Worked example
Choose report families and frequencies
Frequency selection in AR-Cluster 6.6. These examples use WITHIN shorthand. Equivalent comparison expressions are shown where useful.
Choose which report families you want
NOT SKIMMER selects human reports and excludes all skimmer reports, including FT Modes. SKIMMER selects skimmer reports, but does not by itself opt into FT4/FT8. To receive FT skimmer reports, the way a report matches must positively select FTSKIMMER; merely mentioning it in an unrelated alternative is insufficient.
| Reports wanted | Complete command |
|---|---|
| Human only | SET DX FILTER NOT SKIMMER |
| CW/RTTY skimmer only, no FT | SET DX FILTER SKIMMER AND NOT FTSKIMMER |
| FT skimmer only | SET DX FILTER FTSKIMMER |
| Human and CW/RTTY skimmer, no FT | SET DX FILTER NOT FTSKIMMER |
| Human and FT skimmer, no CW/RTTY skimmer | SET DX FILTER NOT SKIMMER OR FTSKIMMER |
| Both skimmer families, no human | SET DX FILTER SKIMMER OR FTSKIMMER |
| All three families, including FT | SET DX FILTER NOT SKIMMER OR SKIMMER OR FTSKIMMER |
Human reports outside two frequency windows
SET DX FILTER NOT SKIMMER AND NOT (FREQ WITHIN (14074/14077.5,21074/21077.5))This keeps human reports outside the two inclusive windows and excludes every skimmer report. A human report at 14075.2 kHz is excluded even though it is not exactly at the 14074 base frequency; one at 14078.0 passes. These are illustrative frequencies, not additional observed reports. Frequency alone cannot establish mode: every human report inside either window is excluded, whether it reports FT8 or something else.
FT skimmer reports inside those windows
SET DX FILTER FTSKIMMER AND FREQ WITHIN (14074/14077.5,21074/21077.5)This opts into FT reports inside either window. Human and CW/RTTY skimmer reports are excluded. FT reports on other frequencies, such as 10136.0, are excluded too.
Human and CW/RTTY anywhere, FT only in those windows
SET DX FILTER NOT FTSKIMMER OR (FTSKIMMER AND FREQ WITHIN (14074/14077.5,21074/21077.5))The first alternative admits non-FT reports. The second explicitly admits FT reports only inside the windows. To restrict every family to the windows instead, use:
SET DX FILTER (NOT SKIMMER OR SKIMMER OR FTSKIMMER) AND FREQ WITHIN (14074/14077.5,21074/21077.5)FT reports excluding two exact base frequencies
SET DX FILTER FTSKIMMER AND NOT (FREQ WITHIN (21074,14074))The comma selects two exact reported frequencies in kHz, not the interval between them. NOT excludes either match. FTSKIMMER also requires an FT Modes skimmer report. In NG7M’s sample, only AC2Y passes the complete expression:
| Spotter | DX station | kHz | Report | Complete filter result |
|---|---|---|---|---|
| K7CO-# | EA8ACW | 21074.0 | FT8 | Excluded: exact frequency |
| K7CO-# | N0TDJ | 14074.0 | FT8 | Excluded: exact frequency |
| WA2RF | LA3NGA | 14189.0 | Human | Excluded: not FTSKIMMER |
| AC0C-1-# | K3CI | 14041.2 | CW | Excluded: not FTSKIMMER |
| WZ7I-# | KI6MTV/B | 28249.8 | CW beacon | Excluded: not FTSKIMMER |
| WZ7I-# | AC2Y | 10136.0 | FT8 | Passes |
| K3FEF-# | PW8AO | 28013.0 | CW | Excluded: not FTSKIMMER |
| K9IMM-# | PU7KGB | 21074.0 | FT8 | Excluded: exact frequency |
| K9IMM-# | VA2PHB | 21074.0 | FT8 | Excluded: exact frequency |
| K9IMM-# | EA8DGC | 21074.0 | FT8 | Excluded: exact frequency |
| ND7K-# | WB2FUV | 14065.5 | CW | Excluded: not FTSKIMMER |
The frequency condition alone excludes the five reports at 21074.0 or 14074.0; the other six pass that condition. Frequency selection itself does not identify a mode or add a passband. These FT8 reports use base frequencies; other reports can use different frequencies.
The equivalent existing syntax works on released nodes:
SET DX FILTER FTSKIMMER AND NOT (FREQ=21074 OR FREQ=14074)Results assume normal output and feed availability. Each SET DX FILTER replaces the full active expression.
Sample and clarification: NG7M. Frequency shorthand suggestion: Dave N3RD.