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Today's Topics:
1. Re: scheduled transmission using tx_timed_samples.cpp (Josh Blum)
2. Re: LFRX antialiasing (Juul Hamstra)
3. USRP1 receive interface startup time (Almohanad Fayez)
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Message: 1
Date: Thu, 02 May 2013 12:14:07 -0500
From: Josh Blum <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] scheduled transmission using
tx_timed_samples.cpp
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
> Setting device timestamp to 0...
> Start time is 0 7.801e-05
> Sent packet: 363 samples
> Sent packet: 363 samples
> .....
> .....
> Sent packet: 363 samples
> Sent packet: 363 samples
> Sent packet: 199 samples
>
You will see the prints ASAP because the packets go out to the device
ASAP. This means sent to device, not necessarily transmitted.
> However, effect is observed on the following output
>
> Waiting for async burst ACK... success
> Done!
>
> End time is 5 0.00197141.
The time printed here after the ack is a little larger than 5 seconds,
so you can see that the USRP must have held off transmission until 5
seconds and then send the ACK for the end of burst.
-josh
------------------------------
Message: 2
Date: Fri, 03 May 2013 05:26:27 +0200
From: Juul Hamstra <[email protected]>
To: "Marcus D. Leech" <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [USRP-users] LFRX antialiasing
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
I'm using for my HAM experiments the SCR Preselector-CAT from HEROS
Technologies: http://www.herostechnology.co.uk/pages/products.html
Best Regards,
Juul Hamstra
Verstuurd vanaf mijn iPad
Op 1 mei 2013 om 21:24 heeft "Marcus D. Leech" <[email protected]> het volgende
geschreven:
> On 05/01/2013 03:11 PM, Jeff Scaparra wrote:
>> I built some band-pass filters for 40 meters as I had FM stations aliasing
>> into receive. That solved the problems but were a pain to build. If your
>> having the same issues I would try building/buying a filter to place inline
>> with the USRP.
> http://www.minicircuits.com/products/filters_coax_low.shtml
>
> Or, if your problems are *just* strong FM stations:
>
> http://www.mcmelectronics.com/product/33-341
>
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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Message: 3
Date: Fri, 3 May 2013 01:02:25 -0400
From: Almohanad Fayez <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [USRP-users] USRP1 receive interface startup time
Message-ID:
<cabv+bnu26gp6nfpcseqb_-snmopfqs5yv9ilz0_9ao6q9vr...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
I'm using a classic USRP with a WBX board and running two separate
flowgraphs receive DBPSK and transmit DBPSK using the USRP1. The
flowgraphs are based of the "dbpsk_loopback,grc" where I isolated the
transmit and receive into separate graphs.
I've been measuring the amount of time it takes to start the flowgraphs in
gnuradio and I was surprised to see that it takes the transmit flowgraph
around 6ms to start up while the receive flowgraph takes around 110ms.
Considering that complexity wise the flowgraphs are similar I expected
that the setup times would be close to each other, but I'm wondering if it
takes significantly longer to setup the USRP's receive interface versus the
transmit interface.
As a sanity check I measured the amount of time it takes to set up the
dbpsk_loopback.grc example and it takes around 6ms, similar to the transmit
flowgraph. Since the loopback flowgraph contains both the transmit and
receive side I expected it to take the longest.
Anyways the question in a nutshell, is the USRP receiver interface supposed
to take a long time to configure and that's why the DBPSK receiver takes
such a long time to start running?
I've ran around 200 iteration for setting each of these flowgraphs (so 600
iterations in total) and the results are consistent so I am inclined to say
yes.
--
Almohanad (Al) Fayez
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