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Today's Topics:
1. Re: MIMO Sample misalignment (iftah giladi via USRP-users)
2. Running the X300 off 12V Input (Robert Palumbo via USRP-users)
3. Re: MIMO Sample misalignment (iftah giladi via USRP-users)
4. B200 Noise (Daniel Malafaia via USRP-users)
----------------------------------------------------------------------
Message: 1
Date: Wed, 28 May 2014 19:14:21 +0300
From: iftah giladi via USRP-users <[email protected]>
To: 'Marcus M?ller' <[email protected]>, "'iftah giladi via
USRP-users'" <[email protected]>,
<[email protected]>
Subject: Re: [USRP-users] MIMO Sample misalignment
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
I think I don?t quit understand what set_time_next_pps has to do with what I am
trying to do?
I am using the mimo cable, non of my usrp has GPSDO in them, they are in dual
eth mod, meaning host per usrp.
The sync is done via this procedure:
1. The slave program set's the time & clk to the mimo:
usrp -> set_time_source("mimo",0);
usrp -> set_clock_source("mimo",0);
and then is sets all the other channel parameter(freq,gain,etc)
2. The master program set's clock source to internal :
usrp -> set_clock_source(ref);
And then sets all the other channel parameter(freq,gain,etc)
3. Then the master program gets time from local machine and set the usrp
time to it:
tod = uhd::time_spec_t::get_system_time();
usrp->set_time_now(tod);
4. As I understand at that point both usrp has the same time and clk.
Then the master program sets a rx_stream
uhd::stream_args_t stream_args("sc16", wirefmt);
uhd::rx_streamer::sptr rx_stream = usrp->get_rx_stream(stream_args);
using this sequence of stream_cmd:
uhd::stream_cmd_t stream_cmd((total_num_samps == 0)?
uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS:
uhd::stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE
);
stream_cmd.num_samps = total_num_samps;
stream_cmd.stream_now = false;
stream_cmd.time_spec = uhd::time_spec_t(tod + seconds_in_future );
rx_stream->issue_stream_cmd(stream_cmd);
5. Mean time the slave program wait to receive a time file from the
master program with the stream_cmd.time_spec which is sent via TCP sockt to the
slave program
6. In the slave program the file is received and then a stream commend
sequence using it is done:
uhd::stream_args_t stream_args(cpu_format,wire_format);
uhd::rx_streamer::sptr rx_stream = usrp->get_rx_stream(stream_args);
uhd::stream_cmd_t stream_cmd((num_requested_samples == 0)?
uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS:
uhd::stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE
);
stream_cmd.num_samps = num_requested_samples;
stream_cmd.stream_now = false;
stream_cmd.time_spec = uhd::time_spec_t(full_sec + frac_sec); // in the
slave device this should be recived from the master host via lan
rx_stream->issue_stream_cmd(stream_cmd);
7. Then they both wait for the time = tod + seconds_in_future, and then they
both sample and create a file.
8. Later on I get this file to the same computer to process with MATLAB.
So I don?t get where is set_time_next_pps get's in and what is it for/what
does it do?
Maybe the phenomenon that I see in the samples is not a time misalignment, it's
phase misalignment, could that be the case? How can I tell between them?
Thanks,
iftah
From: Marcus M?ller [mailto:[email protected]]
Sent: Wednesday, May 28, 2014 9:53 AM
To: iftah giladi; iftah giladi via USRP-users; [email protected]
Subject: Re: [USRP-users] MIMO Sample misalignment
Hi iftah,
Have you tried explicitly setting the time using "set_time_next_pps"?
Greetings,
Marcus
On May 27, 2014 1:01:18 PM CEST, iftah giladi via USRP-users
<[email protected]> wrote:
Hello all usrp users,
I am using a 2 usrp N200, connected with MIMO cable, and configured as MIMO,
using:
usrp -> set_time_source("mimo",0);
usrp -> set_clock_source("mimo",0);
on the slave device.
I am using a strem_cmd.stream_now = false;
And
Stream_cmd.time_spec = start_time;
And rx_stream->issue_stream_cmd(stream_cmd);
In order to make shore that both usrp start sampling together at the same time
Furthermore I would expect the sample file from both usrp to be aligned, after
all they are using the mimo cable so there sampling clock is the same
One, isn?t so?
So I did a test, and connected both of them to the same antenna with a short
equal length cable, and run the code to sample a wifi ping in the lab.
And with MATLAB I was surprised to see the misalignment in the sample between
the 2 files?.(see attachment)
If this is the real case this system would not make a real mimo signal
processing as the channels are not synced in time and phase.
Would really appreciate to read your opinion of what is going on here.
What am I doing wrong?
Thanks head,
iftah
_____
USRP-users mailing list
[email protected]
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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Message: 2
Date: Thu, 29 May 2014 09:02:34 -0400
From: Robert Palumbo via USRP-users <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [USRP-users] Running the X300 off 12V Input
Message-ID:
<cakwzk9zegiqzbsyezl0nnqreojplgb_cwqoxqgcsqfrgw-5...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hey all,
I'm currently powering an X300 with 12V direct, rather than the power
adapter, and it's working well (as expected).
My legacy system I'm trying to use the X300 on currently runs off 13.2V.
What's the range of input voltage that the X300 can safely run at? Will it
work at 13V equally well?
I took a look at the schematic of the X300, and it looks like all of the
power supplies running off the 12V input rail would operate fine at 13V,
but I was curious if there's anything specifically designed for 12V that
wouldn't support any variation.
