[TangerineSDR] [hamsci-grape] Re: [HamSCI] Power Outage Detected by VLF System

Wed Dec 13 06:42:32 EST 2023

I was able to look at the 5 hour period during the power outage. Here is
the amplitude plot of the 180 Hz harmonic:
[image: Screen Shot 2023-12-04 at 10.09.25 PM.png]
This is the frequency deviation plot of the 180 Hz harmonic showing noise
during the period in which the power was completely out.
[image: Screen Shot 2023-12-12 at 10.42.53 PM.png]

When the power is on, SNR is high enough so the FM detector doesn't output
noise spikes of larger magnitude.

Jonathan
KC3EEY

On Tue, Dec 12, 2023 at 9:15 AM Graham c <colonelkrypton at gmail.com> wrote:

> This discussion has been most interesting.
>
> You may or may not be aware that there is a study program at the
> University of Tennessee operated by the Power Information Technology
> Laboratory ( Professor Yilu Liu ). I have been hosting one of their power
> line monitors for more than 15 years.
>
> web site here:  https://fnetpublic.utk.edu/index.html
>
> more information and links to papers (etc) here:
> https://powerit.utk.edu/index.html
>
> cheers, Graham ve3gtc
>
>
>
> On Tue, Dec 12, 2023 at 6:50 AM Jonathan <emuman100 at gmail.com> wrote:
>
>> One of the benefits of vlfrx-tools is how powerful its signal processing
>> tools are. I wanted to investigate the power line frequency over time to
>> understand how it varies throughout the day. With GPS timestamped and
>> sampled aligned data, I can see how the 180 Hz harmonic varies over time.
>> To do so, I feed the stream into a brick wall filter centered at 180 Hz
>> that is 2 Hz wide. Then, after downsampling, I feed it into an FM
>> demodulator, which gives me a frequency deviation output. This frequency
>> deviation output gives me the frequency variation that I'm looking for. I
>> downsample some more to a rate of 1 Hz/sec to decimate and plot the data.
>>
>> Here is a plot of the 180 Hz harmonic over a span of 4 hours showing the
>> deviations in hundreds of mHz:
>> [image: Screen Shot 2023-12-11 at 5.52.29 PM.png]
>> The vertical scale is in mHz and the horizontal scale is in
>> seconds, spanning 4 hours. You can see the deviation spanning ±200mHz which
>> is really interesting! This might represent the variations in load on the
>> local and regional grid.
>>
>> Jonathan
>> KC3EEY
>>
>> On Sun, Dec 10, 2023 at 9:59 PM Jonathan <emuman100 at gmail.com> wrote:
>>
>>> Here on the day of the annular eclipse, powerline hum levels were low
>>> enough that the 180 Hz harmonic seemed to have exhibited ionospheric
>>> propagation. Notice the drop in amplitude at dawn. To me, this shows
>>> daytime D layer absorption as seen in other signals:
>>> [image: Screen Shot 2023-12-10 at 9.41.07 PM.png]
>>> You'll also notice a slight decrease in absorption during eclipse time
>>> which is expected.
>>>
>>> As time went on, background hum levels increased, so this ionospheric
>>> propagation can't be seen on those days. Here is a plot of the last 60 days
>>> since the eclipse showing an increase in power levels of the 180 Hz
>>> harmonic:
>>> [image: Screen Shot 2023-12-10 at 9.49.02 PM.png]
>>> Despite this, you can still see some cyclic nature from diurnal to
>>> diurnal that could indicate ionospheric propagation. The break in the data
>>> was when there was an issue with the system.
>>>
>>> Jonathan
>>> KC3EEY
>>>
>>> On Wed, Dec 6, 2023 at 7:38 AM Phil Erickson <phil.erickson at gmail.com>
>>> wrote:
>>>
>>>> Hi all,
>>>>
>>>>   We should also emphasize that power line radiation is not just
>>>> local.  In case you hadn’t seen it, power line harmonics have also been
>>>> detected in near-Earth space right out to the edge of the ‘VLF bubble’ and
>>>> beyond (bubble extent = the plasmasphere boundary layer, 14000 - 20000+ km
>>>> altitude) essentially out to the extent of VLF transmissions and those
>>>> latitudes where humans live.  This was discovered long ago by the Stanford
>>>> group (Don Carpenter, Chung Park, etc.) using ground based VLF whistler
>>>> observations in the Antarctic and Arctic (e.g. Roberval in Canada).
