HAM

A pure javascript audio waterfall / panadapter

Waterfalls: not the river kind, but the audio kind. Also known as sonograms, those are 2D+1 representations of the spectrum of a signal: the X axis usually represents the frequency, the Y axis the time (or the other way around), and the power of each frequency is drawn on a color gradient.

In the ham radio world, waterfalls are a great way to visualise part of the frequency spectrum. Depending on the type of radio you have – SDR or not, really – , you can either display a fairly wide part of the spectrum, or just a few kilohertz. But in any case, this visualisation will give you a new way of understanding what is going on around you, RF-wise.

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HAM

KX3 Extended temperature compensation

During a lot of digital mode QSOs in the beginning of 2013, I regularly got feedback from the other party that my signal seemed to be drifting slightly. PSK31 having a very narrow bandwidth, even a small transceiver drift can be an issue during a QSO. This is usually partially hidden thanks to AFC on the receiver side, but good hams never fail to notice the problem and kindly point it out – at any rate, I was grateful several people did, since it is not always easy to spot this by yourself.

The Elecraft KX3 is a transceiver which uses a Silabs Si570 oscillator. While this is a good quality frequency source, it also drifts significantly depending on its internal temperature. It is part of the design of the chip, which contains a temperature sensor to compensate for this in software. The KX3 therefore is able to compensate for this drift by using an internal table.

Unfortunately, the drift compensation table is specific to individual units, and populating it requires connecting the radio to a known and very stable frequency source, and go over the whole oscillator temperature range. Doing this in factory is not practical as this requires way too long.

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HAM

Heat Sink for the KX3

Just received the Heatsink I had ordered from Fred Meier, VE7FMN ( fsmeier with “telus.net” behind the “@” sign). Very impressed after a quick test, I was able to sustain a long PSK31 QSO on 20m at 10W with PA.I temperature hovering around 43°C. I could not do 10W on PSK31 previously for more than 30 seconds at a time before heating HI TEMP.

Fred told me he can make those heatsinks for the following prices:

  • In the white- $60.00
  • matte black powder coated- $93.00 (the one on the pictures below)
  • Screw and wrench set  - $5.50 (on the pictures below too)

Reach out to him directly for a quotation or drop me a line in the “contact” section of the site, I will forward the message.

Very happy so far, I will report further as I use it.

Update 2014.04.18: still happy, after a few weeks of use, this heat sink really makes my KX3 fully usable on PSK31 at any power level it can handle, even in fairly warm environments. In my experience, Olivia is one of the most punishing modes for the output stage, I have yet to do proper tests on that one.

KX3 Heatsink 1

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Aerodynes

Seiki 4K 39″ display

Screen Shot 2014-02-28 at 09.50.59This is the latest large addition to my home office: a shiny new Seiki SE39UY04 39 inch – 100cm – display for my Mac, with 4k resolution: 4k in this instance means a massive 3840×2160 pixels. Talk about large.

Two noteworthy things: first of all pixel density works out really well with this screen size: it is very similar to my mac’s 15inch display, which means that text is super readable, an essential factor for a display especially if you sit in front of it a significant number of hours each day.

Second, this display is pretty much the best bargain you can find: I bought it on Amazon for $399. Compare this with your average large Dell monitor that will set you back $800, and it is easy to understand why it is so popular at the moment on Amazon!

One of the reasons why this display is cheap, is that it is not sold as a computer monitor, but as a TV: it has a TV tuner built in and most of its settings are really TV oriented, not computer oriented. But with a little bit of work, you will get excellent results as a computer monitor!

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HAM

DRM – Digital Radio Mondiale

logo1If you are a computer geek like me, the first thing you will think about when I tell you “DRM” is “Digital Rights Management”. You know, this process that consists in giving you both encrypted content and the keys to decrypt it, but in a really obfuscated way to attempt to discourage you from doing the decryption yourself… anyway, this is not the subject of this post. The DRM I want to talk about today is “Digital Radio Mondiale”. A strange acronym choice if you ask me, but there you go…

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AVR Projects

Mini game of life

Two months or so ago, the kids and I bought a few bits and pieces at www.adafruit.com to build small LED badges. They had been staying in their box since then, but I eventually got to it with my youngest this Sunday afternoon.

