4 Jan
2014
4 Jan
'14
1:34 p.m.
Hi,
I have questions on usage of rtlsdr_read_sync(dev, buffer, out_block_size,
&n_read):
For example, if sampling rate is 1Msps, and out_block_size is 1000000,
question is:
1. the rtlsdr_read_sync() will cost 1s exactly? Or is there any lower level
device/driver buffer, which perhaps feed rtlsdr_read_sync() with history
data quickly and makes rtlsdr_read_sync() return in a time shorter than 1s?
2. in this infinite processing loop:
while(1)
{
rtlsdr_read_sync(dev, buffer, out_block_size, &n_read);
processing_function(buffer); // let's assume that this cost 0.001s
}
Those samples during the 0.001s processing period will be losted or not? Is
there any method to not lost them?
Thanks very much!
BR
Jiao Xianjun
On Thu, Jan 2, 2014 at 9:25 PM, Jiao Xianjun <putaoshu(a)gmail.com> wrote:
I see some UDP packet performance issues in my laptop
(but not in my
desktop computer). Will the common (interleave multiple receives) UDP link
helps?
The issue is that fread for the second dongle in matlab get less data than
expectation sometimes. Seem that fread for the first dongle works well.
------------------------------
From: Sdr Guru <sdrguru1(a)gmail.com>
Sent: 2014/1/2 5:39
To: osmocom-sdr(a)lists.osmocom.org
Subject: Re: How to get IQ samples from multiple rtl-sdr dongles in
asynchronized manner?
Hi
rtl-sdr-relay
Some of the recommendations.
Please add PPM error calculation, exactly like new rtl_test -p
but multiple receivers simultaneously.
It provides immediate information if something is wrong with USB or
dongles.
https://github.com/keenerd/rtl-sdr/commit/b5f89dcf40463130e717b6c9bb3a39a3c…
https://github.com/keenerd/rtl-sdr/blob/master/src/rtl_test.c
Please add automatic eeprom PPM calibration
https://github.com/keenerd/rtl-sdr/commit/ecf267737ca52f5005b7a12a352307e8c…
default sample rate 2.4M (28.8/12) or 1.2M (28.8/24), probably lower jitter
MAX_NUM_DEV 4->16 :)
Some nice to have features.
ip binding
multicast support
one common (interleaved) stream of all the receivers
timestamped stream
I'm trying to convert MATLAB script to Ocatve.
SG
On Mon, Dec 30, 2013 at 9:38 AM, Jiao Xianjun <putaoshu(a)gmail.com> wrote:
> Hi guys,
>
> For the multiple dongles synchronization in signal level instead of
> bits/packets level, I setup a working repo in github, and write a initial
> demo framework. See below:
>
> https://github.com/JiaoXianjun/multi-rtl-sdr-udp-relay.git
>
> You may find information and instruction of demo quickly by reading the
> README.
>
> My initial purpose is performing in-fly calibration for multiple dongles
> according to some pre-known signal (GSM, ADS-B?) to let them work together
> coherently.
>
> An ideal scheme may be that we should generate a very narrow band and
> very week signal in (or just located at the edge of) target working band of
> dongles, and perform the software in-fly calibration in background (or
> driver level). This would be user friendly.
>
> I know it is far from final state currently, and many things are not
> clear yet (See TODO). But please join me if you also think this is a good
> idea. Just check out the demo and run it to have a look.
>
> Currently I just test the demo in Ubuntu-Linux.
>
> BR
>
> Jiao Xianjun
>
>
4 Jan
4 Jan
7:02 p.m.
New subject: How to get IQ samples from multiple rtl-sdr dongles in asynchronized manner?
I've been monitoring this thread and am interested in the progress.
I'm a HAM and in the 2 meter FM band allocation we have APRS beaconing
that I think could be used for synchronization. It doesn't matter GPS
disciplined or anything, sync based on reception of an APRS packet and
then take into account known distance from the APRS digipeater... just
an idea.
