It's rather of academic interest to cryptologists to argue much but
essentially only intellectually about cryptology in here.

The mention of the US military SINCGARS family might be a more
practical homebrew application of actual R/Ts that might be built using
FHSS or Frequency-Hopping Spread Spectrum. The US military has
over a decade of operational experience with FHSS in the field, to the
severe environment experienced by the military...with a lot of success.
The mode works very well.

The problem is that the mode may not be within the various adminstration
allocations for amateur radio. However, that should not prohibit bench
testing and simulation of links that do not radiate RF. Another problem is
that the FHSS now used by the military is definitely not the conventional
narrowband, one-user, single-modulation type "traditional" in amateur
radio use.

However, SINCGARS is definitely not a wideband modulation spectrum
hog such as with DSSS or Direct Sequence Spread Spectrum common
on WLANs and newer cordless phones. FHSS can have thousands of
separate radio circuits operating in a relatively small bandwidth without
mutual interference...and with little interference to conventional modes
of communication. Wide bandwidth necessary to handle rapid frequency
jumping already exists in modern amateur transceivers...that is not any
real problem. Some means of synchronization and capture to get into a
circuit is an area ripe for experimentation. Super-accurate timebases
have already been worked up and shown on such sites as TAPR.

The concept of FHSS is intriguing in its possibilites for the future...if
only
enough wish to truly experiment in new things. Just some idle thoughts.

Len Anderson
retired (from regular hours) electronic engineer person