[USRP-users] USRP and GPS antennas
Hi there, A few months ago I ended up with a pair of USRP E312's and u-blox ANN-MB-00 GPS antennas. I was able to synchronize both devices and acquire properly aligned samples and things are looking good. However, today I realized that the u-blox antenna I have is an active antenna and checking its datasheet it looks like it requires 15 mA/3-5 V DC supply for the integrated LNA. Does this mean that the GPS port of 312 has a bias-tee that supplies the necessary currents? If there is a bias-tee, where can I find information about it? Also checking the Ettus store, it looks like different antennas are compatible with different USRP models. For instance "3V Active GPS Antenna for N series" is apparently compatible with E310 both not compatible with X and B series. Which factor determines the compatibility? Best regards, Temir ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com
[USRP-users] Re: USRP and GPS antennas
On 2021-12-14 12:12, Temir Karakurum wrote: Hi there, A few months ago I ended up with a pair of USRP E312's and u-blox ANN-MB-00 GPS antennas. I was able to synchronize both devices and acquire properly aligned samples and things are looking good. However, today I realized that the u-blox antenna I have is an active antenna and checking its datasheet it looks like it requires 15 mA/3-5 V DC supply for the integrated LNA. Does this mean that the GPS port of 312 has a bias-tee that supplies the necessary currents? If there is a bias-tee, where can I find information about it? Also checking the Ettus store, it looks like different antennas are compatible with different USRP models. For instance "3V Active GPS Antenna for N series" is apparently compatible with E310 both not compatible with X and B series. Which factor determines the compatibility? Best regards, Temir ___ USRP-users mailing list --usrp-users@lists.ettus.com To unsubscribe send an email tousrp-users-le...@lists.ettus.com I think the bias-T on both X and B series puts out +5V. MOST GPS antennas are perfectly happy to deal with anywhere between 3-5V. Nearly all GPS antennas these days are *active* antennas and MOST are 3-5V happy. ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com
[USRP-users] Re: USRP and GPS antennas
Hi Marcus, Thanks for the quick reply! Is the bias-tee available only for the GPS port? Can you similarly provide DC power to an LNA through the RF ports? Best, Temir On Tue, Dec 14, 2021 at 8:17 PM Marcus D. Leech wrote: > On 2021-12-14 12:12, Temir Karakurum wrote: > > Hi there, > > A few months ago I ended up with a pair of USRP E312's and u-blox > ANN-MB-00 GPS antennas. I was able to synchronize both devices and acquire > properly aligned samples and things are looking good. > > However, today I realized that the u-blox antenna I have is an active > antenna and checking its datasheet it looks like it requires 15 mA/3-5 V DC > supply for the integrated LNA. Does this mean that the GPS port of 312 has > a bias-tee that supplies the necessary currents? If there is a bias-tee, > where can I find information about it? > > Also checking the Ettus store, it looks like different antennas are > compatible with different USRP models. For instance "3V Active GPS Antenna > for N series" is apparently compatible with E310 both not compatible with X > and B series. Which factor determines the compatibility? > > Best regards, > Temir > > ___ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com > > I think the bias-T on both X and B series puts out +5V. MOST GPS antennas > are perfectly happy to deal with anywhere between 3-5V. > > Nearly all GPS antennas these days are *active* antennas and MOST are 3-5V > happy. > > > ___ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com > ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com
[USRP-users] Bias power on E312's RX ports (was: USRP and GPS antennas)
Dear Temir, https://files.ettus.com/schematics/e310/ , the daughterboard schematic (e310_db.pdf), page 7: no, there's no biasing on the RF ports. Best regards, Marcus DISCLAIMER: Any attached Code is provided As Is. It has not been tested or validated as a product, for use in a deployed application or system, or for use in hazardous environments. You assume all risks for use of the Code. Use of the Code is subject to terms of the licenses to the UHD or RFNoC code with which the Code is used. Standard licenses to UHD and RFNoC can be found at https://www.ettus.com/sdr-software/licenses/. NI will only perform services based on its understanding and condition that the goods or services (i) are not for the use in the production or development of any item produced, purchased, or ordered by any