|Subject:||Re: LF: Small MF ferrite antenna games|
|From:||Markus Vester <[email protected]>|
|Date:||Wed, 27 May 2015 06:32:43 -0400|
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Yes Stefan, bring colour into your life ;-) Even after more than 10 years, I still sometimes enjoy just sitting and watching things roll by on the colour-RDF screen.
With crossed loops and an E-field antenna you have a number of options.
1. The colour-DF scheme takes the E-field on one channel and a 90°-combination from two loops on the second, providing omnidirectional reception with 360° RDF functionality. The combiner is simple to make, and you'll have to add a second RX channel. A stereo soundcard can be used, and SpecLab has everything needed onboard. Having a 475 kHz directional grabber available in Heidelberg would surely be very useful to the community.
2. Then you can hardware-combine whip and loop for a unidirectional cardioid pattern. This is equivalent to K9AY or similar antennas, which on LF have provided outstanding results for a few observers in quiet locations. The crossed loops can be used with electronic steering or a small goniometer, which allow you to virtually rotate the cardioid in the shack. Note that the phase-based colour-DF scheme still works if the cardoid antenna instead of the whip is used as intensity source. I have tried this on LF, but in my location SNR gain was not up to expectations because my loops are too much affected by noise from underground cables.
3. The next step would be downconverting and digitizing all three channels separately, allowing you to steer the cardioid by software and even monitor different beam headings simultaneously. But a three channel digitizer is not so easily available, and you'll need dedicated software for postprocessing. Paul Nicholson can do this at VLF, using three stereo soundcards augmented by GPS ticks, and a posteriori synchronisation in his own software.
All the best,
Von: DK7FC <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Mi, 27 Mai 2015 2:13 am
Betreff: LF: Small MF ferrite antenna games
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