[RTTY] Digital Operators Band Plan Committee - Current thoughts and status

[Kok Chen]

On Apr 5, 2014, at 9:03 AM, Peter Laws wrote:

> You're confusing two things here, software development and
> communications protocols.

I agree with Peter.

Personally, I prefer proper engineering documentation of the protocol than just be given open sourced code.

Open sourcing allows you to copy the code at will (up to the restrictions of the Copyright), but the salient properties of the protocol is often obscured.  This makes it harder to improve on the demodulator, or produce cleaner transmissions.

As example, on one hand I can give you MMTTY code to implement RTTY.  On the other hand, I can define Amateur RTTY as "45.45 baud Frequency Shift Keying, with 170 Hz shift, and encoded with 5-bit ITA2 ("Baudot") start-stop code, using 1, 1.5 or 2 stop bits."    And include a supplement that defines options such as how USOS works.

It is much harder to improve demodulator for the first case than for the second case.

This is even more true for advanced modes.  If I were to give you a page of code that implements Viterbi decoding of a convolution code, the actual meaning is lost, compared to the case where I document the actual equations that defines the convolution code that is used.  You can then go off and implement it by using the Viterbi algorithm, or with a syndrome decoder, or whatever else you like.

Many of you own an ST-8000 and has its Technical manual.  Go look through the schematics and try to decide how the ST-8000 handles multi-path, and you see a bunch of XOR gates.  However, the engineering description makes it clear how the circuit corrects multi-path.  Source code is akin to schematics.

So, it depends on your goal.  If it is just to let someone else duplicate your code (e.g., to let someone else decode your Pactor 4 transmissions), then open sourced code is fine.  However, if you want to allow someone else to improve upon what you have done (e.g., to make Pactor 4 operate at a lower SNR), then I myself prefer good engineering (or Patent) documentation.

73
Chen, W7AY