LTE Upgrade Add-ons
The LTE upgrade kit enables support for LTE and GNSS for the Comet. This upgrade kit includes components that integrate cellular antennas optimized and tuned for the Comet. All the components including the modem are mounted inside the enclosure. We are offering this in 2 different variations -
LTE/GNSS Upgrade Kit (with modem)
This includes the modem, antenna brackets, and connection cables. We are shipping the Quectel EM060K-GL as Comet’s officially supported modem, this connects on the Comet’s M.2 slot. The antennas are being designed and tested for this specific modem.
The Quectel EM060K-GL modem will enable Data, Voice (+VoLTE), SMS and GNSS related features. This option is available in selected regions and countries (see below).
LTE/GNSS Upgrade Kit (without modem)
This includes everything mentioned in #1 other than the modem. You will have to procure the modem separately at your end, there are a number of online websites that list the modem and ship internationally. There are a few caveats to this -
- The Quectel EM060K-GL available off-the-shelf is limited to DATA-only, SMS* and GNSS - it won’t enable Voice features. We have worked with Quectel to enable Voice in the firmware we ship with. For regulatory reasons we cannot give you access to enabling this feature.*VoLTE-only networks can restrict SMS without voice.
- You can also bring-your-own LTE modems but they will be considered community supported and their support can largely vary. See the section below under Bring your own modem.
This option is available for all countries we ship the Comet to. For regulatory reasons we cannot ship the modem variant to all regions.
You can always opt for LTE upgrade in the future, we will be listing these addons on our website for purchase. Installing the antenna components and modem is trivial and easily DIY-able.
Regions we’re shipping with modem
🇪🇺 Countries within European Union
About Quectel EM060K-GL
The Quectel EM060K-GL is a globally supported, CAT 6 LTE modem. Here are some additional details -
- Data speeds: Up to 300 Mbps download and 50 Mbps upload on LTE, these are capability numbers - actual speeds received will vary based on antenna performance and environment.
- Carrier aggregation and MIMO: Supports 2‑carrier downlink aggregation and MIMO, so it can combine two LTE channels and use multiple antennas for higher speeds and a more reliable connection.
- 3G fallback: If LTE isn’t available, the modem can switch to older 3G networks so you can still get a connection.
- GNSS: Integrated positioning supports GPS, GLONASS, BeiDou and Galileo and A-GPS for faster time-to-first-fix.
- Dimensions: M.2 Key-B package measuring 42.0 × 30.0 × 2.3 mm.
You can find more detailed specification using the link below.
Quectel EM060K-GL Modem (quectel.com)Bring your own modem
Our official support will be tied to the Quectel EM060K-GL. In case you decide to bring your own modem here is everything we want you to know.
The standard included antenna kit has only 2 feed points - one for the main antenna (RX/TX) and the other one for GNSS/diversity. The diversity antenna is used for unlocking higher bandwidth speeds using spatial separation. If you use a modem with 3 separate feed points for Main, Diversity and GNSS, you can either get Main + Diversity or Main + GNSS.
We will be offering a 3-feedpoint antenna kit in the near future, that is also compatible with 5G.
The Comet’s M.2 B-key pinout does not offer PCM. If you are using Voice features ensure the modem supports USB Audio.
Review ModemManager’s support for your modem or via resources available on the internet.
We use the M.2 B-key form factor on the Comet, recommended size is 30.0 mm × 42.0 × 2.5 mm or under, and preferably no components below its PCB for better thermal dissipation.
We can help you evaluate them - you can submit a post on our forum and we will get back.
Band support planned
Here are the bands we plan to support officially from an antenna tuning and regulatory point of view. We’ve curated this list to get sufficient carrier support across the target regions.
Low bands
| Band | UL (MHz) | DL (MHz) | Regions |
|---|---|---|---|
| B71* | 663 - 698 | 617 - 652 | US, CA |
| B12 | 699 - 716 | 729 - 746 | US, CA |
| B28 | 703 - 748 | 758 - 803 | EU, UK, IN, AU, NZ |
| B13 | 777 - 787 | 746 - 756 | US, CA |
| B20 | 832 - 862 | 791 - 821 | EU, UK |
| B26 | 814 - 849 | 859 - 894 | US |
| B5 | 824 - 849 | 869 - 894 | US, CA, AU, NZ |
| B8 | 880 - 915 | 925 - 960 | EU, UK, IN, AU, NZ |
*B71 is the lowest-frequency band, making it the most difficult band to tune for. We are working closely with our antenna designers to ensure sufficient performance for this band.
