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February 2, 2022 / Jim Fenton

Chasing Power Anomalies

Recently, we and a number of our neighbors have been noticing our lights flickering in the evening and early morning. While we have considered it to be mostly an annoyance, this has bothered some of our neighbors enough that they have opened cases with the utility and began raising the issue on our street mailing list.

Pacific Gas and Electric (PG&E) responded to these customers with a visit, and in some cases replaced the service entrance cable to the home. In at least one case PG&E also said they might need to replace the pole transformer, which would take a few months to complete. I have heard no reports that these efforts have made any difference.

This isn’t our first recent challenge with voltage regulation in our neighborhood. Our most recent issue was a longer-term voltage regulation problem that occurred on hot days, apparently due to load from air conditioners and the fact that our neighborhood is fed by older 4-kilovolt service from the substation. This is different, and raised several questions:

  • How local are the anomalies? Are neighbors on different parts of the street seeing the same anomalies, or are they localized to particular pole transformers or individual homes?
  • What is the duration and nature of the anomalies?
  • Are they only happening in the evening and early morning, or do we just notice them at these times?

To try to answer these questions, I found a test rig that I built several years ago when we were noticing some dimming of our lights, apparently due to neighbors’ air conditioners starting on summer evenings. The test rig consists of a pair of filament transformers: 110 volt to 6 volt transformers that were used in equipment with electronic tubes, which typically used 6 volts to heat the tube’s filament. The transformers are connected in cascade to reduce the line voltage to a suitable level for the line-in audio input on a computer. An open-source audio editing program, Audacity, is used to record the line voltage. I often joke that this is a very boring recording: mostly just a continuous 60 hertz tone.

At the same time, I started recording the times our lights flickered (or my uninterruptable power supply clicked, another symptom). I asked my neighbors to record when they see their lights flicker and report that back to me.

I created a collection of 24-hour recordings of the power line, and went looking for the reported power anomalies. It was a bit of a tedious process, because not everyone’s clocks are exactly synchronized. But I was successful in identifying several power anomalies that were observed by neighbors on opposite ends of the street (about three blocks). Here’s a typical example:

Typical power anomaly

As you can see, the problem is very short in duration, about 60 milliseconds or so.

I was getting a lot of flicker reports, and as I mentioned, searching for these anomalies was tedious. So I began looking at the analysis capabilities of Audacity. I noticed a Silence Finder plug-in and attempted to search for the anomalies using that tool. But Silence Finder is designed to find the kind of silence that one might find between tracks on an LP: very quiet for a second or so. Not surprisingly, Silence Finder didn’t find anything for me.

I noticed that Silence Finder is written in a specialized Lisp-like signal processing language known as Nyquist. So I had a look at the source code, which is included with Audacity, and was able to understand quite a bit of what was going on. For efficiency reasons, Silence Finder down-samples the input data so it doesn’t have to deal with as much data. In order to search for shorter anomalies, I needed to change that, as well as the user interface limits on minimum silence duration. Also, the amplitude of the silence was expressed in dB, which makes sense for audio but I needed more sensitivity to subtle changes in amplitude. So I changed the silence amplitude from dB to a linear voltage value.

The result was quite helpful. The modified plug-in, which I called “Glitch Finder”, was able to quite reliably find voltage anomalies. For example:

Power recording 1/29/2022-1/30/2022

The label track generated by Glitch Finder points out the location of the anomalies (at 17:05:12, 23:00:12, and 7:17:56 the next morning), although they’re not visible at this scale. Zoom in a few times and they become quite obvious:

Power anomaly at 1/30/2022 7:17:56

Thus far I have reached these tentative conclusions:

  • The power problems are primarily common to the neighborhood, and unlikely to be caused by a local load transient such as plugging an electric car in.
  • They seem to be concentrated mainly in the evening (4-11 pm) and morning (6-10 am). These seem to be times when power load is changing, due to heating, cooking, lighting, and home solar power systems going off and on at sunset and sunrise.
  • The longer term voltage goes up or down a bit at the time of a power anomaly. This requires further investigation, but may be due to switching activity by the utility.

Further work

As usual, a study like this often raises new questions about as quickly as it answers questions. Here are a few that I’m still curious about.