73
-Ron / KB1UMH
On Sat, Jan 4, 2014 at 7:34 AM, Jiao Xianjun <putaoshu(a)gmail.com> wrote:
Hi,
I have questions on usage of rtlsdr_read_sync(dev, buffer, out_block_size,
&n_read):
For example, if sampling rate is 1Msps, and out_block_size is 1000000,
question is:
1. the rtlsdr_read_sync() will cost 1s exactly? Or is there any lower level
device/driver buffer, which perhaps feed rtlsdr_read_sync() with history
data quickly and makes rtlsdr_read_sync() return in a time shorter than 1s?
2. in this infinite processing loop:
while(1)
{
rtlsdr_read_sync(dev, buffer, out_block_size, &n_read);
processing_function(buffer); // let's assume that this cost 0.001s
}
Those samples during the 0.001s processing period will be losted or not? Is
there any method to not lost them?
Thanks very much!
BR
Jiao Xianjun
On Thu, Jan 2, 2014 at 9:25 PM, Jiao Xianjun <putaoshu(a)gmail.com> wrote:
I see some UDP packet performance issues in my laptop (but not in my
desktop computer). Will the common (interleave multiple receives) UDP link
helps?
The issue is that fread for the second dongle in matlab get less data than
expectation sometimes. Seem that fread for the first dongle works well.
________________________________
From: Sdr Guru
Sent: 2014/1/2 5:39
To: osmocom-sdr(a)lists.osmocom.org
Subject: Re: How to get IQ samples from multiple rtl-sdr dongles in
asynchronized manner?
Hi
rtl-sdr-relay
Some of the recommendations.
Please add PPM error calculation, exactly like new rtl_test -p but
multiple receivers simultaneously.
It provides immediate information if something is wrong with USB or
dongles.
https://github.com/keenerd/rtl-sdr/commit/b5f89dcf40463130e717b6c9bb3a39a3c…
https://github.com/keenerd/rtl-sdr/blob/master/src/rtl_test.c
Please add automatic eeprom PPM calibration
https://github.com/keenerd/rtl-sdr/commit/ecf267737ca52f5005b7a12a352307e8c…
default sample rate 2.4M (28.8/12) or 1.2M (28.8/24), probably lower
jitter
MAX_NUM_DEV 4->16 :)
Some nice to have features.
ip binding
multicast support
one common (interleaved) stream of all the receivers
timestamped stream
I'm trying to convert MATLAB script to Ocatve.
SG
On Mon, Dec 30, 2013 at 9:38 AM, Jiao Xianjun <putaoshu(a)gmail.com> wrote:
>
> Hi guys,
>
> For the multiple dongles synchronization in signal level instead of
> bits/packets level, I setup a working repo in github, and write a initial
> demo framework. See below:
>
> https://github.com/JiaoXianjun/multi-rtl-sdr-udp-relay.git
>
> You may find information and instruction of demo quickly by reading the
> README.
>
> My initial purpose is performing in-fly calibration for multiple dongles
> according to some pre-known signal (GSM, ADS-B?) to let them work together
> coherently.
>
> An ideal scheme may be that we should generate a very narrow band and
> very week signal in (or just located at the edge of) target working band of
> dongles, and perform the software in-fly calibration in background (or
> driver level). This would be user friendly.
>
> I know it is far from final state currently, and many things are not
> clear yet (See TODO). But please join me if you also think this is a good
> idea. Just check out the demo and run it to have a look.
>
> Currently I just test the demo in Ubuntu-Linux.
>
> BR
>
> Jiao Xianjun
>
>
6 Jan
6 Jan
10:34 a.m.
New subject: How to get IQ samples from multiple rtl-sdr dongles in asynchronized manner?
Hi,
Today I did some experiments using CW signal which is generated by signal
generator. The conclusion is a little bit sad.
sync read and UDP lose samples/data high probably:
1. If there are some other operations (which costs some time) between two
successive sync reads, some samples will be lost.
2. Some times, UDP packets are just lost.
So, seems that I have two choices:
1. struggle to use async read mode.
2. use rtl_tcp utility directly, which is offered with rtl-sdr code. This
program use async mode and TCP, which has avoided the two shortcomings I
addressed.
