Scanline Studio User Guide

Getting started

Welcome to Scanline Studio

Scanline Studio is a cross-platform amateur-radio application for receiving, preparing, transmitting, organizing, and logging analog SSTV pictures. It is a ground-up rewrite of YONIQ, an MMSSTV fork, with a modern audio, CAT, image, and logbook workflow.

The four main tabs

Getting started

What you need

The exact station varies, but a typical on-air setup contains these parts.

• A Windows, Linux, or macOS computer with Scanline Studio installed.
• A sound input carrying the radio's received audio.
• A sound output connected to the radio's transmit audio input.
• An amateur-radio transceiver suitable for the SSTV activity you plan to use.
• A legal station licence and operating privileges for your frequency, mode, and location.
• Optional CAT/PTT control through linked Hamlib, rigctld, or flrig.

CAT is optional. With None (no radio control) selected, you can still receive and generate TX audio, but you must tune and key the radio outside Scanline Studio.

Getting started

First-time setup

Complete the audio and station steps first. Add CAT control only if you want Scanline Studio to read and control the radio.

1. Open Options from the main menu.
2. On Audio, choose the capture device connected to RX audio and the playback device connected to TX audio.
3. Leave the sample rate at its default unless you have a specific DSP-rate requirement. A measured transmit sound-clock correction belongs in TX clock offset, not Sample rate. Choose the correct stereo capture source if your interface exposes two channels.
4. On Station, enter your callsign, name, and Maidenhead grid square. These values feed templates and log records.
5. On General, choose your language and review the storage locations.
6. If you use CAT, configure and test it on Radio / CAT. See Radio and CAT setup.
7. Select Save.

Options tabs at a glance

Getting started

Tour of the workspace

The fixed main window keeps station state at the top and task-specific tools in four tabs below.

Menu bar

Header and transceiver controls

• Frequency and mode show the connected radio's current state. You can request a frequency or supported radio mode when CAT is linked.
• Favourites recall a stored frequency, mode and filter bandwidth in one action. Use Store current or Edit list… to manage them. See Radio and CAT control for how the bandwidth part behaves.
• Calling frequencies (the ▾ button right of the frequency) lists popular SSTV and HamDRM calling frequencies by band. Picking one tunes the radio and sets its mode and filter width. See Radio and CAT control.
• RX level shows live capture level. Avoid a permanently low reading and avoid red clipping.
• Pwr is the application's TX playback gain. It is not the operating system's device volume, and not the radio's RF power setting. It keeps a separate level for SSTV and for HamDRM: the label (Pwr · SSTV or Pwr · HamDRM) follows the mode selected on the Transmit tab and shows which level you are setting.
• Receiving starts or pauses SSTV search. Capture pauses automatically during a Scanline Studio transmission and resumes afterwards. The label reads Transmitting for that whole window (a real Transmit or a Tune tone), then returns to Receiving once it finishes. Otherwise the label switches to RX Muted whenever capture is stopped. It blinks amber and reads Decoding while an image is being decoded. The blink can be turned off in Appearance options. The matching status-bar chip does the same, so the transmitting and decoding state is visible from any tab, not only Receive.
• Stop TX, next to Receiving, cancels an in-progress transmission immediately. It is always visible, regardless of which tab you're on, so it is reachable without switching to the Transmit tab first.

Status indicators

CAT linked

The configured radio backend is connected.

TX ERROR

The last transmit attempt ended in an error or automatic SWR cutoff. It reports the last outcome. It does not permanently lock out the next attempt.

Line, slant, buffer, frames today, log entries

Compact operating telemetry for the current session.

Receiving

Receive your first picture

Scanline Studio normally identifies the incoming mode from its VIS header and fills the image from top to bottom as lines arrive. See Supported SSTV modes for the full list of modes it recognizes.

1. Tune the radio to the SSTV activity and select the correct sideband and filter.
2. Confirm the RX meter responds without spending much time in the red clipping range.
3. Confirm the header's Receiving toggle is on (it starts on by default), then on Receive set Auto-detect to Listening. Both are needed: Receiving controls audio capture, Auto-detect controls whether the decoder searches that audio.
4. Wait for a valid header. The detected mode, line progress, and incoming image update automatically.

If the sender's header is missing or damaged, use a quick-mode button in the MODE card on the Receive tab to force the next decode into that mode. Right-click a slot for two more options. Hold this mode locks every following reception to that mode and ignores the sender's VIS header until you select Release. Reassign this slot points the slot at a different mode.

Actions on the incoming frame

• Export frame… exports the current image to a location you choose.
• Abort abandons the current reception and returns to searching.
• Decode WAV… selects recorded audio and runs it through the decoder again.
• Copy to TX sends the received picture to the Transmit workspace.
• Log QSO begins a log entry associated with the reception.
• Record saves incoming audio for later diagnosis or re-decoding.

Receiving

Reception controls and telemetry

The Receive tab shows what the decoder is doing. You rarely need to adjust anything here.

Stations heard and worked-before

• Stations heard is a running list of identification the application has automatically read from FSK or CW sent around other stations' pictures. No action is needed from you. Each line shows the decoded identification (a callsign, or a full CW text such as "DE W1AW"), whether it came from FSK or CW, the time in UTC, and the SSTV mode, newest first, up to the most recent 20. Turn FSK or CW decoding on or off in Station identification.
• Worked before checks the current reception's callsign against your logbook and shows either New station or the band and date of your most recent prior contact with it. Once you have logged that callsign more than once, a count appears in front. It is a quick heads-up, not a substitute for checking your log before claiming a new one.

Frame metadata

The FRAME METADATA card next to the incoming picture shows the current reception's Callsign, NR/RST, CW ID, Name/QTH/Grid from QRZ.com, Frequency, Mode/VIS, Started time, and file size, plus a per-frame Note and Flag.

The callsign fills automatically from decoded FSK or CW identification. If it decoded wrongly or not at all, type it into Override callsign, then select Lookup QRZ to pull name, QTH, and grid. This requires QRZ.com to be configured in Options.

Sync & slant

• Source reports whether the decoder is searching, locked, or in AVT training.
• Slant ppm estimates sound-clock mismatch that would tilt the picture.
• Re-sync asks the decoder to reacquire line timing.
• Correct slant redraws buffered lines using the current correction when buffering is enabled.
• Squelch level changes how strong a signal must be before it is treated as SSTV. Higher settings reduce false decodes but can miss weak signals.

