Extreme narrow band

General discussions
kc6ete
Posts: 11
Joined: Wed Apr 26, 2017 7:37 pm

Extreme narrow band

Postby kc6ete » Fri Apr 28, 2017 2:48 pm

Ok, my unit arrived last night, and I've been poking around in SDR Console V3

How can I best configure for very narrow band CW in the 600 meter band?

The smallest bandwidth I can select under Home, Bandwidth is 500kHz, so I used that.
I have the display set to 200Hz wide, and I'm receiving, but each signal is a hill rather than a peak.

I'm looking for how to use as much horsepower as possible to dig down for weak signals.
Last edited by kc6ete on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

mikexeno
Posts: 35
Joined: Wed Jul 08, 2015 3:18 am

Re: Extreme narrow band

Postby mikexeno » Fri Apr 28, 2017 7:36 pm

This is how you set the CW bandwidth filters in Console v3

http://imgur.com/yfM9DWf

Reason: No reason

kc6ete
Posts: 11
Joined: Wed Apr 26, 2017 7:37 pm

Re: Extreme narrow band

Postby kc6ete » Fri Apr 28, 2017 7:51 pm

Ok, I already got that, but at least my current understanding is that the system is taking in lots more data than it needs to, and discarding most of it.

The resolution within that 200Hz slice isn't very good. I'd really like to see much finer, 1hZ if I can get it. I don't know what's possible.
Last edited by kc6ete on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

DaveB
Posts: 129
Joined: Sun Feb 01, 2015 6:04 pm

Re: Extreme narrow band

Postby DaveB » Fri Apr 28, 2017 10:32 pm

The most likely reason the signal appears as a hill rather than a peak is the resolution of the FFT display in the spectrum.

Narrow band modes isn't my thing - I'm into FM DX-ing - but I did a bit of checking on v3. If you click on the View Tab and click on the Resolution icon in the toolbar that appears you can enhance the resolution of the waterfall. At x8 you can clearly see two cw signals at 20 Hz separation. Click on the the Options icon on the toolbar and you can do some adjustment to the spectrum but it doesn't improve the resolution.

I think the x 8 waterfall resolution in the waterfall will give you what you are looking for better than improving the resolution of the spectrum. As an aside in SDR# you can increase the resolution of the spectrum but it slows down the response a lot, but I can't see how to enhance the resolution of the waterfall.

You can adjust the characteristics of the CW filter by clicking on the ellipsis [...] under the Filter settings to open up a drop down box - see mikeexeno's post. Choose which filter you want to play with highlight it and then click edit. You have an option to alter the length of the filter - which is set at 257 by default. See what happens to the embedded chart of the filter shape when you slide to the right - the skirt selectivity becomes much steeper. The 200 Hz filter goes from -20dB at +/- 200 Hz to -100 dB at +/- 150 Hz. If, before altering anything save a copy, then you can make the change re-title the sharper filter and save it. After that you can spend ages deciding on the difference/improvement this makes - the trading off might be in intelligibility / aural fatigue.

David

I hope that gives you something to work with.

Reason: No reason

kc6ete
Posts: 11
Joined: Wed Apr 26, 2017 7:37 pm

Re: Extreme narrow band

Postby kc6ete » Mon May 01, 2017 6:34 pm

I have the waterfall resolution maxed out already.

"As an aside in SDR# you can increase the resolution of the spectrum but it slows down the response a lot, but I can't see how to enhance the resolution of the waterfall."

What is SDR#?

I'm not too concerned about the response. The "Dits" I'm looking for are 100mS long.
Last edited by kc6ete on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

kc6ete
Posts: 11
Joined: Wed Apr 26, 2017 7:37 pm

Re: Extreme narrow band

Postby kc6ete » Mon May 01, 2017 6:38 pm

How can I get more resolution over my small band of interest?
Last edited by kc6ete on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

octave9
Posts: 59
Joined: Sun Feb 19, 2017 7:54 pm

Re: Extreme narrow band

Postby octave9 » Sat May 06, 2017 1:34 pm

I seem to get better visual resolution of CW signals in SDRUno AUX SP window, with Refresh Rate set to its fastest, FFT Avg on 1 and the 'Flat Top P401' FFT Window setting (it has its own SET dialog). Probably not good enough for your requirements though. Hard to see fast changes between dits and dahs. Can only just hear the difference.

It's a good place to set notch filters too.

Reason: No reason


Return to “General”

Who is online

Users browsing this forum: vapedbuh, vikuz and 5 guests