EMF Hub

You may have noticed my blog has been a little quiet recently. This is because my attention is currently focussed on the EMF Hub, a multimode Amateur Radio "hub" that bridges DMR, Echolink, AllStar and IRN.

There will also be onsite DMR and FM gateways linked through to the hub at Electromagnetic Field "a temporary village of geeks, crafters, and technology enthusiasts that's lit up by night, and buzzing with activity during the day." which runs from the 31st of August through to the 2nd of September.

You can follow updates for the EMF Hub here

MB6IEF on the test bench

Setting up an APRS Digipeater with an Orange Pi Zero, Direwolf, and a Tait 8105

Several members of my local club M0HSL are experimenting with APRS and Packet Radio, so I thought I'd dip my toes in the water. The most common method is to use a Hardware TNC device and a radio aimed at amateur use, but I like doing things in software where I can ( and I'm a cheapskate )

I have used Direwolf in the past with an RTL-SDR dongle to receive APRS traffic, so I thought I'd give it a go with a physical radio, a Tait 8105. Unfortunately it's a UHF model, but the setup and programming is identical between the UHF and VHF version.

To control the handle the audio and PTT, I am using a modified CM108 USB sound fob.

Faking a routed subnet with OVH / SoYouStart

I am currently in the process of decommissioning my trusty SoYouStart server (Part of OVH) so I thought I'd best document some of the stuff that may be useful in future.

You can purchase additional IP addresses off SoYouStart (SYS) however they work a little differently to the norm. I think the best way to describe it is they use static ARP to associate a public IP with a MAC address, and drop any traffic from a public IP unless its originating from the same MAC that was statically mapped. Because of this, the gateway isn't in the same subnet as the public IP range.

Before being decommissioned I was using the server as a VM Host and to mimic a 'real' setup I wanted a virtualised router / firewall between the internet and the Virtual Machines. Those of you that follow my blog will know I am a Mikrotik fanboy, so I decided to use the Mikrotik CHR (Cloud Hosted Router) as it was cheap and flexible.

To get this working I purchased an additional /32 for the routers 'external' interface and a /28 for the routers 'internal' interface. It's also required to reconfigure the SYS server's network configuration to use a bridge rather than having its IP directly on the interface.

Disclaimer: This is not a full guide, and should be considered "inspiration"

Converting a CM108 USB fob for amateur radio use

The CM108 USB audio chip has become a popular choice for Amateur Radio usage, due to its cheap price, good performance, and its exposed GPIO pins. The GPIOs can be utilised for triggering the PTT and detecting COS (When the radio is receiving a valid signal)

Due to its popularity, it has been integrated into app_rpt, a channel driver for Asterisk aimed at repeater usage, used in the popular AllStar Asterisk distribution and also supported in Hamlib, a "standardised API to control any radio oriented equipment through a computer interface", which Direwolf conveniently supports.

The following guide documents how to convert one for use with a radio. This is not my design, but the combined work of WB6NIL (SK), W9SH, M0NFI, G7RPG and many others. Pictures supplied with permission from M0NFI

Using darkcast and icecast to stream audio from a Linux ALSA audio interface on Debian

This is a quick and dirty guide to streaming audio from a sound card, physical or otherwise to the internet as an MP3 stream. I am using a new, stock Debian 9 installation and the ALSA audio driver.

Darkice captures from the sound card and pushes it to Icecast. Icecast then streams the audio to connected clients. I am also using nginx to prevent users accessing the admin interface, for a layer of security.

As this is a quick and dirty guide, its assumed you have some Linux experience. If you get stuck, feel free to leave a comment.

Hot to get a neutral wire to a UK light switch [Theoretical]

For the majority of UK homes (The older ones at least) our lighting switches are wired up with a system called 'loop in ceiling' where all the light fittings in the ceiling (ceiling roses) are wired in a loop, with a switched live being taken from the rose to the switch. This can potentially save cable and simplify installation, but causes issues when you want to install Home Automation type switches such as the Sonoff T1 that need a Neutral to be able to power themselves.

This is something I've been mulling over for a while, and someone has asked for more details. So here it is, a quick and dirty blog post.

Below shows a standard wiring layout for a single switch and bulb, as you can see there's no neutral in the switch, only live in and switched live out.

The Problem (Click to expand)

So, can we get a neutral to the switch without tearing the walls apart? Kind of!

I am not an electrician. This may not meet building or safety regulations. This is untested! Do so at your own risk! Electrical work should be carried out by a qualified electrician! ETC

Broadlink RM Mini 3 Black Bean IR Blaster - Walkthrough

I thought I'd try something different and make a video for Youtube. In the video I talk about the Broadlink RM Mini 3 Black Bean IR Blaster, a device that will allow you to control Infrared devices such as TVs and Set-top boxes using your smart phone.