Hi Albert,

OK, I had some other priorities the last couple of days, so .. with some 
delay.



On 15-04-13 03:48, Albert Cahalan wrote:
> Uh, shift the signal upward?
>> Increasing the frequency of the signal would also increase its
>> bandwidth, which is the opposite we want to do.
> Yeah... but depending on how bad the situation with
> hardware is, you might make that choice.
Well, you are free to give it a try if you want.

I would however propose that -at least for the preamble and the c2gmsk 
versionid signalling- you stick to the standard modulation sceme so that 
the modems that do not support this modulation sceme can -at least- 
identify the version of the stream.


The versionid information is a table of 16 codes. What you can do it 
either use the last one of the table (which is a code that can be used 
for "experimental modes") or create a new code for yourself. The only 
thing I would ask is that you make sure it has at least a distance of 8 
to all other codes in the default table.



The modem is open-source so feel free to create your version on top of 
it, as long as you also publish your code under an equivalent license.


> This wasn't what I was referring to though. I was referring to getting 
> your preamble cut off or having an unmodulated carrier because one 
> device (serial or audio) has high latency. You can also cut off the 
> other guy's preamble if you don't switch back to receiving fast enough.

Concidering the receiver lags the transmitter, by the time the receiver 
has played out its last audio-frame, the sender is already stopped 
transmitting for about a second ago and it already in "receive" mode.

So I don't think this is a real issue. :-)




> Running everything through the same type of hardware will even things 
> up, which is generally a large step in the right direction. 
Feel free to create and publish a one-in-all application if you think 
there is a need for it.

This is the open-source world. There is more then sufficient place for 
multiple applications or even multiple protocols. I do not think I hold 
the patent on being "the only and best modem" out there. Far from.

My only issue is that we have to make sure that there is a standardised 
way to identify the version of the stream so the receiving software can 
descide what to do with it; even if it does not support the format itself.

That's why the "versionid" code is there!




73
Kristoff - ON1ARF

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