All posts by Andy VE7CXZ

Playing with packet radio in the CRD

The Capital Regional District (commonly referred to as the CRD) is the name for the region that contains and surrounds Victoria, the capital of BC. The CRD is made up of a number of municipalities, and through Emergency Management BC, each municipality has its own Emergency Operations Centre, or EOC. Part of each EOC usually includes some kind of communications facility, which is run by licensed amateur radio volunteers, and the facility normally has a packet station that can be used to pass messages back and forth.

What this means is that if packet radio is something you’re interested in, Victoria has plenty to keep you occupied.

Connecting to a node

First, pick a node from the CRERCC Packet Station page. For this example, I went with VE7SEP-7, which is located at the Saanich EOC.ve7sep7

For anyone familiar with packet nodes, the above should look pretty familiar. If you’re not, then the basic functionality is that you can connect through to another node, list the other nodes that this node has heard, and disconnect.

I hit J (or Heard) to see the other nodes than VE7SEP-7 had heard, and you can see that my call is the latest in the list:-

ve7sep7-2

Connecting to other nodes

While you’re connected to a node, you can usually use the C (or Connect) command to connect to another node that’s on the same frequency. This is useful if you can’t hit the other node directly, but the node you’re connected to can hit you and the other node.

For example, from Langford I can’t connect to VE7PEP-7 directly, but I can – as we saw above – connect to VE7SEP. When we looked at the nodes that VE7SEP-7 has heard recently, we can see that VE7PEP-7 is in there, which means there’s a good chance VE7SEP-7 can connect to it. To try it, we can type C VE7PEP-7, and cross our fingers:-

ve7sep7-3

Success! We’re now connected to VE7PEP-7 and can use it as if we were connected directly. This also means in theory that we could jump to yet another node, although this is not always a good idea, which I’ll touch on later.

Using digipeaters

The above method for reaching packet nodes that we can’t hit directly works, but is a bit cumbersome. What if we could connect to our intended node via the closer node, but without having to manually connect to the closer node first? We can, and it’s known as digipeating.

In this example, I can’t connect to the packet station VE7RAH-7:-

term-ve7rah-1

(I’m using Linux for these examples – AX25 is well maintained, relatively easy to set up and simple to use, and I’ll cover it in a future post)

As you can see, I tried to connect using the axcall command, but I didn’t get a response and eventually aborted the connection attempt. As before, I know I can reach VE7SEP-7 directly, so let’s adjust our command:-

term-ve7rah-2

 

ve7rah-digi

…and we’re connected!

There is a subtle difference at work here, and that’s that in our first example, we were creating separate connections first to a nearby node, then from the nearby node to a distant node, while in our second example we’re creating a single connection to a distant node, but relaying it through a nearby node . The configuration needed to support these two different methods is different, so while one may work, the other may not. From the examples above, we can see that VE7SEP-7 supports both.

A further example to highlight this is that although I can connect to WF7W-7 (and, although not shown, I know WF7W-7 can see VE7RAH-7):-

wf7w-7

…trying to use it as a digipeater fails:-

wf7w-digi

 

A word about too many hops

As fun as bouncing around different nodes can be, it’s best to keep it to a minimum. For starters, for each hop you add to the connection, the more delay there will be when issuing commands to the intended node. This is because each node in the path has to retransmit your packet and wait for a response before it can reply back to you. Add other stations into the mix or any sort of interference and having any more than 1 or 2 hops can be unusable.

The second – and perhaps bigger – problem is that all these additional packets being generated will tie up the channel, making it more difficult for other users on the same channel.

What next?

What I’ve shown above is just scratching the surface, and in future posts I’ll cover setting up AX25 on Linux, and how a tool call RMS Express is used to provide worldwide e-mail services over packet radio networks!

Radio Weekends: HF digital modes

This Saturday, Josh VA7ACQ, Dom VA7CRO and myself stationed ourselves at various places around the CRD with the intention of running a few tests with various digital modes on HF. Dom went up to Sidney and Josh set up at Beaver Lake, while I headed for the usual spot down at Esquimalt Lagoon.

VA7CRO, VA7ACQ and VE7CXZ spread out across the CRD
VA7CRO, VA7ACQ and VE7CXZ spread out across the CRD

We settled on using 20m, hoping for a balance of less QRM and greater efficiency with the compact vertical antennas that Dom and I were using, while being not as useful for ground-wave as 40m may have been. After a bit of tweaking of audio levels and picking a dial frequency of 14.088MHz, Dom and I made contact with PSK31.

Working VA7CRO with BPSK31
Working VA7CRO with PSK31

Once we’d played with PSK31 for a while, we then moved to a much older mode by the name of Hellschreiber. Developed in the late 1920s, Hellschreiber (or Feldhellschreiber) sends text as a series of pixels, scanned left to right.