>>>>
>>>> https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JA080i031p04249
>>>>
>>>> https://link.springer.com/article/10.1007/BF00173690
>>>>
>>>>   DEMETER satellite data, at 600 km altitude, has also clearly detected
>>>> power line harmonics in the topside ionosphere in its data.  See this
>>>> article and related ones:
>>>>
>>>> https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2006JA012134
>>>>
>>>>   So it is truly everywhere.
>>>>
>>>> 73
>>>> Phil W1PJE
>>>>
>>>> On Wed, Dec 6, 2023 at 06:29 Jonathan <emuman100 at gmail.com> wrote:
>>>>
>>>>> Mike,
>>>>>
>>>>> At ELF, ULF, and VLF, powerline hum (including harmonics) is
>>>>> omnipresent and comes from many different sources, meaning the VLF receiver
>>>>> detects power line emissions from the house, surrounding houses,
>>>>> surrounding power lines, both access, distribution, and transmission lines,
>>>>> and anything else supplied by mains within hundreds of miles. There is
>>>>> never any “one source” of powerline hum and it will always be present on a
>>>>> VLF receiver. In many VLF applications, power line hum is filtered so as
>>>>> long as it’s not at high enough levels that it causes clipping at the data
>>>>> acquisition input. I filter in my signal processing chain, but before I do,
>>>>> I continually monitor levels of 60Hz and 180 Hz
>>>>>
>>>>> Steve,
>>>>>
>>>>> I’ve heard of many cases where solar panel inverters create lots of
>>>>> noise at HF, but few have been characterized at VLF. I would imagine making
>>>>> these inverters VLF quiet will take much more legwork, as it always does
>>>>> with VLF.
>>>>>
>>>>> With vlfrx-tools and Spectrum Lab, an adaptive mains filter is
>>>>> included and is very effective. Here
>>>>> <http://www.abelian.org/vlfrx-tools/hum.mp3> is a sample containing
>>>>> 50 Hz hum and harmonics with the adaptive mains filter in vlfrx-tools.
>>>>> After a few seconds, it locates the fundamental and odd/even harmonics and
>>>>> adaptively notches them out. It tracks them as the line frequency changes
>>>>> throughout the day. Once it kicks in, you can hear sferics and the VLF
>>>>> spectrum quite easily. It notches harmonics up to 6 kHz by default, but can
>>>>> notch up to 8 or 10 kHz in mains-heavy environments. Using it, you can
>>>>> easily hear natural radio events and amateur radio transmissions in the VLF
>>>>> band.
>>>>>
>>>>> Dana,
>>>>>
>>>>> Mains harmonics usually extend up to ~6 kHz but could extend much
>>>>> higher in heavy harmonic environments. Those noises you hear are not
>>>>> usually related to power line emission, but could be synchronous to 60 Hz
>>>>> because they originate from power converters synchronous to power line
>>>>> frequencies.
>>>>>
>>>>> Jonathan
>>>>> KC3EEY
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Dec 5, 2023 at 1:01 PM Eric Nichols <kl7aj72 at gmail.com> wrote:
>>>>>
>>>>>> Golden Valley Electric association up here has always been very
>>>>>> competent and eager to solve noise problems.   Probably because the head of
>>>>>> engineering for many decades was a ham.  I believe he also trained his
>>>>>> underlings well...the systems seems to be incredibly clean.   This may not
>>>>>> be the case elsewhere, but I'm very grateful for our power folks up here.
>>>>>>
>>>>>> 73!
>>>>>>
>>>>>> Eric
>>>>>> On 12/5/23 06:45, Dana Whitlow wrote:
>>>>>>
>>>>>> David,
>>>>>>
>>>>>> As I've tried to emphasize above, all i've looked at so far is the
>>>>>> "raspy buzz"
>>>>>> impulsive form of noise, which I've normally tended to regard as the
>>>>>> most
>>>>>> objectionable.  However, I do recognize that the "fuzzy hum" form
>>>>>> would
>>>>>> likely turn out to be more of a problem for very narrowband analyses,
>>>>>> which
>>>>>> is my usual case, if a harmonic should land too close to the signal
>>>>>> band of
>>>>>> interest.
