Re: [Discuss-gnuradio] E100 Performance
Am 29.06.2011 16:34, schrieb Marcus D. Leech:
On 29/06/2011 9:11 AM, Ralf wrote:
Hi,
the simple GRC in the attachment creates lots of underflows on our
E100 ("U" on console)
and dropouts when looking at the spectrum.
Is this as expected or how can this overload of the embedded Linux be
avoided?
Thanks,
Ralf
Well, for one, 60Khz isn't a proper divisor of the 128MHz sample rate
of the DAC, which means it can't be properly interpolated.
The minimum sample rate that you can deliver to the USRP-E100 is
128MHz/512 = 250kHz, so you'll have to interpolate your
data stream up to 250kHz prior to "presentation" to the UHD sink block.
Hi Marcus, thanks for your reply.
That is very important for us to understand. How is the divider 512
determined? It is in the FPGA I suppose.
Where can read more about the FPGA besides this small text?
http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html#fpga
Can we only put proper divisors of 128MHz in terms of datarate into the
UHD sink even above 250kHz?
Actually we need to put ~10kbit/s of data onto a ~400kHz carrier. Is the
GRC repeater the right functionality
to interpolate the small datarate as shown in the attached setup?
Regards,
Ralf
Thu Jun 30 11:09:05 2011
options
id
tx
_enabled
True
title
author
description
window_size
1280, 1024
generate_options
qt_gui
category
Custom
run_options
prompt
run
True
realtime_scheduling
_coordinate
(10, 10)
_rotation
0
blks2_dxpsk_mod
id
blks2_dxpsk_mod_0
_enabled
True
type
dqpsk
samples_per_symbol
4
excess_bw
0.35
gray_code
True
verbose
False
log
False
_coordinate
(313, 259)
_rotation
0
random_source_x
id
random_source_x_0
_enabled
True
type
byte
min
0
max
255
num_samps
10
repeat
True
_coordinate
(73, 259)
_rotation
0
uhd_usrp_source
id
uhd_usrp_source_0
_enabled
True
type
complex
dev_addr
ref_clk
sync
clock_rate
0.0
num_mboards
1
sd_spec0
sd_spec1
sd_spec2
sd_spec3
nchan
1
samp_rate
100
center_freq0
0
gain0
0
ant0
bw0
0
center_freq1
0
gain1
0
ant1
bw1
0
center_freq2
0
gain2
0
ant2
bw2
0
center_freq3
0
gain3
0
ant3
bw3
0
center_freq4
0
gain4
0
ant4
bw4
0
center_freq5
0
gain5
0
ant5
bw5
0
center_freq6
0
gain6
0
ant6
bw6
0
center_freq7
0
gain7
0
ant7
bw7
0
center_freq8
0
gain8
0
ant8
bw8
0
center_freq9
0
gain9
0
ant9
bw9
0
center_freq10
0
gain10
0
ant10
bw10
0
center_freq11
0
gain11
0
ant11
bw11
0
center_freq12
0
gain12
0
ant12
bw12
0
center_freq13
0
gain13
0
ant13
bw13
0
center_freq14
0
gain14
0
ant14
bw14
0
center_freq15
0
gain15
0
ant15
bw15
0
_co
Re: [Discuss-gnuradio] E100 Performance
On 06/30/2011 05:27 AM, Ralf wrote: > > > Hi Marcus, thanks for your reply. > > That is very important for us to understand. How is the divider 512 > determined? It is in the FPGA I suppose. > Where can read more about the FPGA besides this small text? > http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html#fpga The FPGA supports a maximum interpolation ratio of 512. Interpolation ratios must be even. > > Can we only put proper divisors of 128MHz in terms of datarate into > the UHD sink even above 250kHz? Yup. Only bandwidths that result in an even interpolation ratio from the 128MHz DAC sample rate can be used. > > Actually we need to put ~10kbit/s of data onto a ~400kHz carrier. Is > the GRC repeater the right functionality > to interpolate the small datarate as shown in the attached setup? > Normally, if you need to use a "weird" sample rate, you'd use something like the fractional interpolator block just before you send the stream to the UHD sink. Do you mean a carrier that is 400kHz in bandwidth, or a carrier at 400kHz center frequency? The center frequency isn't really relevant to this discussion, but the bandwidth is. -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] E100 Performance
Am 30.06.2011 um 11:27 schrieb Ralf:
> Am 29.06.2011 16:34, schrieb Marcus D. Leech:
>> On 29/06/2011 9:11 AM, Ralf wrote:
>>> Hi,
>>>
>>> the simple GRC in the attachment creates lots of underflows on our E100
>>> ("U" on console)
>>> and dropouts when looking at the spectrum.
