Why AirPods Max Doesn't Have a U1 Chip?

What is the U1 chip?

　Apple's U1 chip is 10m using UWB communication built into iPhone 11, iPhone 12, Apple Watch series 6, HomePod mini It is a dedicated chip that identifies positions with a mutual error of several centimeters within the range of degree. A device sends out a pulse wirelessly, and the device that receives it returns a pulse, so that the positions of the products can be measured (see Fig. 1). Since very weak pulses are used, they are transmitted over a wide band at the same time, so they are easily detected by the receiving side without being affected by noise. The accuracy of position measurement is said to be less than 10 cm. At the moment, it is only used to visualize the direction of the other party's device when exchanging photos with AirDrop between iPhones, but an API called NearByInteraction is open to the public, and various interactive applications that utilize the functions of the U1 chip are available. applications can be developed.

In fact, it is expected to be installed in the AirTag (provisional) (*1), which is rumored to be released by Apple in the near future. , the position of the target can be determined much more accurately. It is attracting attention as a device that may encompass a wide range of uses such as IC tags, not only for preventing forgotten items, but also for managing items and preventing lost children (1, 2, 3). There are also rumors that the AirTag will be powered by the undisclosed R1 chip instead of the U1 chip. In that case, it's probably a subset of the U1 chip, focused on the features required on the Tag side. Other details such as the appearance have also been leaked (4), but we do not yet know the authenticity.

Note 1: Apple has not announced anything at the time of this writing, so the name is tentative. Below, we will omit the description of "temporary" and proceed with the story assuming that AirTag will be released in the near future.

(1) Yahoo! News, The surprising potential of the "U1 chip" secretly installed in Apple Watch series 6, 2020.9.17

(2) Drunken Man's Blog WP, "AirTags uses the 'R1' chip, and there may be an iPhone app called 'Find My Tag'" 2020.6.17

(3) Apple Informed, “AirTags to use “R1” chip and may have an iPhone app named “Find My Tag””, 2020.6.17

(4) Engadget Japan version "Apple's AirTag, an anti-lost item tag, announced at an event? Rendered image based on the 'real thing' released" 2020.9.15

AirPods Max does not have a U1 chip!

The "U1 chip" or "ultra-wideband chip for spatial recognition" is not listed on the "Specifications" page of Apple's AirPods Max (as of January 1, 2021). Various media have also reported that the U1 chip is not installed (5,6,7). After the product was released, iFixit released an AirPods Max disassembly report (8), but no U1 chip was found in it. According to famous leaker Jon Posser's remarks (9), many future Apple products will be equipped with the U1 chip, and various convenient ways to use it will be shown by utilizing mutually obtained location information. It is considered Of course, one of the favorite devices is AirTag, and the other is Apple Glass (provisional) (*2). The lack of it has sparked arguments for and against.

Note 2: This name is also tentative. AR glasses that are rumored to be announced and released by Apple in the near future.

(5) Macrumors “AirPods Max Don't Contain U1 Chip for Ultra Wideband” 12/8

(6) Continental drift "U1 chip also used for iPhone 11, AirPods Max not installed?"

2020.12.9

(7) Apple Insider “Apple's AirPods Max likely lacks U1 Ultra Wideband chip”

12.8

(8) iFixit, AirPods Max Teardown, 2020.12.17

(9) Jon Prosser's twitter

　By the way, there are typically two problems with the "search" function because AirPods Max does not have a U1 chip.

1. I can't find other U1 chips from AirPods Max.

2. I can't find AirPods Max from my iPhone or Apple Watch.

In fact, there were rumors that AirPods Max was trying to distinguish left and right when worn by the U1 chip (10). It is expected that the U1 chip will probably be attached to the front or back of the left and right ear cups, and the difference in radio wave characteristics when received by the other will be used. They probably thought that because radio waves mainly pass through the nasal cavity in the front and the cerebellum in the back (see Fig. 2). As a simpler thing, it seems to be able to identify non-wearing and case storage. Since AirPods Max also has an inner microphone, it seems that it is possible to distinguish between left and right using sound based on the same principle. I think that speakers and microphones have high performance, so it is also possible to use ultrasonic waves that are inaudible to humans. In any case, it is expected that it took time to improve the identification performance, and that it was postponed this time. According to a recent patent, Apple puts sensors that see the movement of the skin surface around the ear in the ear cups to enable voice commands and silent gestures (movements of the jaw and bottom without making a sound). (11). Perhaps this sensor is more suitable for left and right discrimination. On the other hand, the U1 chip may also be useful for sensing silent gestures.

(10) Slashgear AirPods Max announcement is also controversial without the latest U1 chip for UWB

12.9

(11) Patently Apple, Apple Reveals new Bioauthentication Sensors for future AirPods, Headphones & HMD that Learn the owner's Voice Commands & Silent Gestures

Why is there no U1 chip?

Generally, it is said that various functions were omitted due to delays in development. One of them is the U1 chip, which is probably one of the left/right identification left behind mentioned above. However, if it was only that, it might have been possible to insert the U1 chip and later update the firmware.

