APRS ..yms. radioamatööritoimintaa


Todella mahtava projekti

Clocks that read time via received radio signals have several advantages over their Internet-connected, NTP-synchronised brethren. The radio signal is ubiquitous and available over a fairly large footprint extending to thousands of kilometres from the transmitting antennae. This allows such clocks to work reliably in areas where there is no Internet service. And compared to GPS clocks, their front-end electronics and antenna requirements are much simpler. [Erik de Ruiter]’s DCF77 Analyzer/Clock is synchronised to the German DCF77 radio signal, which is derived from the atomic clocks at PTB headquarters. It features a ton of bells and whistles, while still being simple to build. It’s a slick piece of German hacker engineering that leaves us amazed.
Kriisi- ja turvaviestintäpalvelin käynnistyi Itä-Suomessa.

Radioharrastajavoimin toteutettu turvaviestintäserveri LARS 4.17 on nyt toiminnassa Kolin automaattisella tuvitoistinasemalla OH7RAC. Tarmon OH6ECF erityisesti kriisiviestinnän tarpeita ajatellen koodaama radioverkkojen kevyt tilannetieto- ja johtamisjärjestelmäsofta auttaa yhteyskatkostilanteen spontaaneja 'kaaosverkkoja' järjestäytymään toimiviksi tilapäisradioverkoiksi.

LARS toimii Kolin tuviasemalle asennetussa Raspberry-tietsikassa akkuvarmistettuna. Sen etusivun yhteysverkkokartalle voivat turva- ja kriisiviestintätilanteisiin varautumisesta kiinnostuneet lisätä omat radioasema- ja radioyhteystietonsa, ja päivittää niitä ajan tasalle.

Palvelimen radioverkkokartalle hyväksytään tavallisesti kaikki poikkeustilanteiden kriisiviestintään soveltuvat radioyhteydet. Näitä ovat lähes kaikki yleiset VHF- ja UHF-radiopuhelimet, kuten RHA68, LA, meri-VHF, elinkeinoelämän radiopuhelimet, PV:n pataljoonaradiot, PMR446, sekä radioamatöörien radiot.

Kolin turvaviestintätoistinta käytetään kehitysalustana tutkittaessa mahdollisuuksia luoda välttämättömimpiä pitkän maakuntakantaman hätä- ja kriisiviestintäyhteyksiä tavallisten radioverkkojen välille. Tämän kaltaisilla tuvitoistimilla on mahdollistaa muodostaa poikkeustilanteiden viestintää varten erillisistä VHF- ja UHF-radiopuhelimista verkkoja, hieman samaan tapaan matkapuhelintukiasemat muodostavat verkkoja kännyköistä.

Oheiskuvissa on esimerkkejä Larsin etusivusta radioyhteys- ja paikkatietokarttoineen, viestipaneeleineen, etäohjausoptioineen, miniwikisivuineen ja chatteineen. Nämä Kolin Larsin sivut aukeavat osoitteessa: http://lars.dy.fi/ . Verkko-osoite voi myöhemmin muuttua.

2017-05-13 - OH7RAC turvaviestintäserveri LARS 4.17 Kolilla (c) OH7HJ.JPG

2017-05-13 - Kolin OH7RAC turvaviestintäserverin LARS etäohjaus- ja viestipaneelit (c) OH7HJ.JPG

2017-05-13 - Esimerkkejä Kolin turvaviestintäserverin LARS toiminnoista sen wikistä (c) OH7HJ.JPG

Kriisiviestinnän kokeilualustana toimivan Kolin automaattisen tuvitoistinaseman ylläpitäjinä ovat enimmäkseen reserviläisistä ja radioharrastajista koostuvat vapaaehtoiset turvaviestintäaktiivit.


Välineitä poikkeusolojen viestinnän tarpeisiin: https://www.facebook.com/groups/1519431578386685/1743723752624132/
LARS-kokeilua, keskustelua ja esittelyä: https://www.facebook.com/groups/1519431578386685/permalink/1736189626710878/
LARS:in viestipaneeli: https://www.facebook.com/groups/1519431578386685/permalink/1712330015763506/

KRH-verkon prototyyppivaiheessa oleva "taktinen netti" on nyt saanut ytimekkään nimen LARS: https://www.facebook.com/groups/1519431578386685/permalink/1719743991688775/
FB:n turvaviestintäsivu: https://www.facebook.com/groups/108089039526164/
Kolin tuvitoistimen OH7RAC wikisivu: https://fi.wikibooks.org/wiki/Radiotaajuuskirja/OH7RAC

OH7RAC välittää sanomayhteyksiä osana radioamatöörien maailmanlaajuista digimodeverkkoa: http://guardian.no-ip.org:81/ChatNetwork.htm
Digimodeverkon BPQ32-palvelin OH7RAC-tuvitoistimella: http://koli.dy.fi:85/Node/Nodes.html
Turvaviestintätekniikan ketju kerhofoorumilla: http://www.oh7ab.fi/foorumi/viewtopic.php?f=15&t=225&start=70#p2274

- Juha​
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Pulaajan hätäradio

A standard early electronics project or kit has for many years been the construction of a small broadcast transmitter with enough power to reach the immediate area, but no further. These days that will almost certainly mean an FM broadcast band transmitter, but in earlier decades it might also have been for the AM broadcast band instead.

The construction of a small AM transmitter presents some interesting problems for an electronic designer. It is extremely easy to make an AM transmitter with a single transistor or tube, but it is rather more difficult to make a good one. The modulation has to be linear across the whole amplitude range, and its effect must not pull the frequency of the oscillator and cause FM distortion.

