Better modulation for the Baofeng UV-5RA

Sunday 2015-05-10

baofeng-uv-5ra-plusUndoubtedly the Baofeng UV-5Rx delivers a lot of radio for your buck. However some models in the range have a bad reputation for the transmitted audio sounding soft and muffled.

In 2013, Remco PA3FYM obtained the schematics of the radio and devised a modification where transistor Q17 of the VOX is re-purposed as preamplifier in the microphone audio circuit. It works wonders for your radio. For people needing a bit more visual guidance, below is a walktrough of how I did this to my Baofeng UV-5RA.

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Import/export an Oracle Schema using JDBC

Friday 2015-01-02

Everybody gets a database!When doing integration testing or fixing a bug in a piece of Java code that uses Oracle as a database, being able to do quick exports and imports of your schema can be a big help. Sometimes just calling Oracle’s imp/exp commandline tools from your code can be of help, but I was looking for something a bit more portable and less demanding on my local development machine. I found that Oracle’s datapump functionality can be called from stored procedures, which in turn can be called from a normal JDBC statement.

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Arduino and the QVGA 2.2″ TFT SPI screen

Monday 2014-11-17

QVGA SPI 2.2" 320x240 screenI went through all the struggles everybody else seems to be going through to get this screen connected to my Arduino Nano. I had the 5V to 3.3V voltage conversion problem, and the “only works with software interrupts” problem which makes the display run slow. The solutions are not complicated but not very wel documented. Until now.

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IARU Region 1 Bandplan up to 500MHz

Sunday 2014-11-02

For some reason I have trouble finding a document which lists the complete IARU Region 1 Band Plans. To end my “can I transmit here” quests, I’ve combined the information from several resources into a usable graphical representation of all Amateur Radio bands and modes up to 500MHz. I’ve not listed bands above 500MHz, please post links to those in the comments if you have them.

Exact use of a frequency may differ in your local region, so always listen first.

IARU Region 1, Up to 500MHz


Hand me a napkin

Saturday 2014-08-16

wheelchair jokeIt’s not until you or someone very close to you becomes dependant on a wheelchair until you notice that the world is not as wheelchair friendly as you might think. Hotel rooms are wheelchair accessable, but the lobby can only be reached by stairs. People with kids can take strollers all the way up to the airplane seat, but people in wheelchairs need to magically heal themselves and leave the wheelchair at the gate.

But this is not a rant about inconsiderate travel company employees. This is about helping people with “a challenge”, as our funny American neighbours tend to call it. And no, this is also not a rant about helping in a big way, raising a million for a cause, getting all the local supermarkets to give away groceries to people in wheelchairs, or TV shows selling tear-jerking advertisement minutes while building a house for a familiy who really needs it.

No, this is about the little things. Things that make you and me different. Things that require only a little twitch of a muscle for healthy people. Quirky things like aligning the napkin to the edge of the table, or petting a cat, or getting a different color straw because it doesn’t match the color of your shirt.

Imagine you had to ask somebody to align your napkin to the edge of the table. That person would find you demanding, and because he doesn’t see what’s solved by doing that, it’s very likely that the napkin will never move. Soon, you will stop asking people to do the little things that used to make you who you were.

It’s a tough choice. Loose friends because they think you’re too much of a demanding prinsess, or loose friends because you stop being you.

When you see or know somebody in a wheelchair, remember that their mind still wants to do those quirky things that make them who they are. It’s okay to say no, but please consider this little blogpost when somebody asks you to straighten their bracelet or clean their glasses.

The world does not need one-time big-mouthed Facebook-selfie heroes. The world needs polite people who can discretely hand over a napkin without asking what’s it for.


Print posters on a regular printer with Excel.

Thursday 2014-05-15

TS-50-RX-TX-board-banner

I recently needed to print out a big schematic diagram of the RX/TX board of a Kenwood TS50 Transceiver. This did not fit on a single piece of paper. Instead of downloading all kinds of crappy tools or uploading the image to some “free” site which is going to use it for whatever they think justifies their definition of “free”, I found out you can do this in Excel. Here’s how:

  1. Make sure the image you want to print out as a poster has a decent resolution
  2. Open Excel (maybe this will work in LibreOffice too, I haven’t tested, let me know)
  3. Drag the image into a new worksheet so that it is top-left of the sheet.
  4. Open the “Print preview” (the little icon in the bottom left of the window)
  5. Resize the image so that it covers more than one page, up to the number of pages you’d like the poster to be. Your screen should now look somewhat like this:
    Screen Shot 2014-05-15 at 21.58.23
  6. Optional: Adjust the page margins.
  7. Print.

After this, you’ll be gluing the pages together, but I think you already figured that out beforehand.

Have fun!

 


Open a port in OSX Mavericks’ Firewall

Saturday 2014-05-10

FirewallThe new firewall in Mavericks is great. For the common user. For a developer, not so much. If you are a Java developer like me, and you just need to open one port (say, 8080) so that the web application you’re working on is accessable from another computer, you can’t. I disabled the Firewall altogether for a few days, but it didn’t feel right.

I googled around and to make a long story short, here’s how to open port 8080 on any interface to any application on your OSX Mavericks installation in 3 steps:

sudo vim /etc/pf.conf

Then add the following lines at the end of the file:

# Open port 8080 for TCP on all interfaces
pass in proto tcp from any to any port 8080

Test (and, according to the documentation, load) your edits with:

sudo pfctl -vnf /etc/pf.conf

Reboot.

(I have found at least 5 pieces of voodoo to make the Firewall restart and reload, but none of them seemed to work reliably, so pardon the reboot)

You can close it by commenting out the lines in pf.conf and reboot again. If anybody knows of an easier way to do this, preferably in one terminal command, and without rebooting, let me know.

Hope this helps.


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