>>>
>>> Is this as expected or how can this overload of the embedded Linux be
>>> avoided?
>>>
>>> Thanks,
>>> Ralf
>> Well, for one, 60Khz isn't a proper divisor of the 128MHz sample rate of the
>> DAC, which means it can't be properly interpolated.
>>
>> The minimum sample rate that you can deliver to the USRP-E100 is 128MHz/512
>> = 250kHz, so you'll have to interpolate your
>> data stream up to 250kHz prior to "presentation" to the UHD sink block.
>>
>
> Hi Marcus, thanks for your reply.
>
> That is very important for us to understand. How is the divider 512
> determined? It is in the FPGA I suppose.
> Where can read more about the FPGA besides this small text?
> http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html#fpga
>
> Can we only put proper divisors of 128MHz in terms of datarate into the UHD
> sink even above 250kHz?
>
> Actually we need to put ~10kbit/s of data onto a ~400kHz carrier. Is the GRC
> repeater the right functionality
> to interpolate the small datarate as shown in the attached setup?
>
> Regards,
> Ralf
There is a collection of lots of internal details of the USRP1 under
www.gnuradio.org/redmine/attachments/129/USRP_Documentation.pdf
They might also apply to the operation of the E100's FPGA logic.
You can also look at the source code directly
http://ettus-apps.sourcerepo.com/redmine/ettus/projects/uhd/repository/revisions/master/show/fpga
Regards,
Matthias
___
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] OFDM modulation in tunnel.py example [USRP2 platform]
Dear GNU Radio list, I've being diving into some GNU Radio examples in order to communicate two USRP2s (e.g. USRP2 #1 pings USRP2 #2). Following the example "tunnel.py", in $GNURADIO_PATH/gnuradio-examples/python/digital, I've been able to do it, but with a GMSK/DBPSK/DQPSK modulation scheme. My goal is to use the tunnel.py example but using a different modulation scheme, i.e. OFDM. I've seen the example "tunnel.py" in another directory ($GNURADIO_PATH/gnuradio-examples/python/ofdm), which uses a OFDM modulation scheme but it seems that it's only working for USRP1. Is it possible nowadays to use tunnel.py (transmit and receive flow-graph in the same USRP2) with OFDM in an USRP2 platform? Thank you for your help. My equipement is: 2x USRP2s + XCVR2450 daughterboard Linux 10.04 (Lucid) - 32 bits GNU Radio version 3.3.0 (stable version) Kind Regards, Juan Ramon Gutierrez Agullo ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] WBX CW transmit problem
Dear all, I have been testing USRP2 with WBX board (#957). Using GNU Radio, I have created a simple CW TX system. The problem: output signal is oscillating when I set the TX frequencies to 900MHz band. Signal output (in time domain) at TX/RX connector from the FSL analyzer is in the attachment. Settings: 868 MHz, 200 kSps, gain 15 dB Same results with: ./tx_waveforms --rate 25 --freq 86800 --gain 15 The oscillation with ca. 1dB amplitude is present for almost all gain settings except the lowest values. I have observed the problem at several frequencies from 700M to 1G, sometimes with amplitude over 2dB. Any ideas about the cause of this problem? Some PA instability or AGC loop issue? Thanks, Ales <>___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] UHD FPGA problem
Hello! I bypassed successfully the ADC lines directly to the DAC lines using the GNU Radio FPGA code but I tried to do the same with the UHD code and it was impossible, I always get zero as amplitude. I am doing this bypass into the u2_core module. Does anyone have an idea about what is going on? A lot of thanks! Eduardo. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] WBX CW transmit problem
I have seen the same issue in the last couple of days. My setup: Ubuntu 10.04 laptop UHD + GNUradio 3.3 USRP2 with WBX TX parameters: 15dB gain, 1090MHz center frequency 4MS/s transmission RX parameters: 25dB gain, 1090MHz center frequency 4MS/s acquisition transmitted signal: U(t) = 10mV + 5mV * sin(2*pi*f*t) f = 100 kHz I observe unexpected sinusoidal oscillations in the amplitude at about 400kHz Oscillation amplitude is on the order of 1mV. Dave Aleš Povalač wrote: > > Dear all, > > I have been testing USRP2 with WBX board (#957). Using GNU Radio, I > have created a simple CW TX system. The problem: output signal is > oscillating when I set the TX frequencies to 900MHz band. Signal > output (in time domain) at TX/RX connector from the FSL analyzer is in > the attachment. > > Settings: > 868 MHz, 200 kSps, gain 15 dB > > Same results with: > ./tx_waveforms --rate 25 --freq 86800 --gain 15 > > The oscillation with ca. 1dB amplitude is present for almost all gain > settings except the lowest values. I have observed the problem at > several frequencies from 700M to 1G, sometimes with amplitude over > 2dB. > > Any ideas about the cause of this problem? Some PA instability or AGC > loop issue? > > Thanks, > Ales > > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > -- View this message in context: http://old.nabble.com/WBX-CW-transmit-problem-tp31963722p31964536.html Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] UDP broadcasting