>>>>>>
>>>>>> Many of my experiments have involved a final measurement bandwidth of
>>>>>> less than 1 Hz, so I should be alert to this possibility.
>>>>>>
>>>>>> Dana
>>>>>>
>>>>>>
>>>>>> On Tue, Dec 5, 2023 at 9:38 AM David G. McGaw <
>>>>>> david.g.mcgaw at dartmouth.edu> wrote:
>>>>>>
>>>>>>> Generally, transformers do not make noise.  All the electronic loads
>>>>>>> in the neighborhood on the line will create a certain amount of harmonics,
>>>>>>> though the larger loads are required to include power factor control to
>>>>>>> minimize this.  Defective insulators or branches and such across the wires
>>>>>>> do create pulse noise.
>>>>>>>
>>>>>>> You are correct, if you can localize the source of the interference,
>>>>>>> the power company will fix it.  They do not have the capability of finding
>>>>>>> it themselves so rely on us to find and report it.  In New England, we have
>>>>>>> created a task force under ARRL to help, see
>>>>>>> <https://nediv.arrl.org/spectrum-protection-utilization/>
>>>>>>> <https://nediv.arrl.org/spectrum-protection-utilization/>, "Noise
>>>>>>> Identification".
>>>>>>>
>>>>>>> 73,
>>>>>>>
>>>>>>> David N1HAC
>>>>>>>
>>>>>>> On 12/5/23 10:34 AM, Dana Whitlow wrote:
>>>>>>>
>>>>>>> Michael,
>>>>>>>
>>>>>>> Since there is no electrical connection to the top end of the pipe,
>>>>>>> basic EM theory says that the pipe is actually irrelevant to common-
>>>>>>> mode current flows.  Whether or not the pipe provides any shielding
>>>>>>> for E-fields is another matter, of course.  I have not looked at the
>>>>>>> E-field issue, because even if the pipe is *not* grounded, the 40
>>>>>>> ft of
>>>>>>> unshielded wiring from the pole to the top of the pipe would by far
>>>>>>> be the dominant radiator, and there is nothing I could do about it.
>>>>>>>
>>>>>>> Your mention of the transformer itself being noisy is scary, because
>>>>>>> the ultrasonic test would almost certainly fail to detect such a
>>>>>>> problem, probably making it rather difficult to persuade the power
>>>>>>> company to change out the transformer "on speculation".
>>>>>>>
>>>>>>> As far as power outages are concerned, I'd love to see a county-wide
>>>>>>> outage at night in clear WX, just so I could enjoy a dark sky for a
>>>>>>> change.  But preferably in the summer, you understand.
>>>>>>>
>>>>>>> Dana
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Tue, Dec 5, 2023 at 9:01 AM 'Black Michael' via HamSCI <
>>>>>>> hamsci at googlegroups.com> wrote:
>>>>>>>
>>>>>>>> Make sure your metal pipe is grounded to the ground rod at your
>>>>>>>> breaker panel.
>>>>>>>> You should see almost 0 Ohms between the pipe and ground connection.
>>>>>>>>
>>>>>>>> It may be more likely coming in the wiring.  Do you have an oscope
>>>>>>>> you can use to see what's on the wires/pipes?
>>>>>>>>
>>>>>>>> The power outage is a good clue and you may be able to get the
>>>>>>>> power company to come out based on that observation.
>>>>>>>> Noisy transformers are common and they are required to replace them.
>>>>>>>>
>>>>>>>> Mike W9MDB
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Tuesday, December 5, 2023 at 08:55:58 AM CST, Dana Whitlow <
>>>>>>>> k8yumdoober at gmail.com> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Michael,
>>>>>>>>
>>>>>>>> I've only tried that once, during an episode of the raspy buzz form
>>>>>>>> of the problem.  I used a battery-powered AM radio in the AM BC
>>>>>>>> band so that I could use the ferrite bar antenna.
>>>>>>>>
>>>>>>>> The breaker panel is located on the outside of the house, and the
>>>>>>>> incoming power comes down through a metal pipe which extends
>>>>>>>> up through the eave, with the wiring from the pole entering said
>>>>>>>> pipe through the usual arrangement used to keep rain out.
>>>>>>>>
>>>>>>>> Anyway, before I turned off any breakers I moved the radio around
>>>>>>>> and concluded that the noise was manifested (at least primarily) as
>>>>>>>> a common-mode current through the metal pipe.
