How to use PB and PG


PB is used for download of files from the digital satellites (AO-16, LO-19, KO-23, etc.) and features automatic directory updates, rules based download of files and commands for manually requesting download of wanted files. PB uses the broadcast protocol, an AX.25 application developed specifically for the pacsats.

As PB ‘listens’ to the transmissions from the satellite, it receives all broadcast packets and builds directories and partial files in the current directory. If the contents of the ‘subject’ line of a directory entry matches the download request file (see later), PB sends a download request for the particular file to the satellite. This download request may also be forced with the utility ‘filerequest’ (see later). Partially downloaded files are stored with the extension .act. When the file is complete, the extension is changed to .dl. Information on the missing parts (the ‘holes’) is stored in a file with the extension .hol. Directory entries are stored in files having names such as pb__001.pfh. The file pfhdir.hol contains a list of the ‘holes’ in the directory. Each directory file is approx. 25 KB long.

PB does not produce any visible output – except possible error messages. Instead it listens on a control FIFO (/etc/pbpg/pb-fifo).  If it receives a monitor command on this FIFO, it will begin transmitting status and other data on another FIFO specified in the monitor command. Please refer to the section on PBCTRL in README

Details on the control of PB is found in the document ‘Controlling_PB’.


PG is used for upload to the satellites and it uses the FTL0 protocol for
the upload.

Files for upload must have a proper FTL0 header added. This can be done with utilities such as ‘pfhadd’ from the PacsatTools package by John Magliacane, KD2BD. Pfhadd will give the upload file the required extension .out.

When launched, PG scans the current directory for partially uploaded files (files having extension .pul) and new files to upload (files with extension .out). It then tries to establish a link to the satellite, either immediately or, if so configured with the MAXWAIT parameter, when it hears the satellite. If successful, the file is uploaded and PG searches the current directory for the next file to upload. If unsuccessful, PG waits for a BBSTAT message with contents ‘Open’. When this message is heard, the program re-attempts to establish a link to the satellite.

This continues until either all files are uploaded or nothing is heard
from the satellite within a configurable time. In both cases the program terminates normally.

A successfully uploaded file is given the extension .ul. 

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