[Lowfer] Lowfer HK

[Garry]

Mike,

Yes, that's SIW sending EbNaut on 185.185... kHz and HK weakly above it 
in frequency. Here HK was at least 10 dB weaker than SIW. It's farther 
away but not that far. I understand it's using a simple monopole without 
top hat for the antenna and running a bit over 100 ma RF current. When a 
top hat is added it should perk up somewhat. Working on lowering ground 
and tuning inductor loss might raise the antenna current too.

As to the EbNaut spectrum, it's sine(x)/x in form with the central band 
a bit less than 0.5 Hz. I use ARGO at QRSS120 to see the central band 
and a few sidebands. The bandwidth is specific to the symbol duration (4 
sec), number of characters (3), coding (8K19A), and crc (16).  A nice 
signal calculator is at http://abelian.org/ebnaut/calc.php. The 
transmission length is 27 min, 44 sec beginning top of hour. After 
finishing, a carrier is sent until the next top of hour.

73, Garry, K3SIW, EN52ta, Elgin, IL