>>>>>>>>
>>>>>>>> Next I began turning off individual breakers to see if the problem
>>>>>>>> was confined to a single circuit, but apparently it was not.
>>>>>>>>
>>>>>>>> Then, with all the individual breakers back on, I opened the master
>>>>>>>> breaker, with the same result.  The noise remained in all its glory.
>>>>>>>>
>>>>>>>> I suspect a problem with the pole about 40 ft from the house, but
>>>>>>>> did not have an ultrasonic snooper at the time.  I acquired one of
>>>>>>>> those only very recently, but have not yet put it to the acid test.
>>>>>>>>
>>>>>>>> I have not yet found anybody selling giant clamp-on ferrite chokes
>>>>>>>> for  "cables" about 4 inches in diameter  :-)
>>>>>>>>
>>>>>>>> Also, I have not yet investigated the fuzzy hum form of
>>>>>>>> interference.
>>>>>>>>
>>>>>>>> Dana
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Tue, Dec 5, 2023 at 8:25 AM 'Black Michael' via HamSCI <
>>>>>>>> hamsci at googlegroups.com> wrote:
>>>>>>>> > Can we assume you've tested cutting power to your house so you
>>>>>>>> can determine if it's YOUR house causing any of the hum?
>>>>>>>> >
>>>>>>>> > Mike W9MDB
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > On Tuesday, December 5, 2023 at 05:34:33 AM CST, Jonathan <
>>>>>>>> emuman100 at gmail.com> wrote:
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > A benefit to powerline hum (radio emissions of 60Hz and harmonics
>>>>>>>> radiated by power lines) being omnipresent even in the most RF quiet
>>>>>>>> locations is that you can monitor local and regional power outages very
>>>>>>>> closely with a VLF receiver. A local power outage occurred around the
>>>>>>>> vicinity of the VLF receiver at Spring Brook Township, PA. Here is a plot
>>>>>>>> of the amplitude level of 180 Hz, a harmonic of 60 Hz, showing some power
>>>>>>>> loss at ~2030UT and completely at ~2100UT:
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > Here you can see the hum level in greater temporal detail.
>>>>>>>> What is so impressive about this power outage is how low the hum levels
>>>>>>>> got. I will be pulling the audio file and listening to this period.
>>>>>>>> Unfortunately, there were no whistlers or dawn chorus, but hum levels this
>>>>>>>> low are quite a treat:
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > After the power outage ended, there were some interesting spikes,
>>>>>>>> possibly due to inductive inrush, then hum levels returned to normal:
>>>>>>>> >
>>>>>>>> > The VLF system was on a UPS during the power outage, so
>>>>>>>> there definitely is benefit to keep the system up and running during local
>>>>>>>> power outages, especially if the magnetosphere decides to be generous.
>>>>>>>> Power grid studies are often done using VLF receivers and the benefit is
>>>>>>>> that no attachment to the power lines are required.
>>>>>>>> >
>>>>>>>> > Jonathan
>>>>>>>> > KC3EEY
>>>>>>>> >
>>>>>>>> >
>>>>>>>> >
>>>>>>>> > --
>>>>>>>> > Please follow the HamSCI Community Participation Guidelines at
>>>>>>>> http://hamsci.org/hamsci-community-participation-guidelines.
>>>>>>>> > ---
>>>>>>>> > You received this message because you are subscribed to the
>>>>>>>> Google Groups "HamSCI" group.
>>>>>>>> > To unsubscribe from this group and stop receiving emails from it,
>>>>>>>> send an email to hamsci+unsubscribe at googlegroups.com.
>>>>>>>> > To view this discussion on the web visit
>>>>>>>> https://groups.google.com/d/msgid/hamsci/CAOY0kB1bH8_cOqH0diQ7vBBaCHzuZo0h2FNRkGDkfHvA2YK23Q%40mail.gmail.com
>>>>>>>> .
>>>>>>>> >
>>>>>>>> > --
>>>>>>>> > Please follow the HamSCI Community Participation Guidelines at
>>>>>>>> http://hamsci.org/hamsci-community-participation-guidelines.
>>>>>>>> > ---
>>>>>>>> > You received this message because you are subscribed to the
>>>>>>>> Google Groups "HamSCI" group.
>>>>>>>> > To unsubscribe from this group and stop receiving emails from it,
>>>>>>>> send an email to hamsci+unsubscribe at googlegroups.com.
