Friday, August 19, 2022

Lockheed P-38 Lightning Design

Here's Dad in his P-38 Lightning:

 Henry C. "Hank" Liebold

Recently I uncovered a few vintage technical aircraft magazines with some very detailed descriptions of the P-38. I thought these might be of interest to other vintage aircraft fans. Click on each cover below to download a zip file of the article scans.

Saturday, June 18, 2022

2013-2015 Xterra Pro-4X Atoto Stereo Head Unit Upgrade with Wiring Harness Chart

Installing an Atoto Android Head Unit in a Nissan Xterra: 2013-2015 Xterra Pro-4X Stereo Head Unit Upgrade with Wiring Harness Chart.


Installing an Atoto S8 Ultra Gen 2 in a Nissan Xterra or Frontier with a Rockford Fosgate amplifier and subwoofer.

(Thanks to those that came before, especially packpride85 from I wouldn't have done this project without your pioneering the work.)

I have a 2014 Nissan Xterra Pro-4x with 5.8 display, navigation and Rockford Fosgate powered audio system including an amplifier, enclosed subwoofer and 9 speakers and this post should apply to the 2013-2015 Xterra Pro-4X. (It should also apply to the 2013-2021 Frontier Pro-4X and SL with the Rockford Fosgate system and 10 speakers)

Why I upgraded the OEM head unit and only the head unit

The Rockford Fosgate system includes a well liked 380W DSP amplifier. The system also has Rockford Fosgate’s “PUNCH bass tuning” (I found this “Punch tuning” overemphasized the bass and was happy to find this goes away with a new head unit). The Xterra has 7 speaker channels and 9 speakers (I think the Frontier has an extra subwoofer speaker for 10 total speakers). The speakers are fairly nice and designed to mate with the Rockford Fosgate amplifier. Note that if you want to upgrade the speakers or amp you will likely have to upgrade both at the same time, as they are a low impedance (2 ohm) system and will likely not work properly unless they are matched.

I was pleased with the OEM sound (after turning down the over-punched bass) but I was unhappy with the navigation and other music apps or lack thereof. After a bit of research I found that while many name brand units offer Android Auto or Apple CarPlay, they don’t allow you to run apps on the head unit itself. If you want to run a mapping application or even google maps on the head unit itself, you need an Android head unit.

I also wanted to retain the Rockford Fosgate amplifier, subwoofer, speakers and all of the OEM features: steering wheel controls, backup camera that automatically comes on in reverse, USB and AUX in the console between the seats, GPS antenna, and the FM antenna.

After a bunch of research on head units, I chose the Atoto S8 Ultra Gen 2.

This unit is readily available on Amazon in the USA and has many users here. There are other good units, like the Joying, that seem preferred in other countries.

The Atoto S8 Ultra Gen 2 (S8G2A78UL-N) features a 7 Inch QLED display that fits well in the dash, Android in-Dash Navigation (no phone required), Wireless CarPlay & Wireless Android Auto, Dual BT w/aptX HD, Gesture Operation, Rear View Camera, a built-in 4G Cellular Modem, 4G RAM and 64G Flash Storage.

This is an Android head unit, meaning it actually runs Android, just like a tablet or phone. It can also do wireless Android Auto and wireless Apple Carplay. Now, I think most people don't need a full blown Android head unit like this. The benefit of it is that you don't need a phone connected to the unit to run any apps. And the unit can run apps like Torque for OBD, or a music app to manage a large music library on an attached USB drive. You can play YouTube, etc. You can also run an off-road mapping app right on the head unit. (But note that while the unit has a very good GPS function, it does not include a compass or accelerometer, so mapping functions can show some confusion when moving slowly and backing up and things like that.) I really wanted a unit like this so my phone was not necessary.

I’m not going to detail all the steps to install the Atoto head unit, just some of the details that I found important. 

First let me address a few concerns:

Current drain: I heard some complaints about excessive current drain from the head unit. I bench tested mine before installing it, and about a minute after turning off the ignition the current drain fell to a very reasonable 11mA. I suspect some installers may not configure the ACC wiring correctly. It is important to connect the constant 12 power to the proper input and the ACC wire to the ACC wire from the truck. The ACC wire tells the head unit the truck is off, and that it should turn off soon. Do not wire the ACC to a constant 12V source.

Line level Outputs: I also used the “line level” RCA connector outputs from the Atoto head unit to connect to the OEM Rockford Fosgate amp. I was concerned that this might not include the low frequencies the Amp would need to synthesize the proper signal for the subwoofer. But this was not a problem, the Atoto head unit provides full range signals to the left and right line level output channels and the Rockford Fosgate amp properly sent the necessary signal to the subwoofer.

