Abstract: A novel and useful mechanism for detecting intrusion and jamming attempts by an imposter node. A time window defined as an emergency window is reserved after the end of a packet and before an acknowledgement window. Nodes that detect the presence of an intruder transmit an emergency packet during the emergency time window to inform the receive node that the packet it received was sent from an imposter node. Attempts to jam the transmission of the emergency packet from the victim node to the receive node are detected by listening during the emergency window time period for carrier signal that indicates that an emergency packet is trying to be sent. An emergency packet request message is sent by the receive node in response which causes the victim node to resend the emergency packet.

Abstract: A method and apparatus for performing a radix-4 fast Hadamard transform (FHT) with reduced complexity and for directly determining the maximum output of a fast Hadamard transform using either a radix-4 transform or radix-2 transform without actually generating the outputs. The radix-4 fast Hadamard transform is implemented using only seven operations. To find the maximum value of the output of a fast Hadamard transform and its corresponding index, the N?1 stages of a conventional N stage fast Hadamard transform are computed while a find-maximum stage is inserted in place of the Nth stage. The invention also provides a methodology for constructing fast Hadamard transforms of the form H2N using radix-4 FHTs and permuting the results to achieve the correct outputs.

Abstract: A method and apparatus for performing a radix-4 fast Hadamard transform (FHT) with reduced complexity and for directly determining the maximum output of a fast Hadamard transform using either a radix-4 transform or radix-2 transform without actually generating the outputs. The radix-4 fast Hadamard transform is implemented using only seven operations. To find the maximum value of the output of a fast Hadamard transform and its corresponding index, the N-1 stages of a conventional N stage fast Hadamard transform are computed while a find-maximum stage is inserted in place of the Nth stage. The invention also provides a methodology for constructing fast Hadamard transforms of the form H2N using radix-4 FHTs and permuting the results to achieve the correct outputs.

Abstract: An apparatus for and method of generating normalized soft decision information output from an inner decoder (i.e. equalizer) in a communications receiver. The invention is operative to normalize the soft decision information before it enters a soft outer decoder. The normalization is performed using a noise power estimate that is dynamically calculated in response to changing noise statistics on the channel. The normalized soft decision output is then applied to the soft outer decoder thus realizing maximum performance therefrom. The noise power estimate is derived from the training sequence and/or the data portion of the received signal. Both types of estimates are calculated. A binary or smoothly weighted average is calculated using both types of estimates. The weighting factor is determined based on one or more performance metrics, such as the Signal to Noise Ratio (SNR).

Abstract: A novel and useful apparatus for and method of securely downloading and installing a patch program in a processing device. Each processing device is assigned a unique key embedded therein during manufacture and has knowledge of a shared key. The program patch is encrypted using the shared key and transmitted over a communication link, such as a satellite radio link, to each device. The patch is decrypted using the shared key and re-encrypted using the unique key known only to the device itself. The re-encrypted patch program is stored in nonvolatile memory and upon reset of the device, the encrypted patch contents are read out of the nonvolatile memory, decrypted using the unique key and loaded into patch memory for execution by the processing device.