entity with a footnote 1 designation in the license requirement column of Supplement No. 4 to Part 744, U.S. Export Administration Regulations and (ii) such a company is not a party to the transaction. If our understanding is incorrect, please notify us immediately because a specific authorization may be required from the U.S. Commerce Department before the transaction may proceed further. On 14.12.21 18:22, Temir Karakurum wrote: Hi Marcus, Thanks for the quick reply! Is the bias-tee available only for the GPS port? Can you similarly provide DC power to an LNA through the RF ports? Best, Temir On Tue, Dec 14, 2021 at 8:17 PM Marcus D. Leech wrote: On 2021-12-14 12:12, Temir Karakurum wrote: Hi there, A few months ago I ended up with a pair of USRP E312's and u-blox ANN-MB-00 GPS antennas. I was able to synchronize both devices and acquire properly aligned samples and things are looking good. However, today I realized that the u-blox antenna I have is an active antenna and checking its datasheet it looks like it requires 15 mA/3-5 V DC supply for the integrated LNA. Does this mean that the GPS port of 312 has a bias-tee that supplies the necessary currents? If there is a bias-tee, where can I find information about it? Also checking the Ettus store, it looks like different antennas are compatible with different USRP models. For instance "3V Active GPS Antenna for N series" is apparently compatible with E310 both not compatible with X and B series. Which factor determines the compatibility? Best regards, Temir ___ USRP-users mailing list --usrp-users@lists.ettus.com To unsubscribe send an email tousrp-users-le...@lists.ettus.com I think the bias-T on both X and B series puts out +5V. MOST GPS antennas are perfectly happy to deal with anywhere between 3-5V. Nearly all GPS antennas these days are *active* antennas and MOST are 3-5V happy. ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com
[USRP-users] Re: N310 - unexpected DC offset and harmonics
Dear Huacheng, while it's hard to rule something like that out, it'd be surprising. Maybe you had a very strong interferer that led to undesired intermodulation? Next time it happens, try to scan through the overall spectrum (not only within your bandwidth of interest!) with a spectrum analyzer, or drastically reduce the RF gain in your N310: if reducing the frontend gain improves DC offset performance, chances are the mixer doesn't operate in the expected regime due to external power. Best regards, Marcus DISCLAIMER: Any attached Code is provided As Is. It has not been tested or validated as a product, for use in a deployed application or system, or for use in hazardous environments. You assume all risks for use of the Code. Use of the Code is subject to terms of the licenses to the UHD or RFNoC code with which the Code is used. Standard licenses to UHD and RFNoC can be found at https://www.ettus.com/sdr-software/licenses/. NI will only perform services based on its understanding and condition that the goods or services (i) are not for the use in the production or development of any item produced, purchased, or ordered by any entity with a footnote 1 designation in the license requirement column of Supplement No. 4 to Part 744, U.S. Export Administration Regulations and (ii) such a company is not a party to the transaction. If our understanding is incorrect, please notify us immediately because a specific authorization may be required from the U.S. Commerce Department before the transaction may proceed further. On 13.12.21 15:53, Zeng, Huacheng wrote: Hi Marcus, I constantly observed the DC offset and harmonic peaks yesterday. But they simply disappeared today. I am pretty sure I did not make any changes on hardware or software. One possibility is that they were caused by a long time use or the temperature change (room temperature < 25C). I will report here if I can reproduce the problem. Thanks anyway! Huacheng On Sun, Dec 12, 2021 at 2:24 PM Marcus D. Leech wrote: On 2021-12-12 11:57, Zeng, Huacheng wrote: Hello, I am using N310 to observe its received signal in its four channels. I observed some unexpected DC offset and harmonics as shown in the attached figure. It happened only at channels RF0 & RF2; the signal from channels RF1 & RF3 looks normal. I disconnected the antennas but the DC and harmonics are still there. And they would not change if I change the center frequency, sampling rate, or RF gain. The GNU RADIO and UHD versions are below: [INFO] [UHD] linux; GNU C++ version 7.5.0; Boost_106501; UHD_3.15.0.HEAD-0-gaea0e2de I also attached my python script code in case it would be useful for you to identify the problem. Any suggestions? Thank you in advance! Hua ___ USRP-users mailing list --usrp-users@lists.ettus.com To unsubscribe send an email tousrp-users-le...@lists.ettus.com Also, could you try explicitly specifying a subdev-spec of: "A:0 A:1 B:0 B:1" ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com