  1. What is the actual effect on lights that causes people to notice these anomalies so easily? I currently have an oscilloscope connected to a photoelectric cell, set to trigger when the lights flash. It will be interesting to see how that compares with the magnitude of the anomaly.
  2. Do LED lights manifest this more than incandescent bulbs? It seems unlikely that such a short variation would affect the filament temperature of an incandescent bulb significantly.
  3. Do the anomalies correlate with any longer-term voltage changes? My test rig measures long-term voltage in an uncalibrated way, but the processing I’m currently doing doesn’t make it easy to look at longer-term voltage changes as well.
December 5, 2021 / Jim Fenton

Sussex Day 11: Padding(ton) Home

Sunday, November 14, 2021

We got an early start, said good-bye to Celeste (who got to stay in the room a little longer), and headed for Paddington Station about 7 am to catch the Heathrow Express. We bought our tickets, got out on the platform, and were greeted with a message board saying that there were delays on the line and that some trains had been canceled. This made us a little nervous, but the Network Rail application on my phone reassured us that there would, in fact, be a train soon. Although we had a bit more than the usual wait for Heathrow Express, the train proceeded normally and was not excessively crowded.

After the usual long walk, we reached the ticket counter and checked in. They were thorough in checking our vaccination and COVID testing status, although not to the point of actually checking the QR codes associated with each. After checking bags, there was another long walk to the vicinity of the gate. United’s lounge in London is still closed, but in the meantime they have an arrangement with Singapore Airlines for the use of their lounge where we were able to get breakfast.

At the gate, Kenna was diverted for extra security screening because the “SSSS” designation was printed on her boarding pass. Following that inconvenience, our flight departed on time, which given that we have only a 2-hour layover in Chicago (including customs and immigration) we appreciated. However, our arrival gate was occupied by another plane, resulting in about a 30 minute delay which made us understandably nervous.

Greenland from the air

Having seen US Customs signs back in San Francisco promoting the Mobile Passport immigration application for our phones, we entered our passport information and customs declaration. But after racing to the immigration hall, we were told, “We don’t use that any more. Get in line.” More nervousness about the time. After getting through Customs (which left us outside security), we took the tram to Terminal 1 for our flight to San Francisco.

Here we noticed that Kenna didn’t have the TSA Precheck designation on her boarding card, probably as a result of the SSSS designation earlier. It may not have mattered; there were signs saying precheck was closed and the people checking boarding passes didn’t seem to know. So we both went through the “slow line”, and unfortunately Kenna set something off and had to go through some extra screening. Apparently they thought there was something about one of her shoes, which they ran through the X-ray machine again; more delay. It was interesting that there were a number of women having their shoes rechecked at the same time.

We raced to our gate, nearly the furthest from the security checkpoint, and made it in enough time, but with not much to spare. The ride to San Francisco was unremarkable, and we collected our bags and caught our ride home, according to plan.


Arriving home we were severely jet lagged as expected, but tried to stay up as late as we could manage. After a few hours of sleep, I awoke about 2 am. I could hear some water dripping, which I attributed to a downspout being clogged with leaves following some recent rainfall. So I got up to investigate, and instead discovered that there was a substantial amount of water dripping from the ceiling into our guest room. It turns out that a hot water pipe in the attic had developed a pinhole leak and over time had soaked one wall. So we now have a new project.

This article is the final installment in a series about our recent travels to southern England. To see the introductory article in the series, click here.

December 4, 2021 / Jim Fenton

Sussex Day 10: London

Saturday, November 13, 2021

London isn’t in Sussex, that’s just the theme of the trip.

Celeste expressed a lot of interest in visiting the Imperial War Museum, which none of us had visited, so we decided to make that our first destination. After a quick Pret a Manger breakfast, we took the Tube to the south side of London. The first thing you notice is the battleship guns at the front. My interest was also piqued by a short segment of Berlin Wall near the front entrance.

The museum has a large collection on several floors, with areas emphasizing World War I, World War II, the Cold War, the Holocaust, etc. One could easily spend several days to see all of the exhibits. Toward the end of our visit, we went in to the World War II gallery (having already seen quite a number of exhibits dealing with WW II), and it went on…and on. The gallery was very large and went into great detail, including many stories about participants in the war, German as well as Allied. We hadn’t expected the gallery to be nearly as large as it was, and might have allocated more time if we had.

Early in the afternoon we tired of the museum and decided to look for lunch. We thought we might like German food, so guided by our phones, we walked north and came to Mercato Metropolitano, a large semi-outdoor food court with sustainable food from many world cuisines. Each of us selected something we like, but we never found the German restaurant we thought was there.

