[Boatanchors] Making Stable Inductors for 2 MHz

[Jim Wiley]

John -


Why is shaping required?  Does it have to do with some property of the 
signal that determines the ability of the LORAN receiver to provide 
location information, or is shaping used in an attempt to reduce the 
occupied bandwidth of the transmitted signal?  If it is the latter, then 
shaping would not be important to the demonstration project, assuming 
there is no intent to actually radiate a signal.


Since LORAN signals were repetitive pulses, which by their very nature 
occupy very wide bandwidths, then  shaping would have been  an absolute 
requirement if the service was not to interfere with the top end of the 
standard AM broadcast band, as well as the nearby 2-MHz marine channels, 
the distress channel at 2182 kHz being an obvious example.


Among other things, the bandwidth of the antennas in use would have some 
narrowing effect, not unlike the very earliest days of spark 
transmissions, where the natural resonance of the antennas used was 
often the only  tuning available.  These antenna limitations would have 
provided some pulse shaping.  As an interesting aside, this is the 
reason that ELF and VLF signals, such as those used to contact submerged 
submarines,  have severe limitations on the keying speeds that can be 
used - the antennas, particularly for ELF, simply cannot be "started" 
and "stopped" very quickly.  I read somewhere that it can take several 
tens of seconds to send a single character at ELF.  I have no direct 
experience with this last item.   The actual facts may be a bit 
different.  Perhaps someone here can offer additional information.  


- Jim, KL7CC



J. Forster wrote:
> The pulse needs to be shaped in amplitude. That gets more complicated.
>
>   
>