[USRP-users] Re: In-place Local Clock Update
Hi Jason, if I understand your problem correctly, this is a bit like the problem that, say, independent user equipment (UE) devices (==mobile phones) need to solve in a cellular network: they all need to align their clocks to the network-provided time, based on some synchronization signal. You *can* do that, but I don't think it has much to do what you mention here. Let me sketch what I think you should consider: 1. let's assume for the time being that your two UEs and the network have the same notion of *frequency*, so f₁ = f₂, and because they're USRP, that also means their sampling rates are identical. 2. However, both UE have totally independent notions of time, because both started running at different times (t₁ ≠ t₂) (i.e., relative to network time, UE1 and UE2 had their zeroth sample late by t₁ and t₂, respectively); also, the network time t₀ is also different (t₁ ≠ t₀ ≠ t₂; wlog t₀ = 0) However, since the sampling rates r are identical, a time interval T means the same exact time difference to all three. 3. Now, on UE1, a synchronization burst is observed. This gives us the information that at sample n₁, which, in terms of time for UE happened at sample r·t₁+x₁=n₁; it however, knows from the type or content of the burst that it happend at n₀=r·t₀+y on the network side. 4. UE1 now calculates the difference between the known network time of the burst and the observed time: r·(t₀-t₁)=y-x₁; since r, y and x₁ are know to UE1,this gives the time by which the UE lags t₀. That means we need to "jump" the time by -(t₀-t₁). 5. UE2 does the same calculation, but for-(t₀-t₁. 6. Both USPRs use a fixed time m₁, m₂ *by their own* counting, to set the internal time to m₁-(t₀-t₁), and m₂-(t₀-t₁), respectively. There's ways to implement 6.: I can't remember whether the X310 in absence of an external PPS source synthesizes an internal PPS every (master clock rate) clock ticks. If that's the case: just loop till get_time_last_pps() changes, then add 1-(t₀-t₁) to it, and set the result set_time_next_pps. If that's not the case, you can either modify the FPGA image to make that happen, or just use the GPIO API, which you can use with timed commands, and a cable from the front panel GPIO back to the PPS input, to emulate the same. Best regards, Marcus M DISCLAIMER: Any attached Code is provided As Is. It has not been tested or validated as a product, for use in a deployed application or system, or for use in hazardous environments. You assume all risks for use of the Code. Use of the Code is subject to terms of the licenses to the UHD or RFNoC code with which the Code is used. Standard licenses to UHD and RFNoC can be found at https://www.ettus.com/sdr-software/licenses/. NI will only perform services based on its understanding and condition that the goods or services (i) are not for the use in the production or development of any item produced, purchased, or ordered by any entity with a footnote 1 designation in the license requirement column of Supplement No. 4 to Part 744, U.S. Export Administration Regulations and (ii) such a company is not a party to the transaction. If our understanding is incorrect, please notify us immediately because a specific authorization may be required from the U.S. Commerce Department before the transaction may proceed further. On 08.12.21 21:14, Jason Merlo wrote: Hi All, I’m currently working to synchronize multiple X310’s clocks without a PPS input, however right now the best method I can find to update the clock from a host PC (using the C++ API) is to query the current time from the USRP device (using usrp::multi_usrp::get_time_now), add a time delta to the current time, then send back the new clock time to the USRP device (using usrp::multi_usrp::set_time_now). Unfortunately, this method introduces large timing errors due to the nondeterministic nature of packet processing on both he CPU and network stack. I’m wondering if anyone knows of any other techniques for an "in-place" time update. I.e., is there a method for the host PC to send a time delta to the USRP which would be added to the clock register in a single operation? I see there are other get/set_time_now functions in the rfnoc::mb_control and rfnoc::radio_control classes, but I’m not sure if these would allow me to accomplish this using only the C++ API. I can’t seem to find much documentation on this aside from the examples in the “uhd/host/examples/rfnoc*” folder. If it’s not possible to accomplish this using a purely C++ approach, is it possible to do this through a custom RFNoC block? I don’t have experience with RFNoC at the moment and I’m not sure if that register is exposed to user blocks, or if so, if the register update would be deterministic in time, but if there’s motivation I would be willing go down the RFNoC path. Thanks in advance, Jason ___ USRP-users
