[amsat-bb] Re: Decoding wideband recordings

Tom Azlin N4ZPT tom at n4zpt.org
Wed Aug 17 18:20:32 PDT 2011


Thanks Bruce.

I think I need to go get a preamp and filter!  And try again.

73, tom n4zpt

On 8/14/2011 12:06 PM, Bruce Robertson wrote:
> On Sat, Aug 13, 2011 at 7:07 PM, Phil Karn<karn at philkarn.net>  wrote:
>> On 8/10/11 8:24 PM, Tom Azlin N4ZPT wrote:
>>> I have a Fun Cube Dongle so I would Phil. Thanks and 73, Tom n4zpt
>>
>> Okay, everybody make and keep your wideband I/Q recordings and I'll work
>> on an enhancement to my demodulation/decoding software to process them.
>> It may not run in real time on slower machines because of the need to
>> search a wider frequency range, but this won't matter if it can work on
>> a recording.
>>
>> I can probably speed things up by including an orbit model in the modem
>> to predict Doppler open-loop, but this will take time to implement and
>> it will still be vulnerable to small errors in the elements and/or your
>> clock, especially around closest approach. So record the date and time
>> of your recordings and the current eleset at that time.
>
>
> For those who have not noted this feature, HDSDR will open a recording
> scheduler if you right click on the 'record' button. It saves files
> with UTC time appended. The tricky part is that you have to set the
> scheduler manually in local time.
>
> I've been thinking it would be a nifty hack to make a FCD recorder for
> a set of satellites using a very small computer, like the BeagleBoard.
> It seems to me that a daily cron job with 'Predict' would just about
> do what was necessary, especially now that we have a commandline tool
> for the FCD. The only part that would take some fiddling would be
> piping the USB sound card into a file with the proper headers for
> HDSDR.
>
> 73, Bruce VE9QRP
>
>



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