Paul Hardy Alexander

US Patent:

6487294, Nov 26, 2002

Filed:

Mar 9, 1999

Appl. No.:

09/264867

Inventors:

Paul F. Alexander - Potomac MD 20854

International Classification:

H04K 100

US Classification:

380270, 380 30, 713168

Abstract:

A secure satellite communications system for mobile users. The secure satellite communications system includes an orbiting communications satellite which performs the function of relaying communications to and from a plurality of earth stations. The secure satellite communications system provides a public key system for satellite communications systems to establish private communications. Communications messages are sent by a transmitting earth station encrypted by a public encryption procedure for a particular receiving earth station. The public encryption procedures are broadcast along with other system status and operational information on a common signaling broadcast channel. The receiving earth station utilizes a private decryption procedure to decrypt the received communications messages. The receiving earth station also validates the transmitted communications messages received by the receiving earth station by utilizing a cyclic redundancy check on the received communications messages.

US Patent:

6529547, Mar 4, 2003

Filed:

Sep 20, 1999

Appl. No.:

09/214065

Inventors:

Paul Francis Alexander - Potomac MD
David John - Buckinghamshire, GB

Assignee:

International Mobile Satellite Organization - London

International Classification:

H04Q 120

US Classification:

375224, 375219, 375220, 340605, 340620

Abstract:

Digital audio recording equipment is used to record modulated signals, such as the RF test signals generated by test modems. If the modulated signals are outside the audio frequency range, they are down-converted into the audio frequency range using a mixer, local oscillator and a filter. The digitally converted data are recorded onto a suitable medium, such as a DAT, CD or a computer memory. The data is then disseminated for reproduction by a suitable digital audio player. The reproduced audio signal may be up-converted to the desired radio frequency using a mixer, local oscillator and a filter. The reproduced signal may be used to test demodulators, codecs or transceivers. The signals output by the transceiver and the reproduced signal may be recorded on different channels of the digital audio recording equipment. The recording equipment may be used to capture RF signals for later analysis. The player may be used for reproducing modulated signals for broadcast.

US Patent:

20030012306, Jan 16, 2003

Filed:

Sep 17, 2002

Appl. No.:

10/244427

Inventors:

Paul Alexander - Potomac MD, US
David John - Buckinghamshire, GB

Assignee:

International Mobile Satellite Organization - London

International Classification:

H03K009/00

US Classification:

375/316000

Abstract:

Digital audio recording equipment () is used to record modulated signals, such as the RF test signals generated by test modems. If the modulated signals are outside the audio frequency range, they are down-converted into the audio frequency range using a mixer (), local oscillator () and a filter (). The digitally converted data are recorded onto a suitable medium, such as a DAT, CD or a computer memory. The data is then disseminated for reproduction by a suitable digital audio player (′). The reproduced audio signal may be up-converted to the desired radio frequency using a mixer (), local oscillator () and a filter (). The reproduced signal may be used to test demodulators, codecs or tranceivers. The signals output by the transceiver and the reproduced signal may be recorded on different channels of the digital audio recording equipment (). The recording equipment () may be used to capture RF signals for later analysis. The player (′) may be used for reproducing modulated signals for broadcast.