Input chain

• BPF controls RX band-pass sharpness. Wide is the recommended starting point. Sharper filters reject adjacent interference but tolerate less drift. Despite its name, Normal switches the filter off entirely. The same setting is in Options → Decode (see Decode options). A mid-picture change waits until that reception ends.
• Notch suppresses a narrow interfering tone. Click the spectrum trace to choose its frequency, then switch it on. It is off by default, and it is not remembered between sessions.
• Leave the notch off unless you can actually see a carrier in the spectrum. It is a narrow filter placed inside the signal band, so it removes picture along with the interference. That trade is worth making against a real carrier and is a pure loss without one. Switch it off again once the interference goes away.
• AGC gain, buffer, XRUN, and clipping help diagnose the audio path.

DSP

• AFC switches automatic frequency control on or off. It is on by default. AFC measures the sync tone and shifts the decode back toward its nominal frequency, which corrects a station that is tuned slightly off. Switch it off if you suspect AFC is locking onto interference instead of the signal.
• The change applies during the current picture. From the next line onward the correction is no longer added, and the tone detectors return to their nominal frequencies. Lines already decoded keep the correction they were given.
• While AFC is off, the Sync tone row on the Signal quality card shows a dash, because no correction is being measured.
• AVT mode never uses AFC, whatever this is set to.

Signal quality: SNR

The SNR row on the Signal quality card, and the SNR chip in the status bar while a picture is being received, show the signal-to-noise ratio of the incoming signal in decibels. Higher is better. As a guide from real off-air recordings: readable pictures measured about 5–14 dB, and pictures that were pure noise measured below 0 dB. Use it to compare pictures and conditions rather than as a fixed pass mark.

• It is measured on the sync pulse of every line (in most modes at the start of the line; in Scottie modes in the middle). That pulse is a steady tone, so the application can separate the tone from the noise around it. The noise is counted over a fixed 400–2500 Hz reference band, which contains the whole SSTV signal.
• The live figure is the median over the last 16 lines. When the picture ends, one figure for the whole picture (the median over all of its lines) is stored with the image and shown in the Gallery.
• Readings below −10 dB show as < −10 dB and above 50 dB as > 50 dB.
• It shows a dash while idle, when Measure reception SNR is off in Options → Decode (see Decode options), during the first lines of each picture while the sync pulse is being located, and in AVT mode, which has no sync pulses.
• It measures only. Decoded pictures are identical with it on or off.
• With Auto-slant off, a large sound-card clock error can make the sync pulse drift away from where it is measured. The figure then reads low or disappears. Switch Auto-slant back on.

Receiving

Spectrum and waterfall

The spectrum shows the current audio-frequency distribution. The waterfall adds time history. These displays help you see an SSTV signal, interference, drift, and clipping symptoms.

Clicking the spectrum selects the RX notch frequency. The notch affects the decoder input. The plotted spectrum and waterfall do not show the filtered result. Use Peak hold to tell a carrier from picture content: a carrier holds one frequency, and picture content does not.

Receiving

Record and re-decode audio

Audio recordings let you retry a marginal reception and preserve evidence for troubleshooting.

1. Select Record on the Receive tab before or during the signal you want to preserve.
2. Select Stop recording when finished.
3. Choose Tools → Decode WAV file… or the frame's Decode WAV… action.
4. Select the WAV file and monitor the Receive tab as the decoder replays it. When HamDRM receive is on, the same replay also decodes any HamDRM transmission in the file.

Try a forced quick mode only when you know the transmitted mode and the replay does not acquire it automatically. If the original recording clipped or omitted the signal, re-decoding cannot restore the missing audio.

Transmitting

Transmit a picture

Prepare the picture and radio before keying. The editor produces the exact pixel dimensions required by the selected SSTV mode. To send digitally with HamDRM (EasyPal) instead, see Send a picture with HamDRM (EasyPal).

1. On Transmit, select a mode (see Supported SSTV modes for the full list) or leave mode following on Auto to reply in the last received mode.
2. Use Browse…, a stock image, a received image, or the blank editor as your source.
3. Crop, adjust, and add template elements.
4. Confirm the output device, duration, identification, Pwr level, and radio state. Then select the big TRANSMIT button to apply your edits and start sending in one step. With the CAT backend set to None, Scanline Studio sends no keying command. See What you need for keying the radio yourself.

During transmission, progress shows percentage and remaining time. Select the header's Stop TX button, next to Receiving, to abort. See Tour of the workspace.

While transmitting

The Power/ALC meter shows live PWR, ALC, and SWR readings from the connected radio, when it reports them. It also shows a tone map of the audio-frequency range the current mode uses, and a TX clock readout. Together these confirm the transmission is progressing, not just that time is passing.

Sent frames

A "Sent frames" list on the Transmit tab keeps a short history of this session's transmissions. Each entry shows its outcome (Sent, Stopped, or Failed). Right-click a frame for Resend (transmit the same frame again) or Save… (export a copy of it). This history is session-only. It does not persist between application restarts the way the Gallery's receive history does.

Transmitting

Send a picture with HamDRM (EasyPal)

HamDRM sends the picture as a compressed JPEG 2000 file instead of as analogue SSTV tones. It is compatible with EasyPal and QSSTV. A HamDRM picture arrives without noise or slant, or not at all, so it suits good paths and higher resolutions. Scanline Studio sends and receives HamDRM; see Receive a HamDRM picture below.

1. On Transmit, select HamDRM (EasyPal) at the end of the mode list.
2. Pick a Profile: Robust for weak or fading signals, Normal for typical HF paths, or Fast for a strong, clean channel.
3. Pick a Size (320 × 240, 640 × 480 or 800 × 600) and a File size (4–100 KB). The editor composes at the chosen size, exactly as it does for an SSTV mode.
4. Prepare the picture in the editor, check the Estimated row, and select TRANSMIT.

File size and airtime

The picture is compressed to roughly the chosen file size. A larger file looks better but takes longer to send. The Estimated row shows the real compressed size and the airtime for the current picture and settings; it updates a moment after you change something. Each transmission gets a new time-stamped file name, so receivers never mistake a repeat for a picture they already have. The name is taken from the background picture's file, or "image" for a blank canvas.

Transmission settings

Open Transmission settings to see what the profile sends. Changing any field switches the profile to Custom, which keeps your values.

Mode

A is the most stable, B is the standard choice, E is the fastest.

Bandwidth

2.2 kHz or 2.5 kHz occupied bandwidth. Use 2.2 kHz if your transmitter filter is narrow.

Modulation

4-QAM is the most robust, 64-QAM the fastest.

Protection

High adds more error protection than Normal.