Continuing north, we got to the Borough Market, a large trading market established in 1756. Perhaps because it was a Saturday, it was very crowded. Normally this might not have been as notable but that since the COVID epidemic we have avoided and become unaccustomed to crowds. We walked through quickly and then continued on to the Thames, where we went along the south shore to the Millennium Bridge. We walked out on the bridge, took some pictures, and continued west to the Westminster Bridge. All along the way there were people — lots of people.

After crossing the Westminster bridge, we took a short Tube ride to the West End. Again, everything was crowded. We tried a couple of places for dinner, but nothing was available without an advance booking. The Five Guys burger restaurant was jammed, and there was even a long queue at McDonalds (!). We couldn’t figure out the attraction there.

We finally settled on Itsu, the same Asian-themed fast food chain that we had tried in Brighton. We were able to find a table and had an enjoyable light meal.

The big event of the day was this evening: we had tickets to Back to the Future: The Musical, playing at the Adelphi Theatre on The Strand. This is a new show that that just opened in July 2021 and has not yet made it to the United States. The theatre was, as expected, nearly full. But we had been told that COVID vaccination, negative tests, and the wearing of masks would be required. In fact, we were never asked about vaccinations or tests, and the majority of the audience did not wear masks. We felt somewhat less safe as a result.

Still, the show was very enjoyable. As Celeste pointed out, this is a “tech show” with the strong point being special effects. Most of the performances, particularly Doc Brown, were excellent as well, although Celeste noted that some of the actors had trouble with American accents.

We took the Tube back to our hotel and are retiring quickly. Tomorrow will be an early day for Jim and Kenna’s flight back home.

This article is part of a series about our recent travels to southern England. To see the introductory article in the series, click here.

December 3, 2021 / Jim Fenton

Sussex Day 9: Brighton to London

Friday, November 12, 2021

Since it is now 2 days before our return to the United States, today was the day for our pre-trip COVID test. We were a little nervous about that because, of course, it determines whether we return as planned. Expecting a similar experience as for our Day 2 test, we were a bit surprised that this time we would have to do a proctored test where the proctor would watch us take the test via video chat. The next surprise was that you seem to need both a smartphone to run their app and some other device for the chat session. So we got out our iPads, and (third surprise) there was apparently a bug in their application causing it not to work on an iPad. So we got out my Mac laptop and (fourth surprise) couldn’t use my usual browser, Firefox, but could fortunately use Safari. Each test took about half an hour, including a 15-minute wait for the test to develop. Following the wait, a second video chat was set up where they read the test with you and issued your certificate. Very fortunately, both of our tests were negative.

We checked out of the apartment/hotel just before checkout time and stored our bags. Then the question was what to do until Celeste finished classes so we could all take the train to London. The answer was the Sea Life Brighton, apparently the oldest aquarium in the world. While not an extensive collection, many of the exhibits were in a classic style with ornate frames supporting the glass windows. There was a very enjoyable tunnel where you can sit while fish (and turtles!) swim overhead. The aquarium covered a number of regions of the world, with more of an emphasis on fresh-water fish than many others we have seen.

After browsing a bookstore for a while, we collected our bags and headed for the train station. Trains run to Victoria Station in London every half hour, and fortunately that connected well with the train Celeste took from Falmer to meet us.

After the train trip and Tube ride to Paddington Station, we walked the short distance to our hotel, a newly renovated boutique hotel called Inhabit. We chose it largely because it had nice triple rooms, including an actual bed (not sofa bed) for Celeste. No London trip would be complete without a hotel where it’s necessary to lug your bags up a flight of stairs, but fortunately this one only required a single flight. Our room was modern and comfortable.

I had booked a table at the Victoria, a pub in the Paddington area, and we were seated in a pleasant and not noisy dining room upstairs. Dinner was excellent. Upon returning to the hotel, Celeste immediately collapsed for the night on her cozy bed.

This article is part of a series about our recent travels to southern England. To see the introductory article in the series, click here.

December 2, 2021 / Jim Fenton

Sussex Day 8: Hove and Skating

Thursday, November 11, 2021

While Celeste was in classes, Kenna and I set out on foot for Hove, Brighton’s “twin” city to the west. We had a rather pleasant walk through a shopping district, but there wasn’t much remarkable to see. In Hove, we turned south and followed the main road along the Channel back to the west. We stopped to look at one of the characteristic crescent-shaped residential developments, and continued toward Brighton. We considered going on the i360 observation tower, but it wasn’t particularly clear and the expense didn’t seem worth it.