[USRP-users] Re: Bias power on E312's RX ports (was: USRP and GPS antennas)
Hi again, Thanks for pointing me to the schematic. I guess my final question is why Ettus' official store recommends different antennas for different USRP series. For instance; datasheet of 3V GPS antenna ( https://www.ettus.com/wp-content/uploads/2019/01/Trimble_GPS_Antenna_DS.pdf) for N-series (as well E310) states that it is compatible with 3 or 5 V supply (15 mA typ. for 3V and 30 mA max for 5V). However, the store webpage (https://www.ettus.com/all-products/gps-ant-3v/) states that this antenna* is not* compatible with X and B series. Marcus Leech's previous reply states that X and B bias-T's provide 5V supply so I am kind of confused regarding the compatibility problem. Is it due to some current threshold? If so, where can I find the specs regarding the aforementioned limits? All the best, Temir On Tue, Dec 14, 2021 at 9:51 PM Marcus Müller wrote: > Dear Temir, > > https://files.ettus.com/schematics/e310/ , the daughterboard schematic > (e310_db.pdf), page > 7: no, there's no biasing on the RF ports. > > Best regards, > > Marcus > > DISCLAIMER: Any attached Code is provided As Is. It has not been tested or > validated as a product, for use in a deployed application or system, or for > use in hazardous environments. You assume all risks for use of the Code. > Use of the Code is subject to terms of the licenses to the UHD or RFNoC > code with which the Code is used. Standard licenses to UHD and RFNoC can be > found at https://www.ettus.com/sdr-software/licenses/. > > NI will only perform services based on its understanding and condition > that the goods or services (i) are not for the use in the production or > development of any item produced, purchased, or ordered by any entity with > a footnote 1 designation in the license requirement column of Supplement > No. 4 to Part 744, U.S. Export Administration Regulations and (ii) such a > company is not a party to the transaction. If our understanding is > incorrect, please notify us immediately because a specific authorization > may be required from the U.S. Commerce Department before the transaction > may proceed further. > > On 14.12.21 18:22, Temir Karakurum wrote: > > Hi Marcus, > > > > Thanks for the quick reply! Is the bias-tee available only for the GPS > port? > > Can you similarly provide DC power to an LNA through the RF ports? > > > > Best, > > Temir > > > > On Tue, Dec 14, 2021 at 8:17 PM Marcus D. Leech > wrote: > > > > On 2021-12-14 12:12, Temir Karakurum wrote: > >> Hi there, > >> > >> A few months ago I ended up with a pair of USRP E312's and u-blox > ANN-MB-00 GPS > >> antennas. I was able to synchronize both devices and acquire > properly aligned > >> samples and things are looking good. > >> > >> However, today I realized that the u-blox antenna I have is an > active antenna and > >> checking its datasheet it looks like it requires 15 mA/3-5 V DC > supply for the > >> integrated LNA. Does this mean that the GPS port of 312 has a > bias-tee that > >> supplies the necessary currents? If there is a bias-tee, where can > I find > >> information about it? > >> > >> Also checking the Ettus store, it looks like different antennas are > compatible with > >> different USRP models. For instance "3V Active GPS Antenna for N > series" is > >> apparently compatible with E310 both not compatible with X and B > series. Which > >> factor determines the compatibility? > >> > >> Best regards, > >> Temir > >> > >> ___ > >> USRP-users mailing list --usrp-users@lists.ettus.com > >> To unsubscribe send an email tousrp-users-le...@lists.ettus.com > > I think the bias-T on both X and B series puts out +5V. MOST GPS > antennas are > > perfectly happy to deal with anywhere between 3-5V. > > > > Nearly all GPS antennas these days are *active* antennas and MOST > are 3-5V happy. > > > > > > ___ > > USRP-users mailing list -- usrp-users@lists.ettus.com > > To unsubscribe send an email to usrp-users-le...@lists.ettus.com > > > > > > ___ > > USRP-users mailing list -- usrp-users@lists.ettus.com > > To unsubscribe send an email to usrp-users-le...@lists.ettus.com > ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com
