GSM Phone Network At EMF Camp Built On Raspberry Pi And LimeSDR

August 30, 2018 by Jenny List 22 Comments

The Electromagnetic Field 2018 hacker camp in the UK will have its own GSM phone network, and as we have already covered its badge will be a fully-functional GSM phone. This is as far as we are aware a first in the world of badges, and though it may not be a first in hacker camp connectivity it is still no mean achievement at the base station side. To find out more we talked to two of the people behind the network, on the radio side Lime Microsystems‘ [Andrew Back], and on the network side Nexmo‘s developer advocate, [Sam Machin].

There are sixteen base stations spread around the site, of which each one is a Raspberry Pi 3 B+ with a LimeSDR Mini. Development of the system was undertaken prior to the release of the Raspberry Pi Foundation’s PoE board, so they take a separate 24V supply which powers the Pi through a DC-to-DC converter. This arrangement allows for a significant voltage drop should any long cable runs be required.

On the software side the base stations all run the Osmocom (Open Source Mobile Communications) cellular base station infrastructure package. It was a fine decision between the all-in-one Osmocom NITB package and the fully modular Osmocom, going for the former for its reliability. It was commented that this would not necessarily be the case at a future event but that it made sense in the present. It appears on the network as a SIP phone system, meaning that it can easily integrate with the existing DECT network. Let’s take a look at how the network operates from the user side, and the licencing loophole that makes everything possible.

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Particle Introduces New Hardware, Adds Mesh Support

February 13, 2018 by Brian Benchoff 34 Comments

Particle, makers of the WiFi and Cellular IoT modules everyone loves, is introducing their third generation of hardware. The Particle Argon, Boron, and Xenon are Particle’s latest offering in the world of IoT dev boards, and this time they’re adding something amazing: mesh networking.

The three new boards are all built around the Nordic nRF52840 SoC and include an ARM Cortex-M4F with 1MB of Flash and 256k of RAM. This chip supports Bluetooth 5 and NFC. Breaking the new lineup down further, the Argon adds WiFi with an ESP32 from Espressif, the Boron brings LTE to the table with a ublox SARA-U260 module, and the Xenon ditches WiFi and Cellular, relying only on Bluetooth, but still retaining mesh networking. This segmentation makes sense; Particle wants you to buy a ton of the Xenon modules to build out your network, and use either the Argon or Boron module to connect to the outside world.

The form factor of the boards conforms to Adafruit Feather standard, a standard that’s good enough, and much better than gigantic Arduino shields with offset pins.

Of particular interest is the support for mesh networks. For IoT solutions (whatever they may be), mesh networking is nearly a necessity if you have a sufficient number of nodes or are covering a large enough area. The technology going into this mesh networking is called Particle Mesh, and is built on OpenThread. While it’s a little early to see Particle’s mesh networking in action, we’re really looking forward to a real-world implementation.

Preorder pricing for these boards sets the Argon module at $15, the Boron at $29, and the Xenon at $9. Shipping is due in July.

Behind The Scenes At A Pair Of Cell Sites

January 10, 2018 by Dan Maloney 17 Comments

Those who fancy themselves as infrastructure nerds find cell sites fascinating. They’re outposts of infrastructure wedged into almost any place that can provide enough elevation to cover whatever gap might exist in a carrier’s coverage map. But they’re usually locked behind imposing doors and fences with signs warning of serious penalty for unauthorized access, and so we usually have to settle for admiring them from afar.

Some folks, like [Mike Fisher] aka [MrMobile], have connections, though, and get to take an up close and personal tour of a couple of cell sites. And while the video below is far from detailed enough to truly satisfy most of the Hackaday crowd, it’s enough to whet the appetite and show off a little of what goes into building out a modern cell site. [Mike] somehow got AT&T to take him up to a cell site mounted in the belfry and steeple of the 178-year old Unitarian Church in Duxbury, Massachusetts. He got to poke around everything from the equipment shack with its fiber backhaul gear and backup power supplies to the fiberglass radome shaped to look like the original steeple that now houses the antennas.

Next he drove up to Mount Washington in New Hampshire, the highest point in the northeast US and home to a lot of wireless infrastructure. Known for having some of the worst weather in the world and with a recent low of -36°F (-38°C) to prove it, Mount Washington is brutal on infrastructure, to which the tattered condition of the microwave backhaul radomes attests.

We appreciate the effort that went into this video, but again, [Mike] leaves us wanting more details. Luckily, we’ve got an article that does just that.

