[hpsdr] QSD gain and noise.

[Phil Harman]

Hi Phil.

Just use the sign bit from the NCO  and use this to generate a square wave. 
I think that Johan has this working already.

Phil...


----- Original Message ----- 
From: "Philip Covington" <p.covington at gmail.com>
To: "Johan Maas" <johan.maas at hetnet.nl>
Cc: <hpsdr at hpsdr.org>
Sent: Monday, September 24, 2007 9:18 PM
Subject: Re: [hpsdr] QSD gain and noise.


> ***** High Performance Software Defined Radio Discussion List *****
>
> On 9/24/07, Johan Maas <johan.maas at hetnet.nl> wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>>
>>
>>
>>
>> Hello All,
>>
>>
>> Together with Ramkrishnan(VU3RDD) iam working on design an ISD based
>> receiver by using 180 degree switches.
>>
>> The idea is to make use of an NCO implemented in the ozy FPGA and 
>> controlled
>> via powersdr (realized).
>>
>> In the attachment you will find a scheme which will be used for further
>> experiments (different configuration options can be set by jumpers). It
>> contains an balanced and unbalanced exit.
>>
>> But after reading some previuos mails i think we should an additional 
>> buffer
>> for low impedance output!
>>
>> Goodluck,
>>
>> 73 Johan PA3GSB
>
> Hello,
>
> You might want to consider replacing the fixed bias on the switches
> with an adjustable source.  Look at the TI BUF01900/1  - I2C
> programmable voltage source.
>
> Also for the diff amp take a look at the TI THS4520.
>
> I am a bit confused about the NCO in OZY.  Where is the DAC?
>
> 73 Phil N8VB
> _______________________________________________
> HPSDR Discussion List
> To post msg: hpsdr at hpsdr.org
> Subscription help: http://lists.hpsdr.org/listinfo.cgi/hpsdr-hpsdr.org
> HPSDR web page: http://hpsdr.org
> Archives: http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/
>
>
> -- 
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.488 / Virus Database: 269.13.30/1025 - Release Date: 
> 9/23/2007 1:53 PM
>
> 


 1190640221.0