After running a few tests, seems like it is AC interference after all. I took the antenna away from the apartment and all noise disappeared. Brought it back...
12910
Ray 9H1RA
abelaraymond
Apr 1, 2009 8:58 am
... Hi, It is very difficult to eliminate such mains hum... !! If you switch off everything in your house and disconnect all the plugged cables you still have...
12911
Paul
paul@...
Apr 1, 2009 9:33 am
A good deal of hum is to be expected when the antenna is indoors or near the house. The mystery is why it goes right across the spectrum. I'm still not...
12912
Alan Melia
g3nyk
Apr 1, 2009 10:53 am
Hi Siddharta, well I am sure there is more information in multihop signals, but I would liken it to receiving 3 pages of text instead of just one page......the...
12913
John
af4ex.radio
Apr 1, 2009 10:55 am
... Best results are obtained in quiet places. ShawnK, for example, drives up into the Rockies, for which he is rewarded with fantastic results. But unless you...
12914
df3lp
Apr 1, 2009 11:02 am
Hi Rich, ... It's NAU. I'm receiving it up to 15 dB above noise from 22 to 07 utc every night here at Europe. Unfortunately 40-50 KHz is highly polluted by...
12915
John
af4ex.radio
Apr 1, 2009 1:12 pm
... Hi Peter, I see faint lines at 12kHz, 12.5kHz and 15kHz, which I presume are the Russian Alpha signals. Why do these appear so weak? I know they're...
12916
jcal1001
Apr 1, 2009 2:35 pm
You don't mention what kind of shielding you are using. Shielding is the most important aspect of reception in noisy environments and especially with indoor...
12917
mike l dol dormann
w7dra
Apr 1, 2009 3:45 pm
how about trying a DAN, like Dennis uses at MSFC? There is one out there in the community that you could probably get. mike w7dra ...
12918
MarkD
marky26_uk
Apr 1, 2009 4:44 pm
Hi Paul, Ø Is it just my imagination, or are the tweeks appearing ... Can’t say I noticed myself. Mark From: VLF_Group@yahoogroups.com...
12919
John
af4ex.radio
Apr 1, 2009 5:51 pm
... Paul, What are your thoughts on a tweek detector? They're easy to pick out by ear, so one would think a software detector would also be easy to build. ...
12920
df3lp
Apr 1, 2009 7:43 pm
Hi John, ... Yes and no; indeed these are ALPHA-Signals. They are such faint due to the 1 min. averaging process (averaged from 1 sec. raw file), the raw...
12921
Ned Lewis
ned2lewis
Apr 1, 2009 9:52 pm
Nasa article about solar minimum. http://science.nasa.gov/headlines/y2009/01apr_deepsolarminimum.htm?list161186...
12922
Alan Melia
g3nyk
Apr 1, 2009 10:48 pm
I think there is a well known saying that goes "predictions are always very difficult ............. particularly so when they involve the future !" Alan G3NYK ...
12923
vlf4me
Apr 1, 2009 11:14 pm
Not as easy shielding VLF loops from magnetic interference eh John? At least at ULF the interference is ABOVE the spectrum you're looking at. Jim...
12924
Siddhartha Jain
losttoy2000
Apr 1, 2009 11:30 pm
Thanks Alan. Once my receiving stations goes into "production", I can hopefully start doing more advanced tweaks to it :) Here is one observation I found...
12925
Siddhartha Jain
losttoy2000
Apr 2, 2009 2:16 am
Hi John, No shielding on the antenna. Should I simply wrap the whole antenna in aluminum foil? Thanks, - Siddhartha...
12926
Siddhartha Jain
losttoy2000
Apr 2, 2009 2:54 am
I wrapped the loop with aluminum foil. Result: All signals including interesting ones got attenuated with the audio still filled with hum noise. - Siddhartha...
12927
John
af4ex.radio
Apr 2, 2009 3:11 am
... Siddhartha, You're supposed to leave a gap in the shield, 180 degrees away from the grounding point. Otherwise the shield actually performs as a shield and...
12928
jcal1001
Apr 2, 2009 4:16 am
Yes Siddhartha aluminum foil is fine but you will need to put a break in it at some point around the circumference to avoid the shorted turn effect. Operating...
12929
Siddhartha Jain
losttoy2000
Apr 2, 2009 5:25 am
Thanks for that correction, John. Will reconfigure the shield. Btw, I turned off the mains in the apartment and it did not make any difference to the hum...
12930
Richard B Georgina
wd4rbx@...
Apr 2, 2009 11:19 am
Hi,all Someone was wondering how (I think it was TFK)on 37.500 was being received across the pond. I ran SpecLab with a waterfall scroll interval of 1 min. TFK...
12931
John
af4ex.radio
Apr 2, 2009 12:53 pm
... Rich, I think this is a good example of how the bottom of the ionosphere and surface of the Earth form a waveguide, equivalent to those rectangular wave...
12932
Thomas D. Dean
tomdean@...
Apr 2, 2009 1:14 pm
... The foil should not make a complete turn - leave a small gap. Was the foil grounded?...
12933
Thomas D. Dean
tomdean@...
Apr 2, 2009 1:15 pm
I have an SDR14-IQ. I have two orthogonal loops on a PVC frame, 12"w x 36"h x 12"d. I have tried coupling loops, tuning with varactors, and direct connection....
12934
tomdean1939
Apr 2, 2009 1:16 pm
I tried to post to the group with preamp in the subject. I never saw it. Why?...
12935
tomdean1939
Apr 2, 2009 1:16 pm
I have been looking at preamps and cables. I want to move my loop about 1000 foot from my receiver. I made a preamp and cable driver using op275's and...
12936
Mark Karney
mkarney19
Apr 2, 2009 1:24 pm
... Hi Tom, Welcome to the VLF_Group. By default, all new members to the group have their posts moderated. Even if you've been a member for a long time, and...
12937
Alan Melia
g3nyk
Apr 2, 2009 1:30 pm
Hi Rich and John, yes that is it....in daytime the upper "wall" of the waveguide is very lossy so the range is restricted though "skywave" does propagate. At...
12938
Alan Melia
g3nyk
Apr 2, 2009 2:02 pm
Hi Tom I assume you are parallel tuning the loop.....but you could series tune it. It all depends on what signal levels you have to contend with locally....
