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Re: Ozy/Janus and Linrad
- Subject: Re: Ozy/Janus and Linrad
- From: Leif Asbrink <sm5bsz.com; leif@xxxxxxxxxxxxxxxx>
- Date: Sat, 1 Mar 2008 13:54:16 +0100
Hi John and All,
> No, that would not be the case ,, ozy/janus do not look like a pc
> sound card. I have been able to get hold of some early source that
> connects janus/ozy to the jack audio connection kit .. but I think I'd
> have to modify linrad to be a jack client in order for that to be
> useful. At this point I'm playing around with the ozyjack code plus
> dttsp and a java gui interface. Once that's all working properly
> perhaps I'll look at hooking linrad to it. I'm definitely not
> interested in windows solutions ..
Maybe jack will be OK for ozy/janus, but there is also ozy/mercury.
At the hpsdr site I can read:
"the Mercury board will enable direct sampling of the 0-65MHz
spectrum. Based on a Linear Technology LTC2208 130MSPS 16-bit
A/D converter  the board will contain it's own FPGA to undertake
Digital Down Conversion (DDC) to 250 kSPS or less for transfer
over the Atlas bus to the USB interface on the OZY board."
In case 250kHz is not an upper limit set by the hardware I will be
very interested in interfacing Linrad to the hpsdr for a bandwidth
of at least 1 MHz. New phenomena occur when the bandwidth becomes
sufficiently large. Some cathegories of spurs can be removed completely
with the noise blanker and static rain also. I have done both of these
things decades ago with analog circuitry at bandwidths of 5 MHz and
more, but then the system was sensitive to interference from any strong
signal within the large bandwidth. With Linrad such interference is
notched out and I expect interesting performance.
I think it will be necessary to connect Linrad directly to ozy,
at 1 MHz bandwidth, maybe 40 megabit per second I would guess
the CPU load by going through Jack would not be negligible.
Presumably a Linrad interface to ozy/mercury will work with Janus
I hope to be able to make Linrad run with the Perseus hardware
at 1 MHz. That will be under Windows only unfortunately.
Leif / SM5BSZ
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