Long time monitoring with Linrad

[ON4KHG]

Dears, Leif,

I'd like to monitor 2m using Linrad. I intend to monitor for 24 hours or so, to assess if the noise I have in a given QTF is due to solar panels or if there is a correlation in time with another (to be identified) event.

If I launch a recording for a so long duration, I have no idea on the size it could lead to, huge I fear ?

And even if the size is acceptable, is there a mean to "replay" the 24 h recording so that it is displayed as a whole on the S-meter ?

Thanks in advance.

73,

Gaëtan, ON4KHG

[Earl Shaffer]

Hi Gaëtan

Believe it or not, I am looking at the same thing.

I think I have a neighbor with a grow light that changes output to simulate natural

sun angles. What is not working real well is to check Linrad when I wake up at night.

I have saved some screen shots.  The RTL dongle is useful for this.

A few decades ago I was doing Lowfer activity and I see that two different softwares

are still used for QRSS commonly used on the 160 to 190 Khz band here in the US.

Beacons would send with 30 second long dots and I was copying these 1 watt stations

at nearly 1000km. Probably today there are better digital modes, but it was really neat to

see CW appear on the waterfall overnight. The two programs to use are Argo and Spectran.

These are programs that use an audio input. I don't think the files size is really all that big.

I don't know if Linrad can be made to run as slow as Argo. Please let me know if you make

some progress on this. It may be very useful to me and might allow me to sleep better.

My noise is 30db over a dummy load and has spurs every 63Khz. These spurs look like

fast dashes on the waterfall and give a pattern of wideband noise between the spurs. At times

the broadband noise almost covers up the spurs, I presume when it is at full output. I also

see a strong correlation with their basement light.  The spurs jump in frequency between 1 and 3 Khz

and return right away. I presume this is some sort of feedback loop in action.

What I have found to be real useful for tracking this noise is an old Realistic Patrolman Mini modified for AM detection and external BNC antenna jack. I use a 5 element 2 meter yagi to track noise. The bandwidth is between 50 and 100 Khz which is ideal for noise tracking. I have not been able to duplicate

this function with any ham rig.

WB9UWA

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There is an excellent Linrad User Guide by Gaetan, ON4KHG, at:
http://w3sz.com/Linrad%20Installation%20&%20Configuration%20User%20Guide%20-%20V1-0.pdf
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Earl Shaffer,  WB9UWA

 

My EME array photos

https://www.dropbox.com/sh/bbn2ktonko8e3az/AACHBBOhf6Djk5Pf2c86Br5ja

Detailed array photos

http://www.gm4jjj.co.uk/WB9UWA/

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[Rod]

Hi Earl and Gaetan,

This describes an extremely accurate noise locating antenna. It is accurate enough
to detect which power pole is causing the noise, and even which cross-arm, and
even which side of the cross-arm has the problem!

Posts: 75

Villard Cage: very accurate electrical noise locator « on: October 16, 2020, 11:08:08 PM » Quote Modify This is to describe a direction finding device is called a Villard Cage("CAGE" herein). The CAGE is sharp enough you can find an offending power pole, and identify which crossarm is the noise source, and even which side of the crossarm is the noise source. It was developed by Oswald Villard, probably while he was doing early research on over-the-horizon radar. Google Oswald_Garrison_Villard_Jr I have tried in vain, but documentation on the CAGE is apparently lost to history. WHAT IT IS It is an electrostatically shielded dipole, with a VHF AM  receiver. Imagine a section of rain-downspout, about 36 inches long. Now cap each end with a pyramid of sheet metal. With that view in mind, image the CAGE being built with wire-frame construction instead of a downspout-and-sheet-metal-pyramids, SEE SOME PICTURES See the attached pictures. Please be aware the four "box" shaped wire stiffeners are for mechanical convenience only. You can place as many as you like in arbitrary positions down the length of the CAGE. A dipole is deployed down the center-line of the cage. At the center of the dipole install a radio listening device where the red letter 'O' appears. HOW I BUILT IT I used #10 bare copper wire from Home Depot. I made the CAGE an arbitrary length, about 30 inches (limited by mechanical constraints). I made the cross section of the CAGE square, but I am sure that is not critical. I suspended a dipole along the centerline by using monofilament fishing line for end insulators. I used an old Radio Shack VHF AM aircraft radio reciever, which I kind of jam-fitted inside the cage. Instead you could use the $80 SA for EMI testing. The sensing receiver must be an AM receiver, or a device that shows signal amplitude. IT IS IMPERATIVE THAT THE DIPOLE AND SENSING RECEIVER ARE COMPLETELY INSIDE THE CAGE WITH NO CONDUCTORS EXITING THE CAGE!! HOW TO USE IT To use it, tune the VHF receiver to a frequency that sounds like the interference you are getting at HF. Grasp the CAGE at the middle, at hold it at shoulder level, pointing front-and-back, with the receiver near your ear so you can hear the offending signal and see the direction the CAGE is pointing. To find a noise source, rotate the CAGE both in azimuth and elevation until you find a deep null. The CAGE has EXTREMELY deep and sharp nulls off each end. So,When the null is found, the CAGE end is pointing directly at the noise source. In another post I will provide the 4nec2 file I used to create the geometric images. The 4nec2 file may not be valid for modeling; I just used it as a convenient 3d visual model. 73, Rod KM6SN