>>>>>>>> > To view this discussion on the web visit
>>>>>>>> https://groups.google.com/d/msgid/hamsci/2099478555.158709.1701786348336%40mail.yahoo.com
>>>>>>>> .
>>>>>>>> >
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Please follow the HamSCI Community Participation Guidelines at
>>>>>>>> http://hamsci.org/hamsci-community-participation-guidelines.
>>>>>>>> ---
>>>>>>>> You received this message because you are subscribed to the Google
>>>>>>>> Groups "HamSCI" group.
>>>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>>>> send an email to hamsci+unsubscribe at googlegroups.com.
>>>>>>>> To view this discussion on the web visit
>>>>>>>> https://groups.google.com/d/msgid/hamsci/CADHrwpdx6v8A5%3Dhr3fN0wpcAR0Tq1kbLB1dpnBaeQmuw%3DLZK9Q%40mail.gmail.com
>>>>>>>> .
>>>>>>>>
>>>>>>>> --
>>>>>>>> Please follow the HamSCI Community Participation Guidelines at
>>>>>>>> http://hamsci.org/hamsci-community-participation-guidelines.
>>>>>>>> ---
>>>>>>>> You received this message because you are subscribed to the Google
>>>>>>>> Groups "HamSCI" group.
>>>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>>>> send an email to hamsci+unsubscribe at googlegroups.com.
>>>>>>>> To view this discussion on the web visit
>>>>>>>> https://groups.google.com/d/msgid/hamsci/2096484717.169585.1701788450009%40mail.yahoo.com
>>>>>>>> .
>>>>>>>>
>>>>>>> --
>>>>>>> Please follow the HamSCI Community Participation Guidelines at
>>>>>>> http://hamsci.org/hamsci-community-participation-guidelines.
>>>>>>> ---
>>>>>>> You received this message because you are subscribed to the Google
>>>>>>> Groups "HamSCI" group.
>>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>>> send an email to hamsci+unsubscribe at googlegroups.com.
>>>>>>> To view this discussion on the web visit
>>>>>>> https://groups.google.com/d/msgid/hamsci/CADHrwpeHA9SDaKf_hUY1rKt-aDeJJrh-P-ZOhcEZuLgRNr1h%2Bg%40mail.gmail.com
>>>>>>> <https://groups.google.com/d/msgid/hamsci/CADHrwpeHA9SDaKf_hUY1rKt-aDeJJrh-P-ZOhcEZuLgRNr1h%2Bg%40mail.gmail.com?utm_medium=email&utm_source=footer>
>>>>>>> .
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Please follow the HamSCI Community Participation Guidelines at
>>>>>>> http://hamsci.org/hamsci-community-participation-guidelines.
>>>>>>> ---
>>>>>>> You received this message because you are subscribed to the Google
>>>>>>> Groups "HamSCI" group.
>>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>>> send an email to hamsci+unsubscribe at googlegroups.com.
>>>>>>> To view this discussion on the web visit
>>>>>>> https://groups.google.com/d/msgid/hamsci/7fba57a4-23ad-48c3-b245-34e874f1c86e%40dartmouth.edu
>>>>>>> <https://groups.google.com/d/msgid/hamsci/7fba57a4-23ad-48c3-b245-34e874f1c86e%40dartmouth.edu?utm_medium=email&utm_source=footer>
>>>>>>> .
>>>>>>>
>>>>>> --
>>>>>> Please follow the HamSCI Community Participation Guidelines at
>>>>>> http://hamsci.org/hamsci-community-participation-guidelines.
>>>>>> ---
>>>>>> You received this message because you are subscribed to the Google
>>>>>> Groups "HamSCI" group.
>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>> send an email to hamsci+unsubscribe at googlegroups.com.
>>>>>> To view this discussion on the web visit
>>>>>> https://groups.google.com/d/msgid/hamsci/CADHrwpeP7tZvK8Q1zjP_8JA_wtPwBCr5g4m%2BiKfR9UtjyLrYdg%40mail.gmail.com
>>>>>> <https://groups.google.com/d/msgid/hamsci/CADHrwpeP7tZvK8Q1zjP_8JA_wtPwBCr5g4m%2BiKfR9UtjyLrYdg%40mail.gmail.com?utm_medium=email&utm_source=footer>
>>>>>> .
