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Section 3 26 uvpacket
Choose UVPACKET from the DIGITAL row. UVPacket is not one of the WSJT
weak-signal modes: it is a packet protocol for private amateur VHF/UHF
groups, carried as a short π/4-DQPSK burst. Where FT8 and its relatives carry a
<to> <from> <grid> message, a UVPacket frame carries an application byte
pipe — the sender's own data, tagged with a small application number and a
sequence number and split into 1–32 blocks of twelve bytes. What is inside is up
to the group using it: a sentence, a short status line, or a packed binary
struct.
Where it is. Anywhere a group has agreed a channel — typically on VHF/UHF, where a 1200-baud packet burst fits a narrow FM or SSB voice channel. There is no calling frequency and no band plan; tune the dial to the group's channel. The modem's tones sit 800–2600 Hz above the dial, so the panel's decoder searches a fixed audio window regardless of the cursor.
What you see. Two panes. FRAMES is the rolling list of what has been decoded — time, sub-mode, application number, sequence, payload size and SNR — and FRAME is the one selected, with every header field and the payload shown two ways: as text when it is printable, and always as a hex dump. The sub-mode (Robust, Standard, Ultra, Express) is detected from the preamble, so there is nothing to choose: each frame is labelled with the one it arrived at.
Frames are not slotted. Unlike every other mode in this chapter, a UVPacket frame can begin at any instant, so there is no clock to watch and no turn headers. The receiver keeps a rolling window of the last several seconds of audio and re-scans it, so a frame appears a moment after it ends. A frame that arrives twice is shown once; a repeated transmission more than a few seconds later is a new frame.
Receive only. Transmit is not wired in this build: UVPacket is a byte pipe whose contents are the application's, and this program has no application to put in it. The panel decodes what the group is sending.
From the User Manual. Home.