Re: LF: Throb -2- beacon 503.000

[Andy Talbot <andy.g4jnt@googlemail.com>]

VAC can cause timing problems inteh conversion of one sampling rate to another as it crosses the Virtual Audio backplane.

 

I use cheap 'headphone dongles'  to add additional soundcards for the SDR then cross-patch the audio leads as necessary.    That way timing issues due to poor sample rate conversion are removes, leaving just frequency innaccuracies which are hardly ever a problem.

 

The only downside is that many of the low cost units (£5 from Ebay, for example) only have a mono microphone input, meaning they can't be used with I/Q inputs from Softrockks or similar.   However, the headphone O/P is stereo, but you need to be aware that the headphone ground usually sits at a few volts positive so needs to be isolated to avoid damage.

 

I'vew used many of these modules, sometimes building them into equipment to give a simple USB audio interface, and having the USB's 5V supply to play with as well.

Andy
www.g4jnt.com

this email has been scanned for political correctness by the nanny state

2009/10/28 Horst Stöcker <horst.stoecker@web.de>

to Lubos (and anyone who may be interested):
Did you ever hear of a software named "virtual audio cable"? For example you can send your SDR-signal to the virtual Soundcard. From that you can decode THROB or what ever. So you do not need a second computer for decoding. The speed of the computer who has to mange both must be higher, of course.
Horst DO1KHS

> -----Ursprüngliche Nachricht-----
> Von: "Lubos OK2BVG" <bvgbob@hotmail.com>
> Gesendet: 27.10.09 22:51:54

> An: <rsgb_lf_group@blacksheep.org>
> Betreff: RE: LF: Throb -2- beacon 503.000

Hello Graham, LF!
> Sorry, but I use my computer together with SDR-IQ as a LF receiver

> and I havenŽt got the other PC for decoding THROB packets. But your

> signal is nice!
>
> Lubos, OK2BVG
>
> From: g8fzk@g8fzk.fsnet.co.uk

> To: rsgb_lf_group@blacksheep.org

> Date: Tue, 27 Oct 2009 21:34:27 +0000

> Subject: Re: LF: Throb -2- beacon 503.000
>

> Tnx Lubos
>
> Are you able to decode any of the signal ???
>
> I use > http://www.w1hkj.com/Fldigi.html
>
> Tnx - Graham ..
>
>  *From:*Lubos OK2BVG

>  *Sent:* Tuesday, October 27, 2009 9:05 PM

>  *To:*rsgb_lf_group@blacksheep.org
>  *Subject:* RE: LF: Throb -2- beacon 503.000
>

> Hello Graham, LF!
> I see your beaconŽs packets very well.

>
> 73!
>
> Lubos, OK2BVG, JN88KS
> From: g8fzk@g8fzk.fsnet.co.uk

> To: rsgb_lf_group@blacksheep.org

> Date: Tue, 27 Oct 2009 17:28:12 +0000

> Subject: LF: Throb -2- beacon 503.000
>
> Running THROB-2- Beacon 503.000 khz centre frequency
>
> TX set 502.000 USB
> Audio 1000 Hz cent frequency
>
> Repeat time 60 seconds
>
> RX 'ON' during cycle tx 'off' time
>
> Reports / observations
>
> Tnx Graham
>
> G0NBD - IO83LK
>

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