Anchor Panadapter for Zoom
Posted: Thu Jul 17, 2025 1:07 pm
When using zoom controls on the waterfall/panadapter display, both the left and right frequency limits adjust proportionally around the center frequency. For example, zooming from a 50.0-51.0 MHz span results in something like 50.25-50.75 MHz.
Requested Behavior
Provide an option (toggle button, right-click menu, or modifier key) for "left-anchored zoom" where:
The left frequency edge remains fixed
Only the right edge moves when zooming in/out
Example: 50.0-51.0 MHz span zooms to 50.0-50.5 MHz, maintaining 50.0 MHz on the left
Use Case
This feature is valuable for:
Monitoring specific frequency boundaries (band edges, repeater inputs, etc.)
Maintaining reference to a known starting frequency while exploring nearby spectrum
Following signal activity that originates from a fixed frequency point
Easier frequency coordination and spectrum management
Suggested Implementation
Add a toggle button near existing zoom controls labeled "Anchor Left" or similar
Alternative: Right-click context menu on frequency scale with "Zoom from left edge" option
Could be extended to also support right-anchored zoom for completeness
Similar Features
This type of anchored zoom functionality exists in other SDR software and spectrum analyzers, making it a familiar workflow for users transitioning between platforms.
Requested Behavior
Provide an option (toggle button, right-click menu, or modifier key) for "left-anchored zoom" where:
The left frequency edge remains fixed
Only the right edge moves when zooming in/out
Example: 50.0-51.0 MHz span zooms to 50.0-50.5 MHz, maintaining 50.0 MHz on the left
Use Case
This feature is valuable for:
Monitoring specific frequency boundaries (band edges, repeater inputs, etc.)
Maintaining reference to a known starting frequency while exploring nearby spectrum
Following signal activity that originates from a fixed frequency point
Easier frequency coordination and spectrum management
Suggested Implementation
Add a toggle button near existing zoom controls labeled "Anchor Left" or similar
Alternative: Right-click context menu on frequency scale with "Zoom from left edge" option
Could be extended to also support right-anchored zoom for completeness
Similar Features
This type of anchored zoom functionality exists in other SDR software and spectrum analyzers, making it a familiar workflow for users transitioning between platforms.