[hpsdr] multiple receivers - is it really nesesary

[alex]

as said in other message just sent, i am talking about multiple rx's in 
one merc, not about diverisity rx etc.

any cw am or fm decoding wouldn't require phase info so wouldn't need 
what i described as "demodable" signals, only ssb or phase related signals


> Alex,
>
> If you  just want to look at what signals are on a particular band 
> without the ability to actually demodulate all (say 7 or 8) of them 
> then you are correct.  All you need to do is to hop the CORDIC  to 
> each band of interest, send a block of samples to the PC, do an FFT 
> and then display the result then hop to the next band and repeat the 
> process.
>
> In fact that is where my SDR journey started, I did this in hardware 
> with a DDS LO and a 45MHz first IF, the PC code was in VB.  I could 
> see 6 bands in 'real time' and spot any openings as they occurred.
>
> The problem was I had to sweep the LO to cover each band, and needed a 
> narrow IF filter to see weak signals so need to slow the sweep rate 
> right down.
>
> So much easier to do this in software and much better performance.
>
> With Mercury we can see 192kHz and demodulate any signal in that 
> bandwidth whilst looking at 0-55MHz of spectrum. Soon we will be able 
> to select what frequency/bandwidth you want to look at on the wide 
> bandscope and after that we will add multiple receivers just as Alex 
> VE3NEA has done.
>
> The limitation of this with one Mercury board is  that your antenna 
> must cover all the bands you want to view or you need some form of 
> combiner.
>
> If you are a contester I can imagine being able to run 7 or 8 copies 
> of CW skimmer so you can see all signals on all the ham bands at once 
> may give you a slight edge....
>
> We also intend to support multiple Mercury boards on the Atlas bus all 
> phase locked to the same clock.  That will give you the potential for 
> diversity reception or take the output of your Four Square into four 
> Mercury boards etc....
>
> As to why you would want to do that....well in my case it gives me 
> plenty to think about when I'm wide awake at 2am :)
>
> 73's Phil....VK6APH
>
>
> ----- Original Message ----- From: "alex" <ajbr at btconnect.com>
> To: <hpsdr at openhpsdr.org>
> Sent: Saturday, August 01, 2009 10:30 PM
> Subject: [hpsdr] multiple receivers - is it really nesesary
>
>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> on the hpsdr website there was talk of having multiple receivers on a
>> single mercury, on the qs1r site it talks about how it is possible to
>> fit 7 independent rx into the fpga.
>>
>> what is the point, if you want to have multiple bandscopes (like w3sz's
>> mac setup) then why go to all the trouble of having demod-able signals
>> just for the bandscope, by tuning the lo and simply recording the
>> amplitude of the if then you get the frequency info without having to
>> worry about doing an fft,
>>
>> infact this could drasticaly reduce the computing power needed for
>> normal rx by having the demod and fft seperate.
>>
>> (i hope that makes some sembelence of sense)
>> _______________________________________________
>> HPSDR Discussion List
>> To post msg: hpsdr at openhpsdr.org
>> Subscription help: 
>> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org
>> HPSDR web page: http://openhpsdr.org
>> Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/
>>
>
>
> -------------------------------------------------------------------------------- 
>
>
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.5.392 / Virus Database: 270.13.40/2276 - Release Date: 
> 08/01/09 18:04:00
>


 1249230299.0