[hpsdr] New kid on the block --> TransFox SDR

[Glenn Thomas]

My thoughts exactly. The block diagram is similar (though not identical) 
to the FlexRadio SDR in that it uses an analog superhet front end and an 
SDR I/F system rather than the direct-to-digital approach of HPSDR. I do 
like the very wide operational bandwidth of the TransFox though...

73 de Glenn wb6w


On 10/8/2010 11:40 AM, Curt, WE7U wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> On Fri, 8 Oct 2010, Phil Harman wrote:
>
>> Re the TransFox, my concern would be trying to maintain an acceptable
>> image rejection over such a wide frequency range. Whilst 70dB may be
>> acceptable on the HF bands, since images may be hidden under the general
>> band noise, at VHF and UHF this will not be the case.
>
> Looking at the block diagram I see what I think are two PLL's, one
> labeled "Wide band loop" and one labeled "Auxiliary loop", created
> in the left box with an ASIC and other components external to the
> ASIC.
>
> In the right box, I & Q signals are combined with the "Auxiliary
> loop" output, run through a 1 GHz IF filter, then mixed together in
> a high-level mixer with the "Wide band loop" output. From there it
> goes through RX/TX switches to switch between PA's and LNA's, then
> to RF bandpass filters.
>
> The whole thing looks more like a two-PLL-loop HF rig, but with an
> extremely wide IF designed for I/Q signals, rather than something
> like an HPSDR that processes the RF directly. I admit I'm not
> trained in RF so my understanding may be incomplete (Digital EE &
> S/W spoken here).
>
> Comments from the experts?
>

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