Celeste and a friend of hers (another exchange student from Colorado) joined us in the afternoon to go ice skating at the Royal Pavilion Ice Rink. While I am used to hockey skates, it was a bit of an adjustment to the others who are used to the toe picks on figure skates. We all got the hang of it; the ice was beautifully maintained (although with some puddles) and the rink was not particularly crowded for our 3 pm session.

After skating we sat in the attached cafe to chat until it was time for dinner, which we had at an Italian restaurant, Bella Italia, in the Lanes.

This article is part of a series about our recent travels to southern England. To see the introductory article in the series, click here.

December 1, 2021 / Jim Fenton

Sussex Day 7: Pavilion and Museum

Wednesday, November 10, 2021

Celeste has a busy class schedule the early part of the day, so Kenna and I set out on our own, first for a hearty breakfast at Billie’s Cafe and then to the Royal Pavilion, one of the sightseeing highlights of Brighton. Originally a country estate, it was remodeled by King George IV into an ornate building, with the exterior having an Indian theme and the interior extensively decorated and furnished in Chinese style.

Brighton’s Royal Pavilion has had a varied history, having been of less interest to Queen Victoria (George IV’s successor in the throne) who moved most of the furnishings to London and sold the building to the City of Brighton. Over the years it has been refurnished in the original style and with many of the original furnishings, some of which have been loaned by Queen Elizabeth. The Pavilion was in the process of being decorated for Christmas, which reminded us of a visit we made two years ago to Filoli in California.

After the Pavilion, we went across the garden to the Brighton Museum, which had a wide range of exhibits ranging from ancient history of the British Isles and ancient Egypt to LGBT styles of the late 20th century and modern furniture.

Having finished her classes, Celeste joined us for lunch at Itsu, one of a chain of Asian-inspired fast food restaurants. We then returned with Celeste to the museum to see a bit more and allow her time to do some research she had planned.

We then made our way behind the Pavilion, where a seasonal ice rink is set up for recreational ice skating. With its location next to the Pavilion it is a particularly scenic place to skate. We are looking forward to doing that tomorrow.

Celeste returned to campus, and Kenna and I, having had a substantial lunch, opted for a light dinner at Ten Green Bottles, a local wine bar.

This article is part of a series about our recent travels to southern England. To see the introductory article in the series, click here.

November 30, 2021 / Jim Fenton

Sussex Day 6: Downtime

Windmills on the English Channel

Tuesday, November 9, 2021

Somewhat at the midpoint of our trip, it was time to take care of a few things like laundry. It’s also time for the thrice-annual Internet Engineering Task Force meeting, which was supposed to be in Madrid, but is being held online (again) due to the pandemic. I co-chaired a session from noon to 2 pm local time today, so I needed to be at the hotel for that. Meanwhile Kenna and Celeste did some exploring around the little shops in the Brighton Lanes.

Our downtime day also gave us an opportunity to do some laundry. One of the attractive features of our “aparthotel” is a compact combination washer/dryer. Our room also came with a couple of detergent pods, which were unfortunately and unexpectedly heavily scented. We will be using our own detergent in the future. The dryer was slow, but it did the job.

IETF virtual venue

I am again thankful for the good internet service here; the meeting went without a hitch (my co-chair is in Melbourne, Australia). Kenna and Celeste brought lunch from Pret a Manger to eat between meeting sessions I needed to attend. Following the second session we went off for dinner at a pizza place we had discovered, Franco Manca. The pizza and surroundings were outstanding; we would definitely return (and Celeste probably will). We then saw Celeste off to her bus back to campus and we returned to our hotel.

This article is part of a series about our recent travels to southern England. To see the introductory article in the series, click here.

November 29, 2021 / Jim Fenton

Sussex Day 5: Lewes

Monday, November 8, 2021

We started our day fairly early, getting a quick Starbucks breakfast before getting on the bus to University of Sussex to meet Celeste at 9:30 am. Celeste has an hour-long radio show, “Oops That Had Banjos”, on the campus radio station, University Radio Falmer. She invited us to co-host the show. The studio was exactly as I had imagined, and it was a lot of fun doing the show with her. We each contributed a couple of songs to the playlist, and got to introduce them briefly.