It’s a task [Joe Sousa] has tackled, with his one tube AM transmitter in a Campbell’s soup can. His write-up of the transmitter contains a full description of the problems he faced, and how his design overcomes them. His oscillator is a cathode follower, with the tube biased in class A mode to ensure as undistorted a sine wave oscillation as possible. Modulation is provided through the suppressor grid of the pentode tube he’s using.

The completed transmitter is mounted inside the iconic soup can, with the mains transformer mounted on a removable bottom plate. There is a provision for both loop and wire antennas to be connected.

It is probable that this transmitter falls under the so-called “Part 15” rules for unlicenced low-power broadcasting in the USA, however it should be borne in mind that not every territory has this provision. If you build this transmitter, make sure you’re not going to attract the interest of your local equivalent of the FCC.




At first glance, the ColibriNANO SDR looks like another cheap SDR dongle. But after watching [Mile Kokotov’s] review (see video below), you can see that it was built specifically for software defined radio service. When [Mile] takes the case off, you notice the heavy metal body which you don’t see on the typical cheap dongle. Of course, a low-end RTL-SDR is around $20. The ColibriNANO costs about $300–so you’d hope you get what you pay for.

The frequency range is nominally 10 kHz to 55 MHz, although if you use external filters and preamps you can get to 500 MHz. In addition to a 14-bit 122.88 megasample per second A/D converter, the device sports an Altera MAX10 FPGA.

In addition to interfaces to different software packages, the dongle works with remote software. The idea is to put the dongle and an antenna somewhere advantageous (that is, high and radio-quiet) and then use a Raspberry Pi or similar computer to pipe signal over the Internet.

If you don’t want a dongle, we can endorse [Lukas’] build from scratch. If you are looking more for a getting started resource, check out what [Richard Baguley] had to say about SDR.


If you’re a first responder — say, searching for someone lost in the outback, or underneath an avalanche — and you’re looking for someone with a radio beacon, what’s the fastest way to find that beacon? Getting up high would be a good idea, and if you’re using radio direction finding, you’ll want to be able to cover a lot of ground quickly if only to make the triangulation a bit easier. High and fast — sounds like the perfect opportunity for a drone, right?

[Phil Handley]’s Bloodhound project is an autonomous drone that can scan a wide area, listening for emergency beacons while alerting the search and rescue personnel. His test bed tricopter uses DT750 brushless outrunners controlled by 18A Turnigy Plush ESCs and powered by a 2200mAh LiPo. A metal-gear servo works the yaw mechanism. He’s also got a Pixhawk Autopilot, a ArduPilot flight controller, a NavSpark GPS, a software defined radio dongle, and a Raspberry Pi. He made the air frame out of wooden dowels, following RCExplorer’s tricopter design.

The next challenge involves radio direction finding, essentially creating Bloodhound’s foxhunting skills. It needs to be able to autonomously track down a signal by taking readings from multiple angles. In addition to finding lost skiers, [Phil] also envisioned Bloodhound being used to track other beacons, of course—such as wildlife transponders or errant amateur rockets.



The third version of [Henrik Forstén] 6 GHz frequency-modulated continuous wave (FMCW) radar is online and looks pretty awesome. A FMCW radar is a type of radar that works by transmitting a chirp which frequency changes linearly with time. Simple continuous wave (CW) radar devices without frequency modulation cannot determine target range because they lack the timing mark necessary for accurately time the transmit and receive cycle in order to convert this information to range. Having a transmission signal modulated in frequency allows for the radar to have both a very high accuracy of range and also to measure simultaneously the target range and its relative velocity.

Like the previous versions, [Henrik] designed a four-layer pcb board and used his own reflow oven to solder all the ~350 components. This process, by itself, is a huge accomplishment. The board, much bigger than the previous versions, now include digital signal processing via FPGA.

[Henrik’s] radar odyssey actually started back in 2014, where his first version of the radar was detailed and shared in his blog. A year later he managed to solve some of the issues he had, design a new board with significant improvements and published it again. As the very impressive version three is out, we wonder what version four will look like.



Most new hams quickly learn that the high-frequency bands are where the action is, and getting on the air somewhere between 40- and 160-meters is the way to make those coveted globe-hopping contacts. Trouble is, the easiest antennas to build — horizontal center-fed dipoles — start to claim a lot of real estate at these wavelengths.

So hacker of note and dedicated amateur radio operator [Jeri Ellsworth (AI6TK)] has started a video series devoted to building a magnetic loop antenna for the 160- and 80-meter bands. The first video, is an overview of the rationale behind a magnetic loop. It’s not just the length of the dipole that makes them difficult to deploy for these bands; as [Jeri] explains, propagation has a lot to do with dipole height too. [Jeri] covers most of the mechanical aspects of the antenna in the first installment; consuming a 50-foot coil of 3/4″ copper tubing means it won’t be a cheap build, but we’re really looking forward to seeing how it turns out.




Air Traffic Controllers use Automatic Dependent Surveillance-Broadcast (ADS-B) as an alternative to secondary radar to track aircraft. The ADS-B is transmitted by the aircraft and contains information such as GPS position, pressure, altitude, and callsign among other things at a 1090 MHz frequency, which can be decoded using any of a number of software tools.

[Mike Field] lives near an airport, and decided he wanted to peek into the tracking signals for fun. He turned to an RTL-based TV Dongle. Since the stock antenna was not cutting it, he decided to make one specifically for the 1090 MHz signal. His design is based on Coaxial Collinear Antenna for ADS-B Receiver by [Dusan Balara] which uses pieces of the coaxial cable cut to the right length. There are a number of calculations involved in determining the size of the cable, however, the hack in this design is the way he uses a USB based oscilloscope to measure the speed of RF waves inside the line in question.