More information on the FCDTN net for tonight from Barry K3EUI, what to expect when using VARA FM.
If we are successful sending and receiving VARA FM emails tonight via the 147.270 repeater using Winlink (via N3MEL-10 Gateway or Peer-to-Peer P2P to each other) then the RECEIVING station's VARA FM modem Window should look something like this after receiving an email.
Each box on the right represents modulation data using multiple carriers with phase-shift information and amplitude information. The data points ought to fall INSIDE one of these boxes, but not on an edge. The GRAPH on the left represents the DATA SPEED, in bits per second (bps) plotted against the TIME of the link. Note how VARA changes speeds without human intervention, based on quality of the signal.
The "ACK" box lights up when you receive data without errors. The "NACK" box means errors and the need to repeat the data transmission. The TX delay might be interesting when trying this via an analog voice FM repeater!!
The VARA FM (narrow) mode has a wide range of "levels" or speeds ( I call them gears ) and gear #12 is very fast. Note in this case the excellent S/N of +28 dB we are getting very fast data rates. Compare this VARA FM speed to 1200 baud PACKET (1200 bit/second). The top speed we use with FLDIGI (8PSK1000F) on 2m FM is about 3000 bit/second.
Here are the SPEEDS (levels) of VARA FM narrow mode and VARA FM wide mode. We can only practice VARA FM "narrow" on the repeater (limited bandwidth)