[AMRadio] sdr-iq


Jay Bromley jayw5jay at cox.net
Wed Feb 10 19:19:20 EST 2010


HI Bernie,
John had a great idea and that makes sense that you could have a record loop 
or maybe you are using some sort of 3D imaging.  That sure kicked my 
backside for a  while helping a friend on his computer.  So look for 
software enhancements like that.

On the Perseus SDR the more sampling rate you use the more CPU is eat up. 
If I bump it up the sampling rate from 125 KS/s to 2000 KS/s while also 
putting the Span(KHz)to 6.3 while the RBW(Hz) is set to 7.6, that will get 
the CPU attention big time.  The CPU goes from a mild 7% to 32% in the above 
example.  However I rarely run it like that or need to even if I am looking 
at a signal in great detail.

Really my SDR sounds pretty impressive and I think in the long run I can 
make it even better.  Kinda of weird not to be spending many hours behind a 
soldering gun to make an old rig sound as good as this was does right out of 
the box.  Now if they could make the console look like it was glowing in the 
dark, now that would make me happy!  :-)

73 de w5jay/jay..

--------------------------------------------------
From: "Bernie Doran" <qedconsultants at embarqmail.com>
Sent: Wednesday, February 10, 2010 4:09 PM
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Subject: Re: [AMRadio] sdr-iq

> Hi Jay.
> I do have  mid to upper range sound card, the processor shows that it is
> running at about 65 to 80 %, so I assume that is ok.  I also notice the
> latency, about .5 sec and the noise floor does seem high, not a problem on
> 80 however. I am interested to see what it sounds like on 10.  the filter 
> is
> great as is the spectrum display, just the poor audio, and I am not one 
> opf
> the audio nuts, so it must be really bad.   I know the Flex takes a lot of
> computer, I could use a little better video card as the waterfall does 
> slow
> down on full screen.  just seems weird when I can watch a DVD with good
> audio.  Bernie----- Original Message ----- 
> From: "Jay Bromley" <jayw5jay at cox.net>
> To: "Discussion of AM Radio in the Amateur Service"
> <amradio at mailman.qth.net>
> Sent: Wednesday, February 10, 2010 4:00 PM
> Subject: Re: [AMRadio] sdr-iq
>
>
>> Hi Bernie,
>> I am running a Perseus SDR receiver with 2.5 GHz Asus quad core CPU and 8
>> MB
>> of ram.  The OS is Win 7 64 bit.  No echo here unless I am sync up to the
>> Icom receiver and trying to use them both at the same time.  There is a
>> little bit of latency with the SDR.  The sound is very good and the Sync
>> detector is the best I have used so far.  It's a little on the noisy side
>> with no signals.  A hint was given on the reflector to bump up the AGC
>> threshold and that seems help some.  Also a suggestion from Robert, 
>> W0VMC,
>> was to use a better sound card instead of the internal sound card that is
>> on
>> the motherboard.  The Perseus doesn't use the sound card for 
>> demodulation,
>> but for audio out.  In a way I wish the receiver had it's own line level
>> out
>> instead of using the computer's sound card.  A better sound card with 
>> more
>> ram should off load the CPU, but not sure that would help the latency
>> much?
>> I am mainly wanting to lower the noise floor even more if that is
>> possible.
>> The spectrum scope and waterfall are very useful.  I got another program
>> called HF span that makes it into a nice 40 MHz spectrum analyzer.
>> Overall
>> a very powerful box.
>>
>> 73 de w5jay/jay..
>>
>> --------------------------------------------------
>> From: "Bernie Doran" <qedconsultants at embarqmail.com>
>> Sent: Wednesday, February 10, 2010 12:02 PM
>> To: "Discussion of AM Radio in the Amateur Service"
>> <amradio at mailman.qth.net>
>> Subject: [AMRadio] sdr-iq
>>
>>> I purchased an SDR-iQ about five weeks ago and while it performs great 
>>> in
>>> a
>>> number of areas it seems to be poor in the audio demodulation, at least
>>> on
>>> AM,  I am getting what sounds like a low level echo and a general
>>> artificial
>>> quality of sound, my 75A2 sounds much better and that certainly is not
>>> good
>>> quality audio. it is difficult to copy a moderate level AM signal. the
>>> computer plays DVDs and CDs fine and sounds good. I talked to the store
>>> that
>>> I purchased it from and they said they have heard this before and that I
>>> should not expect it to sound like a VT receiver!!!!! that was a  shock,
>>> what did I buy it for?.  computer is a single core 2.8 gig, it shows it
>>> running at about %75. any one else use these things? or have experience
>>> with
>>> the Flex 5000a? Bernie
>>>
>>>
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>
>
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