Is there a status indicator in the USRP2 C++ interface that flags
underflows? I am trying to push samples (using the std::complex
type) to the USRP2 at an interpolation factor of 4. It seems to be
working, but I require hard evidence that I am not underflowing.
--
+
Peter:
I've been tracking L2C this summer also. I can verify that there is NO
DATA on any of the L2C capable SVs. The US Coast Guard has a great GPS
status site at http://www.navcen.uscg.gov/. The GPS constellation status
is listed at:
http://www.navcen.uscg.gov/navinfo/Gps/ActiveNanu.aspx
Give this man a round of applause!
--
[EMAIL PROTECTED]
NASA Goddard Space Flight Center
AETD - Mission Engineering and Systems Analysis
Component and Hardware Systems Branch
Mail Code 596, Greenbelt Rd.
Greenbelt, MD 20771
(301) 286-6565
(301) 286-3823 (fax)
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To the USRP experts out there:
I reclocked my USRP from 64 to 65.536 MHz and have recently discovered
that the I & Q samples are no longer orthogonal, rather they seem to be
only 70 degrees or so apart. I would guess this is due to some hard
coded values in the CIC or HB filters? Is there a US
Chris:
So you are not tracking the signal in the traditional sense, only
looking at the frequency and delay estimate of your FFT acquisition. How
far spaced are your Doppler bins in the FFT acquisition? If you are
using a 1 ms integration time, and hence a 500 Hz bin spacing, if the
signal's
After reading a bunch of questions about GPS antennas I am making myself
the guinea pig. I just ordered the "Mighty Mouse 3" active GPS antenna.
The spec sheet quotes +5dBi gain at zenith and -1dBi at 10 degrees. I
ordered the antenna from:
http://www.gpszone.ca/accessories/antennas/mm3.php
T
Bryan:
The DBS-RX is the way to go. I use the +5V bias on the DBS-RX, and it
works fine, with the added benefit of not adding another AC-DC brick to
your setup. To enable the +5V bias just short J101 on the DBS-RX card.
Checkout www.gps-sdr.com, you might be interested.
If you have data I could look at that would be great, but in my post I
did not mention I am using a USRP I clocked externally with a signal
generator. In your message you indicate that you were successful
extending correlations to 20 ms when you used a better clock, which
tells me I am screwing
For all the GPS users out there, has anyone been able to extend
correlations to 20 ms? I have had a heck of a time extending the
correlation interval without hosing my 3rd order PLL.
--
[EMAIL PROTECTED]
NASA Goddard Space Flight Center
AETD - Mission Engineering and Systems Analysis
Component
Trying to sort out an email problem.
--
[EMAIL PROTECTED]
NASA Goddard Space Flight Center
AETD - Mission Engineering and Systems Analysis
Component and Hardware Systems Branch
Mail Code 596, Greenbelt Rd.
Greenbelt, MD 20771
(301) 286-6565
(301) 286-3823 (fax)
_
Would anyone be interested in an additional decimation stage after the
CIC and the halfband filters? The usable bandwidth is ~25-50% of the
actual post decimation sample rate, an additional decimation stage (no
filtering, just a plain decimation) would allow the sample rate pushed
across the US
To all the GPS geeks:
If anyone is attending ION GNSS this year in Fort Worth we should
schedule a rendezvous sometime during the conference. Would anyone have
suggestions as to a time?
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htt
I have some C/C++ functions that utilize MMX and/or SSE available that
work on 16 bit signed integers. The URL is:
http://www.ngs.noaa.gov/gps-toolbox/Heckler.htm
They work particularly well for building a software correlator :).
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Trond:
Tuning the down-converter on the DBS-RX card consists of programming the
values of 2 dividers. The R divider divides down the reference clock
frequency (4 MHz, which derives from the 64 MHz board clock). The N
divider divides down the LO frequency. The R divider has a range from 2
to 2
Is there a proper way to format comments in my DBS-RX driver's source to
be included in the doxygen documentation? I would like to do this prior
to submission of the driver. Thanks.
