Monday, October 06, 2014

50 Mhz dipole made of reed.

On 50 MHz I never heard anything using a G5RV antenna so I decided to make a dedicated antenna for this HAM band. The band runs from 50 to 52 MHz. So the antenna tunes to 51 MHz.


50 Mhz dipole made of reed.
As a mast I used a plastic pole. For the horizontal part I used reed that grows in my garden.
After I picked the reed I dried it for several years in my shed and now its hard as steel and its still flexible. Ideal antenna material.
Duck-tape fits everything together.
RG-58U coax with two insulated wires hang from the reeds where duck-tape keeps them placed.
I noticed the SSB DX is found between 50.100 and 50.200 MHz. 

Thursday, February 13, 2014

How to concat in Cognos report studio, blank / null problem Oracle


In certain reports, either data contains null values or the results of a complex query can return null values.
When performing a calculation, null values will cause the calculation to return a null value.
When concatenating names consisting of  surname, prefix and initials if one of the 3 is missing the result is a complete blank.

In most cases this may not be the desired result.

Only Oracle databases have this problem, other databases work fine.
IBM states its Oracles fault because Oracle does not do standard SQL.

One of the solutions is to change the data-items you want to concatenate so that a value is returned if the field is a blank. Here is an example:

[DATABASE].[EMPLOYEE].[PREFIX]


Change the above data-item into:
if
( [DATABASE].[EMPLOYEE].[PREFIX] is  NULL)
then
(  '  ' )
else
( [DATABASE].[EMPLOYEE].[PREFIX] )

Or change the above data-item into:
coalesce (  [DATABASE].[EMPLOYEE].[PREFIX] ; '  ' )



Do this with all the fields that may contain any blanks or null values in the whole Oracle database.
After this is done it is finally possible to concatenate the several database-fields in Oracle even if one field is NULL or blank.

Thursday, January 16, 2014

GMC-320 Geiger counter online with Ubuntu

Recently I bought a Geiger Muller counter from GQ electronics and connected it to my Ubuntu 12.04 and Ubuntu 13.10 laptop with the supplied USB cable.
GMC-320: A,B and Gamma radiation detector with on-board logging and viewing of data capabilities, a 'clicking' sound and USB connector.
With the terminal command dmesg I saw that the device was recognized correctly.

I would love to see graphics of the log and remote view the data via the internet but the provided software only runs on an expensive disk operating system called "Microsoft Windows".

But luckily there is a free Linux alternative. This will work on any Linux machine but the instructions below are tested on Ubuntu. Following the instructions below will result in a nice dot on a map and access to all kind of log graphics.
PC1MH background radiation
I went to www.radmon.org and downloaded pyradmon.py.

Register at: http://radmon.org/index.php/register

Download, unzip and save pyradmon.py to your home folder. Make the file executable, add your username to the group dialout and reboot.

Run in terminal: 
sudo chmod +x pyradmon.py
sudo apt-get install python-serial
sudo adduser yourusername dialout
sudo reboot


(Sure it can be done other ways but a reboot is the most simple and I like simple.)

Log back in and open a terminal.

Run pyradmon:

sudo python -u pyradmon.py

The pyradmon script will generate a configuration file in the same directory for you and stops.

Now edit the configuration file.(config.txt)

Fill in your username and password. (Same as the one registered at the site.)
Usually the serial port will be /dev/ttyUSB0 unless you have other devices connected.
Set the baud rate suitable for your counter, e.g. 2400 for MyGeiger.
Set the protocol to gmc. Save the file.

Run pyradmon.py in terminal:
sudo python -u pyradmon.py
To run python as a separate process use:
sudo nohup python -u pyradmon.py &


Now this is all fine until you plug out the usb cable of the Geiger counter and plug it back in. It can become another USB port and the config.txt will be wrong.

You need to create a new UDEV rule to make sure the config.txt always points to the correct port.

udevadm info -a -p $(udevadm info -q path -n /dev/ttyUSB0)

Go to /etc/udev/rules.d and create a file named "geiger.rules"

Edit the file and put the following line in it.

SUBSYSTEM=="tty", ATTRS{idVendor}=="067b", ATTRS{product}=="USB-Serial Controller", ATTRS{idProduct}=="2303", SYMLINK+="geiger"

After reboot a device called @geiger will be created in /dev
Edit the pyradmon config.txt and set the serial port to /dev/geiger


For more information about monitoring radiation with your Geiger counter go to: www.radmon.org 

Tuesday, January 14, 2014

Cognos Report Studio: How to add one title to one list.

How to add one title per list. If there are two lists in one page body the titles should appear only at the top of the list it belongs to and not at the top of any other list or page.




Under menu item View select Page Structure.
Select the list you want to add a title to. Go to properties and on Column Titles Properties change it to "At Start of Details".

 
  Add List Header to the List from menu item Structure > Header and Footers.