Ways to record WF for up to 24 hours

K9RX
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Ways to record WF for up to 24 hours

Postby K9RX » Fri Mar 11, 2022 2:50 pm

I'm looking for a way to record noise on a band. This is because I have a horrendous noise source that isn't there always. I suspect it is a pot farm or something else illegal ... hoping not the case. It does sound like PL noise and when on it completely wipes out 160 - 6M in that direction. But it is so clean turning on and off I suspect man-made.

So - looking to record the WF, narrow frequency range is fine - for up to 24 hours. Any suggestions? If it can be done using PSDR/VAC that would be great. If there is another app that can be loaded and run that would use the VAC line to do this.

I do have an RSP1A as well if there's no solution for Anan/PSDR.

thanks for any help with doing the recording. I'm set to go hunt for it using a 705 and a 6M DF loop... but since it is erratic at best I'd like to see what pattern, if any it has. When there it cycles on and off - off from 20 secs - 3 mins and its on for 2 - 7 minutes. It also appears to be distant as my 4 element 15 at 36' is much lower than the 6 element at 90'.

Gary
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w-u-2-o
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Re: Ways to record WF for up to 24 hours

Postby w-u-2-o » Fri Mar 11, 2022 3:14 pm

Gary,

You mention "PSDR". It's been so long since I've used PowerSDR that I don't know if this will work, however with Thetis you can go to Setup > Display > RX1 and change the update rate of the waterfall to a very slow value. For instance, I use a 30 FPS setting on the Display > General tab, and if I set the waterfall to update over 900 frames it will update once every 30 seconds. Assuming you noise source stays on for many minutes at a time, this is not too slow a sampling rate.

After that, it's a question of how many horizontal pixels you have on your waterfall. You can maximize those by selecting waterfall display mode instead of panafall, and going into "collapse" mode. I was able to get enough pixels to record 26,000 seconds, or well over 7 hours.

You can see where in time something happened on the waterfall by mousing over the waterfall and looking at the time display in the bottom left corner of the waterfall on the status line.

Of course this all only works in Thetis, only will cover 7 hours, and requires the noise to be present for minutes at a time so that it will be caught by a sampling rate of once every 30 seconds.

If that won't work for you then screen recording software in time lapse mode is probably your next best bet: https://www.easeus.com/screen-recording ... order.html

Probably the best approach is to use one of the low cost SDR app's like SDR Sharp, Airspy or Spectrum Spy, as they are designed to do what you want. But for that you would need to buy a compatible SDR receiver, like the Airspy HF+.

It's probably easiest and fastest just to go with the first idea and simply return to check on the radio once every 6 hours. Do you really have no feel at all for the time of day the interference occurs? If it is a grow operation, legal or otherwise, the lights are almost always on a schedule.

73,

Scott
K9RX
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Re: Ways to record WF for up to 24 hours

Postby K9RX » Sat Mar 12, 2022 5:16 pm

I've seen it on in the middle of the night - I've seen it turn off, the last time around 8PM and stay off until about 5 or so the next day.... when it is on it will cycle from on to off. On might be as little as 2 minutes but generally is in 3 minutes or more - and can be as long as 7 minutes. Off can be as short as 22 seconds and as long as 3 minutes. The transition is clean, off to on, on to off. NOT like I'd expect if it were a bad connection on a power line. On 15M using 6/6 stack (think low AOR due to its top height of 2 WL's) the difference is 25 db! On the bottom antenna it is less, on the BOP stack it is lower still, and on the lowest antenna, a 4 element SteppIR yagi it is just a bit lower so it definitely appears to be more distant as opposed to closer.

This AM I set up a camera on the display - used a cell phone with an app to view it - my wife set watching that as we drove around so we could pull over when it shut off (a real PITA in traffic) ... and I had the AM radio on as well as a IC705 with 6M DF loop that she was twisting 90°. Found nothing along the vector formed by the antennas. There's a good 1.5 miles of just trees in between road access points however so who knows what is in those woods.

It makes the radio completely useless.

I was hoping, just to gather more data, that by looking over 24 hours and then days in comparison I MIGHT see a pattern.

Gary
K9RX
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Re: Ways to record WF for up to 24 hours

Postby K9RX » Sat Mar 12, 2022 5:17 pm

"5 or so the next day" is 5 PM - so off for nearly 24 hours!
K1LSB
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Re: Ways to record WF for up to 24 hours

Postby K1LSB » Tue May 24, 2022 8:39 pm

Gary,

Simon Brown's SDR Console has the ability to record the full IF bandwidth that Thetis can deliver to it thru VAC1. It can record as much signal as your hard disk has room for, and you can play back the recording later and even listen to any signal found anywhere in the captured segment of spectrum. With that said, be aware that IF recordings can quickly get VERY big so it would be to your advantage to reduce your IF bandwidth to only that portion of spectrum you actually want to capture.

Mark
K4IBC
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Re: Ways to record WF for up to 24 hours

Postby K4IBC » Wed May 25, 2022 6:04 pm

K9RX wrote:I've seen it on in the middle of the night - I've seen it turn off, the last time around 8PM and stay off until about 5 or so the next day.... when it is on it will cycle from on to off. On might be as little as 2 minutes but generally is in 3 minutes or more - and can be as long as 7 minutes. Off can be as short as 22 seconds and as long as 3 minutes. The transition is clean, off to on, on to off. NOT like I'd expect if it were a bad connection on a power line. On 15M using 6/6 stack (think low AOR due to its top height of 2 WL's) the difference is 25 db! On the bottom antenna it is less, on the BOP stack it is lower still, and on the lowest antenna, a 4 element SteppIR yagi it is just a bit lower so it definitely appears to be more distant as opposed to closer.

This AM I set up a camera on the display - used a cell phone with an app to view it - my wife set watching that as we drove around so we could pull over when it shut off (a real PITA in traffic) ... and I had the AM radio on as well as a IC705 with 6M DF loop that she was twisting 90°. Found nothing along the vector formed by the antennas. There's a good 1.5 miles of just trees in between road access points however so who knows what is in those woods.

It makes the radio completely useless.

I was hoping, just to gather more data, that by looking over 24 hours and then days in comparison I MIGHT see a pattern.

Gary

This sounds more like a temperature controller rather than grow lights. Could be someone close by that brews his own moonshine or beer. They are using some type of Bang Bang controller rather than PWM control given the clean on off.
K9RX
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Re: Ways to record WF for up to 24 hours

Postby K9RX » Thu May 26, 2022 12:02 pm

thanks guys - fortunately, it has been gone now for months - just after I posted this thread. Seems the nature of these things at times. I still have noise from another direction that is pretty severe - haven't been able to track it down as yet.

Gary
K9RX

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