Greg Heckler
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To all concerned parties:
I think I've discovered the problem. My "tune" routine chose the R and N
dividers to minimize the difference between the command and desired LO
frequencies. For L1 this ended up being 64 and 25197. The refclk was set
at 4 MHz, producing an R divider frequency of 62500
Brian:
From what I see it does not continuously stream data, which is a
requirement for my needs. Additionally I am looking at recording GPS L2C
and the new Galileo frequencies, so a tuneable front end is a must.
Greg
Brian Padalino wrote:
On 3/6/07, Gregory W Heckler <[EMAIL PROTEC
I've hit a wall with using the DBSRX to record GPS L1 C/A code data. The
signal path consists of the following:
Spirent GPS Simulator -> 2 MHz wide SAW @ L1 -> +40 dB Miteq Amp ->
DBSRX -> USRP
Notes/Settings:
1) Spirent Simulator:
Static scenario, 39 deg North, -84.866 deg West, 0.0 meter h
Before I submit my DBSRX C++ driver, I need some tips on the preferred
style to the GnuRadio mods out there:
Should the DBSRX class (db_dbs_rx) inherit the usrp_standard_rx class
(currently I pass a handle to an already created usrp_standard_rx handle
in the contructor)?
Should the interface
Has anyone successfully collected any GPS L1 data with the DBSRX
daughterboard. If so what decimation, gain, and filter values did you
use to do so? Thanks!
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I'm in the process of debugging my DBSRX driver, and have verified the
following:
1) The GC1 input voltage from the aux_dac can be properly commanded.
Verification was carried out by probing the GC1 pin on the Max2118 chip,
and observing the voltage sweep from .75 to 2.6 Volts.
2) The enable
Doh, you are exactly right! *Flagellates self*
Joshua Lackey wrote:
Quoting Gregory W Heckler ([EMAIL PROTECTED]):
[...]
in order to perform the charge pump calibration the read_i2c function
keeps returning a null string. Any ideas on what might be the problem?
This is basically the read_i2c
Hey, I'm almost done with the C++ port of the DBSRX driver, I'm stuck
with one thing though. When I attempt to read the Max2118 status bytes
in order to perform the charge pump calibration the read_i2c function
keeps returning a null string. Any ideas on what might be the problem?
This is basic
In the file "usrp_i2c_addr.h" the I2C addresses for the receiver
daughterboards are 0x57 and 0x55, respectively. In the python code
self.i2c_addr = (0x67, 0x65). Which one is correct?
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You can do this externally by putting in a bias-tee in the RF line prior
to input to the USRP. I've personally used the following from MiniCircuits:
http://minicircuits.com/pdfs/ZFBT-4R2G-FT.pdf
Or if you want to take a more risky route, on the DBSRX daughterboard
there is header to input a DC
Did anyone have the addendum to the Max2118 data sheet that gives
specific details on how to program the LO frequency? It is not available
on the Maxim website. Thanks.
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I guess this implies there is no C++ native DBSRX support at this time?
Does there exist an ICD to the DBSRX daughterboard that I could write a
C++ driver to?
-Heckler
Marcus Leech wrote:
Gregory W Heckler wrote:
Is there a missing class for the DBSRX daughterboard not include in
the CVS
Is there a missing class for the DBSRX daughterboard not include in the
CVS repository? There seems to be no way to command the LO frequency
tuning word of the MAX2118 downcoverter chip.
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Sorry if this is a repost:
I just received my USRP and I'm interested in using the USRP as a GPS
signal recording device. My goal is to build a win32 library available
to MSVC (.lib file and associated .h files) in order to integrate the
usrp/host/lib code into my preexisting GPS software receive
I just received my USRP and I'm interested in using the USRP as a GPS
signal recording device. My goal is to build a win32 library available
to MSVC (.lib file and associated .h files) in order to integrate the
usrp/host/lib code into my preexisting GPS software receiver. Would MSYS
or Cygwin b
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