Interleave

Long spreads errors over more time and is recommended. The labels describe what is actually sent.

Error correction

Extra Reed-Solomon data (RS 1 to RS 4) lets a receiver rebuild the file when some segments are lost. Higher values send more data.

Callsign and VOX tone

HamDRM sends your callsign from Station options in a short 9-character label using plain Latin letters. The Callsign row shows what goes on air; it turns red, with a hint, when that differs from what you entered. The VOX tone (a 1 s tone before the signal, for VOX keying) is set in Station options.

Setting the HamDRM level

SSTV is a constant tone, while HamDRM has a high PAPR: its peaks are about 12-14 dB above its average. So Scanline Studio keeps a separate Pwr level for HamDRM. With HamDRM selected, the header and Transmit-tab Pwr slider read Pwr · HamDRM and set only the HamDRM level; your SSTV level stays as it is. The Radio / CAT tab in Options shows both levels.

1. Select HamDRM on the Transmit tab, ideally into a dummy load.
2. Select Tune on the Transmit tab or in the Tone generator. With HamDRM selected, the tone plays at the HamDRM level.
3. Raise Pwr until the radio's ALC just starts to move, then back off a little. The tone sits slightly above HamDRM's real peaks, so this is a safe ceiling.
4. Expect an average output of only about 20-30 % of the radio's rated power on HamDRM. That is normal; the peaks still reach full output.

Receive a HamDRM picture

HamDRM receive is on by default. It listens to the same audio as SSTV receive, so you do not select a mode. A HamDRM transmission from EasyPal or QSSTV is received while SSTV receive runs.

• While a file arrives, the Receiving toggle turns amber and reads Decoding, as for SSTV. A status-bar chip shows HamDRM, the robustness mode, the sender's callsign and the progress in segments, for example HamDRM B · PA0ABC · 12/40. Hover over the chip for the file name.
• HamDRM · sync lost shows for 5 seconds when the signal drops before the file is complete. If the signal comes back in that time, reception continues.
• HamDRM · received and the file name show for 8 seconds when a file is complete.

Every received file is saved unchanged in the drm subfolder of the RX images folder. A picture also appears in the Gallery and in the receive history with the sender's callsign.

To switch HamDRM receive off, clear Receive HamDRM alongside SSTV in Options → Decode. Not available yet: requests for missing segments (BSR) and waterfall text.

Transmitting

Edit the outgoing image

The TX image editor is the main pane of the Transmit tab. There is no separate editor window to open. It combines non-destructive framing, image adjustments, and overlay composition: text, boxes, lines, and extra pictures on top of your base photo, also called the background (see Background vs. backdrop). Its mode-exact preview shows the pixels prepared for transmission.

Frame the base image

• Use Move, Crop, Scale, and Rotate tools on the canvas.
• Preserve aspect (letterbox) keeps proportions and fills unused frame space rather than stretching the image.
• Lock crop to mode constrains the crop rectangle to the selected mode's aspect ratio.
• Safe area displays a composition guide. It does not crop the transmitted frame.
• Snap grid snaps an element to a 5% grid after a drag or resize.
• Use Fit, 100%, and the zoom controls to change only your view of the editor.

Add and arrange elements

The + Text, + Box, and + Line tools place new overlay elements on the canvas. Picture elements come from the Insert Image controls covered in Templates, text, boxes, and images, which also describes the styling options for each element type.

• Click an element to select it. Shift-click additional elements on the canvas to select several at once. A multi-selection can be dragged, nudged, duplicated, or deleted together. It cannot be resized, aligned, or restyled as a group. Style and geometry changes apply to one element at a time.
• Lock an element to stop it from being dragged by accident. Duplicate makes a copy, which is a quick way to build a related element.
• Copy, Cut, and Paste move or duplicate elements through the clipboard. Copy Style and Paste Style carry a text, box, or line element's appearance (color, outline, font, and similar) onto another element of the same type, without changing its position or content. They are greyed out for image elements and when the copied and target types do not match.
• The right-click menu's Arrange submenu reorders layers: Bring to front, Bring forward, Send backward, Send to back. A separate item on that same right-click menu, Flatten into image, permanently merges one element into the background photo. After that you cannot move or restyle it.
• The right-click menu's Rotate submenu turns a text, box, line, or picture element. Rotate 90° Clockwise, Rotate 90° Counterclockwise, and Rotate 180° turn it immediately. Rotate… opens a small field for an exact angle in degrees. Rotate is greyed out while the element is locked, and for a box or picture element while Perspective is active on it — turn perspective off first.
• A picture element's right-click Fit submenu has two groups. Stretch, Contain, and Cover change how the image's pixels fill its current box. Fit safe area, Fit width, and Fit height resize the box to match the Safe area guide (its full size, its width only, or its height only), centered. Both groups are greyed out while the element is locked.
• Undo/Redo cover the editing session.

Background vs. backdrop

These sound similar but are not saved the same way:

• The background is the one photo the whole frame is built on. Load it with Browse or a stock image thumbnail, both in the Background section of the Transmit tab's sidebar. There is always exactly one. Loading a new one replaces it. You can load the first background at any point in the session, even with text, box, or picture elements already on the canvas. Those elements are kept. Once a background is loaded, Browse and the stock thumbnails stay disabled. To switch to a different photo, select New template first, which starts a fresh card. Undo and Remove background both still work. The background is never saved with a template. A template only stores its overlay elements, so you can reuse the same template with a different photo for every contact.
• A backdrop is an inserted picture element (+ Image) that has been sent to the very back of the layer stack and stretched to fill the frame. The right-click menu's Set as backdrop item does this. Unlike the background, a backdrop is saved with the template. Use it to build a template with a fixed, reusable photo baked into its design (a logo card, a fixed QSL background, and similar).
• Right-click the empty canvas and select Turn into backdrop to convert the current background into a backdrop element. This is useful right before saving a template that should always include a specific photo. It bakes in the current crop and adjustments, then leaves the background blank.
• Right-click a backdrop element and select Turn into background to convert it back. It replaces whatever is currently loaded as the background and removes the element, immediately, on one click. Undo restores the previous background and the removed element together. A backdrop element is locked, which can block the canvas's right-click menu. If right-clicking the canvas shows no menu, use the Turn into background button on the element's row in the ELEMENTS list in the docked sidebar.
• Right-click the empty canvas and select Remove background to clear the current background photo without keeping it as a backdrop element. Unlike Turn into backdrop, the photo is discarded, immediately, on one click. Use Undo to bring it back.
• Only one backdrop can exist at a time. Setting or promoting a new one replaces the previous backdrop automatically.

