Sound Card Playing with 474.2 kHz WSPR

[jwt873]

I kind of touched on this in another thread, and thought I'd expound on it here..

My IC-7600 tunes down below the broadcast band. Using my 80 meter inverted vee antenna I've listened occasionally on the 630 meter band (472 - 479 kHz), but have never heard anything.

I installed some digital sound card software on my PC a few weeks ago: -- WSJT-X https://physics.princeton.edu/pulsar/k1jt/wsjtx.html and thought I'd see if I could copy anything on 630 meters. (WSPR works with signals that are too weak to hear. They can be so weak, that without the sound card software, you don't even know that there are signals there).

I've left in on for a couple of evenings now.. Darned if I wasn't copying ham stations from all over the US that are beaconing on the band. Now I'm kind of hooked.

I looking at building a better receiving antenna to see how far away I can hear.. (There are WSPR stations on the 630 meter band all over the world). The WSJT-X program allows you to send the call signs of stations you spot over the internet to WSPRnet | Welcome to the Weak Signal Propagation Reporter Network They have a map utility that lets you see graphically what you've received. (Below is a screen grab I made of their map from yesterday evening).

Since monitoring WSPR stations is receive only, you don't need a ham license. You'll need a stable receiver capable of tuning SSB signals in the 472 kHz range and the ability to connect it up to the sound card of your computer. There is a wiki here on RR Connecting Radios to Soundcards - The RadioReference Wiki

Note also that there are WSPR beacons on most of the ham radio bands (HF and VHF/UHF) so you aren't limited to 630 Meters.

 

[ka3jjz]

There are a couple of things here. Most folks don't have the room for a loaded tower or similar (which requires a huge ground to be even minimally efficient at these frequencies), so loops are the weapon of choice for receiving down here...see this wiki article

Loops - The RadioReference Wiki

wiki.radioreference.com

The other is getting slop from the MW band. This is a very common issue. Fortunately there are filters you can buy for this...Mike

 

[prcguy]

An active receive loop like the W6LVP should work well for 630M but you could also short the coax out on your 80m inverted V and feed that to your receiver as a vertical with capacity hat and that should receive 630m a lot better. If it gives better but noisy reception you can then optimize it with a loading coil at the feedpoint and work it against some ground radials or chicken wire and use an effective common mode choke in the feedline, etc.

 

[a417]

Does anyone in this thread have experience with the infamous pa0rdt mini whip that Univ. of Twente has on their web sdr?

It seems to be quite effective -

 

[prcguy]

I have the highly regarded AMRAD active whip that was designed specifically for high performance VLF work and due to local noise my W6LVP loop works much better. I think the PA0RDT whip would work similar or possibly worse due to its lower signal handling capability.

Does anyone in this thread have experience with the infamous pa0rdt mini whip that Univ. of Twente has on their web sdr?

It seems to be quite effective -

 

[jwt873]

I have a Wellbrook loop that I thought was kaput.. It stopped working over a year ago so I pulled it down. This LF/MF stuff renewed my need for it. I checked out the coax run and found that it had been shorted somehow. (Might have been chewed by mice). So I replaced the coax and it started working again.

I don't have one of their actual loops. Wellbrook sells an amp and power inserter that's meant to work with a loop that you construct yourself. Medium Aperture Loop Antenna ALA100LN N. Am. (I built a 30 foot vertical loop out of wire spread on a square frame)

I fired it up on the 2200 meter band last night at 136 kHz using WSPR. Right off the bat I managed to pick up WH2XND in Phoenix (1427 miles away). I never managed to log any others. I checked wsprnet.org and noticeded that there are only about 4 stations beaconing on 137 kHz WSPR. So at least I got one of them. (Out of interest, WH2XND was running 20 Watts into a top loaded Marconi).

 

[ka3jjz]

The OP's band of interest is a bit higher than that - it's a relatively new allocation between 472 and 479 Khz. This page gives you a pretty decent summary of the band and restrictions...

nofars.net - New Low Frequency Bands

Mike

 

[ka3jjz]

Here's a site with just a ton of useful links about the LW allocations...

472kHz.org

Useful links: Information about the 472 kHz amateur radio band

www.472khz.org

Mike