VE7CXZ, VA7CRO and VA7ACQ (in that order) working with Feld-Hell
VE7CXZ, VA7CRO and VA7ACQ (in that order) working with Feld-Hell

After this, we tried a whole bunch of other modes, including RTTY, MT63, Olivia, and MFSK – where Josh and I even managed to exchange small images! It was also a useful test of the RSID functionality in both FLdigi (which I was using) and DM780 (which both Josh and Dom were using), which sends a brief burst of MFSK before the actual transmission to both identify the mode being used and to centre the decoder on the right frequency.

I forgot to take any more screenshots, so here's another Feld-Hell one. You start to get a bit silly when you're sat in a cold truck at the seafront...
I forgot to take any more screenshots, so here’s another Feld-Hell one. You start to get a bit silly when you’re sat in a cold truck at the seafront…

Some findings from the afternoon’s experiments were that MT63 can be very particular about being on the correct frequency, that DM780 uses fixed centre frequencies for MT63 whereas FLdigi doesn’t, and – very much related to the first two – that the USB sound card I use for digital modes produces audio that is off by a not insignificant amount – about 40Hz.

By now it was starting to get a bit on the cold side, so we all made our way to Six Mile to warm up and for a much-needed beer.

The (temporary) return of M0VKG

It’s been almost two years since I got my Canadian amateur radio licence, but before then I was licensed in the UK as M0VKG. When I first moved to Canada in July 2012 I operated for a while as M0VKG/VE7, but since then – other than a visit back to the motherland in February of this year – my UK callsign has been mostly dormant.

Mostly.

International agreements can be complicated affairs, and amateur radio doesn’t escape this fact. The CEPT agreement is probably the biggest, and generally allows an amateur radio operator from one country to operate temporarily in another country, and in some cases actually acquire a licence in the other country based on their existing one.

Another agreement, which is much closer to home, is that between Canada and the US, which allows most amateur radio operators of both countries to operate in both countries. I say most, because the agreement states that it applies to citizens of both countries. This means that technically, if you aren’t either a Canadian or a US citizen, you’re not covered by the agreement. As a British citizen, this means it doesn’t cover me!

I recently had my application for permanent residency in Canada approved, which meant – for boring immigration reasons I won’t go into – that I had to leave the country and reenter again. From here, that means the easiest way is to drive to the US border, which is what I did. However, as explained above, I can’t legally operate as VE7CXZ in the US, so I had to fall back on M0VKG. Luckily, the Kenwood TM-D710 has a features which lets you store different ‘profiles’ in the radio, while sharing the same channel memories. This means that I was able to set up a profile on the TM-D710 that instead of using my usual callsign and SSID of VE7CXZ-1, I could quickly switch to using M0VKG-9 at – literally – the touch of a button.

Which, to wrap it all up, explains the reason for this map:-

APRS track from Victoria, BC to Ferndale, WA and back
APRS track from Victoria, BC to Ferndale, WA and back

Above the clouds with APRS

While out at my new favourite spot for HF radio the other weekend, I happened to notice an odd callsign pop up on APRS:- IMG_20140803_185248

Holding a UK callsign, it doesn’t take much to recognise  another one when you see it. This wasn’t any normal APRS station, though – it was a high altitude balloon on its way around the world!

Leo Bodnar M0XER has been making and releasing high-altitude balloons for some time, and a few have made it all the way around the world. At the time, this one (using the SSID M0XER-6) was just over 100km south of me, over the Olympic National Park in Washington state. It eventually came within 95km of me, before heading eastwards and eventually crossing the border into Canada.

Leo’s balloons are a great example of what APRS can be used for, and more information (including a map of the flight path) about this particular balloon (also known as B-66) can be found here.

VE7CXZ/P from the Coburg Peninsula

image
The Focus of Doom, ready for portable HF

I’ve recently started operating portable from the Coburg Peninsula, which is a narrow strip of land by the historic Fort Rodd Hill and Fisgard Lighthouse. Situated in the south of Colwood, BC, it looks out onto the Strait of Juan De Fuca and therefore has great takeoff on HF, especially to the south towards Washington and the rest of the continental US.

image
Working AF7ES with PSK31

So far I’ve managed to work all over the US and in Europe, including W1AW/P and stations in Hungary and Slovenia. I’m using a Kenwood TS480SAT for SSB and a Yaesu FT897D for digimodes, with an Acer netbook running FLdigi for the digimodes and logging.

I’m hoping to get my second callsign of VA7HTJ on the air over the coming weeks, and some testing for the upcoming CQWW SSB contest.