Must Be Art > Amateur Radio > SANDPAC > Logo
The following explanation of the San Diego Packet Radio Association logo was printed in the October 1986 issue of the SANDPAC Newsletter. It was written by the winner of the logo contest, Paul Williamson, KB5MU.
The figure above illustrates how the waveform in the SANDPAC logo is derived. I wanted the waveform to be reproducible, so only a few bits could be encoded. 16 seemed like about the right number of bits, so two ASCII characters would have to do. The obvious choice was "HI". After some experimentation, I chose lowercase characters for aesthetic reasons. So, consulting my handy ASCII chart, "hi" (F in the figure) translates to 6869 hex (E), or 0110100001101001 binary (D). This waveform is shown at C in the figure. I wanted to add a little twist, and work in the packet theme, so I decided to encode the data in NRZI ("non-return-to-zero inverted") format like we do on packet. In NRZI format, a zero is encoded as a transition. A one is encoded as a lack of a transition. The resulting waveform is shown at B, with the apparent binary representation shown at A. This is the waveform used in the SANDPAC logo.
Those of you with sharp eyes will notice that the waveform in the logo is missing the rightmost bit's worth of data. You can take your choice of the following explanations. (1) I chopped off the tail on purpose to make it look prettier. (2) I blew it and forgot that the tail was part of the encoded data. (3) I wanted it to look like 16 bits so nobody would think of decoding it as NRZI. (4) The waveform actually encodes a Satanic message, and this article is just a coverup. (5) My Art teacher once told me that you should always introduce one apparent mistake to see if anybody's paying attention. Hello? Hello? Darn it, they dozed off again. Guess he was wrong.