Update on GPS Constellation Monitoring S/W

I’ve been fortunate enough to be able to do a bit of correspondence with 4river, the author of the NMEA Monitor, as well as a bunch of other interesting s/w tools. He updated NMEA Monitor based upon my recommendation to add the ability to display lat/lon in decimal degrees as well as the ddmmss and ddmm.mmmm formats. I don’t think well in sexagesimal, so having dd.dddddd is handy for me. In case you’re interested, decimal degrees are now included as an option in NMEA Monitor V 2.0.

More on the NEV

Very early this morning I was unable to sleep, so I retired to the shack to draw up the battery system for the NEV.

The first figure is the original battery layout. It helps to realize that the batteries are located under the driver’s bench seat. The bench seat hinges in front and tilts up toward the front of the vehicle. Unfortunately, the steering wheel is enough in the way that the seat will not stay in that position, so I need to use a piece of rope or a couple of bungie cords to hold the seat in the open position. The dashed box in the first drawing shows the limited access to the batteries from this opening. In the original design, the rear 3 batteries are partially covered by the back of the front seat and a plastic cowling which is impossible to remove without removing the rear seat assembly, which is an extra pain.

Figure 2 shows the new battery layout. Only significant change is that the rear 3 batteries have been turned around so that the positive terminals are clearly accessible.

Figures 3 through 6 provide a little detail on the old versus new battery configuration, from a dc resistance point of view. The long and short of it is that even though the new configuration makes for longer jumpers, the exclusive use of 2 gauge copper jumper cable actually provides for a lower total resistance, making the battery assembly that much more efficient.

Tonight I’d prefer to sleep as opposed to thinking more about this right now.

Getting the NEV Running Again!

What’s an NEV, inquiring minds ask? Why, it’s a Neighborhood Electric Vehicle!

Yes, it looks a lot like a golf cart, and to the uninspired, it smells and feels like one, but to the IRS and the DMV it’s a potentially street-legal electric-powered vehicle. Importantly, here in Arizona it’s a vehicle covered here under Arizona Title 28 Transportation, which describes the street-licensed vehicle parked in my driveway.

This particular one was a boondoggle purchase way back in 2009, due to some extremely generous federal tax credit legislation passed in 2008. Basically, the vehicle was a serious bargain. Runs off 48 VDC (eight 6-volt US Battery 250HC XC batteries), has a speed governor set to 25 MPH max, will easily run miles and miles on a single charge, has a AZ state license plate and registration, and has seat belts, headlights and turn signals.

In our neighborhood, which is gated with private streets, I can run the thing all day. Speed limit in the neighborhood is 20 MPH, with only 4 stop signs and over 2 miles of paved street. If I want to sneak out of the closed neighborhood, according to the statute (noted above) the vehicle is street-legal on roads with speed limits no greater than 35 MPH, and is permitted to cross streets with higher speed limits.

The NEV had been sitting in the boneyard for a few years and the batteries were in pretty poor condition. I know, I should know better on how to manage heavy expensive batteries, but the way the vehicle was built it is a bit challenging to water the batteries and they seem to, from day one, vent copious amounts of sulfuric acid vapor, causing all sorts of corrosion and erosion. Since each battery weighs about 40 kg, pulling all 8 batteries to properly inspect and water is a royal pain. However, I tore the vehicle apart again last month and determined to make all new cables, clean up all the corrosion, and get the thing running again.

For the most part, it’s all back together again and appears to work fine. I purchased 20′ of 2 gauge Excelene welding cable, 25 2-gauge solid copper tinned terminals, and an 8-ton handy-dandy hydraulic crimper tool with a bunch of dies (in case I want to go all hard-core with some 4/0 cables). This wealth of stuff set me back about $80. Add to this some silicone adhesive/sealant, adhesive-backed heat-shrink tubing, and boom! I’ve got new jumper cables to run from the motor controller to the battery bank.

This time I reorganized the batteries so that all the positive posts are completely accessible any time, so that I can more easily clean off the buildups of copper oxide/sulfide/sulfate residues that collect in mere days. This means that some jumpers are a little longer than in the original setup, but since they were using 4-gauge cable before I can stand the slightly greater lengths without sacrificing much at all. The maintenance headache reduction and reduced back strain to me are worth much more.

So, what do I do with this puppy? Well, not much, actually. When I first got it I did take it for some 5 to 10 mile drives, found my way (accidentally, really, truly) on to some golf course roads, went to the grocery store a few miles away (at night, no less), and even took it through the drive-through at Jack in the Box. Beyond that, none of my once-vaunted dreams to add wireless telemetry, GPS, audio, etc., ever transpired. However, I’m feeling the urge to finally get to these projects.