Mid bands
| Band | UL (MHz) | DL (MHz) | Regions |
|---|---|---|---|
| B3 | 1710 - 1785 | 1805 - 1880 | EU, UK, IN, AU, NZ, CA |
| B4 | 1710 - 1755 | 2110 - 2155 | US, CA |
| B66 | 1710 - 1780 | 2110 - 2200 | US, CA |
| B2 | 1850 - 1910 | 1930 - 1990 | US, CA |
| B25 | 1850 - 1915 | 1930 - 1995 | US |
| B1 | 1920 - 1980 | 2110 - 2170 | EU, UK, IN, AU, NZ |
Upper mid bands
| Band | UL (MHz) | DL (MHz) | Regions |
|---|---|---|---|
| B40 | 2300 - 2400 | 2300 - 2400 | IN, AU |
| B41 | 2496 - 2690 | 2496 - 2690 | US, IN |
| B7 | 2500 - 2570 | 2620 - 2690 | EU, UK, CA, AU, NZ |
Carrier support
Existing modem certifications
The Quectel EM060K-GL is widely certified across multiple regions and carriers. Here is a summary of all existing certifications the module has.
| Regions | Regulatory | Carrier |
|---|---|---|
| Global | GCF | Carrier independent certification |
| North America | PTCRB | Carrier independent certification |
| US | FCC | AT&T, T-Mobile, Verizon |
| CA | ISED | Telus |
| UK | UKCA | BT |
| EU | CE RED + DA | Deutsche Telekom, Telefónica, Vodafone, Orange, Swisscom |
| AU | RCM | Telstra |
| NZ | via RCM | None |
On field carrier acceptance testing
Over and above this, we are doing on-ground testing with the modem and verifying capabilities with carriers in the regions we ship to.
Here is the current status, this is an ongoing activity - we will keep updating the list here. This is not a complete list of carriers, we will keep expanding this list as testing progresses.
| Region | Carrier | Data | SMS | VoLTE | Remarks |
|---|---|---|---|---|---|
| AU | TPG Telecom | - | - | - | |
| Optus (Singtel) | - | - | - | ||
| CA | Bell | ✅ | ✅ | ✅ | |
| Rogers | ✅ | ✅ | ✅ | ||
| Telus | - | - | - | ||
| CH | Swisscom | - | - | - | |
| EU | A1 Telekom Austria | - | - | - | |
| Deutsche Telekom | - | - | - | ||
| Drei | ✅ | ✅ | ✅ | Tested in Austria | |
| Iliad | - | - | - | ||
| KPN | - | - | - | ||
| Magenta Telekom | ✅ | ✅ | ✅ | Tested in Austria | |
| Orange | ✅ | ✅ | ✅ | Tested in Austria | |
| Proximus | - | - | - | ||
| Telefónica | - | - | - | ||
| Telenor Group | - | - | - | ||
| Telia Company | - | - | - | ||
| TIM | - | - | - | ||
| Vodafone Group | - | - | - | ||
| IN | Bharti Airtel | ✅ | ✅ | ✅ | |
| Reliance Jio | ✅ | ✅ | ✅ | ||
| Vodafone Idea | - | - | - | ||
| NZ | One NZ | - | - | - | |
| Spark | - | - | - | ||
| UK | BT Group | - | - | - | |
| Virgin Media O2 | - | - | - | ||
| VodafoneThree | - | - | - | ||
| US | AT&T | ✅ | ✅ | ☑️ | |
| T-Mobile | ✅ | ✅ | ✅ | ||
| Verizon | ✅ | ✅ | ✅ |
We’re erring on the side of caution, but so far results look promising. The Quectel EM060K-GL is also added to the ChromeOS approved vendor list. Learn more
Risks and challenges
Adding LTE support is a complicated requirement in terms of RF design, regulatory and software. Here are some risks we would like you to understand and consider.
Coverage & Performance
After months of designing we are at a stage where meeting the below efficiency in the antenna is now feasible.
- Low Bands (<960 MHz): 25-30% efficiency
- High Bands (>960 MHz): 35-40% efficiency
These are close to what a mid-end smartphone‘s LTE antenna efficiency would be.
We are yet to tune the antenna and confirm this performance, tuning the antenna requires production-spec housing that we are actively working on. We will confirm exact results once the tuning is completed.
Regulatory
We are offering the LTE modem in regions where the modem is already certified and we are reasonably confident about meeting additional device-level regulatory requirements. In an unlikely scenario we may hit a roadblock with the compliance that can cause delays.
Carrier Support
We’ve picked this modem for its wide regional and carrier-level certifications, in spite of that it is likely that some carriers may disallow some or all services for this modem. There is no easy way to know this without foot-on-ground testing, we are expanding our on-field testing over the next few months and will keep updating the carrier list above.
Software
Though we are actively working on adding the software support for cellular, we may have feature gaps initially that will be patched over subsequent releases.
Refund Policy: In case of any carrier support issues that cannot be resolved, we will offer a full refund for the LTE upgrade kit purchased, other than the return shipping costs.
Continue reading
Frequently asked questions
How can I add the LTE support to my existing preorder?
You can login to the Mecha Hub using your registered email address (or Kickstarter email address), go to your pre-order and add the LTE Upgrade Kit add-on to your Comet.
Until when can I upgrade my pre-order to include LTE?
You can add the LTE addon up to 🗓️ 31st October on your pre-order, and we will pre-assemble the kit for your order.
You can also buy the LTE upgrade kit later from our website after we ship the first preorder batch. Installation is as easy as unscrew-screw and attach some cables.
