-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello Khalid,
> rather than having a standalone USB connection to the computer, is > there anyway to piggyback the temperature data from the temp sensor > onto the digital interface to the FPGA board of the N200? That's what you would do if you attached a sensor to the FPGA's debug header, modified the FPGA image and the host driver and got your data out of that. Definitely possible, definitely a huge effort for a few bytes of data. I'd either go with the GPIO interface[1], or use the fact that the N2x0 works on standard Gigabit Ethernet / IP, and you can simply attach any networked hardware to a Gigabit Ethernet switch. Raspberry Pi comes to mind, if you want something rather capable and running a stock linux, for which many kernel drivers already allow you to talk to hardware attached to things like I2C or SPI. Currently I'm playing around with a stamp-sized openWRT-running board that would potentially even fit inside the casing of the N200, but I don't think that would be a good idea (it being a least cost, and definitely not EMI-tested, one-man project). Greetings, Marcus [1] which many daughterboards expose; what daughterboard are you using? The information about the X3x0's front panel GPIO applies to the N2x0 GPIO, too, mostly: http://files.ettus.com/manual/page_gpio_api.html On 12/03/2014 01:51 PM, khalid.el-darymli wrote: > Thank you Ralph and Marcus for this information. That is so > helpful. One final question on this, rather than having a > standalone USB connection to the computer, is there anyway to > piggyback the temperature data from the temp sensor onto the > digital interface to the FPGA board of the N200? > > Thank you. > > Best regards, Khalid > > > On Wed, Dec 3, 2014 at 3:36 AM, Ralph A. Schmid, dk5ras > <ra...@schmid.xxx> wrote: > >> In my job we have learned that lesson and fitted on all our DSP >> systems (you could call them direct digitizing SDRs, although we >> do not radio stuff) a cheap I2C temperature sensor. No big thing >> by means of software, costs and PCB space, but already proved >> being very useful. Could be considered for future products… >> >> >> >> Ralph. >> >> >> >> *From:* USRP-users [mailto:usrp-users-boun...@lists.ettus.com] >> *On Behalf Of *Marcus D. Leech via USRP-users *Sent:* Tuesday, >> December 2, 2014 4:11 PM *To:* khalid.el-darymli *Cc:* >> usrp-us...@lists.ettus.com; Discuss-gnuradio@gnu.org *Subject:* >> Re: [USRP-users] How to correct for the drift in an (FMCW) Rx >> signal? >> >> >> >> On 12/02/2014 10:06 AM, khalid.el-darymli wrote: >> >> Hi Marcus, >> >> Is there a temperature sensor on-board the N200 unit? If not, >> does it support installing any such sensor? >> >> Thanks. >> >> No, and no. >> >> But there are a tonne of USB-based temperature sensors out there. >> Google is your friend, etc. >> >> >> >> >> >> >> Best regards, Khalid >> >> >> >> On Fri, Nov 28, 2014 at 5:44 PM, Marcus D. Leech >> <mle...@ripnet.com> wrote: >> >> On 11/28/2014 03:41 PM, khalid.el-darymli wrote: >> >> >> >> >> >> Back to my original question, what should I do to correct for >> this? >> >> >> Thanks in advance. >> >> >> Best, Khalid >> >> >> >> Khalid: >> >> Thanks very much for the very-extensive data. My main concern, >> as one of the Ettus support team, was that there was something >> wrong with the hardware, but the magnitude of both the apparent >> phase and magnitude drift is entirely consistent with >> analog-hardware temperature effects, unrelated to clock >> stability, etc. >> >> Coax cables, for example, will change their loss characteristics >> and *effective length* with temperature, so with precise hardware >> like USRPs, it's easy to see these effects. >> >> FMCW radar isn't my area of expertise, so hopefully others can >> comment on RX-processing strategies to deal with this, as it >> *must* also be a problem with non-SDR FMCW radar >> implementations. >> >> >> >> >> >> >> >> On Fri, Nov 28, 2014 at 12:08 PM, <mle...@ripnet.com> wrote: >> >> What is the magnitude of the frequency drift? >> >> What is the magnitude of the gain drift? >> >> What are you measuring backscatter *from*? >> >> >> >> >> >> >> >> On 2014-11-28 10:14, khalid.el-darymli via USRP-users wrote: >> >> Hi, >> >> Given a set of synced *(i.e., using external GPS REF/PPS)*, >> time-commanded and calibrated *(i.e., through compensating for >> the phase/mag offset between digital Tx chirp prior to >> transmission and ADC'ed Rx signals) *N200 devices with LFTX/LFRX >> daughterboards, that work with coherent LFMCW chirps, I am still >> seeing a tiny drift (both in the magnitude and frequency) of the >> calibrated back-scatter Rx chirp received at time t1 when >> compared to an Rx chirp received at an earlier time t0. >> >> The more the N200 device runs (e.g., 5 hours), the greater the >> drift is. Obviously, this drift is pertinent to both the DAC and >> ADCs and the GPS referenced clocks of the N200 devices. >> >> >> My questions are: >> >> 1- Why I still see such drift although my devices are synced with >> an external GPS? and how do I correct for it? >> >> >> 2- Can the *PLL Carrier Tracking *block in GRC be used to track >> and correct for such a drift? If so, how do I set the max/min >> freq inputs for this block? >> >> 3- Can *AGC2* or *AGC3 *block be useful in this regard? If so, >> are there any examples to explain how the input parameters of >> these blocks can be set up? >> >> Thanks. >> >> Best regards, >> >> Khalid >> >> >> >> _______________________________________________ >> >> USRP-users mailing list >> >> usrp-us...@lists.ettus.com >> >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >> >> >> >> >> >> >> >> >> >> - -- >> >> Marcus Leech >> >> Principal Investigator >> >> Shirleys Bay Radio Astronomy Consortium >> >> http://www.sbrac.org >> >> >> >> >> >> >> >> >> >> >> -- >> >> Marcus Leech >> >> 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 > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUfx8hAAoJEAFxB7BbsDrLWnUH/3sBlb+RSjnsUlgW5GASYbOw d2un2ueRY5GddfVopqnHFlj6e8bIKaOq/Ct5VcnX3133pskTnGPVyIsB5kgLLty+ Dws33Smo2FaA0YiqxrqZF4/O+35ZvYzIlkDtCeXIHr6TXw9eUQFZOEiOfglaHuTj 2WlJd8sRTx+gIqoWmuWROAz7qESsYIydz9rIHJuvn2HHn7LGfsWJBYLWRYEDx9Ds vatFqNEu8ZUICnfUep2m1Bo5cIAYpISB1JmXTDGEDob26sJTWfe5mBxxF6XnDNBN gHiMI9e2fT2mtQseIKkZ8FNL62+U1CY8bo5V0k8J0pVfXZcKkHEHYc2ZlJFA43Y= =eEXe -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