Is a “Line Out Converter” needed? Some have used a device called a “Line Out Converter” or LOC so they could use the Atoto head unit’s speaker level outputs and reduce those signals with the LOC for the amplifier. I did some testing and the signals direct from the Atoto’s RCA line level outputs seem well matched to the Rockford Fosgate amplifier. No “Line Out Converter” is needed.

Popping sounds from the speakers at turn on? I have not experienced that. I was careful to properly connect the Constant +12V, ACC and "amp turn on" connections to their respective connections. I suspect some who experience popping sounds at turn on do not have the "amp turn on" signal properly connected from the head unit.

System Update

The first thing I did was "bench test" my unit to makle sure everything worked properly. And then I updated the software on the unit. The latest update was required for Wireless Android Auto to work.

"Secret" Atoto Upgrade Site: Note this site seems to be in a "phone" web format.

The Wiring Harness 

Making the wiring harness is the hardest part of the project. You remove the OEM radio and unplug all the connectors on the back of it. Then you plug adapters into those harness so you can connect the existing vehicle wiring to the new head unit.

Here are the harnesses and connectors that I used:

  1. Metra 70-7552 Radio Wiring Harness For Nissan 2007-Up/Select Subaru 2008-Up
  2. CESS-064-1f Speaker Cables to RCA Plugs Adapter, 2-Channel (1 Foot) (2 needed)
  3. Metra Electronics 40-NI12 Antenna Cable to Aftermarket Radio Adapter for Select 2007-Up Infiniti/Nissan Vehicles,Black
  4. Axxess AXNISUSB2 Fits Nissan USB Adaptor Retain OE USB Retention Metra Harness
  5. Axxess AXBUCS-NI246V Back Up Camera Ret Harness w/ SWC for select Nissan 2011-Up (SWC connection not used for this vehicle)
  6. aide Electronic GSM Antenna Extension Cable Fakra D Female to SMA Male Connector pigital Cable RG174 20cm (15cm)
  7. onelinkmore SMA Female to Female Barrel Adapter Antenna Jack Adapter for Antennas Wireless LAN Devices Coaxial Cable Pack of 2
  8. Eightwood Fakra C Plug to SMA Plug Male Car GPS Antenna Cable 6 inch for Vehicle GPS Navigation Radio Stereo Head Unit GPS Receiver

I made a chart showing to connect the Atoto head unit harness and back panel connectors to these harnesses.You read this chart across the rows, for example: On the Atoto Harness, pin 13, the pink wire connects to the AXBUCS-NI246V harness's pin 28 green/purple wire.

Here is a picture of the completed harness. I used a Wirefly heat shrink butt connectors and the appropriate Wirefly crimper.

Here is the pair of cables and barrel connector I used to make an adapter to connect the Atoto GPS connector to the Nissan's GPS connector: 

Here are all the harnesses plugged into the Nissan truck's harness. I have used a towel to protect the dash and center console from scratches.

I didn't want the cables to rattle in the dash, so I wrapped them with soft foam adhesive weatherstripping:

 Mounting brackets for the head unit

The Atoto 7" head unit is requires and adapter to fit properly in the dash. I tried two versions. 

Below, on the left is the Metra95-7619 Car Stereo Installation Dash Kit for 2013-Up Nissan Frontier/Titan/Xterra, (Black)It did fit well, but will need thin large washers under the screws into the plastic. Also the plastic brackets provide no inherent chassis ground. And finally, I did not like how it framed the Atoto screen, the sides are deep and square.

On the right is the Ai NDK780 2011-2014 Nissan Multi Dash Kit Single ISO , Black attached to the factoru metal bracket and the Atoto radio.

The NDK780 trim kit comes in 3 pieces that snap together. I trimmed it a bit so the pieces fit together better and then used superglue to assemble them permanently.

Unfortunately the neither the holes in this trim piece nor in the Nissan factory bracket line up properly with the side winds that come with the Atoto radio. I slotted the hole in the NDK780 plastic trim as shown below.

And I slotted the holes in the factory Nissan brackets as well. I have marked those with red circles on the bracket below. It is necessary to do this to both brackets.

And here is the Atoto radio installed in the dask panel using the Atoto side wings, the factory metal brackets and the NDK780 trim kit:


And then I put the truck back together... and it looks great!

In the picture above you can see the trim kit has beveled edges on the left and right side: the dash slopes in to the face of the display. This is why I preferred this trim kit. The other Metra trim kit has sides that are square to the display and does not have these sloped sides.