>>>>>>
>>>>>> --
>>>>>> Eric P. Nichols, KL7AJ
>>>>>> AlasKit Educational and Scientific Resources138 Shenandoah Drive
>>>>>> Fairbanks, AK 99712 <https://www.google.com/maps/search/138+Shenandoah+Drive%0D%0AFairbanks,+AK+99712?entry=gmail&source=g>
>>>>>> (907)371-7120www.alaskit.netkl7aj72 at gmail.com
>>>>>>
>>>>>> --
>>>>>> Please follow the HamSCI Community Participation Guidelines at
>>>>>> http://hamsci.org/hamsci-community-participation-guidelines.
>>>>>> ---
>>>>>> You received this message because you are subscribed to the Google
>>>>>> Groups "HamSCI" group.
>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>> send an email to hamsci+unsubscribe at googlegroups.com.
>>>>>> To view this discussion on the web visit
>>>>>> https://groups.google.com/d/msgid/hamsci/af7ffc79-f5cd-4c6c-a14b-b568ed0b12ac%40gmail.com
>>>>>> <https://groups.google.com/d/msgid/hamsci/af7ffc79-f5cd-4c6c-a14b-b568ed0b12ac%40gmail.com?utm_medium=email&utm_source=footer>
>>>>>> .
>>>>>>
>>>>> --
>>>>> You received this message because you are subscribed to the Google
>>>>> Groups "hamsci-grape" group.
>>>>> To unsubscribe from this group and stop receiving emails from it, send
>>>>> an email to hamsci-grape+unsubscribe at googlegroups.com.
>>>>> To view this discussion on the web visit
>>>>> https://groups.google.com/d/msgid/hamsci-grape/CAOY0kB3B%2B3ei3xqrVpssGfiCXvyJK9j9s3kk4uRJR4wgrGSYNQ%40mail.gmail.com
>>>>> <https://groups.google.com/d/msgid/hamsci-grape/CAOY0kB3B%2B3ei3xqrVpssGfiCXvyJK9j9s3kk4uRJR4wgrGSYNQ%40mail.gmail.com?utm_medium=email&utm_source=footer>
>>>>> .
>>>>>
>>>> --
>> You received this message because you are subscribed to the Google Groups
>> "hamsci-grape" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to hamsci-grape+unsubscribe at googlegroups.com.
>> To view this discussion on the web visit
>> https://groups.google.com/d/msgid/hamsci-grape/CAOY0kB2s2eEQQURxCej-yXHZ7t4HPd6d6MoiC98uZbyDGWcmnA%40mail.gmail.com
>> <https://groups.google.com/d/msgid/hamsci-grape/CAOY0kB2s2eEQQURxCej-yXHZ7t4HPd6d6MoiC98uZbyDGWcmnA%40mail.gmail.com?utm_medium=email&utm_source=footer>
>> .
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.tapr.org/pipermail/tangerinesdr_lists.tapr.org/attachments/20231213/a361a3c9/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Screen Shot 2023-12-10 at 9.41.07 PM.png
Type: image/png
Size: 14882 bytes
Desc: not available
URL: <http://lists.tapr.org/pipermail/tangerinesdr_lists.tapr.org/attachments/20231213/a361a3c9/attachment-0005.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Screen Shot 2023-12-10 at 9.49.02 PM.png
Type: image/png
Size: 15578 bytes
Desc: not available
URL: <http://lists.tapr.org/pipermail/tangerinesdr_lists.tapr.org/attachments/20231213/a361a3c9/attachment-0006.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Screen Shot 2023-12-11 at 5.52.29 PM.png
Type: image/png
Size: 34374 bytes
Desc: not available
URL: <http://lists.tapr.org/pipermail/tangerinesdr_lists.tapr.org/attachments/20231213/a361a3c9/attachment-0007.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Screen Shot 2023-12-12 at 10.42.53 PM.png
Type: image/png
Size: 29938 bytes
Desc: not available
URL: <http://lists.tapr.org/pipermail/tangerinesdr_lists.tapr.org/attachments/20231213/a361a3c9/attachment-0008.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Screen Shot 2023-12-04 at 10.09.25 PM.png
Type: image/png
Size: 15122 bytes
Desc: not available
URL: <http://lists.tapr.org/pipermail/tangerinesdr_lists.tapr.org/attachments/20231213/a361a3c9/attachment-0009.png>