v1.png (17.41 KB, 1280x1000 - viewed 273 times.)  v2.png (22.79 KB, 1280x1000 - viewed 229 times.)  v3.png (28.21 KB, 1280x1024 - viewed 234 times.)

[ON4KHG]

Hi Earl,

 

 

Thanks for the info. For long term monitoring, Spectrum Lab (DL4YHF) can be used too (scripts can be written on purpose).

But I prefer to use Linrad to avoid multiplying tools.

73,

 

Gaëtan

To view this discussion on the web visit https://groups.google.com/d/msgid/linrad/CABipsT0%3DnYQbRw1m54JVaobfxpyz90CiX_wTeDD9UDnks%3D6x5g%40mail.gmail.com.

Garanti sans virus. www.avast.com

[Earl Shaffer]

Hi Gaëtan

Please let me know what you come up with re Linrad.

WB9UWA.

To view this discussion on the web visit https://groups.google.com/d/msgid/linrad/006501d82f4b%24f4da9cd0%24de8fd670%24%40voo.be.

[Leif Asbrink]

Hello Gaëtan,

Have a look here:
http://sm5bsz.com/linuxdsp/usage/am1030.htm
A recording that lasts about 12 hours. The narrow bandwidth, 48 kHz,
was selected to make the file size small. It is 9 gigabytes and
Linrad can run through it in about five minutes on a fast computer
if the audio output is dumped (with the F3 key.)

I think you can run it much faster if you do not click on any
signal and select the appropriate number of fft1_b threads.

If you want to save 24 hours at 2 MHz sampling rate the file size
should become about 670 gigabytes. That should not be a problem today.

73

Leif

[Jeffrey Owen Katz]

Hi,

I have used linrad for such things. Just re-route the audio output into
audacity, or even arecord. Set the bandwidth wide, if desired, and record
in mono at 44K, or even 22K. I took recordings lasting 5 days with no
problems! A little bash scripting goes a long way.

By the way, I am using Linux (Debian 8).

I also captured the Linrad screen (including S chart) at intervals to .pgn
files, so there were no gaps. Was looking for long-delayed echos!

Jeff AC2BQ

> http://w3sz.com/Linrad%20Installation%20 <http://w3sz.com/Linrad%20Installation%20&%20Configuration%20User%20Guide%20-%20V1-0.pdf> &%20Configuration%20User%20Guide%20-%20V1-0.pdf

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>
>
>
>
>
>
> --
>
> Earl Shaffer, WB9UWA
>
>
>
> My EME array photos
>
> https://www.dropbox.com/sh/bbn2ktonko8e3az/AACHBBOhf6Djk5Pf2c86Br5ja
>
> Detailed array photos
>
> http://www.gm4jjj.co.uk/WB9UWA/
>
> Facebook
>
> http://www.facebook.com/earl.shaffer
>
> Linkedin
> http://www.linkedin.com/pub/earl-shaffer/12/881/735
>
> --
> There is an excellent Linrad User Guide by Gaetan, ON4KHG, at:

> http://w3sz.com/Linrad%20Installation%20 <http://w3sz.com/Linrad%20Installation%20&%20Configuration%20User%20Guide%20-%20V1-0.pdf> &%20Configuration%20User%20Guide%20-%20V1-0.pdf

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> --
> L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
> https://www.avast.com/antivirus

>
> --
> There is an excellent Linrad User Guide by Gaetan, ON4KHG, at:
> http://w3sz.com/Linrad%20Installation%20&%20Configuration%20User%20Guide%20-%20V1-0.pdf
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[ON4KHG]

Hi Leif,


Many thanks for the info. Starting to play with the recordings... amazing !
73,

Gaëtan

To view this discussion on the web visit https://groups.google.com/d/msgid/linrad/20220304025451.c624ea870b6b592c238ca08a%40sm5bsz.com.