Output Level Testing 

Before I removed the original Rockford Fosgate head unit, I ran it through a series of tests with pink noise and a few test tones. I wanted to see what levels the unit put out through each channel at different volume settings. I chose to test at 1/4, 1/2 and 3/4 volume settings for most of the tests.

Interestingly, the stock volume seemed biased be louder from the right speakers... this is probably to make the sound more symmetrical for the driver.

I ran the same tests with the Atoto unit. Note the Atoto default has the loudness set on and I tested it that way. I also ran a few of the tests with the Loudness set off, that data is in [x]. It did not seem to make a significant difference.

I interpret these results to show that using the Atoto RCA connector line level outputs with the original Nissan Rockford Fosgate amp is perfectly appropriate.

Other Notes 

  • Wireless Android Auto works fine! However, I prefer to disable that so that I am using the built in Android on the Atoto. This allows me to more easily use the various apps on the head unit.
  • The backup camera was too dim at first, but was fine after Iturned up brightness and adjusted lines in the app, just touch the screen while in backup mode to see the settings screen.
  • The radio volume was too loud compared to the other sources. I found that it was boosted in the secret* settings and I lowered it to normal.
  • You may need to install a particular "Files" app for some apps to work properly. For instance some Android music players may not be able to find music on an external USB drive. You need to install the proper DocumentsUI for Android 10. Without it you can't write to an external USB drive with other file managers. That is because the documentsUI is missing. Install it, open it once and afterwards your file managers can use it to get access.
  • Note: this installs a "different" Files app from the one currently on the google store. I'd suggest removing the current/new "Files by Google" app if you install this one via DocumentsUI.

*Secret Settings & Password 

In case don't know this already, you can access the secret OEM settings on the ATOTO S8 unit this way:

Settings > System, click this option four times continually >input 3368, you will enter into the secret OEM Settings.

Three small problems I had to solve after the Installation 

I think these were all caused by doing some testing in the truck without all the dash wiring connected or by leaving the truck battery disconnected for a couple days.

  1. I had an engine warning light. I disconnected the battery for an hour and drove the truck again and the engine warning light was off.
  2. the airbag warning light was on. This was probably caused by testing the head unit in the car with the passenger airbag light disconnected. I followed these directions to clear the airbag warning light.
  3. My OBD reader showed a P0603 (ICM Keep Alive Memory Error). I have read this error code comes from having the battery disconnected for an extended time. This is a “permanent” error code, which just means it will persist until the vehicle has been driven enough to determine nothing is wrong. Generally this will go away after some days of driving, but I just took a 30 mile drive with a bunch of stops and it went away. Technically, you have to complete some specific driving patterns to make the code clear. One that I read was to start the vehicle, idle more than 30 seconds, drive more than 5 minutes at highway speeds, stop and idle another 30 seconds before turning the truck off. But it can apparently be more complicated than that.

Screen Protector

I wanted a screen protector as I intend to off road in the desert and sand gets everywhere....
The ones that came with the unit were horrible, but I found some I really like on AliExpress. These are 9H tempered glass: I ordered the 153x85mm size. These leave a bit of room on each edge, about 1 mm. This allows for easier installation and removal.
Install was VERY easy compared to those silly plastic ones.
You can see the edge of the protector and the gap it leaves in the picture below.

Alternate Parts 

I did not use these, but they are available. Shortcomings that I noticed are listed.

Bonus Extra! 

While I had the dash all apart... I decided to "upgrade" one of the charging ports.

Note the transparent cover lets you see the battery status through it. Kind of cool.

 Installing this charger was harder than I expected. Removing the stock power outlet either requires a special tool that is hard to find or some real finesse. And getting access behind the dash in this spot isn't easy either.

Here is the power outlet I used:

12 Volt USB Socket Outlet, Qidoe 30W USB C PD3.0 Waterproof USB Charger Socket & QC3.0 Power Outlet with ON/Off Switch Voltmeter for 12V-24V Car RV Golf Cart Boat Marine ATV Motorcycle and More

Monday, June 14, 2021

13" Laptops compared: Apple Macbook Air M1 vs Microsoft Surface Laptop 4

on the left: Apple Macbook Air M1, on the right: Microsoft Surface Laptop 4

I use a variety of machines every day. Right now I'm typing this on my windows machine, my primary workstation. Since 2013, Lorraine and I have used matching "mid 2013" Macbook Air laptops as our portable machines. I bought those back then because I didn't consider any of the Windows "Ultrabook" hardware comparable. But the screens relatively low resolution was showing it's age and I decided we could justify an upgrade after 8 years.

For my Lorraine, I wanted to get another Mac as it would keep everything the same and easy the transition. But for myself, I was very open, almost excited, to get a windows laptop again. Note the transition is easy for us as we do not use any Mac exclusive software, except the operating system. Google apps and LibreOffice work great on both Windows 10 and OS-X.

