Lorem Ipsum

I spent some time this week tracking down a bug in the firmware I wrote for the Steven's GHT. Most of the time was taken up with refamiliarizing myself with the code. If has been over a year since I last worked on this project. The GHT is a specialized satellite transmitter: GOES HDR Transmitter, where GOES is the US weather satellite system, and HDR means it is the new, advanced version. If you spell it all out GHT stands for "Geostationary Operational Environmental Satellite High Data Rate Transmitter". Geez, what a name. No wonder we call it the GHT.

Anyway, once I found my way back into the depths of the encoding algorithm, it wasn't too difficult to find and fix the bug. The bug hadn't shown up before because no one had tried to send any messages longer than 256 bytes. Most were under 100, but now there is a customer is Austria and he wants to send 600 byte messages. Durn Austrians anyway, always trying to make the machine perform up to it's advertised specs.

Now we need to verify that it is fixed and that means testing. The GHT has three canned test messages it can send: short, long, and extremely long. They are roughly 100, 200 and 500 characters long. The first two are pithy sayings, which are okay, though they were getting a little old. I tried once to come up with something different, but I drew a blank. I come across pithy sayings occasionally, but they never stick. I guess my mind just doesn't work like that.

The third test message is simply the ten digits followed by the alphabet in uppercase and lowercase repeated several times. Looking at this message on the screen it forms a nice orderly block. In one case this is very good. A quick glance at the received message will show you whether it was received intact or whether characters were dropped or garbled. However, in another case, this could have been bad. As the contents repeat after a fixed number of characters, if you have a buffering problem (like we had), and the buffer happens to have the same number of slots as the length of the repeating string, you might never know that you had a problem. The message still looks fine. This did not happen to us, and it would be a very odd situation, but it just illustrates the kind of traps that are waiting out there for the unwary.

Another kind of test message is "Lorem Ipsum". I had seen this stuff before, but I did not know there was a name for it. It is the Latin name of a Latin phrase that is often used for filler on a page where you need some text to make the page look good, or to see what the page is going to look like, but you don't want anybody actually paying any attention to what is written. As few people learn Latin, few people will attempt to read it. Problem with this kind of test message is that it is difficult to tell whether it came through intact, or not. If you use one particular phrase, you might, through osmosis, memorize it, and then be able to recognize it on sight, but that would take some time.

I have seen this stuff, or something similar, on pictures of fake newspaper pages. Someone wants to highlight an article by making it look like it was printed in a newspaper, so they show you a picture of the article in the middle of what appears to be a page of a newspaper. If you look at the text surrounding the article you will find it is gibberish. Quite startling, the first time I noticed it.

Update December 2016 replaced missing picture.