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[Discuss-gnuradio] Re: "Open-Hardware"

From: Patrick Strasser
Subject: [Discuss-gnuradio] Re: "Open-Hardware"
Date: Wed, 12 Jan 2011 02:15:43 +0100
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.6) Gecko/20050602 Thunderbird/1.0.2 Mnenhy/

schrieb Marcus D. Leech on 2011-01-12 01:44:
> Another thought I had earlier today is that with UAC2 (USB Audio Class
> version 2), there's no limit on the sample rate that a UAC2 device
>   can advertise, so it might be nice to make a USB-SDR device "appear"
> to be a UAC2 compliant device. [Well, OK that's not strictly
>   true, you can advertise up to something like 400Msps].
> Perhaps we can overload the control interface a bit (volume control
> becomes RF gain, use some other thingy in the control portion of
>   UAC2 for setting frequency).

You just ad a second interface that is HID, which is available on every
platform and easy to handle. That's how all the soundcard-like DDS do it.

The only problem is that Microsoft promised in 2005 to implement UAC2,
but "forgot" to do it until now. BTW they have a big mess with USB, as
Daniel Mack, Linux UAC2 author wrote: "Inevery cruel reincarnation of
their OS, it has different issues." I spare you the terrible details an
leave out the rest of his summary.

I read the UAC1 specs a year ago and thought "Great, you can advertise
up to 4MSPS on USB Audio!", but it turned out that it was specified for
USB 1.1, which just cannot handle the data rates. :-( Then I found the
SDR Widget, and they really get everything out of the Windows UAC1 driver.



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