Thanks,
Rob
--
Robert A Palumbo
[email protected]
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Message: 3
Date: Thu, 29 May 2014 17:50:36 +0300
From: iftah giladi via USRP-users <[email protected]>
To: 'Marcus M?ller' <[email protected]>, "'iftah giladi via
USRP-users'" <[email protected]>,
<[email protected]>
Subject: Re: [USRP-users] MIMO Sample misalignment
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
I found the bug in my code.
Apparently if you want high precision in the start time parameter you shouldn?t
add int and double without the proper floating point precision routines.
Thanks for the help,
iftah
From: iftah giladi [mailto:[email protected]]
Sent: Wednesday, May 28, 2014 7:14 PM
To: 'Marcus M?ller'; 'iftah giladi via USRP-users'; '[email protected]'
Subject: RE: [USRP-users] MIMO Sample misalignment
I think I don?t quit understand what set_time_next_pps has to do with what I am
trying to do?
I am using the mimo cable, non of my usrp has GPSDO in them, they are in dual
eth mod, meaning host per usrp.
The sync is done via this procedure:
1. The slave program set's the time & clk to the mimo:
usrp -> set_time_source("mimo",0);
usrp -> set_clock_source("mimo",0);
and then is sets all the other channel parameter(freq,gain,etc)
2. The master program set's clock source to internal :
usrp -> set_clock_source(ref);
And then sets all the other channel parameter(freq,gain,etc)
3. Then the master program gets time from local machine and set the usrp
time to it:
tod = uhd::time_spec_t::get_system_time();
usrp->set_time_now(tod);
4. As I understand at that point both usrp has the same time and clk.
Then the master program sets a rx_stream
uhd::stream_args_t stream_args("sc16", wirefmt);
uhd::rx_streamer::sptr rx_stream = usrp->get_rx_stream(stream_args);
using this sequence of stream_cmd:
uhd::stream_cmd_t stream_cmd((total_num_samps == 0)?
uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS:
uhd::stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE
);
stream_cmd.num_samps = total_num_samps;
stream_cmd.stream_now = false;
stream_cmd.time_spec = uhd::time_spec_t(tod + seconds_in_future );
rx_stream->issue_stream_cmd(stream_cmd);
5. Mean time the slave program wait to receive a time file from the
master program with the stream_cmd.time_spec which is sent via TCP sockt to the
slave program
6. In the slave program the file is received and then a stream commend
sequence using it is done:
uhd::stream_args_t stream_args(cpu_format,wire_format);
uhd::rx_streamer::sptr rx_stream = usrp->get_rx_stream(stream_args);
uhd::stream_cmd_t stream_cmd((num_requested_samples == 0)?
uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS:
uhd::stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE
);
stream_cmd.num_samps = num_requested_samples;
stream_cmd.stream_now = false;
stream_cmd.time_spec = uhd::time_spec_t(full_sec + frac_sec); // in the
slave device this should be recived from the master host via lan
rx_stream->issue_stream_cmd(stream_cmd);
7. Then they both wait for the time = tod + seconds_in_future, and then they
both sample and create a file.
8. Later on I get this file to the same computer to process with MATLAB.
So I don?t get where is set_time_next_pps get's in and what is it for/what
does it do?
Maybe the phenomenon that I see in the samples is not a time misalignment, it's
phase misalignment, could that be the case? How can I tell between them?
Thanks,
iftah
From: Marcus M?ller [mailto:[email protected]]
Sent: Wednesday, May 28, 2014 9:53 AM
To: iftah giladi; iftah giladi via USRP-users; [email protected]
Subject: Re: [USRP-users] MIMO Sample misalignment
Hi iftah,
Have you tried explicitly setting the time using "set_time_next_pps"?
Greetings,
Marcus
On May 27, 2014 1:01:18 PM CEST, iftah giladi via USRP-users
<[email protected]> wrote:
Hello all usrp users,
I am using a 2 usrp N200, connected with MIMO cable, and configured as MIMO,
using:
usrp -> set_time_source("mimo",0);
usrp -> set_clock_source("mimo",0);
on the slave device.
I am using a strem_cmd.stream_now = false;
And
Stream_cmd.time_spec = start_time;
And rx_stream->issue_stream_cmd(stream_cmd);
In order to make shore that both usrp start sampling together at the same time
Furthermore I would expect the sample file from both usrp to be aligned, after
all they are using the mimo cable so there sampling clock is the same
One, isn?t so?
So I did a test, and connected both of them to the same antenna with a short
equal length cable, and run the code to sample a wifi ping in the lab.
And with MATLAB I was surprised to see the misalignment in the sample between
the 2 files?.(see attachment)
If this is the real case this system would not make a real mimo signal
processing as the channels are not synced in time and phase.
Would really appreciate to read your opinion of what is going on here.
What am I doing wrong?
Thanks head,
iftah
_____
USRP-users mailing list
[email protected]
http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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Message: 4
Date: Thu, 29 May 2014 16:16:07 +0100
From: Daniel Malafaia via USRP-users <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [USRP-users] B200 Noise
Message-ID:
<cadglneyz5kdasfehbe84fhq0nnbp1pefj7aabeihaqvx3cq...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Dear USRP users,
I'm having a lot of noise problems in the B200, they only appear
when there's a antenna connected even if it's connected to the input I'm
not using.
I'm working with UHD 003.007.001.
Best Regards,
Adrian.
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