SDR for Linux 0.5.1

SDR for Linux 0.5.1

A control-surface release: two VFOs, CTUN, the filter and AGC controls in their own dialogs, a draggable spectrum/waterfall divider and the TX filter drawn on the TX display. Everything below was run live on the ANAN G2E over the past week.

Two VFOs

• A/B and A=B — the classic rig model: A/B swaps what you hear, tune and transmit on, A=B copies the active VFO into the other one. The other VFO reads under the frequency readout (VFO B 7.025.000 · CW) with the two buttons right after it; key b = A/B. The other VFO is free across bands; both persist.

CTUN

• With CTUN on (strip button after BIN), dragging the spectrum pans the DDC centre while the RX dial stays where it is; the green passband is the tuning handle — drag it, wheel over it, double-click to recentre. The offset lives in the WDSP receiver shifter as in piHPSDR, so the TCI IQ stream stays the raw DDC.

Filter and AGC dialogs

• The Filter and AGC dropdowns are gone from the top strip. Two header-bar icons (left of the menu) open the Filter dialog — a passband graph you drag by its edges or as a whole, the mode's presets and Var1/Var2, Low/High rows — and the AGC dialog — Off/Long/Slow/Med/Fast with the hang/decay of the chosen one, a live gain bar and AGC-T mirroring the footer slider. The readout's filter and AGC texts open them too.
• Any preset's edges drag on the spectrum; a dragged preset becomes Var1 with the preset untouched. LSB, CWL and DIGL filters now read as audio Hz, low to high, in the readout and the dialog.
• The frequency readout is plain white text at the top-left (frequency, VFO, band, mode, passband, AGC, the other VFO); the S-meter stays top-right.

Display

• Draggable spectrum/waterfall divider — persisted as a fraction so resizes keep the proportion; double-click on the line resets to 50/50.
• TX filter footprint in red on the TX spectrum and, with "Filter on waterfall", on the TX waterfall; CW and TUNE show the carrier line only, RTTY the FSK pair. RX is green and TX is red throughout the display now.
• The AF slider's floor is a true mute (asked for by FT8 operation, where the side-listen only annoys).
• 60 m starts in USB, with a one-time migration of the saved per-band levels.

Fixes

• The receiver no longer dies when the process is paused (a debugger, SIGSTOP, any ptrace stop): the Protocol 2 listener treated the EINTR of its timed socket as a dead link, stopped the keepalives, and the radio's watchdog stopped streaming — display frozen, process alive. It now rides the pause out and the radio re-arms itself on the next keepalive.
• Discovery keeps one entry per radio even when it answers on several interfaces (link-local included) and the data socket binds on the in-subnet interface — no more 169.254.x.x data links behind a radio that also has a proper address.
• The TX over-stats log line reports mic counters only for overs that actually used the mic (no phantom "mic drops" after TUNE).

TCI

• dds and vfo are broadcast immediately on every tuning step, so skimmers and loggers follow the dial without waiting for the periodic tick.
• Opt-in IQ centre stamps — the per-block DDC centre and the retune boundary in the stream header — for a CTUN-aware skimmer.

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Downloads: AppImage (any distro), .deb (Ubuntu 24.04+ / Debian 13+), .rpm (Fedora 40+). Arch users: sdr-for-linux on the AUR. The headless probes (sdrfl-*probe) are dev-tree binaries — build from source for those.