in a list of frequencies to be monitored and detecting signals in the radio frequency spectrum on other frequencies. The monitoring and scanning may occur simultaneously, sequentially, or in any order or sequence. The frequencies of dominant signals received are determined and added to the list for monitoring. The receiver may be tuned to a frequency determined immediately upon determination of the frequency determined, after storage of the frequency determined, only after a signal on the currently monitored frequency terminates, or upon other conditions.

Abstract: The invention provides an apparatus and a method for determining the frequency of a radio frequency signal. The coherency of a received signal is determined and only the frequency of a coherent signal is determined. Zero amplitude transitions of coherent signals are counted in respective time periods. If the counts in each time period agree within a quantization error, the accumulated counts for a fixed time period are employed to determine a frequency. The frequency determining apparatus and method are particularly useful with a frequency agile radio receiver for detecting the presence of radio frequency signals from nearby mobile and stationary transmitters. Upon determination of the frequency of the nearby transmitter, the channel of transmission can be determined from a memory within the receiver and the receiver can be tuned to monitor the transmission. Additional tests to verify the frequency determination may be applied using squelch and window detector circuits of the radio receiver.

Abstract: A method and apparatus for passively monitoring communications in a trunked communication system. Digital messages transmitted over a control channel at a particular frequency are monitored with a receiver. Transmitted communication signals are demodulated and stored. The stored signals are tested to identify messages and to extract talk group and channel assignment codes. If the talk group is a talk group of interest, the receiver is tuned to the frequency corresponding to the channel assignment code so that voice communications are monitored. The receiver is tuned to the control channel after each voice communication so that a communication including multiple transmissions on different frequencies is coherently monitored by retuning the receiver in accordance with the received channel assignment codes. In an alternative embodiment, separate receivers are provided for the control channel and for voice communications.

Abstract: A method and apparatus for passively monitoring communications in a trunked communication system. Digital messages transmitted over a control channel at a particular frequency are monitored with a receiver. When a first bit pattern is detected in a digital message, subsequently transmitted data is stored. Information is extracted from the stored data to obtain a channel assignment code indicating a frequency over which communications take place and a talk group identification code identifying a talk group in the trunked communication system participating in a communication. If the talk group is a talk group of interest, the receiver is tuned to the frequency corresponding to the channel assignment code so that voice communications are successfully monitored.