----- Original Message ----- 
From: "Alberto I2PHD" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, October 10, 2005 6:37 PM
Subject: Re: [soft_radio] Re: SDRadio - what's next ?


> F6EHJ wrote:
>
>> Including all the hardware control (including DDS LO) imposes the LO (and
>> the DDS) and the associated circuits I suppose, which reduce dramatically
>> the opportunity to have its own hardware and exact duplication will be 
>> the
>> only way to succeed.
>
> I think that the proposal of Tom Holden is a very sensible one, and I 
> probably will write the
> hardware-controlling part of the program in two sections. The first will 
> call an external DLL
> using a published interface, not tied to the specific hardware used. The 
> DLL itself will then
> translate the requests into the specific commands needed for the hardware 
> on hand.
> In this way everybody who would like to use a different hardware could 
> rewrite just the DLL
> for his specific needs.
>
That sounds great. Leaving some flexibility will not stuck to a single 
hardware design.

>> Considering the transmit section a simple12 kHz  I/Q output would be fine
>> and enough. It could be generated with a secondary sound card to avoid
>> sophisticated switching, in this case a single RX/TX command will be 
>> needed.
>
> I don't know which sophisticated switching you are referring to, but if 
> you mean an output
> sampling speed during Tx time different from that used during Rx time, 
> switching the sampling
> speed of a sound card is quite easy, so a separate card in the PC is not 
> needed.

I was thinking about the SDR1000 which now use a full duplex audio card.

> If instead you mean switching the line-out of the card from the speakers 
> (while receiving),
> to the I/Q up-mixer (while transmitting), then a simple relay will do, 
> driven by the PTT
> signal, which the program could activate by using just a pin of the 
> parallel port.

That's fine.
>
> BTW, I have reports that say that some of my programs work correctly with 
> external USB sound
> cards, so this could be a solution for those who have obsolete chip sets 
> in their laptops
> (e.g. not capable of 96 kHz sampling).

Thanks a lot Alberto. I will follow the future development.

Best 73

Gérard/F6EHJ
>
> 73  Alberto  I2PHD
>
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> 




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