Adjust the picture

Brightness, contrast, saturation, gamma, sharpen, and denoise are stored with the working template and applied before overlays are drawn. They do not overwrite the original source file.

Finish or discard

• TRANSMIT (the large, distinctly colored button) applies the editor state to the prepared TX frame and starts transmission immediately. The same card stays open and unchanged afterward, so you can send it again, keep editing, or set it aside while you resend an older frame from Sent frames. This is the only way to send a picture. There is no separate Transmit button elsewhere.
• Undo all undoes every edit in one click, back to the earliest kept step (the undo history holds 50 steps). Redo all is the inverse: it redoes every undone edit in one click.
• New template (in the bar above the canvas, next to Undo, Redo, Undo all and Redo all) is the only action that closes the current card. It discards the card and starts a fresh blank editor, every time. A confirmation dialog appears when unsaved edits would be lost.

Transmitting

Templates, text, boxes, images, and lines

Template elements let you build reusable QSL-style layouts on top of the background photo, then save and instantly recall them for future contacts. See Background vs. backdrop for what does and does not get saved.

Build a layout

• Add Text, Box, Line, or Image elements from the toolbar, or right-click the empty canvas and select one from there. Text, Box, and Line placed from the right-click menu use the click point as the new element's top-left corner. Image sources include a file, the clipboard, the last received image, and receive history.
• Select an element in the Elements list or on the canvas, then use the Inspector's Geometry/Text/Image tabs for exact position, size, and appearance.
• Shift-click additional elements on the canvas to select and move several at once (see Edit the outgoing image for the full selection and layering controls).

Text styling

Text elements can use any bundled font, at a chosen size, bold and/or italic. Beyond a plain fill color, you can add an outline (stroke) with a color and thickness, a drop shadow with an adjustable offset, or a "3D stack" repeated-copy effect with step-offset controls. You can also use a gradient fill, or a picture as the fill instead of a flat color (from a file or the clipboard). Pick whichever combination keeps the text legible over your background photo. To remove a picture fill and go back to a flat color, select Clear picture fill from the right-click menu, or use the CLEAR button next to the picture fill controls.

By default, resizing a text element's box shrinks the font to keep it fitting. Growing the box back does not grow the font past its set size. Right-click a text element and turn on Grow to fill box to let the font also grow larger when there is room. It is off by default and applies per element. Turning it on for one text element does not affect any other. The setting resets to off whenever a template reloads. The grown font size is saved with the template, so a reloaded template still shows text at the size it last grew to, not its original set size.

Box and line styling

Boxes support a fill color or gradient, an optional border with a thickness, rounded corners, and opacity. Lines support a stroke color and thickness. Both are plain geometry, not photos, so they composite cleanly over any background.

Perspective transform

Image and box elements can be skewed to a four-cornered shape instead of a plain rectangle. This is useful for making a flat picture look like it is lying at an angle, for example a photo "taped" onto a background at a slight tilt. Turn on Perspective in the element's inspector, then drag its four corner handles on the canvas.

Insert live fields

The Insert Field menu places tokens like his call, his grid, your call, your grid, frequency, mode, UTC time, date, distance, and bearing into a text element. Typing a value once updates every place that token appears. Fields are grouped by where their value comes from:

• My side — your callsign, name, and grid from Station options, plus the current date and time. Always available.
• Radio — live frequency and mode from the connected rig. Shows blank on the transmitted card if no radio is connected.
• Per-QSO — the other station's callsign, grid, signal report, distance, and bearing. These need a value typed into the QSO FILL bar first, or they show blank — except signal report, which starts pre-filled with your Default RST from Station options and can still be changed per QSO. The QSO FILL bar is the row of fields at the top of the TX image editor that holds the per-contact values for the card about to be sent.

See Macros and template fields for the full token reference and how distance/bearing are calculated.

Save and recall templates

1. Enter a template name and select SAVE. The SAVE button in the bar above the canvas (next to Undo, Redo, Undo all and Redo all) does the same without a typed name, and it is only available, and blue, while the UNSAVED EDITS tag shows. Right-clicking the canvas, or the background/backdrop image, also offers Save Template. If you have already typed a name, it saves immediately with that name. Otherwise it fills in the next free "tmp0", "tmp1", … name and saves right away.
2. Use the Template Library filter to find saved layouts. Switch between LIST and GRID view with the toggle at the top of the panel. Your choice is remembered. Click a row or tile once to select it and show its Load, Pin, Export, and Delete buttons. Double-click to load it, or right-click for the same actions as a menu. Right-click and select Rename to edit the name in place (Enter commits, Esc reverts). A pinned template shows a PINNED badge. Select Pin on a template to place it in the TEMPLATES rack, the strip of nine slots elsewhere in the TX editor.
3. In the Templates rack, click a slot once to select it and show its Load, Unpin, Export, and Delete buttons. Double-click a slot to load it, or right-click it for the same actions as a menu. Right-click and select Rename to edit the name in place (Enter commits, Esc reverts). Number keys 1–9 recall a slot directly when the editor has keyboard focus. This is the fastest way to reply mid-QSO without touching the mouse.
4. Loading over unsaved work asks first: Discard unsaved changes?, naming the template that would replace them. A slot showing Loaded is the one the canvas currently came from. It reads Loaded • edited once you have changed anything since.
5. Deleting from the Templates rack asks for confirmation, naming the template and its slot number. Deleting from the Template Library list asks for confirmation too, naming the template.
6. Use EXPORT to save a single-file bundle you can share with another operator, and IMPORT to load one someone shared with you.
7. Select IMPORT LEGACY to load a .mtm or .mti template file from a legacy YONIQ/MMSSTV install. Most content (text, position, color, images, boxes) carries over; a few legacy-only effects (multi-stop gradients, dash/decorative line styles, underline/strikethrough, most macro tokens other than the sender's own callsign) have no equivalent here and are approximated or dropped. A status message tells you if anything needed adjustment. The full detail is in the log.

Transmitting

Station identification

Identification settings are configured in Options → Identification. The top section (Off / CW / Sound file) and the checkboxes below it control what you send. A separate pair of checkboxes controls what the application automatically hears from other stations.

What you send

• Encode FSK ID on transmit encodes the configured station callsign after the picture when enabled.
• CW (Morse) sends the configured CW ID text at the selected CW ID tone (Hz) and CW ID speed (WPM).
• Sound file plays a supported legacy .mmv audio file instead of CW identification.
• NR/RST can add a configured static sub-packet to FSK ID. It is not automatically filled from the current logbook exchange.

