Cable Modem Turned Spectrum Analyzer

August 27, 2021 by Bryan Cockfield 19 Comments

Hopefully by now most of us know better than to rent a modem from an internet service provider. Buying your own and using it is almost always an easy way to save some money, but even then these pieces of equipment won’t last forever. If you’re sitting on an older cable modem and thinking about tossing it in the garbage, there might be a way to repurpose it before it goes to the great workbench in the sky. [kc9umr] has a way of turning these devices into capable spectrum analyzers.

The spectrum analyzer feature is a crucial component of cable modems to help take advantage of the wide piece of spectrum that is available to them on the cable lines. With some of them it’s possible to access this feature directly by pointing a browser at it, but apparently some of them have a patch from the cable companies to limit access. By finding one that hasn’t had this patch applied it’s possible to access the spectrum analyzer, and once [kc9umr] attached some adapters and an antenna to his cable modem he was able to demonstrate it to great effect.

While it’s somewhat down to luck as to whether or not any given modem will grant access to this feature, for the ones that do it seems like a powerful and cheap tool. It’s agnostic to platform, so any computer on the network can access it easily, and compared to an RTL-SDR it has a wider range. There are some limitations, but for the price it can’t be beat which will cost under $50 in parts unless you happen to need two inputs like this analyzer .

Thanks to [Ezra] for the tip!

3 Words To Describe Any Spot On Earth

September 26, 2019 by Lewin Day 118 Comments

For quite a long while now, latitude and longitude has been the way humankind has navigated the globe. This is a perfectly workable system, but it’s a little overwrought for daily use by the layperson. What3Words seeks to provide a simpler solution.

The system is based on splitting the surface of the globe into a grid of 3 m x 3 m sections. This includes oceans and bodies of water. With the grid layed out, each section is given a name consisting of three English words strung together. For example, ///eggs.form.breakfast denotes a spot in the outskirts of Chengdu, China, while ///crops.cards.gifts is a good approximation of that spot where the Naked Cowboy hangs out in Times Square, New York.

Addresses in this format are written with three leading forward slashes, along with a dot between each word. An attempt has been made to only use uncontroversial words, as well as to make sure no crude addresses are created by awkward combinations. Don’t worry, we checked – but if you do find anything good, drop it in the comments below.

It’s a tool that’s been around for a while, but an interesting one nonetheless. It’s something that needs a wider societal acceptance to become truly useful; we imagine it could be good in a small social circle once everyone is familiar with it. It may yet catch on – only time will tell!

Hackaday.io Land Rush: Vanity URLs

January 20, 2015 by Mike Szczys 79 Comments

Hurry! Carve out your Hackaday.io homestead with a vanity URL. You can see I’ve already secured hackaday.io/mike, but get in before the rest of Hackaday finds out and you can you have ‘/tom’, ‘/jane’, or ‘/zerocool’. (Don’t do it… you can be more creative than zerocool!)

Whether you already have an account, or if you want to create one right now, the next time you log into Hackaday.io the interface will give you the opportunity to choose your vanity address. Like the Oklahoma land rush, we’re sure there will be a swell of folks looking to squat on the most pristine land. So if your first name is already taken, now is the perfect time to re-invent your perfect username.

For those that need a jump start picking their slug, we want to hear your favorite screen name/handle/user alias of all time in the comments. At the risk of embarassing [Jeff Keyzer], I have to say his alias (and company name) Mighty Ohm is pretty spectacular. Can anyone beat it?

Building New, Weird CPUs In FPGAs

March 11, 2013 by Brian Benchoff 40 Comments

CPU

The popularization of FPGAs for the hobbyist market means a lot more than custom LED controllers and clones of classic computer systems. FPGAs are also a great tool to experiment with computer architecture, creating new, weird, CPUs that don’t abide by the conventions the industry has used for 40 years. [Victor] is designing a new CPU that challenges the conventions of how to access different memory locations, and in the process even came up with a bit of example code that runs on an ARM microcontroller.

Most of the time, the machine code running on your desktop or laptop isn’t that interesting; it’s just long strings of instructions to be processed linearly. The magic of a computer comes through comparisons, an if statement or a jump in code, where the CPU can run one of two pieces of code, depending on a value in a register. There is the problem of reach, though: if a piece of code makes a direct call to another piece of code, the address of the new code must fit within an instruction. On an ARM processor, only 24 bits are available to encode the address, meaning a jump in code can only go 16 MB on either side of its call. Going any further requires more instructions, and the performance hit that comes along with that.

[Victor] decided a solution to this problem would be to create a bit of circuitry that would be a sliding window to store address locations. Instead of storing the literal address for jumps in code, every branch in the code is stored as a location relative to whatever is in the program counter. The result is an easy way to JMP to code very far away in memory, with less of a performance hit.

There’s an implementation for this sliding window token thing [Victor] whipped up for NXP’s ARM Cortex M3 microprocessor, and he’ll be working on an implementation of this concept in a new CPU over on his git.

Auxiliary Scoreboard Reads Status Directly From Memory

September 13, 2010 by Mike Szczys 28 Comments

[StaticChanger] built a scoreboard to display his kill statistics from Halo for the PC. Yes, we’ve seen kill counters before, but we like the way that he gathers the data. This project is reading the score directly from an address in memory.

Using a program called Cheat Engine, the memory used by a program can be sniffed. After a few passes, the program will help you find a static memory address for your desired data. Once you have that it’s just a matter of using a pointer to that address in your desired programming language. In this case, a C# program polls the value and instructs an Arduino to display the value on a couple of 7-segment displays. Voila, the number appears next to your screen as you see in the image above.