I will try the 2nd method, and try to move on with calibration.
BR
Jiao Xianjun
On Sat, Jan 4, 2014 at 8:34 PM, Jiao Xianjun <putaoshu(a)gmail.com> wrote:
Hi,
I have questions on usage of rtlsdr_read_sync(dev, buffer, out_block_size,
&n_read):
For example, if sampling rate is 1Msps, and out_block_size is 1000000,
question is:
1. the rtlsdr_read_sync() will cost 1s exactly? Or is there any lower
level device/driver buffer, which perhaps feed rtlsdr_read_sync() with
history data quickly and makes rtlsdr_read_sync() return in a time shorter
than 1s?
2. in this infinite processing loop:
while(1)
{
rtlsdr_read_sync(dev, buffer, out_block_size, &n_read);
processing_function(buffer); // let's assume that this cost 0.001s
}
Those samples during the 0.001s processing period will be losted or not?
Is there any method to not lost them?
Thanks very much!
BR
Jiao Xianjun
On Thu, Jan 2, 2014 at 9:25 PM, Jiao Xianjun <putaoshu(a)gmail.com> wrote:
I see some UDP packet performance issues in my
laptop (but not in my
desktop computer). Will the common (interleave multiple receives) UDP link
helps?
The issue is that fread for the second dongle in matlab get less data
than expectation sometimes. Seem that fread for the first dongle works well.
------------------------------
From: Sdr Guru <sdrguru1(a)gmail.com>
Sent: 2014/1/2 5:39
To: osmocom-sdr(a)lists.osmocom.org
Subject: Re: How to get IQ samples from multiple rtl-sdr dongles in
asynchronized manner?
Hi
rtl-sdr-relay
Some of the recommendations.
Please add PPM error calculation, exactly like new rtl_test -p
but multiple receivers simultaneously.
It provides immediate information if something is wrong with USB or
dongles.
https://github.com/keenerd/rtl-sdr/commit/b5f89dcf40463130e717b6c9bb3a39a3c…
https://github.com/keenerd/rtl-sdr/blob/master/src/rtl_test.c
Please add automatic eeprom PPM calibration
https://github.com/keenerd/rtl-sdr/commit/ecf267737ca52f5005b7a12a352307e8c…
default sample rate 2.4M (28.8/12) or 1.2M (28.8/24), probably lower
jitter
MAX_NUM_DEV 4->16 :)
Some nice to have features.
ip binding
multicast support
one common (interleaved) stream of all the receivers
timestamped stream
I'm trying to convert MATLAB script to Ocatve.
SG
On Mon, Dec 30, 2013 at 9:38 AM, Jiao Xianjun <putaoshu(a)gmail.com> wrote:
> Hi guys,
>
> For the multiple dongles synchronization in signal level instead of
> bits/packets level, I setup a working repo in github, and write a initial
> demo framework. See below:
>
> https://github.com/JiaoXianjun/multi-rtl-sdr-udp-relay.git
>
> You may find information and instruction of demo quickly by reading the
> README.
>
> My initial purpose is performing in-fly calibration for multiple dongles
> according to some pre-known signal (GSM, ADS-B?) to let them work together
> coherently.
>
> An ideal scheme may be that we should generate a very narrow band and
> very week signal in (or just located at the edge of) target working band of
> dongles, and perform the software in-fly calibration in background (or
> driver level). This would be user friendly.
>
> I know it is far from final state currently, and many things are not
> clear yet (See TODO). But please join me if you also think this is a good
> idea. Just check out the demo and run it to have a look.
>
> Currently I just test the demo in Ubuntu-Linux.
>
> BR
>
> Jiao Xianjun
>
>
9:21 p.m.
New subject: GNU RADIO ported to Android
Has anyone had success with GNU RADIO (or some other SDR) ported to Android,
and if they have please give me a place or link to start?
3770
days inactive
3772
days old
3 comments
3 participants
participants (3)
-
Jay Salsburg -
Jiao Xianjun -
Ron Senykoff