Do you have sufficient stock of the modem?
LTE modems are in short supply due to the memory crisis, you will find the Quectel EM060K-GL sold-out on most websites. We have already procured some quantities ahead of time. If we run out of them, we will attempt to procure again and send a notification to all backers.
Does the modem support VoLTE?
Yes, it does, you can refer to the support matrix added above.
Does the modem use USB Audio or PCM?
The audio is connected via USB Audio between the host and the modem, the quality is crisp and clear, we have tested by having full end-to-end conversations.
Is GPS supported? Is A-GPS supported?
Yes, L1 GNSS is supported. Assisted-GPS is supported in a different manner compared to a regular smartphone. Using Quectel Xtra the modem downloads predicted orbital files for the next 7 to 14 days over cellular. Using this predicted satellite orbit data, the GNSS receiver can reduce TTFF (time-to-first-fix) from 30+ seconds to under 2 to 10 seconds, depending on your physical environment.
Is E-SIM supported?
The modem we are using does have an eSIM-capable variant, but we have currently not opted for it due to supply chain shortages. Also, adding eSIM needs a lot of enablement on the software front as well. Sometime next year, we will test the modem’s eSIM variant and make it available.
In the countries or carriers untested yet, what kind of support to expect?
The Quectel EM060K-GL is a global modem, so the support is fairly well tested for the regions it is certified for, and we have sufficient bands supported by our antenna design. Here is what we think based on our current testing efforts, please consider this as strictly guidance and not confirmations.
- ☑️ Data will work in all regions the modem is certified for
- ☑️ SMS will work in all regions the modem is certified for
- ☑️ GNSS will always work irrespective of carrier
- ⁉️ Voice/VoLTE is at times blocked by the carrier and limited to certified devices only, with some carriers it may not work end to end, or drop to GSM bands for voice.
Will Comet undergo carrier certifications?
As of now, we have no plans to get device certification done with carriers. Getting carrier certifications requires elaborate and expensive testing.
How do I extend storage while the modem is connected on M.2?
You can use the MicroSD slot for additional storage. Compared to NVMe SSDs, MicroSD are a lot more power efficient.
The Comet is not a smartphone
By now you must have already seen us plastering this everywhere, we set out to design a handheld computer and not a smartphone replacement. We’d love a Linux-based smartphone too, but we feel there is still a lot of work involved in and around the ecosystem to replace the kind of capabilities the mainstream smartphones offer.
Here are some of the things that we know of that limit the Comet compared to a smartphone available today.
- The software stack on Linux for cellular is still evolving, our software stack will use the standardized libraries such as ModemManager and we will contribute in its development, but they cannot be compared to the software that iOS or Android runs that has seen 2 decades of development.
- Smartphones have advanced emergency calling features that share your location and cellular broadcast for emergency alerts, the modem supports them but we will have to build the software stack around it.
- Smartphones are ridiculously battery optimized, even though we are actively working on improving power consumption on the Comet we may not reach that level.
- On the hardware front there is no earpiece speaker, instead the loudspeaker will have to be repurposed to be used.
- Banking apps even if emulated using Waydroid will not work, you are limited to using their mobile websites.
- We do not support NFC, so tap to pay is not feasible.
Some of the above ones related to software will fix over time, and we are committed to offering a solid platform to all users.
We would not consider the Comet in its current form to simply replace your Android or iOS phone as your only connectivity device unless you are willing to work around some quirks. We want to welcome you to use the Comet as a DIY or hobbyist phone.
Upgrade path to 5G
We recognize that in some regions 4G may get discontinued in coming years and get replaced by 5G, and we’ve designed to that goal. In that direction, we’ve worked with our antenna designers to create provisions already in the Comet’s RF design to allow us to offer 5G RedCap (reduced capability) supported antennas and modem that you can swap with your existing LTE setup.
RedCap stands for Reduced Capability; this is a relatively new specification designed for mid-tier devices, avoiding the full design complexity of 5G. This means the Comet will be able to support 5G but not at the highest bandwidth it can offer; theoretically, 5G RedCap is 223 Mbps / 123 Mbps, which sits between LTE CAT 4 and LTE CAT 6.
Here is how our existing LTE bands we support map to their equivalent 5G band, with the exception being the last two.
| LTE | 5G SA RedCap | Span |
|---|---|---|
| B71 | n71 | 617–698 MHz |
| B12 | n12 | 699–746 MHz |
| B28 | n28 | 703–803 MHz |
| B20 | n20 | 791–862 MHz |
| B26 | n26 | 814–894 MHz |
| B8 | n8 | 880–960 MHz |
| B66 | n66 | 1710–2200 MHz |
| B40 | n40 | 2300–2400 MHz |
| B41 | n41 | 2496–2690 MHz |
| B42+B43 | n78 or n77 | 3400–3800 MHz |
Adding support for a 5G SA RedCap modem will involve additional testing and regulatory certifications. We do not have an exact timeline on when a 5G upgrade kit will be available, but we will get on this sometime in 2027.