The Transmit tab's Tail summary shows whether the current combination is FSK + CW, FSK + sound file, one method only, or off.

What the application automatically hears

Two separate checkboxes let Scanline Studio listen for other stations' identification and log it for you, independent of what you yourself send:

• Decode FSK ID on receive reads FSK identification sent by other stations.
• Decode CW ID on receive reads Morse identification sent by other stations, opening a listening window (CW ID capture window (seconds), 5–20 seconds, default 12) around each reception.

Anything decoded this way appears in Stations heard on the Receive tab. You do not need to do anything else to see it.

Images and logging

Browse received images

The Gallery is the searchable history of completed receptions. Select a thumbnail to inspect and manage that frame.

Find a frame

• Filter by All, Today, Unlogged, or Flagged.
• Use the search field for mode or note text.
• Select Refresh to reload the history and Latest to return to the newest frame.
• The grid shows the newest 300 matching frames. Select Show older below the grid to add the next 300. Search and the Unlogged/Flagged filters cover your whole history when All is selected (Today still narrows it to today's frames), so an older frame is still found even when it is not on screen yet.

Work with the selection

• Add a note or flag important frames.
• The SNR row shows the picture's signal-to-noise ratio as measured while it was received (see Signal quality: SNR). It shows a dash for pictures received before this feature existed, with measurement off, or in AVT mode.
• Select Export to write a copy in a chosen image format. The General tab's JPEG quality applies when you choose JPEG.
• Select Open in log to link the frame to an existing QSO or create and link a new QSO.
• Open the image viewer for Fit/100% zoom, previous/next navigation, clipboard copy, and opening the file location.

Right-click a thumbnail

Right-clicking a thumbnail selects it and opens a menu with the same actions as the Selected-frame panel: Open in log, Export, Send to TX, Flagged, Add note…, and Delete. Flagged toggles the flag directly. Add note… opens a small dialog to type a note without first selecting the frame.

The Storage card shows the active image folder, naming convention, and available disk space. By default, history filenames contain a timestamp, mode, and short identifier.

Images and logging

Log and find QSOs

The Logbook tab stores station contacts alongside receive history in the application database.

Log a QSO

1. Select New, or use Log QSO from a received frame to prefill available context.
2. Enter the callsign, UTC start/end, frequency, radio mode, SSTV mode, sent and received reports, and any station details or notes you have.
3. Select Log QSO. Optional UDP forwarding runs after the local record is saved.

Search and edit

Filter by exact callsign and UTC date range, then select a row to edit it. Choose Save changes to update the record.

ADIF exchange

Use Import… to add records from an ADIF file and Export… to write matching records. A partial-import warning means records already processed may have been added before the bad record was encountered.

Images and logging

QRZ.com lookup and UDP forwarding

Both integrations are optional. Configure them in Options only if they are part of your logging workflow.

QRZ.com

• Enable callsign lookup and enter your QRZ.com credentials under Options → QRZ.com.
• Use Test to check the credentials.
• On the Receive tab's Frame metadata card, select Lookup QRZ next to a received callsign to pull name, QTH, and grid. See Reception controls and telemetry.

This screen configures callsign lookup only. The current application does not provide an Options control for QRZ Logbook uploads.

If the keyring is locked, the password field shows Keyring locked and an Unlock keyring button. Select it to unlock the keyring and show the password. Leaving the field untouched and saving does not change or delete the stored password. If the keyring cannot store the password, Save shows an error and the other settings are not saved either. If the password was stored in a keyring that is not available in this session, the field shows System keyring not available; a password typed there is stored unencrypted in the settings file.

ADIF over UDP

Under Options → Forwarding, add each destination's name, host, and port. Every newly logged QSO is sent to enabled destinations as a WSJT-X protocol LoggedADIF message. Common local ports include 2237 for GridTracker and 2333 for some N1MM Logger+ or Log4OM arrangements. Check the receiving application's documentation for its port.

Radio and audio

Radio and CAT setup

Open Options → Radio / CAT, choose one backend, enter its connection details, test it, save it, and then connect the real radio session. Test connection, Connect, and Disconnect are all on this same tab, below the backend settings, not in the main window's transceiver header.

Once connected, transmit power, the Tune test tone, and the automatic high-SWR cutoff live in a separate topic: see Tune and TX safety.

Linked Hamlib sequence

1. Leave the Hamlib library path blank for normal auto-detection, or browse to a specific shared library. Select Test.
2. Choose a model from the detected list, or enter Hamlib's numeric model ID.
3. Select the CAT serial port and baud rate.
4. Choose PTT. CAT uses the CAT connection. RTS/DTR uses the selected PTT port. VOX sends no keying command and relies on the radio's audio-triggered VOX.
5. Run Test CAT and, when applicable, Test PTT.
6. Select Save, then Connect. Connect uses saved settings, so save newly edited values first.

Filter bandwidth (Transceiver header)

When the connected backend supports it, a small bandwidth control appears on the Transceiver header card at the top of the main window. It is separate from the Options dialog above. It offers three common quick picks, 1800, 2400, and 2800 Hz, but you can type any other value and select Set to request it. Not every backend supports this. flrig does not: its bandwidth readback cannot be reliably converted to a plain Hz value across different radios.

Filter bandwidth stored per Favourite

Each Favourite stores a filter bandwidth alongside its frequency and mode, and applies all three when you select it. Setting the mode makes the radio fall back to its default filter for that mode, which on some radios is far too narrow for SSTV. The bandwidth is therefore always sent after the mode.

The quick picks in the Edit list… dialog follow the mode you choose for that Favourite. SSB and data modes offer 1800, 2400 and 2800 Hz. FM modes offer 9000, 12000 and 15000 Hz. Changing a Favourite's mode between those two groups moves its bandwidth with it. The field stays freely editable, so you can type any value between 50 and 20000 Hz, and a value you type is sent exactly as typed.

A Favourite stored before this feature existed has no stored bandwidth. It uses 2400 Hz on SSB and data modes, and 15000 Hz on FM modes.

Calling frequencies

The ▾ button to the right of the frequency readout opens a list of popular SSTV and HamDRM (EasyPal) calling frequencies, grouped by band from 160 m to 70 cm. Each entry shows its frequency, the sideband its source gives (USB, LSB or FM) and whether it carries analog SSTV, HamDRM or both. EU, US or AU marks a regional calling frequency.