My criteria for a new laptop:

1) 13" displays, thin and light.

2) Quality construction. Solid metal preferred.

3) No vents on the bottom! We actually use our laptops on our laps. This is a remarkably hard feature to find on Windows laptops.

4) The Mac display is 16:10. Most Windows laptops use a 16:9 display. I REALLY wanted a taller display. IMO, it is just so much better to have a taller display for anything that isn't a movie.

So I looked around, and was really happy to find the Microsoft Surface Laptop 4 has a 3:2 display and no vents on the bottom! It does have some on the lower back edge, but it wasn't too bad. The Surface Laptop 4 can be purchased with a variety of options, but for my use the base unit was perfect... except I was a but wary of the Alcantara palm deck.

I ordered a new Apple Macbook Air M1 for Lorraine and a Microsoft Surface Laptop 4 for myself.

Results & Review

Lorraine happily adopted the new Macbook Air. The jump up to a new display and a bigger SSD were just what she needed.

But I my side, I struggled a bit with the Surface Laptop 4

On the positive for the Surface Laptop 4:

+ I liked the exterior and it seemed to be well constructed.

+ The tall 3:2 display was GREAT! It is exactly the same width as the Macbook Air display, and look at the top picture above. It's only about 1cm taller, but between the extra space and how the PC manages the display, you get much more vertical content on the screen.

On the negative for the Surface Laptop 4:

- The display had a bit of a bluish tint. It's probably possible to tune that out but takes some work.

- The font rendering was substantially different than the Mac. I've encountered this before, and fonts are also rendered differently in different browsers. You can play with the ClearType settings and adjust that, but again, it takes some work. I remember having trouble when I last switched from Windows to a Mac, complaining about the situation on the Mac; so it may mostly be "liking what you were used to".

- The Alcantara keyboard deck / palm rest. I didn't like it. I missed the cool feel of the aluminum and I didnt like that I couldn't easily clean it with an alcohol wipe.

- Battery life seemed to less than I hoped. I run my screen bright, and if it is a well lit room like most of our house during the day, the screen will be at 100%. I don't have any objective numbers, but the battery depleted more quickly than I expected. It wasn't obviously better than my old 2013 Mac (that did get a battery replacement a couple years ago). Note the old Macs also had a relatively low resolution display 1440 x 900, and that saves power too.

- I had trouble with the magnetic battery charge cable. Sometimes it wouldn't seem to connect and I'd have to play with it. Once it seemed I had to unplug the cable from the wall and plug it back in to get it to work. (A note, you can charge this laptop over the USB port too.)

- The keyboard flexed a good amount. Many really like the Surface Laptop 4's "bounce", but to me the flex just felt cheap.

- Encryption. Apparently, Microsoft really wants you to let them keep your keys in their cloud. If you set up the machine with only a local account, Windows 10 home edition does not allow you to encrypt your hard drive. You can either upgrade to Windows 10 Pro, or perform some technical maneuvers to get around the problem. This is much easier to avoid on the Mac.

- This isn't really a negative, but personally; I have no use for the touchscreen on the Surface Laptop 4.


The biggest issue for me was not liking the Surface Laptop 4's Alcantara. But the other issues added to my annoyance significantly. The combined negatives outweighed my love of the Surface Laptop 4's 3:2 screen. I was able to play with both machines side by side, and I just preferred the Macbook Air M1. So I sent the Surface back and bought myself a Macbook Air M1.

I should note, I could have paid more for a version of the Surface Laptop for with an aluminum deck. However, to do that I'd have to accept a color I didn't like (Sandstone or Matte Black) and an "upgrade" to the Intel processor. If it were not for the other annoyances I probably would have tried that.

Another note: I like Windows, in many ways more than OS-X. This really wasn't driven by features of the operating system, it was about my preference for the Apple hardware. If I could have gotten the Surface Laptop 4 with a metal deck, the Ryzen 5 processor and maybe one of the other hardware items (better magnetic charging connection, less flexy keyboard, better battery life), that would have tilted me back to the Surface.


Here is a follow up now that I've used the mac some more. The M1 Macbook Air is so similar to my old mid-2013 air that is is hard to come up with new positives. It is a great display and I prefer the stock color rendering and text rendering over that of the Surface.

Just to balance things a bit here are my negatives of the Mac:

- No 3:2 display. Boo.

- I miss the old mac's magsafe power cord (I ordered an external connector gizmo).

- The glass at the top screen gets greasy from opening. (Maybe I can train myself to only open it by the very edge.)