[Discuss-gnuradio] Why does I channel have non-zero data for Q direct sampling mode

[Patrick Sathyanathan]

Hi All,


Not sure which forum to direct this question. I am using a Soft66Q device which 
is an rtl-sdr with Q branch direct sampling mod.



I observed the I and Q channels in direct sampling mode using the osmocom_fft 
program in scope mode run as follows:


osmocom_fft --args="rtl,direct_samp=2" -s 2.4M -f 1.2M -S


I expected the I channel to be 0 or a copy of the Q channel. But I see that 
they are different. Why is this so ? Does the gr-osmosdr driver convert the Q 
channel signal to complex I/Q ? And if so how ?


Thanks for any information,


--Patrick


From: Patrick Sathyanathan 
Sent: Thursday, June 1, 2017 6:41 PM
To: kazunori miura
Subject: Re: Fw: ORDER: RTL-SDR Soft66Q 3kHz to 1.7GHz RTL2832U with RF anp 4 
band filter R820T2, VLF


Thanks, Kazunori. The device works very well.


--Patrick


From: kazunori miura 
Sent: Thursday, June 1, 2017 5:40 PM
To: Patrick Sathyanathan
Subject: Re: Fw: ORDER: RTL-SDR Soft66Q 3kHz to 1.7GHz RTL2832U with RF anp 4 
band filter R820T2, VLF

yes, ant input has capacitor.HF and VHF each.

On 2017/06/02 9:36, Patrick Sathyanathan wrote:
> Hi,
>
>
> I want to connect a signal source with a dc bias to the input of
> soft66q. Does the input has dc blocking capacitor ? Or should I provide
> one externally.
>
>
> Thanks,
>
>
> --Patrick
>
>
>
> 
> *From:* eBay 
> *Sent:* Saturday, September 24, 2016 2:19 AM
> *To:* wp...@hotmail.com
> *Subject:* ORDER: RTL-SDR Soft66Q 3kHz to 1.7GHz RTL2832U with RF anp 4
> band filter R820T2, VLF
>
> Confirmed. ETA: Mon. Oct. 24 - Wed. Nov. 9. eBay will update the
> estimate when it ships to 15861 Northup Way.
>
> eBay
> 
>
>
>
>   Hi Patrick - Order confirmed. eBay will update you when your order
>   ships to 15861 Northup Way
>
> PAID : $52.00 with PayPal
>
> View order details
> 
>
>
> RTL-SDR Soft66Q 3kHz to 1.7GHz RTL2832U with RF anp 4 band filter
> R820T2, VLF...
> 
>
>
>
> RTL-SDR Soft66Q 3kHz to 1.7GHz RTL2832U with RF anp 4 band filter
> R820T2, VLF
> 
> 
>
>
> Estimated delivery: Mon. Oct. 24 - Wed. Nov. 9
>
> Item Id: 201660671703
> Transaction Id 1428115037010
> Quantity: 1
>
>
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[Discuss-gnuradio] Are pmt Message Handled Differently In Hier Blocks

[Sean Horton]

I have a series of tests to test two blocks, where one block
encodes/modulates a message, and the other demodulates/decodes the message.
Since there are several parts of the hier block, to test it I have a series
of tests that do something like this:

A -> ~A
A -> B -> ~B -> ~A
etc (there's ~6 blocks to encode and ~6 blocks to decode)

This allows me to build up the hier blocks piece by piece, and at each step
make sure the decoding block can decode what is encoded. I then have a test
for the hier blocks themselves, which do nothing more than create and
connect all of the blocks that I've already tested, just not inside a hier
block. All of the tests before the test using the hier blocks pass. I've
run the tests 3000 times in a row. But one of my hier blocks doesn't work,
and after hours of debugging, it seems that a message from one of the
blocks isn't propagated to the next block. I added code to print when
message are published and handled, and there's a publish print statement
without a corresponding handled print statement. I've added a message
probe, and it gets the message. This block has worked, but I've changed my
test to only send one message instead of repeating the same message and
expecting to get it at least once.

Thanks,
Sean

-- 
Sean Horton
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[Discuss-gnuradio] 2018 IEEE Aerospace Conference

[Eugene Grayver]

Hello,

I am chairing the Software Defined and Cognitive Radio session at the upcoming 
IEEE Aerospace Conference (http://www.aeroconf.org).  
This large conference will take place March 4-11, 2018 in Big Sky, Montana.  
The conference is held at a ski resort and provides excellent opportunities for 
both networking and recreation (in addition to a world-class technical 
program).   This is one of the few conferences where SDR can be put in the 
context of a complete system and can be applied to new missions and concepts of 
operations.

Abstracts are due shortly, but I can take them a bit later as well, while the 
full paper is due end of October.  This session will focus on flexible radio 
architectures, including the use of DSPs and FPGAs.  Reports of existing 
systems and testbeds are of significant interest.  I am also very interested in 
programmable and flexible RF and analog architectures.

I have either met you at a conference in the past, or have referred to one of 
your works. I look forward to seeing many of you in Montana.

Please forward this to your colleagues working in the areas of SDR and 
cognitive radio.

Thanks,

Eugene.


___
Eugene Grayver, Ph.D.
Aerospace Corp., Sr. Eng. Spec.
Tel: 310.336.1274


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