Current and predicted communications conditions
- Red - high frequencies (HF) are unavailable (>22 MHz)
- Yellow - lowest usable frequency (LUF) and maximum usable frequency (MUF) range is 15-22 MHz
- Green - LUF-MUF range is 8-15 MHz
- Blue - LUF-MUF range is 3-8 MHz
If a communication link is not working at these frequencies, there is a higher probability of malfunctioning equipment and/or jamming as a cause for outage.