I am currently looking at using an Arduino as my real-time sensor controller, collecting battery voltage, maybe battery temperature, day/night light level, stuff like that. I might use Wi-Fi to form an RF link back to the house, possible as I put a 2.4 GHz Wi-Fi AP at 15′ atop the house on an 8 dBi omni antenna. In the Tahoe (which has a 5-6 dBi omni), I can actually get to one end of the neighborhood on the Wi-Fi link. However, I’m thinking more about using the 2m ham band and amateur packet radio, just in case I want to wander a bit further. I happen to have a little 5 watt 2m transceiver module, and a spare Kantronics KPC3Plus TNC, and a little GPS brick. The whole thing should pull less than 600 mW (50 mA average at 12 vdc), and transmit telemetry and position packets every minute. And, aprs.fi is already set up to display things like this, so there’s no backend work for me to do.

I’ve just started new employment, so this project, while exciting and interesting, will probably not get started for a while. But, while I’m continuing to procrastinate, I will also consider another project that I never got started on for this little NEV, and that was to add about 300 to 400 W of solar panel to the roof, so that I can trickle-charge the batteries at up to about 8 A (sadly, this is maybe C/35, so that’s why it’s a trickle charger). To add the panels I’ll need to find someone to weld up a sturdy bracket, and but at least in theory I could really be grid-free at least for short distances! And I’d be the talk of the neighborhood!!!

Happy Chemtrail Conspiracy Day!

This morning I went out to get the car serviced. Wow, what a sky! Our quasi-benevolent alien overlords must be really busy today…

Appears that there’s significant upper-atmosphere water content as it makes for an impressive day of long-lingering aircraft contrails.

Some very discrete trails near the sun

I also tried out the new “Panorama” feature on my iPhone, to grab a pair of 180° views.

Centered on NNW
centered on SSE

Not all the clouds visible are from the contrails. With a little effort, it’s possible to separate some of the naturally occurring cirrus from the a/c contrails, but you can see places where the contrails have smeared out enough that telling the difference becomes more challenging.

Ok, gotta stop this post now. I think they’re on to me.

Wi-Fi Sniffing

I recently downloaded a copy of Vistumbler to my mobile PC. Vistumbler is the NetStumber of the 2010’s, and provides all and more of the features which NetStumbler so admirably provided in the early 2000’s. Since installing Vistumbler, I have collected more than 117, 000 APs here in the general PHX area, including a trip to and from Tucson in the mix.

The author is Andrew Calicutt of MA, and as an added attraction they also have a DB engine which can process the collected files and generate kmz files to display on Google Earth. Phil Ferland is the other major contributor / author, and together they’ve built a very nice system which allows us White Hat wardrivers to putter around our towns and collect Wi-Fi access points which are crying into the dark.

The link to Vistumbler is


and the link to the database is


So far I’ve been able to break the system a couple of times with all the APs I’ve collected. Without growing pains, you never get anywhere…%^)

Good thing that there’s plenty of breweries within range of the house to allow me to collect more access points!

ADS-B Tracking

In the over-60-day period since I put up my first ADS-B receiver, I’ve learned a bit more about the general performance and about 1090 MHz propagation.

I set up a second identical receiver to see if my approach was reproducible, and so far it appears to track the first one, but since the antenna on the second one is just a ground plane, the coverage is somewhat worse. Also, In comparing my receiver(s) to those around me, especially the high-performing stations, it looks like the day-to-day fluctuations I see (and which had me worried more than once) are endemic to all those stations within a 50 mile range, which to me means that it’s not just something peculiar with my station.

I’ve dared to go on Alibaba and found a cavity filter manufacturer in Shenzen who can provide a low-insertion-loss 1090 MHz 10 MHz wide filter, with exceptional out of band rejection from DC to light otherwise. I hope to receive the first sample soon and give it a try. Assuming it works well, the next step will be to move one of my two receivers to a site atop a significant mountain around here, where my radio range should be far superior to my location down here on the valley floor.

Another Interesting Observation from ADS-B Watching

I used to think, perhaps like most people, that most commercial flights are flown to get from point A to point B. Sometimes, it might be a milk run, but that just means that it goes from point A to B to C to D. To that point, I’ve had the admittedly curious experience of flying a Southwest Airlines flight from Burbank (BUR) to El Paso (ELP) via Las Vegas (LAS) and Albuquerque (ABQ). It was a long day and a lot of take-offs and landings. (and I also got to see what I think was a Super Guppy at ELP!)

Obviously, more or less straight-line routes are predominant, following the invisible but well-marked flightways across the US, North America, and the rest of the globe. Just as obviously, I’ve been on a/c flights which had to make significant course adjustments due to weather, whether it was hurricanes, mesoscale thunderstorms, or extremely fast jet streams. These are all reasonable things to do.

In my rabidness with this new ADS-B monitoring, I discovered last week a route I’d never seen a commercial a/c take. A major US freight carrier’s flight entered my ADS-B monitoring space about 150 miles NNE of me, then executed a dogleg around the west side of the greater Phoenix area, then departed my coverage headed to the ESE toward El Paso. The only reason I even noticed it was that it suddenly popped up on my Virtual Radar Server (VRS) display and it was fascinating in the grand arc it traced around Arizona, yet never touching the ground.

This carrier apparently does this regularly, and someone on-line called it a “sweeper” route. The flight is scheduled to depart Denver (KDEN) and arrive Memphis (KMEM), a straight-line distance of only 872 miles. However, it generally takes a circuitous route, which on the day I saw it, was 2108 miles. Here’s a graphic of the same flight, even more extreme, with the route distance well over 2450 miles. The bit that’s in red is the portion that I can hear with my ADS-B receiver.

