System Spec Editor
The System Spec panel defines the operating conditions for the full chain. Click the System Specs bar at the top of the canvas to toggle the editor open/closed. The summary bar shows operating mode, RF/IF/LO center frequencies, input/output power, total gain, and system impedance.
Frequency plan
See Frequency Plan for a full explanation. Quick summary:
| Field | Description |
|---|---|
| RF Center / Bandwidth | Center frequency and bandwidth of the RF band (MHz or GHz) |
Frequency cascade
When the chain contains mixers, a Frequency Cascade section appears below the RF fields. It shows a stage card for each mixer where you enter either the IF center or LO center — the other is derived automatically. See Frequency Plan for details on mixer stage cards and multi-mixer chains.
Frequency spectrum diagram
When frequencies are fully resolved for a mixer chain, a spectrum diagram appears inline showing:
- RF and IF bands (colored regions)
- LO center frequency marker
- Image frequency location
- Harmonic markers (2×, 3×, ...)
Use the Show/Hide Sketch button to toggle the diagram. For a larger view, open the Freq Plan tab in the header.
Operating mode
The mode selector (also in the header) switches between:
- TX — shows transmit metrics (PA drive, output power, headroom)
- RX — shows receive metrics (NF, SFDR)
If blocks are already on the canvas, changing operating mode prompts for confirmation before the switch is applied.
Compression Headroom threshold
The P1dB Headroom field sets the warning threshold for compression headroom. Default: 3 dB. In the Analysis panel, stages with headroom below this threshold show amber; stages exceeding P1dB compression show red.
Boundary block sync
When you set frequency or power values in the System Spec, they automatically propagate to the matching parameters on boundary blocks:
| Spec field | Block parameter |
|---|---|
| RF Center (MHz) | Center freq |
| RF Bandwidth (MHz) | Bandwidth |
| Input Pin (dBm) | Output Power |
| Source Noise Figure (dB) | Source NF |
The sync works in both directions — editing the parameter directly on a boundary block updates the corresponding spec field, and vice versa. Parameters set via the spec are shown with a cyan S (Spec) provenance badge. Editing the block parameter directly syncs the new value back to the spec and the badge changes to U (User).
Additional fields
| Field | Description |
|---|---|
| System Impedance | Characteristic impedance of the RF system (ohms) |
| System Temperature (K) | Noise temperature used for thermal noise floor calculations (default: 290 K) |
| Source Noise Figure (dB) | Noise figure of the signal source boundary block (default: 0 dB) |