After the show, Celeste had classes so we continued on to Lewes. We hadn’t been able to see much on our short visit Sunday evening. We started out at Lewes Castle & Museum, again getting an idea of the history of the place and then visiting portions of the castle itself. It was a clear day, and the view from the top was excellent. As with many of these sites, the castle went through many changes through the centuries as political conditions changed.

After climbing around the castle, we were ready for lunch. We checked out a few restaurants in town before settling on the Riverside Cafe, in an attractive area on the River Ouse. After lunch, we walked among a number of small shops before entering a Waterstones bookstore. How we miss spending time in quality bookstores! I expect we’ll be seeking them out more once we return.

We then took the train back to Brighton, since I had a meeting to attend for work. The meeting went well; the internet connection at the hotel is solid and makes it seem like it hardly matters where in the world I am when attending these meetings.

Celeste came down to Brighton to have dinner with us. We decided to go with Latin American food at a local chain called Las Iguanas. The food was quite good although somewhat standard, at least to those of us from California and Colorado.

This article is part of a series about our recent travels to southern England. To see the introductory article in the series, click here.

November 28, 2021 / Jim Fenton

Sussex Day 4: Hastings

Sunday, November 7, 2021

Having gone west to Chichester yesterday, today we went east to Hastings, notable for the Norman conquest of 1066 (although the actual Battle of Hastings was some distance inland). We arranged to meet Celeste on the train as we passed through Falmer, where her campus is located, for the hour-or-so trip along the coast. Unfortunately, it seems like it’s an hour train ride to most sights outside Brighton.

Hastings is an attractive and somewhat touristy town, along the Channel and in a narrow valley surrounded by substantial hills. We walked through the town, stopping for a fish and chips lunch along the way, and admiring the small shops in the Old Town. We took a funicular up one of the two hills and had an excellent view of the surrounding terrain. Unfortunately, the ruins of the castle at Hastings were closed for the season.

After returning via funicular, we continued through the town to the Hastings Museum, a well curated (and free!) small museum that was thorough in its coverage of the history of the area, from the Iron Age to the present. It also included an extensive collection from a local family that sailed around the world in the 1800s.

Taking the train back, we had a change of trains in Lewes, which Celeste had visited and enjoyed previously. We stopped at the Lewes Arms pub, but unfortunately (since it was Sunday evening) the kitchen had closed so we couldn’t get food. So Celeste returned to campus and got dinner there, while Kenna and I got take-out chicken sandwiches to eat in our hotel.

Our weekly family Zoom conference is on Sunday evening, England time, so we ate our sandwiches while chatting with other family members back home. It’s so much easier to stay in close touch with family while traveling than it was just a few years ago.

This article is part of a series about our recent travels to southern England. To see the introductory article in the series, click here.

November 27, 2021 / Jim Fenton

Sussex Day 3: Chichester and Fishbourne

Saturday, November 6, 2021

After a pleasant breakfast at a cafe in The Lanes, we met up with Celeste at the Brighton train station and rode to Chichester, about an hour to the west. Chichester is a pleasant (and yes, touristy) town with a notable cathedral. Arriving somewhat late, we walked through the town and then found lunch at a small restaurant on a side road as many of the major restaurants in town were quite crowded (it is a Saturday, after all).

One of the main attractions in the area is the Fishbourne Roman Palace, one village to the west. We set out on foot, through a bit of rain, for a walk of a couple of miles. But when we arrived it was well worth the trip. This is an actual Roman palace, constructed in about 79AD, that had been uncovered starting in the 1960s, along with many coins, implements, and other artifacts. The mosaic floors were large and particularly impressive. As a teenager, I got to visit the ruins in Pompeii; these were of a similar nature. This palace and surrounding settlements were key to the Roman development of infrastructure in England.

Returning from Fishbourne to Chichester, we made a short visit to Chichester Cathedral. Unfortunately, the sun had set and it was difficult to see most of the stained glass. At the time of our visit, there was a large model of the Moon, traveling to several locations in Europe, that was hanging from the ceiling in the middle of the church. It was a striking thing to see, especially as we first entered.

After our train trip back from Chichester, we parted with Celeste who returned to campus. Since it was a Saturday night, restaurants were crowded, but we were able to get dinner at a large chain pub, Wetherspoons. The pub was noisy and table service was minimal. We ordered via their website and they only cleared the previous patrons’ dirty dishes when they delivered our food. The food was acceptable, but nothing to blog about.

This article is part of a series about our recent travels to southern England. To see the introductory article in the series, click here.