Saturday, March 27, 2010

The "terminator" antenna line slingshot

I'm running a home made 80m dipole but out the front of the house I didn't have enough room. To run a line over the top of the tree is difficult, the highest I've got was by standing on a ladder with a squid pole.

The obvious answer is some sort of slingshot to fire a line on a sinker over the tree and then pull over a stronger cord. It worked out pretty well and after three shots I was happy with the height.

I need stronger fishing line, the stuff that came with the $12 reel is very stretchy, also the length could be longer as the reel gets in the way of the rubber band pull back.

It's amazing how many people drive and walk by when I'm attempting curious ham radio related activities out the front of the house, one guy kindly offered me a saw as he thought I wanted to remove a dangerous branch.

Tuesday, March 16, 2010

TomTom iPhone app update now includes computer voice

When the TomTom GPS navigator software was released for iPhone I didn't hesitate to buy it so that I could reduce the gadget count by one. It has been a little disappointing, not only the clunky user interface (compared to the high standards I expect from an iPhone app), the poor GPS reception (fixed now with the car kit and it's magic antenna), but mostly because it didn't come with "computer" voices.

Computer voices can pronounce the name of the street you need to turn at. This is really important as particularly in built up areas the GPS can get your position a bit wrong due to reflections.

I'm happy to report that the update released yesterday includes computer voices and the software now speaks road names. It made a right hash of Conemara Avenue, but then so do all the other GPSs I've tried.

This update has numerous improvements, including better integration with the rest of the iPhone. Great stuff.

Sunday, March 14, 2010

Visualizing WSPR Spots

WSPR provides a database of stations who can hear my beacon and stations I could hear, along with their distance and the signal to noise ratio. You can see this data for all users on a world map and as a database here.

I wanted to get a feeling for HF communications to and from my location so I ripped the data for the past 30 days of my activity on 40m. The main variation is the daily cycle as the "grey zone" moves around the world, so I've just plotted against time of the day using gnuplot. Here's the result:

(Click for a larger view).

My simplistic interpretation is that for optimum long distance communication on 40m, the best times are 7:30am - 8:30am and 5:30pm - 8:00pm. The astonishing thing is that 5W can go 17,000Km at all, (remember that half the circumference of the earth is about 20,000km), but that's another story.

Here's my gnuplot script:

set title "VK2TPM WSPR Spots 40m"
set xlabel "Hour of day (Local Time)"
set ylabel "Distance KM"
plot "40mwspr.csv" title "Spots" with points

The data isn't CSV, it's just time space km.

Tuesday, March 09, 2010

ABC2 has The Daily Show & Colbert Report

Screen shot 2010-03-09 at 7.36.17 PM.pngJust spun the FreeView dial here in Sydney and came across Jon Stewart's Daily Show.

I have considered paying for pay TV just to get this show, but the fact that you have to pay for compulsory sport puts me off that idea.

Having said all that, both programs seem heavily edited to remove content that someone assumes would not interest the international audience. I want the original shows please.

The Daily Show is on at 7:15pm followed by Colbert at 7:35. Now it's a classic episode of The Young Ones.

Screen shot 2010-03-09 at 8.31.17 PM.pngThe boys are bored and go to the pub where Madness are playing "house of fun", the boys say "do you know Summer Holiday by Cliff Richard.. the reply: you hum it, I'll punch you in the face".

ABC2 is a great channel, keep it up.

Monday, March 08, 2010

WSPR 2.0 build on Mac ports Snow Leopard 64bit

I've finally been able to build and run WSPR on Snow Leopard on top of the Mac Ports platform.

full wspr.png

At this stage it involved some manual modification of the ./configure generated Makefile.

The "show stoppers" for me were:

portaudio as built with mac ports exits on an assert about integer size. To overcome this I downloaded the latest trunk and built that.

Then used:

./configure \
--with-portaudio-include-dir=/usr/local/include \

Then during linking of wspr I got "/usr/bin/libtool: can't locate file for: -lfftw3f"

The fix for this was to change the Makefile to include /opt/local/lib as follows:

LDFLAGS = -L/opt/local/lib -L/usr/local/lib

I don't know much about mac ports but I'd love to get WSPR in there. Can anyone mentor me on that project?

Thanks to Ross, T61AA for assistance and prodding to get this far, and to John who helped him.

WSPR sure is popular these days:

busy wspr.png

And thanks to Joe Taylor K1JT for coming up with this amazing software.


Seems rock solid on the Mac. WSPR has been running day and night. Not many spots on 80m last night but 40m is looking really good tonight.

Screen shot 2010-03-09 at 7.52.46 PM.png

I'm learning about Macports but still haven't quite got to my objective.

Sunday, March 07, 2010

VK2ZNZ tries a Tecsun loop antenna

Neighbour Rob collects and restores valve radios. I recently suggested that a loop antenna might improve his reception and he picked one up at the Wyong field day.

In this video he shows how well it works. I also show some of his amazing collection as we chat after listening to the WIA Sunday broadcast on 80m.