GPS 747ProS without buzzer

March 20, 2016

For many years I have been using a M-241 GPS data logger for photography. It is really well designed, compact, and has a useful display. But only -158dB of sensitivity and 32 channels. It was time to look for something better.

I settled for a Transystem 747ProS using a MTK-II chip. Well, the documentation is ridiculous, and the LEDs are not self intuitive. But at the end I found out the configuration which I need for constant rate GPS logging. Via software setup, I disabled the “smart” function of the car and of the smart modes. I think, I could as well have bought the 747Pro (without the “S”).

What is the easiest configuration for logging? Put the switch only on “smart mode”, because the car mode requires external poser (via usb) otherwise it goes into sleep. The relevant information is given by the yellow satellite LED, continuously ON means looking for a fix (not logging), blinking means it is working, meaning it has got a fix and is logging.

Next step was to totally disable the buzzer and make that yellow satellite LED a little bit less brighter. First thing, remove the battery and open the housing. I pushed an old credit card between the two shell parts of the housing, starting from the side which is away from the LEDs – the strongest clips are closer to the LEDs, as one can see in the photo below:


Next step is to have a close look at the PCB and find out where is the best location to mod it. Initially I wanted to add a switch to change between the original mode and the no buzz/weaker LED mode, but I had no small switch available, then I just went for the moded version. The photo below shows the PCB and indicates with the red arrow where to cut the track for the buzzer and the yellow LED’s 220 Ω resistor.


Here you can see the detail. The buzz part is easy, just cut the track. I replaced the 220 Ω resistor with an 1 kΩ resistor that I removed from some scrap I had at home. The resistor is really small, therefore make sure you know how to (de-) solder it, you can get some scrap PCBs and do some training first. 1k is a bit too weak for outdoors but perfect for indoors.


That’s it. Now just but the top of the switch back, close the housing, add the battery, and there it goes logging!

I still wish that Holux would make a new M-241 with a better GPS chipset though.


PDF in Kindle 3

October 12, 2011

Many people asking for this feature; while it is possible to use the native viewer, or convert the file via e-mail, the support for PDF in K3 is less than acceptable. The viewer from DuoKan is much better, it is a bit faster, has a better contrast, and it has a very easy and intuitive margin crop feature! I installed the english version from: Now I just need a K3-DX, cuz the small Kindle is still a bit small for some A4 native PDFs.

Wet market in Shanghai

October 1, 2011

Food plays an utmost important role for a Chinese. They seem to be cooking the whole day, starting in the early by going to the market for some very fresh ingredients for the next meal. The best source for vegetables, life sea-food, meat, noodles, and so on is the wet market. You can’t be far away from a wet market in shanghai, they are everywhere, keep the eyes open for some fried food vendors close to a small entrance, with lots of people going in and out.

Green vegetables in a wet-market in Shanghai.

Almost all “conventional” green vegetables are available there and much more, some are shown in the picture above, let’s list them in chinese. The chinese name links to wikipedia.

青菜 – pinying QīngCài (lit. green veg.) – is one of the most common chinese cabbages in Shanghai, is also called 上海白菜 (pinying ShàngHǎi BáiCài, lit. Shanghai white veg.). There is a big pile of those in the left corner of the picture. It is a different variety than the big chinese cabbage 大白菜 (pinying DàBáiCài) and also different from the 小白菜 (pinying XiǎoBáiCài).

韭菜 – pinying JiǔCài (lit. garlic veg.) – garlic chives. Are the long and thin leaves right below the 青菜. Although related it is not garlic nor chives.

生菜 – pinying ShengCài – is the common lettuce on the bottom left corner.
油麥菜; pinyin: yóumàicài) or shengcai (生菜/唐生菜)

莴笋 – pinying WōSŭn – is the long one, almost without leaves at the center bottom. It is also a form of letuce (Celtuce), where the stem is used in dishes, instead of the leafs.

米苋 – pinying MǐXiàn – Is a kind of amaranthus, see the partially red leafs on the right.

PICs on Linux with K149 K150

May 30, 2010

There is a big lack of documentation about how to use the Kitrus programmers on Linux.

Which software to use?
Currently I know two programs, one made in C and the other in Python. They do not work out of the box, because they are made for a specific protocol, which must be matched to the protocol of the K149 (K150) hardware.

pp 0.1 – P018
Tetsujin’s picpro 0.2 – P014

Both have some issues, which solutions I will try to collect here.

merge ps files

May 13, 2010

I spent several hours looking for a viable way to join ps (postscript) files. There are several scripts to Join, Merge, or Concatenate (which is all the same) ps files, but most are based on ghostscript, which actually interprets the file and outputs a new huge plain ps file.

Yet, psjoin does the job! And for PDFs, there is nothing better than Pdftk.

Here is a list of the scripts which simple don’t give the expected results: psmerge, epsmerge, gs, cat + fixps, …
Details on postscript can be found in wikidocs.

How to include GnuPlot scripts into Latex files

February 21, 2010

For some reason I could not find the answer in google, although I would expect to be a common problem.
There are 2 solutions, plus one failed try:

1) gnuplottex (link to ctan)

2) egplot (link to Uni-Heidelberg)
An example of embedded gnuplot script with egplot is given below:

%this makes gnuplot run all scripts in the folder, the command is triggered by dvips
\special{psfile="`gnuplot *.gp"}

   f(x) = 1/(1+ exp((x-1)/1))
   plot f(x)
  \caption{This is fig1}

The first run of latex will give an egp warning, which can be ignored. Just run dvips and latex again.
dvips will execute the gnuplot scripts generating the eps files. The second latex run will include the correct boundingbox from the, by then already existing, eps files.

3) Use DeclareGraphicsRule to create the EPS file on the fly
I tried different versions and also fixed the bounding box, but I get only an empty box in place of the figure.
dvips runs fine, and the EPS file is also generated, but for some reason it is not included in the final ps.

\DeclareGraphicsRule{.gp}{eps}{}{`gnuplot #1}
\DeclareGraphicsRule{.gp}{eps}{}{`gnuplot #1 |<test.eps}
\fbox{\includegraphics[bb=50 50 410 302]{./}}

I found an ugly workaround:

\special{psfile="`gnuplot *.gp"}

\begin{figure}[htp] \centering
\includegraphics[bb=50 50 410 302, scale=0.5]{./test.eps}

4) This is potentially another solution:
Dynamic creation of PostScript graphics files