Hi, I'm trying to get a basic IP-based network running between 2 or 3 USRPs and I'm having trouble trying to send broadcast UDP packets via dial_tone_sink.py in the network examples. I'm sending the packets addressed to 192.168.200.255 with port 0 but this continuously results in a "can't open socket" error. If I address the packets directly to another machine 192.168.200.30, it works fine. Is there something else I need to do to broadcast packets? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Max temperature for usrp2
Eric, in your 2009 experiment indicated below, did the USRP2 sustain the high temperature of 150 F? Is there anybody else who has tried to use USRP2 continuously at a temperature above 105 F? Your feedback is highly appreciated. Andrew On Mon, Jul 13, 2009 at 1:13 PM, Eric Matlis wrote: Hi all- I'm about to conduct some measurements on a running GE aircraft jet engine with the USRP2. The test cell temps could reach 150 F. Is that going to fry my USRP? Thanks, eric ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] OFDM modulation in tunnel.py example [USRP2 platform]
Hi Juan, It isn't too hard to modify the OFDM tunnel script to use UHD instead of the old USRP blocks. You have to change the flow graph in tunnel.py to use new sink and source blocks and update all of the sample rate and frequency setting functions. You can take a look at how I did it here: https://github.com/mogar/uhd_ofdm/blob/master/tunnel.py Hope that helps, Morgan On Thu, Jun 30, 2011 at 7:07 AM, Juan Ramon Gutierrez wrote: > Dear GNU Radio list, > > I've being diving into some GNU Radio examples in order to communicate > two USRP2s (e.g. USRP2 #1 pings USRP2 #2). Following the example > "tunnel.py", in $GNURADIO_PATH/gnuradio-examples/python/digital, I've > been able to do it, but with a GMSK/DBPSK/DQPSK modulation scheme. > > My goal is to use the tunnel.py example but using a different modulation > scheme, i.e. OFDM. I've seen the example "tunnel.py" in another > directory ($GNURADIO_PATH/gnuradio-examples/python/ofdm), which uses a > OFDM modulation scheme but it seems that it's only working for USRP1. > > Is it possible nowadays to use tunnel.py (transmit and receive > flow-graph in the same USRP2) with OFDM in an USRP2 platform? > > Thank you for your help. > > My equipement is: > 2x USRP2s + XCVR2450 daughterboard > Linux 10.04 (Lucid) - 32 bits > GNU Radio version 3.3.0 (stable version) > > Kind Regards, > > Juan Ramon Gutierrez Agullo > > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] MAC layer questions
Hi, I've been working on building a CSMA/CA MAC for the past couple of weeks. I built it in Python, and used ofdm/tunnel.py as a guide. It's working now, but I don't think it's very efficient. I ended up having to relax a lot of timing parameters to get it working, so my throughput is pretty bad. I also get a lot of dropped packets. I think this is also because my timing isn't very accurate, and I end up with more collisions than I would expect. I was wondering if anyone else had had any luck building a CSMA/CA MAC. I saw a few posts on the mailing list from several years ago about people who were working on it, but I don't see any example code anywhere. I also checked out CMUmacs on CGRAN, but that relies on a deprecated version of GNURadio. Is my best bet to rewrite the MAC as a block in C++? Can anyone tell me what kind of speedup that's likely to get me? Thanks, Morgan Redfield ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] OFDM preamble
Hi. I wanted to know about the preambles that are inserted in the ofdm packet. I know they are inserted for the synchronization and frequency offset purposes. But I want to know where in the OFDM packet they are inserted. I have following questions. 1. How can I vary the length of preambles? Can I do that ? 2. On which parameters length of preamble depends? 3. What is the length of preamble sequence if I am using fft-length=512, occupied carriers=200 cp-length=128, size of ofdm packet=400 bytes, modulation='bpsk'. 4. Where are they inserted in the OFDM packet? I mean before Payload? preamble| payload| 5. Both the preambles are inserted at the start ? 6. Which modulation is used for preambles? Need your help Regards ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
