CDMA communications and geolocation system and method

A spread-spectrum communications and geolocation system for communicating message data comprising:

• a generic-chip-code generator for generating a generic-chip-code signal;
• a spread-spectrum modulator for spread-spectrum processing the message data, synchronized with the generic-chip-code signal, as spread-spectrum-processed-message data;
• a combiner for combining the generic-chip-code signal with the spread-spectrum-processed-message data, thereby generating a code-division-multiple-access (CDMA) signal;
• a transmitter for transmitting, using radio waves traversing free space, the CDMA signal over a communications channel;
• a detector, coupled to said communications channel, for detecting the generic-chip-code signal embedded in the CDMA signal, said detector including,
• a receiver-generic-chip-code generator, synchronized to the detected-generic-chip-code signal, for generating a replica of the generic-chip-code signal;
• a message-chip-code generator for generating, synchronized to the replica of the generic-chip-code signal, a message-chip-code signal;
• a product detector for mixing the message-chip-code signal with a received CDMA signal to generate a detected spread-spectrum signal;
• a bandpass filter for filtering the detected spread-spectrum signal;
• a data detector, synchronized with the replica of the generic-chip-code signal, for detecting message data in the detected spread-spectrum signal;
• and
• a range delay circuit, responsive to timing between the detected-generic-chip-code signal and the replica of the generic-chip-code signal, for determining a range between the transmitter and the detector.

A spread-spectrum communications and geolocation method for communicating message data, comprising the steps of:

• generating a generic-chip-code signal;
• synchronizing the message data with the generic-chip-code signal;
• spread-spectrum processing the message data as a spread-spectrum-processed-message data;
• combining the generic-chip-code signal with the spread-spectrum-processed-message data, thereby generating a code-division-multiple-access (CDMA) signal;
• transmitting, using radio waves traversing free space, the CDMA signal from a transmitter over a communications channel;
• detecting, from the communications channel on a receiver, the generic-chip-code signal embedded in the CDMA signal;
• generating, synchronized to the detected-generic-chip-code signal, a replica of the generic-chip-code signal;
• generating, synchronized to the replica of the generic-chip-code signal, a message-chip-code signal;
• mixing the message-chip-code signal with a received CDMA signal to generate a detected spread-spectrum signal;
• filtering the detected spread-spectrum signal;
• detecting, synchronized to the replica of the generic-chip-code signal, message data in the detected spread-spectrum signal;
• and
• determining, using the detected-generic-chip-code signal and the replica of the generic-chip-code signal, a range between the transmitter and the receiver.

A spread-spectrum communications and geolocation method for communicating message data and determining range between a remote unit and a base station, comprising the steps of:

• generating a base-generic-chip-code signal;
• synchronizing base message data with the base-generic-chip-code signal;
• spread-spectrum processing the base message data as a spread-spectrum-processed-message data;
• combining the base-generic-chip-code signal with the spread-spectrum-processed-message data, thereby generating a code-division-multiple-access (CDMA) signal;
• transmitting, using radio waves traversing free space, the CDMA signal from the base station over a communications channel;
• detecting, from the communications channel at the remote unit, the base-generic-chip-code signal embedded in the CDMA signal;
• recovering, at the remote unit, the base message data communicated from the base station;
• generating, at the remote unit, synchronized with the detected-base-generic-chip-code signal, a remote-generic-chip-code signal;
• spread-spectrum processing remote message data as a spread-spectrum-processed-remote message data;
• combining the remote-generic-chip-code signal with the spread-spectrum-processed-remote message data, thereby generating a remote code-division-multiple-access (CDMA) signal;
• transmitting, using radio waves traversing free space, the remote CDMA signal from the remote unit over a communications channel;
• detecting, at the base station, the remote-generic-chip-code signal embedded in the remote CDMA signal;
• recovering, at the base station, the remote message data communicated from the remote unit;
• and
• comparing a timing between the base-generic-chip-code signal and the detected remote-generic-chip-code signal to determine a range between the base station and the remote unit.

A spread-spectrum communications and geolocation method for communicating message data and determining range between a remote unit and a base station, comprising the steps of:

• generating a base-generic-chip-code signal;
• synchronizing base message data with the base-generic-chip-code signal;
• spread-spectrum processing the base message data as a spread-spectrum-processed-message data;
• combining the base-generic-chip-code signal with the spread-spectrum-processed-message data, thereby generating a code-division-multiple-access (CDMA) signal;
• transmitting, using radio waves traversing free space, the CDMA signal from the base station over a communications channel;
• detecting, from the communications channel at the remote unit, the base-generic-chip-code signal embedded in the CDMA signal;
• recovering, at the remote unit, the base message data communicated from the base station;
• spread-spectrum processing remote message data as a spread-spectrum-processed-remote message data;
• combining the detected base-generic-chip-code signal with the spread-spectrum-processed-remote message data, thereby generating a remote code-division-multiple-access (CDMA) signal having a relayed detected-base-generic-chip-code signal;
• transmitting, using radio waves traversing free space, the remote CDMA signal from the remote unit over a communications channel;
• detecting, at the base station, the relayed-detected-base-generic-chip-code signal embedded in the remote CDMA signal;
• recovering, at the base station, the remote message data communicated from the remote unit;
• and
• comparing a timing between the base-generic-chip-code signal and the relayed-detected-base-generic-chip-code signal to determine a range between the base station and the remote unit.