Animated GIF!

Animated GIF!

The idea was to create simple animated badges using the cute 8×8 “mini” LED matrix displays that Adafruit sells, and using some of their small ATTiny45 boards to run the ARV Arduino sketch they described at http://learn.adafruit.com/trinket-slash-gemma-space-invader-pendant/overview .

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Aerodynes

FriedCircuits USB tester and backpack reloaded

This is a test and review of the new version of the FriedCircuits USB tester and backpack. If you read my previous articles on the backpack and its extensions, you already know that I am a big fan of this simple and very useful tool.

Before going further, one quick word in the interest of full disclosure: William kindly sent me the prototype for this backpack, and I actively contributed to influencing (in a good way I hope) the design of this new version.

So what is new ?

This review is actually about two separate items:

  • The FriedCircuits USB tester breakout v2.0
  • The FriedCircuits OLED backpack v2.0

Both have been improved in this new release, both on the firmware and the hardware sides, so let’s dive a bit deeper…

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HAM Toolbox

Sark 110 review

One of the really useful tools you can have as a Ham is an antenna analyser, which enables you to understand better how your antennas and overall RF installation are behaving/performing at various frequencies.

Sark-110 to KX3 Size comparison

Sark-110 to KX3 Size comparison

At the very least, an antenna analyser will let you check the standing wave ratio which, in a very simplified view, is the amount of energy that is being reflected back into your transmitter and not being sent out. A high SWR usually is not a very good thing, though a low SWR does not always mean you have a perfect antenna either, that would be too easy – a 50 Ohm resistor connected to your amplifier will always give you a 1:1 SWR but won’t help you much if you want to make contacts!

Still, understanding how your antenna behaves depending on the frequency, see exactly where it resonates, and how its impedance evolves, is extremely useful. There are many types of antenna analysers on the market, from really cheap kits, to totally awesome tools like the Agilent Fieldfox, or even more advanced stuff that costs as much as a small house… I found a good article at rigexperts which explains a lot of different possible architectures, a good read.

With this in mind, I recently purchased a Sark 110 from Seeed Studio, who sells it for $360 as of January 2014: this antenna analyser is designed for HF to low VHF bands, with a 0 to 230MHz range. This makes it perfect for hams, though being able to include the 70cm band would have been a nice touch. The Sark 110 is fairly priced, especially for what it does: you get much more than a VSWR indicator here!

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HAM

Quick test of the Matchbox antenna

This afternoon, I did a quick test of the “matchbox” end fed antenna from the Honolulu Emergency Amateur Radio Club, up on a hill,  good receptions reports using only 5 to 7 watts, as you can see below – the sun was setting and the band was closing. As a caveat, I am not doing any sort of absolute judgement on this antenna’s performance, just a bit of field test feedback!

Reception reports matchbox antenna

Reception reports matchbox antenna on 20m

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HAM

Digital signals on the waterfall

Collection of various digital modes – images for now, maybe audio later. The idea here is to take waterfall screenshots in ‘real life’ environments, on a noisy waterfall, to serve as a reference on the software I use most often, fldigi.

These are all signals I received on my KX3, unless stated otherwise, and which I successfully decoded. This is a work in progress, I will add additional modes as I go along, so check back every once in a while! If there are modes you would like me to look for, let me know.

Meta digital

A fairly common practice is to use preambles to tell digital software what mode is going to be transmitted. There are mainly two types of preambles: “Reed Solomon ID” and video preamble. A good example of video preamble on a noisy waterfall can be found below:

Video ID then RSID before an Olivia transmission

Video ID then RSID before an Olivia transmission

More info on RSID can be found here: http://www.w1hkj.com/RSID_description.html

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