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Today's Topics:
1. UHD buffer and libusb buffer, socket buffer and mmapped ring
buffer relations. (Nguyen Truong)
2. Re: UHD buffer and libusb buffer, socket buffer and mmapped
ring buffer relations. (Josh Blum)
3. Tuning latency of DBSRX2 for frequency hopping (Birhane Alemayoh)
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Message: 1
Date: Mon, 9 Jul 2012 04:57:57 +0900
From: Nguyen Truong <[email protected]>
To: [email protected]
Subject: [USRP-users] UHD buffer and libusb buffer, socket buffer and
mmapped ring buffer relations.
Message-ID:
<caopsyjtxt0yhun5818k7cnwgdovw+tz0lqjkulxw+jbptyu...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Dears all,
I would like to ask about the relations between UHD buffer and USB buffer
(USRP1 and USRP B100), Ethernet buffer (on USRP2 and USRP N series) and
memory-map ring buffers (USRP E series).
And another question is: does number of samples per packet play any role in
these buffers?
Thank you very much for your answers.
Sincerely,
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Message: 2
Date: Sun, 08 Jul 2012 22:32:13 -0700
From: Josh Blum <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] UHD buffer and libusb buffer, socket buffer
and mmapped ring buffer relations.
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
On 07/08/2012 12:57 PM, Nguyen Truong wrote:
> Dears all,
>
> I would like to ask about the relations between UHD buffer and USB buffer
> (USRP1 and USRP B100), Ethernet buffer (on USRP2 and USRP N series) and
> memory-map ring buffers (USRP E series).
>
I think you will find helpful information here:
http://files.ettus.com/uhd_docs/manual/html/transport.html
> And another question is: does number of samples per packet play any role in
> these buffers?
>
Yes. Therefore, if you want to increase the samples per packet, you will
need to increase the buffer size. Typically this is done to reduce
header overhead.
If you want to decrease samples per packet. Typically to reduce latency
at low samples rates. TX control is already there, you just send smaller
packets. For RX, set the spp parameter, documented here:
http://files.ettus.com/uhd_docs/doxygen/html/structuhd_1_1stream__args__t.html#a4463f2eec2cc7ee70f84baacbb26e1ef
-josh
------------------------------
Message: 3
Date: Mon, 9 Jul 2012 15:40:20 +0300
From: Birhane Alemayoh <[email protected]>
To: [email protected]
Subject: [USRP-users] Tuning latency of DBSRX2 for frequency hopping
Message-ID:
<capf4moz8p6mtbn_ggq2j6nv9rhfho1hnsnjgqn2_dctpifr...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
dear All,
I want implement the frequency hopping in GSM on real time bases using N200
and DBSRX2 doughterboard. That means I want write an application that
follows the hopping and capture the signal accordingly from the host PC.
However, I need to know the tuning latency of the DBSRX2 doughterboard if
this is possible. The dwell time of GSM signal is 4.615 msec.
I could n't get any document that tells the tuning latency of the DBSRX2
doughterboard.
So could you please tell me the tuning latency of DBSRX2?
Can I achieve my requirement using DBRSRX2 doughterboard plus considering
the OS scheduling, IP-stack, Ethernet transit, USRP command processing
issues too.
Thank you
Birhane
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