The AM Forum

Hello gang, I just upgraded to a newer computer that is a Dell 9020 that is fantastic compaied to what I had but my question here is, who is the person that posted that they are running an SDR on the Mass CT border area? I went through the entire list of SDR's that I could find on line but could not find the ham who posted it here on AMFONE? I cannot easily hook up the old computer to find the link to that sdr so maybe someone on here knows who that person is?

Thanks Terry

Terry,
Link below if that's the one you were looking for.

73s  Nigel

http://sigmasdr.ddns.net:8073/

That's the one, Thanks Nigel!

I use that one all the time, Terry.
Don't clog it up by listening to WWV all day  ;D

That is my receiver... glad you longed for it back into your bookmarks. :D

You'd be surprised how many SSB stations operated on WWV freqs if you listen long enough. Mostly Spanish speaking but sometime English comms can be heard, too.

As long as the receiver has an open spot (there are only four) feel free to use it as much as you like. There are times when multiple people are listening to a specific net freq and it gets full but often during the day it isn't.

I am seriously considering adding another receiver if I can get a 4 port receiver multicoupler at a bargain. There are quite a few varied groups that frequent my SDR and I'd like to be able to support more users.

- Rob, N1NTE

Rob, 
This is a valuable tool for on-air testing my latest creations and just checking out who is on at morning coffee. Its just the right distance from here. I use it sparingly but often.  Many thanks for providing this service.

73s  Nigel

The general unwritten rule for these receivers is that if there are open spots on the receiver, there is no problem hanging out and listening as long as you'd like. If spots are scarce then common courtesy says give up your spot if you really aren't actively using it. The admin console allows me to kick a user off if it appears that they are not active or abusing it. Some of the KiwiSDRs have time limits on them.

Be sure to sign in at the top right with your callsign. (You may have to open the browser window up to full screen to see it.) Also, check out what other users are listening to. You can click on the Users button and click on the frequency link (see image) and it will auto tune for you. Sometimes you'll hear some interesting stuff.

Well when the Lonely Guys net is on it would be handy if it would stay open for a few hours but I always seem to get kicked off after one hour if I make no adjustments to the receiver. Let me splain my situation, I lay in bed on my lazy back with your receiver piped in on a 100 mw FM xmitter from down in the basement. I don't have a transmitter here at this location so this is my morning entertainment on Saturday mornings. My motives are purely selfish so I don't expect you to accommodate me  ;D ;D ;D But maybe for us NE guys, 3.875 left open would be handy but with restricted numbers that can operate at one time, what can be done? 

For whatever reason, I cannot sign in? I open the page as large as possible and all I see is a half black page? 

Your receiver has great audio and it gives me great pleasure using it so please don't think I am trying to be a pain in the a$$ here :P :P  Thanks Terry

It’s better to spread out the use of these receivers rather than hang on one for hours. Here are the directories for the most popular receivers:

http://www.websdr.org (Receiver map at the bottom)

http://www.sdr.hu (Receiver map at the bottom)

Two popular receivers in the Northeast:

http://websdr.radioassociates.com:8901/ (WA1QIX)

http://k3fef.com:8901 (K3FEF)

Just doing a little BC AM DX.. so.... How is it that the IQ signal sounds so much cleaner than the normal AM detection? Either USB or LSB sounds as clear, but not nearly as nice as IQ. I've read about the IQ demodulation, even worked on stuff that uses it, but is there a simple answer as to why it's so clear and full-range almost hi-fi?

And thank you for hosting the receiver Rob!

I increased the inactivity time out for you. I might have to change it back if it causes problems with other users taking advantage but enjoy it while it lasts. 😀

Thanks for adjusting the time Rob. That is a very generous setting so I hope users will not load it down by forgetting to sign out when they walk away from the computer?



Thanks Clark. I use a lot of the receivers and finding receivers that do you want sometimes can be a challenge! I use Rob's receiver along with Steve's QIX most of the time as my usage is mostly mornings and these two receiver seem to be best for the eastern NY,MA,NH,CT,RI and Maine crowd. K3FEF is just a bit too far away for that morning crowd but great for listening to the Old Buzzard SSB net on 3.905 around 9 AM week days. I think they are in Bloomberg, PA?

It's certainly a new dynamic for our listening pleasure so a big thanks and shout out to the guys who fund these receivers for the rest of us! There would be no way unless a fund were set up to donate to the different people who set these radios for us users, so maybe donating to a local charity in the name of your favorite receiver operator, would be a way to feel good about all this usage of on line receiver charity?

