- LocationN48 - E11
- CountdownT-00D 00:00
Software Defined Radio (SDR) has finally reached a much broader mass of people, who wanted to play with RF technology, but didn't find the time or resources to learn all necessary skills, to build a hardware based radio. Thanks to the work of the GNU-Radio and OsmoCom developer crowd, this barrier is finally gone and everyone can, more or less, directly access, what the antenna receives.
The last Mission-Log about a GNU-Radio based NFM SDR receiver pulled in a lot of people, looking for examples, to better understand GRC and to improve their own SDR projects. The real beauty about it is this: Unlike hardware receivers, which can't simply be replicated and shared, we only have to come up with good software receivers/transceivers once and then may just share them amongst each other, without any limitation.
However, the antenna itself, is still hardware and will most likely never be replaceable by software. On ##rtlsdr people often ask about antennas, because they are clearly not satisfied (and who could blame them) with the performance of the original L/4 DVB-T stub. Unfortunately, there just is no can-do-it-all-perfectly antenna, even if some despicable corporations try to market their products as such.
Other people often recommend Discone-Antennas for wideband reception, but there also are other, less known alternatives, which still are a very good compromise as a general purpose wideband receiver antenna. Not everyone has the space or possibility to put up a Discone-Antenna, so why not use an antenna, that performs even better than a Discone (at least it did here in direct comparison), is a lot smaller and looks way less “conspicuous”:
One of them was the Dressler ARA-2000, covering 50-2000MHz, designed and built in the 90's. The company died the usual death by capitalism (bought by another company and then stripped down and moved production to China). Today there are only a few of these left in the wild and are traded for unrealistic prices on $bay. This particular one was used for the Argus-Prototype but sacrificed and disassembled with the hope, that replicating the antenna will be easy, so that this knowledge would get openly reseeded into the wild, instead of being lost in some archives of a dead corporation. It would be great, if the following documentation about the ARA-2000 would inspire more people, to build their own Active Wideband Receiving Antenna (AWRA) and try to improve and evolve the concept even further or come up with completely new ideas.
Next generation robots, drones and motorized scooter/skateboard/e-bike projects need efficient and resilient BLDC controllers, so if you're also looking for a solid open-source brushless motor speed controller (BLDC ESC) for your project or knowledge/inspiration to bootstrap your own, then you most definitely want to have a look at VESC.
It's a full open-source breed where hardware, firmware and support-software are available on github and no Windows or other crappy, proprietary systems are required for development or tuning/configuration.
It seems like it's time to pre-warm our oscillators and prepare our SDRs for more DARC action in the near future. For more than the last 4 month, the traffic to The DARC side of Munich revealed an interesting pattern: There was a steady increase of traffic coming first from the big European & Asian automobile manufacturers, then from automotive subcontractors globally and now from Asian electronics manufacturers.
These metrics, their sudden occurrence, the event order and the isolation to mostly automotive context simply suggest that there must be something in the works which will get deployed soon (maybe even already is), to broadcast data to cars via DARC. It will get interesting…
If you want to learn more about voltage-dividers or need a tool to design/verify voltage-divider resistor selection for your next electronic engineering project, try EZVD - Easy Voltage-Divider Calc-/Simulator
If you've missed the opportunity to get a PiGI PCB of the first batch, here's your next chance to turn your Raspberry PI into a versatile Geiger-Counter. All hail Fehlfarbe.
Re-deploying the Ubiquiti Unifi UAP-Pro with OpenWRT (instead of Unifi) at the new base-camp revealed a problem: it simply didn't work anymore. No DHCP reaction, no default IP, nothing. Except for the LED blinking white after a reset, it seemed completely broken. Opening the case and attaching a terminal to the serial console, revealed bootloader output that wasn't promising but at least it wasn't completely dead. So we had to get our hands dirty, pop the hood and hack around to fix this jffs2 corruption issue and revive the AP without costly and probably long/painful RMA. Maybe this knowledge can help you too.
In case you're one of those people using xfce-planet or otherwise depend on our global cloudmap service (introduced here), you'll probably already have noticed that the image wasn't updated for 6 days now. The service itself is running on our side, but it seems as if MTSAT (covering 145E) doesn't send any more images since 2015-12-04. We'll try to get some more information about the outage to provide fresh, free and silky-smooth cloudmaps for everyone again. Sorry for any inconvenience, but we don't manage those birds, unfortunately…
It's always rewarding to see that distributing and sharing open knowledge & tools ultimately leads to much more individual empowerment and faster technological evolution/innovation than “protection” of “Intellectual Property” ever could:
OK3ZB copied and used the AWRA-Cutting-Helper, did a successful rebuild of the Active-Wideband-Receiving-Antenna and came up with a new LNA approach:
More details and photos on: http://blog.brichacek.net/klon-sirokopasmove-aktivni-anteny-ara-2000/
One of the most time consuming aspects of many DIY projects is identifying and sourcing materials. Living in a globalized world and having the ability to link everything online has made this a lot easier. Today, it is by far much more convenient and budget friendly to directly shop in Asia, cutting out all of the so called “added value” (which is just a nice euphemism for making stuff artificially expensive to the end user, so that politicians can claim to “create jobs” and society can try to keep up the illusion of the necessity of full-time employment and camouflaged slavery for everyone).
The last F3l1ks sprint included the task to evaluate carbon fiber as a printing surface, so we had to get carbon and wanted to give the german market another chance. We've found about 15 carbon product manufacturers online with focus on manufacturers and not simple re-sellers. One thing became pretty clear: If you don't have a web-shop or at least a website with information about your products, you simply don't exist anymore. These 15 sources all got the same eMail, describing our needs and specifications in detail (carbon fiber sheets in 0.3 and 0.5mm with the specific size of the printbed and temperature considerations) to get a fair quote with the option to send us test material for free.
Out of these 15, only 7 sent a reply. From these, 2 dropped directly out as being re-sellers, not offering any individual service. One just sent as link to their shop for some carbon foil, clearly not even having read our eMail. One shop replied that they have sent out testing material, but it never arrived and we never heard from them again, another was just trying to rip us off. That left only one carbon supplier on our list, but they came trough all the way:
when you are looking for carbon fiber sources in Germany, you can repeat the whole process as we did (took about 3 weeks to give slower candidates a fair chance) or go directly to:
where you get fair prices and good customer service. And of course we'd like to thank the whole team again for sending us testing sheets for free for our tests and are looking forward to working together in the future, for custom carbon CNC jobs.