As I mentioned above, I just got home from work and discovered several answers. I installed Sigtrax for Android and have experimented with it briefly. It appears to do the job nicely.

You can choose to enter data manually, or use GPS to fix your position and enter the bearing manually, or you can enable the compass and enter bearings visually by sighting across the phone like it was a lensatic compass.

The map display is overlayed on Google Maps so you can invoke high-res sat photos and use buildings or other objects to select a bearing.

By noise, I'm referring to electrical noise. A cracked insulator on a power pole will radiate noise at all frequencies. Using directional antennas you can get a bearing. At UHF frequencies (450 MHz) handheld directional antennas like Yagis are easy to make. These give maximum signal when pointed at the noise source.

At low frequencies, where the wavelength might be hundreds of meters, it's trickier, but there are antennas like the flag antenna that can be used. When hunting noisy power lines, you can start with just a decent AM portable radio. The "loopstick" antenna is directional, but in that case you go for the nulls rather than peaks. With a magnetic antenna like the loopstick, the nulls are much sharper than the peaks. (If you've taken an AM radio apart, you have noticed a ferrite rod with many turns of wire on it. That's called a "loopstick" antenna.)

Since a loopstick antenna is bidirectional, when you find a null you don't know whether your target is in one direction or the opposite. But as soon as you've taken two or more bearings, the correct direction becomes obvious.

This loopstick antenna at low frequencies technique is how LORAN navigation worked, back in the days before GPS. Today, you can use an AM radio and broadcast stations to navigate a sailboat, if you wish. Lol. (Actually, I know I guy who did this decades ago, navigating through fog at night.)

And yes, it would work with sound too if you have a highly directional sound collector.

Yes, for radio (my needs) you use a directional antenna to located the source of the signal (which might be noise). Then you plot a line from your position in the direction of the signal. Then you move to a new location and do it again. Where the two lines intersect is the source of the signal.

You could do the same thing with audible sound, but since the distances are so small, you can just walk towards the source. With radio, the source may be many miles away when you first begin.

My application is locating radio noise sources. A cracked insulator on a power line can arc internally, which generates electrical noise that radiates and interferes with shortwave radio reception.

In my case, the power company does no preventive maintenance that I've ever seen. So I have to track down these faults for them (they should be doing this) and report them.

For one thing, radiating electrical noise and interference is illegal, especially if it interferes with licensed radio services. Secondly, these faults cost the power company money because it's energy that's leaking to ground that's causing the problem.

In Los Angeles, where I grew up, the power company was constantly maintaining the lines, washing the insulators, etc., to reduce leakage and loss. Here, nothing is done. There are cracked insulators, arcing connections, rusty transformers that are older than I am, leaning power poles, and nothing is done unless something breaks.

All nine of the energy management agencies in the USA are non-profit. ERCOT is one. All they do is manage the distribution of power at the top level and report data to the EIA. They have little or no direct authority over the utilities themselves and ERCOT is, of course, populated by cronies chosen by the utility companies.

The State of Texas sold all of its interests in the electrical grid (which is on public land) to private parties. Everything is owned privately in Texas. The impetus for this came from the private parties themselves -- a handful of wealthy investors who bribed politicians to get what they wanted, as usual in the USA.

They did this because if Texas as made independent from the US national grid, then federal regulations would not apply and they could build infrastructure more cheaply. That's how we ended up with non-winterized power plants and wind generators in Texas. The private owners wanted all the income but without making the investments in high quality equipment required by federal regulations. And, that's what they got.

When the winter storm was coming, utility officials lied right up to the last, when everything failed. They deliberately ignored the winter storm possibility -- something that's happened before. So they can't say they didn't know it was possible.

In the summertime especially, I watch this page on the EIA site that gathers real-time data from the nine agencies and breaks it down. https://www.eia.gov/beta/electricity/gridmonitor/dashboard/electric_overview/US48/US48

Which would not have worked in Texas. A whole new design is required for the future, with solar panels and batteries in every home. But the big grid is necessary. Power generation and peak demands are not in the same geographical location.

This is true even if all power is generated locally and there are no big power plants -- especially so, actually.

Big winter storm hits Chicago. Thick cloud deck over the whole region. Solar power is out. No wind. But in surrounding states a thousand or more miles away have plenty of sun and wind. They must route power to hold up the region around Chicago. The big grid is necessary.

And in the summertime, oh my. Watch the EIA site to see when demand climbs to 700 GW, every power plant is running at max, and it's a careful balancing act to keep everything going. It's only because there's a nationwide grid that everything can keep running. If you split that into hundreds of local systems, half the country would be blacked out in summer.

Bear in mind that despite the huge growth in renewables, wind generators as far as the eye can see across Kansas and Wyoming, all of that is still a small fraction of power demand in the USA. The vast majority still comes from coal, gas, and nuclear.

Here in the little state of West Virginia, with a small population, we have 42 big coal-fired power plants because we stand on the world's largest coal deposit. Those power plants are what keep New York running in the summer.

I look forward eagerly to the proliferation of electric vehicles, but I'm very concerned about power generation to keep them all running. Demand is going to increase enormously and none of the local wiring is capable of handling the coming demand.

The bottom line is that independent microgrids have no chance of working. You can't practically build enough generation capacity to handle the peak demands of a certain small place. If you tried, then the average utilization would be like 20 percent. Nobody is going to invest in that. We would need five times to generation capacity that we have now. Sharing is the key. That's why the system is designed as it is.

For example, my wife and I come home from work at 5:30 PM. We plug in our cars and turn on the air conditioning. Wife starts cooking dinner, I take a shower. Power consumption of my house jumps from 1,000 watts to 25,000 watts. I have a big 3,000 watt solar power system and battery that let's me contribute power to the grid most of the time, but not at 5:30 PM. Every house in my city is doing just as I'm doing right now at 5:30.

So where does all that power come from? It comes from the states west / east of me that are in different time zones, that are not at the 5:30 PM rush. They feed gigawatts of power to my region. Later / earlier my region feeds power to them during their rush.

That's the only way the system holds up at all. Otherwise we'd need several times the generation capacity we have today, and most of it would be idle most of the time.