Picking an entry works like selecting a Favourite: it sends the frequency, then the mode, then a filter width through CAT. HamDRM entries request 2800 Hz, because a 2.5 kHz HamDRM signal is wider than the 2400 Hz SSB default. Other entries use 2400 Hz on USB and LSB, and 15000 Hz on FM. When SSB as PKT is checked, USB and LSB entries are sent as their data variants (PKTUSB, PKTLSB), the same as the USB and LSB buttons. FM entries are not changed.

The list comes from pd2tx.com, vk6ysf.com and the Wikipedia article on slow-scan television. Check your own licence and band plan before you transmit.

Which modes a Favourite can use

The Edit list… dialog offers six modes: USB, LSB, FM, DATA-U, DATA-L and DATA-FM. The DATA modes use the radio's data connector rather than its microphone path, which is normally what you want for soundcard SSTV. Not every radio has DATA-FM.

Modes not used for SSTV (AM, CW and RTTY) are not offered. Store current is unavailable while the radio sits on a mode outside those six, so it cannot create a Favourite that the dialog could not display.

Radio and audio

Tune and TX safety

The Radio / CAT tab includes a controlled tone for setting application playback gain against the radio's meters.

1. Use a dummy load or clear test frequency where practical, and begin with low Pwr.
2. Select Tune. Scanline Studio keys PTT and generates a steady tone for up to 30 seconds.
3. Slowly raise Pwr while watching the radio's RF power and ALC indications.
4. Stop before ALC becomes excessive. Select Stop tune or let the time limit stop it.

The Radio / CAT tab has two Pwr sliders, Pwr · SSTV and Pwr · HamDRM, and its Tune always plays at the SSTV level. To tune for HamDRM, select HamDRM on the Transmit tab and use Tune there; see Setting the HamDRM level.

Stop TX if SWR too high cancels an active transmission after the connected radio reports a value over the chosen threshold for two consecutive polls. The option cannot work if the radio or backend does not report SWR.

Radio and audio

Audio settings

Audio settings determine where SSTV enters and leaves the application.

Capture device (RX)

The input carrying received radio audio.

Playback device (TX)

The output feeding the radio's transmit audio path.

Sample rate

The DSP rate in whole hertz, from 5000 to 48500 (11025 Hz is the legacy default). Saving a change applies it live by briefly reopening capture and ending any current reception. If a recording is running, the change may wait until you restart.

TX clock offset

A manual correction, -1500 to 1500 Hz, for a measured transmit sound-clock error, for example when another station reports that your signal sounds slightly fast or slow. It changes generated tone timing, not the device sample rate. Leave it at zero without a real measurement.

Stereo capture source

Mono mixes both input channels; Left or Right selects only that channel.

Send TX audio to both stereo channels separately

Duplicates transmit output for interfaces that require both channels.

Options reference

Decode options

The Decode tab changes receiver behavior. Start with defaults and change one item at a time when solving a specific reception problem. Most of these are the same settings shown on the Receive tab's input chain. Changing one in either place changes both. HamDRM receive is set here only.

Live changes that could disrupt the current picture wait until that reception ends rather than switching algorithms mid-image.

Options reference

General and storage options

The General tab controls language, window behavior, manual JPEG export quality, and application data locations.

Remember window position and size

Restores where you last left the main window (including maximized state) the next time you start Scanline Studio, instead of always opening at the default size and position.

Export quality (JPEG)

1–100 compression quality, used only when you manually export a received frame as JPEG from the Gallery's Export button. Received images are always auto-saved as PNG regardless of this setting.

The Config and Database folder boxes show the active location. A restart prompt appears when a staged database move needs completion.

Options reference

Advanced DSP options

These controls expose low-level demodulator and transmit-filter parameters ported from the legacy application. Almost nobody needs to touch this tab. The defaults already match what the rest of the application expects. It exists for measured experiments and diagnosis, not routine tuning.

PLL demodulator tuning

The PLL (phase-locked loop) demodulator tracks the incoming picture tone's frequency to recover brightness. These values apply whenever "PLL" is the selected demodulator on the Decode tab, and always during AVT training regardless of that selection.

Zero-crossing demodulator tuning

The zero-crossing discriminator recovers brightness a different way, by timing how often the tone waveform crosses zero. It is used whenever "Zero crossing" is the selected demodulator on the Decode tab.

TX audio filtering

These shape the audio Scanline Studio generates when transmitting, independent of the demodulator settings above (which only affect receiving).

Options reference

Appearance options

The Appearance tab changes how the application looks. It has no effect on receiving, transmitting, or your saved data, so it's safe to try and switch back at any time.

All three settings apply immediately once you select Save, the same as everything else in the Options dialog. Reset section to defaults returns all three to Light, Normal, and On, but only takes effect once you save.

Options reference

Station options

The Station tab holds the identity values other features quietly rely on: template macros, identification, and the logbook all read from here rather than asking you to retype them.

Your callsign

Feeds the TX overlay editor's "MY CALL" insert-field, CW-ID text, FSK station identification, the HamDRM station label, and every QSO you log. Leaving this blank breaks all five at once, so it's worth setting before anything else. An empty field shows N0CALL as grey placeholder text — a template's "MY CALL" field or CW-ID falls back to that placeholder too if you transmit without setting a real callsign, but FSK identification, HamDRM transmissions and your logged QSOs still send or record it as blank.

Your name

Available to template overlays as a "MY NAME" insert-field. Purely cosmetic. Nothing else in the application reads it. An empty field shows NONAME as grey placeholder text, and a template's "MY NAME" field falls back to it the same way.

Your grid square

Your Maidenhead grid locator. The field is not validated, so any free-text location you prefer also works. Used for a "MY GRID" overlay field and, together with a contact's grid, to calculate distance and bearing for template fields. An empty field shows XX00 as grey placeholder text, and a template's "MY GRID" field falls back to it — but XX00 is not a real grid square, so distance/bearing calculation still needs a real one set here.

Default RST

Prefills the Sent and Received fields when you start logging a new QSO. Defaults to 595, shown as grey placeholder text until you type your own. SSTV operators exchange Readability/Strength/Video, not the classic Readability/Strength/Tone report used elsewhere in amateur radio, so 599 would be the wrong report to prefill. Clear the field if you would rather prefill nothing and enter it by hand every time.

HamDRM transmit profiles

The three profiles the Transmit tab offers for HamDRM (EasyPal): a name and the six transmission fields each. Leave a name empty to use the default (Robust, Normal, Fast). The Transmit tab's own Custom profile is kept separately.

Send a VOX tone before HamDRM

Sends a 1 s, 1700 Hz tone before each HamDRM transmission so a VOX-keyed transmitter is already on when the signal starts. Off by default.

