Bulletins from the Pacific Packet Radio Society - page 178

Direct ground station link thru PACMMS.

PACMMS acts as a node in a local area network. Ground stations are connected to each other thru the network in real-time.

Telemetry

PACMMS supplies telemetry to the control unit and receives telemetry from the control unit for storage in files or immediate transmission on the data link. PACMMS will supply the ability to send data on the downlink in a broadcast mode, i.e. not to any specific ground station.

Ground stations

PACMMS also lives on the ground. Commands to PACMMS will be parsed on the ground to reduce comm-link requirements. A token language to communicate with satellite resident PACMMS will be developed. PACMMS will be optimized to work with its own ground software, but some less robust interface should be provided to those wishing to develop their own ground software. Access via the simpler interface will not be permitted to adversely affect users of the full ground station software however.

Data compression.

PACMMS ground stations will compress data before transmission and decompress during reception to reduce comm-link loading. A compression standard must be agreed upon and added to the protocol definition. The standard compression must be used when sending commands to PACMMS but any method may be used for data destined for files or store and forward packets. Control and address fields in packets should not be compressed.

Security

PACMMS will provide password security for messages and files. Options include password required to LIST/READ and password required to delete. This will guard against accidental deletion and supply protection against malicious deletion from all but those ground stations with can hear your uplink signal.

Capability must be provided for a "system administrator" to delete messages and files regardless of password protections. One solution is to require that privileged commands be sent thru the control link to "unlock" the data base for a particular user.

Following is a first shot at breaking the PACMMS software down function areas for the purposes of phased development by different groups of developers. Each line item could be a separate task and in most cases can be broken down into several sub tasks.

1 Satellite resident

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