[Lowfer] Modes, signaling, and data recovery

[James Moritz]

Dear Lowfers,

Some differences between Wolf and Jason:

Weak signal capability: Wolf will work at lower signal levels than Jason. 
Of course, you could make a Jason version with longer tone duration that 
would work at lower levels; but whether this is a good thing depends what 
you want to use it for.

Bandwidth: The "raw" Wolf BPSK signal has significant sidebands extending 
over several hundred Hz bandwidth - not acceptable for European LF, but OK 
in the US where powers are lower and more bandwidth is available. It 
requires a few 10s of Hz bandwidth when the proper envelope shaping is 
done, which is still a lot for the narrow Eu allocation, and adds 
considerably to the complexity of the TX. The Jason signal essentially has 
a bandwidth of 4Hz, without requiring envelope shaping.

QSO capability: Jason has TX/RX capability built in, and works in "real 
time", which makes it easy to have a Jason QSO. Wolf signal processing is 
done off line, so is rather time consuming and tricky if you are attempting 
a 2 way contact, although it allows for very flexible post-processing of 
the signal.

Timing and frequency accuracy: To achieve the benefits of integrating the 
signal over a long period, Wolf requires accurate calibration within a few 
parts per million - quite difficult to achieve when an amateur rig and 
sound card is used, and requiring careful calibration procedures. Jason can 
cope with a couple of orders of magnitude poorer accuracy, which means 
normal Ham-type receivers and run-of -the-mill sound cards do not present a 
problem. The Jason waterfall display allows you to make frequency 
corrections on the fly.

GUI: The Jason GUI is very easy to use; most people are used to having a 
graphical presentation, although both programs transmit and receive text 
messages.

So Wolf and Jason are like chalk and cheese, and which one is better 
depends what you are using it for. Wolf is currently better for extreme 
weak signal use, Whilst Jason is much easier to implement and use, at least 
from the European LF perspective.

Cheers, Jim Moritz
73 de M0BMU