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Emergency Cell Tower On A Budget

September 30, 2017 by Brian McEvoy 22 Comments

Cell phone towers are something we miss when we’re out of range, but imagine how we’d miss them if they had been destroyed by disastrous weather. In such emergencies it is more important than ever to call loved ones, and tell them we’re safe. [Matthew May] and [Brendan Harlow] aimed to make their own secure and open-source cellular network antenna for those occasions. It currently supports calling between connected phones, text messaging, and if the base station has a hard-wired internet connection, users can get online.

This was a senior project for a security class, and it seems that the bulk of their work was in following the best practices set by the Center for Internet Security. They adopted a model intended for the Debian 8 operating system which wasn’t a perfect fit. According to Motherboard their work scored an A+, and we agree with the professors on this one.

Last year, the same SDR board, the bladeRF, was featured in a GSM tower hack with a more sinister edge, and of course Hackaday is rife with SDR projects.

Thank you [Alfredo Garza] for the tip.

Hackaday Prize Entry: A Mobile Electric Gate

June 16, 2017 by Lewin Day 12 Comments

Electric gates can be an excellent labor-saving device, allowing one to remain in a vehicle while the gate opens and closes by remote activation. However, it can become somewhat of a hassle juggling the various remotes and keyfobs required, so [bredman] devised an alternative solution – controlling an electric gate over the mobile network.

20 years ago, this might have been achieved by wiring a series of relays up to the ringer of a carphone. These days, it’s a little more sophisticated – a GSM/GPRS module is connected to an Arduino Nano. When an incoming call is detected, the gate is opened. After a 3 minute wait, the gate is once again closed.

[bredman] suffered some setbacks during the project, due to the vagaries of working with serial on the Arduino Nano and the reset line on the A6 GSM module. However, overall, the gate was a simple device to interface with, as like many such appliances, it has well-labelled and documented pins for sending the gate open and close signals.

[bredman] was careful to design the system to avoid unwanted operation. The system is designed to always automatically close the gate, so no matter how many times the controller is called, the gate will always end up in a closed state. Special attention was also paid to making sure the controller could gracefully handle losing connection to the mobile network. It’s choices like these that can make a project much more satisfying to use – a gate system that constantly requires attention and rebooting will likely not last long with its users.

Overall, it’s a great project that shows how accessible such projects are – with some carefully chosen modules and mastery of serial communications, it’s a cinch to put together a project to connect almost anything to the Internet or mobile networks these days. For a different take, check out this garage door opener that logs to Google Drive.

Particle Electron – The Solution To Cellular Things

February 10, 2016 by Brian Benchoff 56 Comments

Just over a year ago, Particle (formerly Spark), makers of the very popular Core and Particle Photon WiFi development kits, released the first juicy tidbits for a very interesting piece of hardware. It was the Electron, a cheap, all-in-one cellular development kit with an even more interesting data plan. Particle would offer their own cellular service, allowing their tiny board to send or receive 1 Megabyte for $3.00 a month, without any contracts.

Thousands of people found this an interesting proposition and the Electron crowdfunding campaign took off like a rocket. Now, after a year of development and manufacturing, these tiny cellular boards are finally shipping out to backers and today the Electron officially launches.

Particle was kind enough to provide Hackaday with an Electron kit for a review. The short version of this review is the Electron is a great development platform, but Particle pulled off a small revolution in cellular communications and the Internet of Things

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Hack Anything Into A Phone

September 29, 2015 by Al Williams 21 Comments

If you’ve spent much time tinkering with electronics, you’ve probably heard of [Seeedstudio] from their development boards, tools, and their PCB fabrication service. Their latest Kickstarter venture is the RePhone, an open source and modular cell phone that will allow hackers to put together a phone by blending GSM modules, batteries, screens, and other stock units, including an Arduino-based processing core, GPS, NFC, and other building blocks.

The funding campaign has already exceeded its goal and delivery is scheduled for next year with a basic kit weighing in at a projected $59, according to [Seeed]. Presumably, the core phone module will have regulatory acceptance, but the other ancillary modules won’t require as rigorous testing and certification.

What would you do with an inexpensive, embeddable cell phone? The modules are tiny, so you could implant them in lots of places. Some of [Seeed’s] more interesting ideas include building a phone into a walking stick, a dog collar, or a kite (although we were thinking quadcopters).

Of course, we’ve seen GSM and cell phone shields for Arduino before. Difficult to imagine sticking those in a dog collar, though, unless you have a fairly large dog. If you are a fan of 1960’s TV, it is easy to imagine a better shoe phone or a working Star Trek communicator.

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