AMFone should have a pinned link or a category in Band Watch or Links or something for online SDR receivers.  This is a handy tool for testing and propagation.  Steve, would that be possible?

Rob, a big thank you.
Very nice SDR site. I just tried it out for a few minutes on 40 using my iPad Pro.
But forgot to sign in.  ;D
I had a little trouble setting bandwidth with “fat fingers” here,  got confused input with frequency but generally very intuitive operation. I expect I’ll have better fine control with a mouse on my other computer.
Excellent audio using phones; -well as good as the SSB transmitting net members heard.

Sign in isn't mandatory... it just helps me figure out who is a regular. I've also seen people I've known from the past on there and it was fun to get in contact with them again.

Tablet functionality was just implemented a couple months ago and I use one often. Mouse control is much smoother but you can enter frequencies directly if you can't get it right. If you are listening to some of the common AM freqs you can click on the presets above the waterfall and it will autotune for you.

I/Q - Yes, I've noticed this as well with some weak signals... haven't been able to explain it either and it only works sometimes.

On days with lots of strong deep QSB, listen to both my and Steve's (QIX) receiver. If you can get them sync'd up to eliminate the delay between them you will notice that there is a distinctive south to north movement to the fade. Haven't seen one in the opposite direction yet but you will certainly appreciate the advantages of diversity reception.

The Grey Hair Net on Tues evenings [http://sigmasdr.ddns.net:8073/?f=1945.00amnz11 (http://sigmasdr.ddns.net:8073/?f=1945.00amnz11)] is also another popular net where my receiver gets quite a bit of use. My antenna isn't overly long but receives pretty well on 160m.

Have fun! No compensation is expected... just pay it forward and do something nice for another ham when you can. :)

- Rob

IQ signals?

https://www.allaboutcircuits.com/textbook/radio-frequency-analysis-design/radio-frequency-demodulation/understanding-i-q-signals-and-quadrature-modulation/ (https://www.allaboutcircuits.com/textbook/radio-frequency-analysis-design/radio-frequency-demodulation/understanding-i-q-signals-and-quadrature-modulation/)

What the hay am I reading? Can someone simplify this for me in a few sentences? I'm getting old and I don't know if I have enough time to learn this?  UPDATE: Just tuned in a ssb signal with IQ. Guess its some kind of magic new signal process that I have not heard of? New to me of course??

Thanks Terry

Thanks for the SDR Rob. My 160M reception is extremely noisey and yours is the best one that I have used for 160. None of the others come close. I cannot monitor my signals though because I have some kind of RFI issue with my tx signal screwing up the internet. Going to try another router. Ferrites did  not help at all.

Larry

Super oversimplified explanation related to SDR receivers is that "with I and Q we are able to determine the instantaneous amplitude and phase of our signal"* and this allows a computer to use/manipulate the I/Q data (a computer-readable stream of data representing the signal) for processing. You can store this data for later playback and run it back through your SDR so that you can apply noise reduction, bandwidth changes, etc rather than it just being a tape recording of the original signal. Anyone else, feel free to chime in and expand on this. :)

*https://www.g0kla.com/workbench/2018/sdr_tutorial7.php  (https://www.g0kla.com/workbench/2018/sdr_tutorial7.php)

- Rob

Quadrature

I worked with NTSC color demodulators. No idea how they ever sounded.. only what the result was on a vectorscope and in the color reproduction fidelity on the TV. The article jumped from analog to something with data coming in and the modulation being digital. The stuff I worked with was all analog. Anyway it sounds pretty good on weaker stations. I know how the I and Q signals were gotten in the chroma demodulator. It involves a CW reference synchronized to an incoming pulsed RF burst, the 'colorburst' signal. The incoming signal to be demodulated by this setup was both amplitude and phase modulated. Guess I have to think about it some more.

It's essentially synchronous detection (probably Costas or some variation). This results in clean detection and some resistance to fading.

https://en.wikipedia.org/wiki/Costas_loop

I & Q sampling occurs when the incoming signal is sampled (or mixed in the analog case) with two ADC or LOs that are 90 degrees out of phase. Pretty standard approach in modern comms.

We could add a on-line SDR topic in the Band Watch section on Amfone. Thanks for proposing this Bob.

Done.

http://amfone.net/Amforum/index.php?board=78.0

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