　Another possibility is that the U1 chip's original function of searching for iPhones and searching for AirTags was also difficult. The biggest factor may be the aluminum cup. As is well known, aluminum is a radio wave absorber and absorbs radio waves over a wide band. I'm sure many of you know that wrapping a mobile phone in aluminum foil prevents it from receiving calls. In particular, when a person is wearing AirPods Max, there is a person's ear on the side without the aluminum cup, and there is (the contents of) the head behind it. This also contains a lot of water, so it is difficult for radio waves to fly. Of course, radio waves will leak from the ear cushions, the microphone hole, and the head, but since the radio waves used in UWB are originally very weak, you won't know until you test it, but at a practical level, it's going outward. There is a possibility that almost no radio waves will fly.

How do you solve the inconvenience of the "search" function? I usually have an iPhone or an Apple Watch. Find it on your iPhone or Apple Watch. There are exceptions, but we'll get to that later.

Regarding 2, "Searching for AirPods Max from other devices", this is when a person is not wearing it, so if you put a U1 chip in it, you can use UWB communication to avoid the adverse effects of the aluminum cup. That should have been enough. However, the AirPods Max is relatively bulky, so it's unlikely that you'll take it out of your room, so Apple's representatives probably thought that it's almost impossible to lose sight of it. And if you have to take it out frequently, you may think that you can attach an AirTag. Best of all (strangely) the AirPods Max ear cups don't have the Apple logo. Isn't it possible that you're doing this to attach an AirTag? Also, isn't there a little extra space in the special case (I can't check it because I don't have the real thing at hand...)? In fact, there are other methods for searching from other devices, so I would like to describe them next.

Another method of location search with AirPods Max (more imaginative story)

　Although it enters the realm of imagination, AirPods Max can locate each other with other devices without a U1 chip There is a way to do it. I mainly think about how to find AirPods Max from iPhone and how to find AirTag on AirPods Max.

You can search for AirPods Max from your iPhone without the U1 chip. The easiest way is using sound (or ultrasound). In other words, the iPhone's speaker emits sound and the AirPods Max's six microphones pick it up and analyze it (see Figure 3). The AirPods Max microphone can be controlled by the iPhone itself, so when viewed from the iPhone, you will be able to make the sound yourself and pick it up and analyze it yourself. It should be easy to analyze the direction of the sound based on the difference in arrival times, volume, etc. There is also a method of using ultrasound even if it is not audible sound. In any case, it is necessary to assume that the AirPods Max has enough battery left, so if you want to find it without a battery, you should attach an AirTag as mentioned above. will be

Next is how to search for AirTags on AirPods Max, but the same method can be used without the U1 chip. This is based on the assumption that the AirTag has a speaker, but if you launch Siri from AirPods Max and say "wallet" by voice, it may be possible to search for the AirTag with UWB from the iPhone and play a sound at the same time. not. Of course, the iPhone uses UWB to capture the relative positions of the AirTag and the iPhone, but at the same time, if the sound is picked up by the six microphones of the AirPods Max, the relative positions of the AirPods Max and the AirTag can also be accurately captured. Whether or not ultrasonic waves can be used, probably ultrasonic waves will not come out from the AirTag speaker. Humans can hear it, so shouldn't it be audible?

　Just one more addition, the aluminum ear cups seem to transmit sound well to the outside. So far, there have been reports that AirPods Max often leaks sound outside, but isn't the aluminum material having a bad effect? Conversely, the sound emitted from AirPods may be captured by other devices such as iPhone. Since these are high-performance headphones, they must be able to emit ultrasonic waves over a considerable range, and they may be heard farther than you expect. This means that the above two can also be reversed, and that other applications such as the "echolocation" of bats may be conceived.

By the way, the use of ultrasound for position measurement has been extensively studied in the research field for over 20 years. The content of this article is more of a familiar technique than a new idea.

Summary

Why is the U1 chip not installed in the AirPods Max? It might be because of the aluminum cup is the simplest answer (I imagine). You don't have to, you can use your iPhone to find an AirTag, and if you want to find an AirPods Max, you can put an AirTag on it is a more defiant answer (I imagine). Even if the iPhone has aluminum, it is only on the sides and both sides are glass. iPads with aluminum backs may not be suitable for the U1 chip, and currently aren't. UWB radio waves will be emitted from the front glass surface, but it seems to be difficult if it is facing down on a metal surface.

The U1 chip is not good at water. It seems that sound and ultrasonic waves can be used underwater. At the time of writing this article, AirTag has not yet appeared, but based on the contents of this article, it may be better to think about the potential and limitations of AirTag, how to use it, and prepare for its appearance. Of course it seems that there is Apple Glass ahead of it.

Wearable Channel (YouTube), Why AirPods Max Doesn't Have a U1 Chip? , 2020.12.28 *3

Note 3 This article is based on this content and has been restructured with new considerations.