Interesting “question-mark” route across US

The purpose for the flight becomes apparent when it was called a sweeper. Just in case extra packages show up at the last minute at PHX, ELP, DFW or somewhere else along the route I suppose this flight can divert and grab those. If another plane has mechanical problems at one of the airports along this route, this flight can stop and grab the freight. If your mission is to guarantee delivery next day of someone’s letter or package, it costs you a lot in money and reputation to blame it on mechanical problems or a bin being already full.

Pretty interesting things to be learned with this ADS-B tracking. In the meantime, I’ve set up an alert at FlightAware for when this flight gets scheduled and I received my first alert just a little while ago.

ADS-B Coverage and Site Performance Update

Today my ADS-B receive site here at the house has moved into position 291 on the FlightAware Leader Board! Just a few days ago it was at around 350.

There’s only so many a/c that can overfly my general coverage area – Scottsdale Arizona is not Amsterdam, London or Paris. Heck, it’s not even the greater NYC area with its multiple major airports and sheer number of flights. In other words, there’s only so much improvement to be had. The site will never even crack the top 100.

In my search for high-ranking sites in the general US west I found the one which I think will be the one to chase. The site is near to the top or atop Abajo Peak (elev 11,365′) in far southeastern Utah. In addition to being a whopping big mountain, Abajo is one of several major laccoliths in the Four Corners / Colorado Plateau region and the tallest thing for 44 miles. There’s even a live webcam atop Abajo.

From atop Abajo, the visible horizon is below 0 degrees in nearly every direction, with the 44-miles-away Mounts Mellenthin and Peale the only pieces of earth that just barely break 0° (0 degrees, or horizontal). Check out Abajo Peak at HeyWhatsThat.

From atop Abajo, a good receiver will capture a fair amount of the commercial traffic crossing over the western US. An aircraft at 40k ft can be over 200 miles from Abajo and still be above the zero-degree horizon. Since the actual horizon at Abajo averages about -0.5 degrees, this adds another 40 miles or so of crows-flight range. And that’s still not including atmospheric refraction and the occasional edge diffraction. Likely that the Abajo Peak site can hear out to 250 mi / 400 km for an a/c at 40k ft.

While a high site is a great thing, the potential number of a/c is limited by population center locations, flight routes, number of flights, number of non-commercial airports, etc. Abajo doesn’t have a major US hub airport next door. Flights headed from Denver to nearly anywhere in the West will pass through, as will flights from ORD to SoCal airports, PHX, and LAS. Flights from DFW headed west to any locations above about Los Angeles will as well, but not the great majority of flights to SoCal, which is a lot of airports. Pretty much any intercontinental from the NE US to the Southwest will intersect that area. There are a bunch of small civil airports in the footprint, as well.

Let’s compare Abajo’s stats to the Scottsdale site’s stats for the past two weeks (I know, that’s not much of a sample set, but that’s all I have).

8-Feb-15 7-Feb-15 6-Feb-15 5-Feb-15 4-Feb-15 3-Feb-15 2-Feb-15 1-Feb-15 31-Jan-15 30-Jan-15 29-Jan-15 28-Jan-15 27-Jan-15 26-Jan-15
Sun Sat Fri Thu Wed Tue Mon Sun Sat Fri Thu Wed Tue Mon
Abajo position reports 189,086 215,723 251,825 259,477 245,641 250,943 242,716 203,284 232,858 269,162 269,226 229,558 224,085 233,383
Scottsdale position reports 206,155 223,556 269,480 268,903 243,494 239,195 223,117 133,820 175,748 158,466 241,074 234,657 203,885 209,868
Difference (%) 8% 4% 7% 4% -1% -5% -9% -52% -32% -70% -12% 2% -10% -11%
Abajo a/c count 1,910 1,939 2,211 2,218 2,021 2,103 2,100 1,762 2,013 2,277 2,240 1,928 1,843 1,964
Scottsdale a/c count 1,491 1,594 1,760 1,747 1,639 1,734 2,063 1,420 1,590 1,624 1,792 1,540 1,475 1,535
Difference (%) -28% -22% -26% -27% -23% -21% -2% -24% -27% -40% -25% -25% -25% -28%

What the above two weeks of data appears to show is that Scottsdale gets somewhere on the order of the same amount of position reports per day, but that Abajo sees a whole lot more a/c per day.

The Scottsdale best-case 30k ft+ range is to the ESE at just over 240 miles. (It may be just as good to the S, but there’s very few a/c flying down there due to the US/MX border.) However, I’d say the average 30k ft+ range is more like 150-160 mi due to the local hills and more distant mountains. In any case, that’s pretty amazing given that the antenna is 15′ off the ground and in a valley. A little of the performance is likely due to the desert climate and general lack of dense vegetation on exposed ridgelines.

I’ll keep working on improving the setup here at Scottsdale and see how the statistics line up with Abajo’s.

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