I am excited to announce a new feature that Jose (EA5JVK) and myself have been diligently working on to enhance your experience: VARA adaptive broadcast speed.
VARA now offers three Speed Levels (SL) for broadcasts:
SL1 – 18bps – the lowest speed capable of reliable decoding even at -21dB.
SL2 – 41bps – can be decoded at -18dB.
SL4 – 88bps – can be decoded at -14dB.
The previously available SL5 level has been deprecated in this version due to inefficiency for our needs.
To ensure a seamless experience, VARA speed will now be selected based on the message length. In essence, shorter messages that can fit into one or two VARA packets will be sent at the lowest possible speed. While there isn't a definitive line for message lengths, your callsign length and destination callsign also play a role. In summary:
SL1 - Up to 3 characters, stretching to 5-6 for messages sent to "ALL" with a short sender callsign. Ideal for simple greetings like "HI" or "GE".
SL2 – 3-33 characters.
SL4 – 33-81 characters.
In the next version of VarAC, we will enforce an 81-character limit (currently 91).
This feature marks a significant improvement in our ability to conduct round-table discussions using broadcasts. I've personally witnessed decoding at -21dB recently, a notable improvement from the typical -12dB using SL5.
I am confident you will appreciate this new feature, which also encourages brevity and effectiveness to benefit from the lower speed levels. Additionally, the next VarAC version will leverage this capability by sending Pathfinder requests and Vmail relay notifications at the lowest speed possible, extending their reach to greater distances.
To enjoy this new feature and ensure compatibility with others, it is necessary to upgrade VARA to version 4.8.3. No changes are required for VarAC.