Tools and reference

Configurations

Configurations are named snapshots for switching groups of application settings, for example between radios, interfaces, or operating setups.

Switch To

Applies the selected saved configuration. Switching is rejected while transmitting or recording.

Reset

Switches back to the Default configuration.

Clone into…

Creates a new configuration from the current one.

Rename…

Changes the configuration's display name.

Delete…

Permanently removes the selected named configuration after confirmation.

A switch is rejected outright when a transmission or audio recording is already active. In other circumstances, a setting that cannot be applied live can produce a partial-application warning. Read the result dialog and restart when instructed.

Tools and reference

Calibration and tools menu

The menu groups self-tests and utilities that are useful during setup or diagnosis.

Calibration

• Loopback self-test encodes and decodes internally to verify the application path. A pass shows the software path works. It does not test your physical sound interface, cable, radio, or RF path.
• Tone generator… produces a chosen audio tone for a chosen duration. Use it carefully. Depending on radio setup, audio may reach a live transmitter.

Tools

• Decode WAV file… replays a compatible audio recording through the SSTV decoder and, when HamDRM receive is on, the HamDRM decoder.
• Export logbook as ADIF… exports QSO log data in ADIF format.
• Macros opens the token reference and a preview resolver.

Tools and reference

Supported SSTV modes

Scanline Studio decodes and transmits the same SSTV mode families as its predecessor applications. Every mode below is available from the mode selector on the Transmit tab, and every one is auto-detected on receive from its VIS header.

The MODE card's quick-mode buttons on the Receive tab (see Receive your first picture) hold a working subset of these. Right-click a slot to reassign it to any mode from the full list above.

The Transmit tab's mode selector also offers HamDRM (EasyPal), a digital mode that is not SSTV and not on the quick-mode buttons. HamDRM pictures are received automatically beside SSTV (see Receive a HamDRM picture). See Send a picture with HamDRM (EasyPal).

Tools and reference

Macros and template fields

Macros replace tokens in TX text elements with current station, radio, time, or QSO-fill values.

Open Tools → Macros to see the exact token spelling available in the running version and preview station/time values. Any {word} you type that is not one of the built-in tokens above becomes a custom field: it automatically adds a matching row to the QSO FILL bar, resolved fresh each time the card is sent. A misspelled token therefore shows up as an unexpected extra QSO FILL row rather than disappearing.

A custom field's value stays filled in when you switch to a different template in the same editor session — so a field like {txt} can hold a note or message reused across several templates without retyping it each time. Clicking the QSO FILL bar's CLEAR button, or starting a new editor session, resets it.

Tools and reference

Keyboard shortcuts

Availability can depend on which tab or editor control currently owns focus.

Support

Files, backups, and privacy

Your active locations are shown under Options → General → Storage. Defaults follow the operating system's application-data convention.

Close Scanline Studio before making a consistent manual backup of the database and settings. Back up the database and RX images together if you want Gallery references to remain useful.

Automatic settings backup. Each time Scanline Studio saves its settings, it keeps the previous version next to it as settings.json.bak. If settings.json is later found damaged (for example after a power cut) or missing, Scanline Studio moves the damaged file aside as settings.json.corrupt-<date>, restores the backup, and tells you at startup. The restored copy is from before your last settings change, so check that change, especially TX power (Pwr), the SWR cut-off and your QRZ.com login. If no usable backup exists, it starts with default settings and tells you so. If a settings file cannot be read or repaired at all (for example because of the permissions of the file or its folder), Scanline Studio uses default or backed-up settings, does not save any setting changes, and tells you at startup; fix the permissions and restart. To reset all settings on purpose, close Scanline Studio and delete both settings.json and settings.json.bak.

• Scanline Studio does not require product telemetry or a cloud account for core use.
• QRZ.com and configured UDP forwarding send data only when you enable and use those integrations.
• The QRZ.com password is kept in the system keyring (Windows Credential Manager or the Linux Secret Service) when one is available, so a copy of settings.json does not include it and a restored backup needs the password entered again. Without a system keyring it is stored without encryption in settings.json. On macOS this is always the case, because Scanline Studio currently does not use the macOS Keychain. Where the password is in settings.json, it is also in settings.json.bak and any settings.json.corrupt-… file. After the password moves to the keyring or is deleted, settings.json.bak still holds it until the next settings save; a settings.json.corrupt-… file keeps it until you delete that file.
• An older Scanline Studio build started after the password moved to the keyring shows an empty QRZ.com password. Enter it again there, or keep using the newer build.
• Help → Open application log opens the current diagnostic log location. Review a log before sharing it because paths, callsigns, hosts, or operating details may be present.
• Help → Report a bug… and Help → Send feedback… open a short form in your web browser. Nothing is sent until you press the form's send button. The form goes to the developer by email through the web3forms.com service, so an internet connection is required. It also includes the application version, operating system and .NET runtime version, which the form shows before you send. Your email address is sent only if you tick Can we contact you by email.
• Each new version shows a short notice at startup with what is new and a request for bug reports and feedback; beta versions also show a beta warning. It shows at every start until you tick Don't show this again for version …, and then again only when a newer version is installed.
• Help → Check for updates… asks GitHub for newer Scanline Studio releases and shows a link to the download page, or tells you that you already have the newest version. A beta version is also told about newer betas. The same check runs once at each start, from the first launch on, and shows a message only when a newer version exists. It contacts api.github.com, which sees your IP address and the application version; nothing else is sent. Tick Never show update notifications in an update message to stop the startup check completely; Don't show again for version … hides one version only. Both can be changed again in any Check for updates… result.

Support

Troubleshooting

Start with the visible symptom, change one thing at a time, and preserve a WAV recording or application log when the failure is intermittent.

The RX meter does not move

1. Check that the header's Receiving toggle is on and Auto-detect on the Receive tab is set to Listening. While Auto-detect is Paused, the waterfall keeps scrolling but the level meter and station-ID decode stop.
2. Confirm the radio is producing audio and the physical cable is connected.
3. Re-select the capture device in Options → Audio.
4. If the device is stereo, test Mono, Left, and Right capture source.
5. Check OS input permission, mute state, and device routing.

Audio is visible, but no picture starts

• Confirm Auto-detect says Listening, not Paused.
• Reduce an overly high squelch level.
• Use a wider radio receive filter and correct sideband.
• If you know the mode and the VIS header was lost, force the next decode with its quick-mode button.
• Record the signal and retry with Decode WAV file.

