Lowest frequency

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Fones
Posts: 17
Joined: Mon Oct 19, 2015 3:42 pm

Lowest frequency

Postby Fones » Mon Oct 19, 2015 6:18 pm

Jon, I seriously suggest that you rethink the claimed 100 kHz start frequency of SDRplay. I would suggest 45 kHz to be a fair assessment. I can decode the strong MSF on 60 kHz and there is another signal, present on both the SDRplay, my 24 bit sound card and my WinRadio G33DDC at 45 kHz. No-one appreciates blagging (and this niche has got one already) but you would be perfectly accepted to claim a 50 kHz start.
Last edited by Fones on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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micked
Posts: 16
Joined: Sat Oct 17, 2015 12:16 pm

Re: Lowest frequency

Postby micked » Mon Oct 19, 2015 9:02 pm

Grimeton will transmit next Saturady 24 oct on 17.2Khz, will try and listen in on that with the SDRplay, will be interesting!!
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Fones
Posts: 17
Joined: Mon Oct 19, 2015 3:42 pm

Re: Lowest frequency

Postby Fones » Tue Oct 20, 2015 11:05 am

17.2 kHz will be too low for SDRplay. However, you can simply use your PC sound card for that.
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micked
Posts: 16
Joined: Sat Oct 17, 2015 12:16 pm

Re: Lowest frequency

Postby micked » Tue Oct 20, 2015 2:40 pm

Yeah, I know anout rx directly on my soundcard with the SAQrx program, but I live quite close (150km) from Grimeton so I will try anyway :)
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DL2ZBK
Posts: 14
Joined: Sun Oct 11, 2015 10:24 am

Re: Lowest frequency

Postby DL2ZBK » Tue Oct 20, 2015 6:59 pm

I tried VLF reception without a converter today. My SDRplay works down to approx 24 kHz. DHO38 (23,4 kHz) is the lowest station i can identify between lots of mirror frequencies. DCF77 is no problem, MSC Crumbia is slightly visible, too. ELF stations like Russian Alpha RSDN20 are not visible. Setting sample-rate, filtering preamp etc. is quite tricky. Sometimes i had to restart SDRsharp.

I´m located right in the middle of Germany, my antenna is a Diamond Diskone D3000 (not really a VLF antenna, but it works perfectly with my Datong VLF converter), i successfully copied SAQ last time.

I attached two screenshots of the VLF spectrum, received with the same antenna at the same daytime and optimized settings for each setup. VLF can be received directly, but is difficult to get usable results.

73´s Joerg DL2ZBK
Attachments
SDRplay with DATONG.jpg
SDRplay VLF with DATONG
SDRplay with DATONG.jpg (195.4 KiB) Viewed 5148 times
SDRplay direct.jpg
SDRplay VLF direct
SDRplay direct.jpg (194.65 KiB) Viewed 5148 times
Last edited by DL2ZBK on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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micked
Posts: 16
Joined: Sat Oct 17, 2015 12:16 pm

Re: Lowest frequency

Postby micked » Sat Oct 24, 2015 1:03 pm

I had no problem reciving SAQ Grimeton on 17.2 Khz today with SDRplay, was very clear on the waterfall, unfortunately no screenshot of hdsdr but I had my spectrumlabs running and here is a screenie, http://imgur.com/kJuiKRK
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Fones
Posts: 17
Joined: Mon Oct 19, 2015 3:42 pm

Re: Lowest frequency

Postby Fones » Tue Oct 27, 2015 8:48 am

Outstanding results! Unfortunately I wasn't around for SAQ (again!).

What antennas are you guys using for VLF?
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micked
Posts: 16
Joined: Sat Oct 17, 2015 12:16 pm

Re: Lowest frequency

Postby micked » Tue Oct 27, 2015 9:48 am

I was using my butternut hf9, not realy good at vlf but I liver quite close, just about 130Km from Grimeton.
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DL2ZBK
Posts: 14
Joined: Sun Oct 11, 2015 10:24 am

Re: Lowest frequency

Postby DL2ZBK » Tue Oct 27, 2015 5:11 pm

Unbelievable, but i get best results with my Diamond D3000 Diskone antenna with approx. 15m H155 Antenna cable. I built up a magnetic loop trimmed exactly to 17.2 kHz, but the Diskone has a better SN ratio although the signal level is lower than the signal level of the loop. I´ll try to get my loop weather-resistant until christmas and will try again on christmas eve.

Joerg.
Attachments
2015-06-28 142947 Bike-Loop SAQ.jpg
2015-06-28 142947 Bike-Loop SAQ.jpg (198.6 KiB) Viewed 4949 times
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g1hbe
Posts: 216
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire

Re: Lowest frequency

Postby g1hbe » Tue Oct 27, 2015 11:58 pm

Hi Joerg.
I find nothing beats my Wellbrook 1530 loop for S/N at low frequencies. All my wires and verticals return lots of local domestic noise here. Only the loop cuts through it. I find the Wellbrook works well down to about 40 KHz at least. It's mounted on a cheap rotator at gutter height. I'm never home to listen for Grimeton.
Last edited by g1hbe on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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Andy


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