• ON4UN "low Band DXing" is an absolute must for anyone interested in antennas for frequencies between 1.8 and  7 MHz. It can be ordered through the  ARRL bookshop or Amazon
  
  
• double L antennas are described in the following article http://www.yccc.org/Articles/double_l.htm
• 
  
• These antennas have been developed to an H form and are described here http://www.iol.ie/~bravo
  
  
• should you be interested of a better understanding of radials, wether buried or elevated consult http://www.cebik.com
  
  
  
• another excellent reference on the subject is http://www.arising.com.au/people/Holland/Ralph/shortvert.htm
  
  
• an excellent description of lazy H (and their horizontal twin the W8JK array) can be found on the cebik site.
  
  
• a simulation software must be used when designing antennas. I have found EZNEC   very usefull although it's inability to cover buried radials is a severe drawback. Please keep in mind that simulation doesn't take into account the real shape of the terrain neither does it reflect the effective ground electrical properties which cannot be measured and taken into account very well. But experimenting is what about ham radio is isn' it ?
  

• ZL1BPU site is a must http://www.qsl.net/zl1bpu/
  
  
• look here to see how several digital modes look like on the waterfall display http://myweb.tiscali.co.uk/g4ucj/index_files/page0003.htm
  
  
  
• Here is a complete collection of spectrums and sound files : http://www.signals.taunus.de/
  
  
  
• for an introduction on how Olivia works and how to configure MixW read http://www.mixw.de/aktuell.htm.
  
  
• Wikipedia has an excellent article on Olivia http://en.wikipedia.org/wiki/Olivia_MFSK
  
  
•  a must read book on the subject, Murray Greenmann, ZL1BPU, Digital Modes, RSGB, 2002, 2004
  
  
• a reference on the subject  is Leon W. Couch, Digital and Analog Communications Systems, MacMillan, check for the latest edition
  
  

• WWV site is well worth reading http://tf.nist.gov/timefreq/stations/iform.html
  
  
• In Europe RWM transmitting from Moscow is easy  to use, the signal is usually strong,  it is a pure carrier. Frequencies are : 4996 kHz, 9996 kHz, 14996 kHz.
  
  
• This is a list of world wide time and frequency standard transmissions
  http://www.hoka.com/tech_info/frequency/frequency_time.htm
  
  
  

Here is an excellent refence on the subject
sw

RF noise ? try this one http://www.ve3hls.com/noise/rfihome.html

• A good and simple introduction to propagation
  http://www.radtelnetwork.com.au/propagation/hfprop.htm
  
  
• zl1bpu gives an excellent intoduction to propagation and  some transient effects
  
  
• for another excellent introduction
  http://www.astrosurf.com/lombry/qsl-hf-tutorial-nm7m8.htm
  
  
• For an evaluation of forecast programs, look at http://www.astrosurf.org/lombry/qsl-review-propagation-software.htm