The image is slanted

• Enable RX buffering and Auto-slant in Options → Decode.
• During reception, inspect Slant ppm and use Correct slant after a stable estimate is available.
• Persistent TX reports about your outgoing slant may indicate a measured TX clock offset is needed. Do not guess the value.

Reception breaks up or XRUN increases

• Close other applications that heavily use the audio device or CPU.
• Confirm the USB audio interface has a stable connection.
• Avoid advanced DSP changes until the audio transport is stable.

CAT or PTT fails

• Save edited Radio / CAT settings before selecting Connect.
• Disconnect the active session before running a backend test.
• Check host/port for rigctld or flrig, and firewall access if it is not local.
• For linked Hamlib, test the library, model number, serial device, baud rate, and PTT method.
• Make sure another program has not exclusively opened the serial port.
• VOX cannot be command-tested: it relies on the radio detecting actual TX audio.

Transmit fails or stops

• Confirm a playback device and prepared image are selected.
• Check PTT and radio state with a short controlled test.
• If the message reports high SWR, stop and inspect the antenna system. Do not merely raise the cutoff.
• Open the application log for the specific error.

A Gallery image will not open

The file may have been moved or deleted outside the application. Select Refresh, check the configured RX images folder, and restore the file from backup if needed.

Dark mode or Large text isn't what you expected

• Confirm you selected Save on the Appearance tab. Both settings apply immediately once saved, but a change left unsaved has no effect.
• System theme follows your operating system's light/dark setting. Pick Light or Dark directly if you want it to stay put regardless of the OS setting.
• Large is a single fixed size, not a slider. There is no in-between value, only Normal or Large.

Stations heard stays empty

• Confirm FSK decode and/or CW decode are turned on in Options → Identification. Both are on by default, but either can be turned off there.
• Not every station sends identification the application recognizes: a station may be using FSK/CW at a speed, tone, or format Scanline Studio doesn't decode, or may not be identifying by tone at all.
• The list only fills from stations you actually receive. It is not a directory of who is active on the band.

Linux: native Wayland (experimental)

• By default Scanline Studio runs through X11 (XWayland on a Wayland desktop). This needs no setting.
• To start the native Wayland backend instead, launch the application from a Wayland session with the environment variable SCANLINE_WAYLAND=1, for example SCANLINE_WAYLAND=1 ./ScanlineStudio.Host. Remove the variable to go back to X11.
• The compositor must offer xdg-shell version 3 or later. This was tested on sway 1.11 and Weston 14. Two compositors that are too old: sway 1.9 and labwc 0.7 offer only version 2.
• If the native backend cannot start, Scanline Studio prints a message that names SCANLINE_WAYLAND and exits. It does not fall back to X11 silently.
• On Wayland the compositor places the window, not the application. Remember window position and size then saves and restores only the size and the maximized state. The position saved from an X11 session stays unchanged.
• Weston's kiosk shell, which forces a fullscreen size smaller than the window, closes Scanline Studio with a protocol error.

Support

Glossary

Hover or focus a dotted-underlined term anywhere in this guide to see its definition without leaving the page. Each term links to the single definition here.

ADIF

Amateur Data Interchange Format; the standard file format logging software uses to exchange QSO records.

AFC

Automatic frequency control; measures the received sync tone and shifts the decode back toward its nominal frequency, correcting a station that is tuned slightly off. It corrects mistuning only. It does nothing about noise or interference.

AGC

Automatic gain control; normalizes received signal level for processing.

ALC

Automatic level control; a radio circuit that reduces drive when transmit audio would otherwise overdrive the final amplifier.

AVT training

A decoder state for the AVT SSTV mode family, which needs to measure the incoming signal before it can lock onto and decode the picture. This is distinct from the normal searching/locked states other modes use.

BPF

Band-pass filter; passes a chosen frequency range and rejects everything outside it.

CAT

Computer Aided Transceiver control: frequency, mode, PTT, and telemetry communication with a radio.

HamDRM

The amateur variant of DRM (Digital Radio Mondiale) that EasyPal and QSSTV use to send a picture as a compressed file over a voice channel. A picture either arrives complete and clean, or not at all.

DSP

Digital signal processing.

FIR

Finite impulse response; one of two common digital filter designs (see also IIR). Always stable, at the cost of needing more computation for the same sharpness.

FSK ID

Frequency-shift keyed station identification data sent around an SSTV transmission.

Hamlib

A radio-control library and toolset supporting many transceivers.

Hilbert transform

A mathematical technique for recovering a signal's instantaneous frequency; the default demodulator method Scanline Studio uses to turn incoming SSTV tones back into brightness values.

IIR

Infinite impulse response; the other common digital filter design (see also FIR). Cheaper to compute, but can behave less predictably if pushed to extreme settings.

LPF

Low-pass filter; passes frequencies below a chosen cutoff and removes everything above it.

Maidenhead grid

A short letter-and-number code (e.g. JO22) that identifies a location on Earth, used across amateur radio for a compact "where I am" instead of a full address.

NR

A serial/reference number, here the optional numeric sub-packet FSK identification can carry alongside your callsign.

PLL

Phase-locked loop; one of the demodulator methods Scanline Studio can use to track the incoming picture tone and recover brightness from it.

PPM

Parts per million; here, a small audio-clock error that can produce image slant.

PAPR

Peak-to-average power ratio; how far a signal's peaks rise above its average power. HamDRM's is high, so its peaks reach full output long before the average does.

PTT

Push to talk; the control that keys the transmitter.

QSO

A radio contact between stations.

QSL

Confirmation of a radio contact; often represented by a designed card or SSTV picture.

RST

Readability, strength, and tone signal report. SSTV exchanges may use related reporting conventions.

SNR

Signal-to-noise ratio, in decibels: how much stronger the signal is than the noise around it. Scanline Studio measures it on each line's sync pulse, against the noise in 400–2500 Hz.

SSTV

Slow-scan television: still images carried as audio-frequency tones over a radio channel.

SWR

Standing wave ratio; an indication of impedance mismatch in the RF path.

UTC

Coordinated Universal Time; the single time zone radio operators use to log contacts so records from different time zones stay comparable.

VCO

Voltage-controlled oscillator; the tunable internal oscillator the PLL demodulator uses to track the incoming picture tone.

VIS

Vertical interval signalling: the SSTV header code used to identify the picture mode.

VOX

Voice-operated transmit; the radio keys itself when it detects input audio.

WPM

Words per minute; the speed unit used for CW (Morse code) identification.

XRUN

An audio buffer underrun or overrun, usually indicating that audio data was not handled in time.