[USRP-users] Re: Bias power on E312's RX ports (was: USRP and GPS antennas)
The X series and B series use the LC_XO series GPSDO modules Jackson Labs. I’d look through the specs for those modules for any Current limits. I’m literally underground in Toronto right now or I’d stuff those documents myself. Sent from my iPhone > On Dec 14, 2021, at 3:42 PM, Temir Karakurum wrote: > > > Hi again, > > Thanks for pointing me to the schematic. I guess my final question is why > Ettus' official store recommends different antennas for different USRP series. > For instance; datasheet of 3V GPS antenna > (https://www.ettus.com/wp-content/uploads/2019/01/Trimble_GPS_Antenna_DS.pdf) > for N-series (as well E310) states that it is compatible with 3 or 5 V supply > (15 mA typ. for 3V and 30 mA max for 5V). However, the store webpage > (https://www.ettus.com/all-products/gps-ant-3v/) states that this antenna is > not compatible with X and B series. Marcus Leech's previous reply states that > X and B bias-T's provide 5V supply so I am kind of confused regarding the > compatibility problem. Is it due to some current threshold? If so, where can > I find the specs regarding the aforementioned limits? > > All the best, > Temir > >> On Tue, Dec 14, 2021 at 9:51 PM Marcus Müller >> wrote: >> Dear Temir, >> >> https://files.ettus.com/schematics/e310/ , the daughterboard schematic >> (e310_db.pdf), page >> 7: no, there's no biasing on the RF ports. >> >> Best regards, >> >> Marcus >> >> DISCLAIMER: Any attached Code is provided As Is. It has not been tested or >> validated as a product, for use in a deployed application or system, or for >> use in hazardous environments. You assume all risks for use of the Code. Use >> of the Code is subject to terms of the licenses to the UHD or RFNoC code >> with which the Code is used. Standard licenses to UHD and RFNoC can be found >> at https://www.ettus.com/sdr-software/licenses/. >> >> NI will only perform services based on its understanding and condition that >> the goods or services (i) are not for the use in the production or >> development of any item produced, purchased, or ordered by any entity with a >> footnote 1 designation in the license requirement column of Supplement No. 4 >> to Part 744, U.S. Export Administration Regulations and (ii) such a company >> is not a party to the transaction. If our understanding is incorrect, >> please notify us immediately because a specific authorization may be >> required from the U.S. Commerce Department before the transaction may >> proceed further. >> >> On 14.12.21 18:22, Temir Karakurum wrote: >> > Hi Marcus, >> > >> > Thanks for the quick reply! Is the bias-tee available only for the GPS >> > port? >> > Can you similarly provide DC power to an LNA through the RF ports? >> > >> > Best, >> > Temir >> > >> > On Tue, Dec 14, 2021 at 8:17 PM Marcus D. Leech >> > wrote: >> > >> > On 2021-12-14 12:12, Temir Karakurum wrote: >> >> Hi there, >> >> >> >> A few months ago I ended up with a pair of USRP E312's and u-blox >> >> ANN-MB-00 GPS >> >> antennas. I was able to synchronize both devices and acquire properly >> >> aligned >> >> samples and things are looking good. >> >> >> >> However, today I realized that the u-blox antenna I have is an active >> >> antenna and >> >> checking its datasheet it looks like it requires 15 mA/3-5 V DC >> >> supply for the >> >> integrated LNA. Does this mean that the GPS port of 312 has a >> >> bias-tee that >> >> supplies the necessary currents? If there is a bias-tee, where can I >> >> find >> >> information about it? >> >> >> >> Also checking the Ettus store, it looks like different antennas are >> >> compatible with >> >> different USRP models. For instance "3V Active GPS Antenna for N >> >> series" is >> >> apparently compatible with E310 both not compatible with X and B >> >> series. Which >> >> factor determines the compatibility? >> >> >> >> Best regards, >> >> Temir >> >> >> >> ___ >> >> USRP-users mailing list --usrp-users@lists.ettus.com >> >> To unsubscribe send an email tousrp-users-le...@lists.ettus.com >> > I think the bias-T on both X and B series puts out +5V. MOST GPS >> > antennas are >> > perfectly happy to deal with anywhere between 3-5V. >> > >> > Nearly all GPS antennas these days are *active* antennas and MOST are >> > 3-5V happy. >> > >> > >> > ___ >> > USRP-users mailing list -- usrp-users@lists.ettus.com >> > To unsubscribe send an email to usrp-users-le...@lists.ettus.com >> > >> > >> > ___ >> > USRP-users mailing list -- usrp-users@lists.ettus.com >> > To unsubscribe send an email to usrp-users-le...@lists.ettus.com > ___ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lis
[USRP-users] Re: Bias power on E312's RX ports (was: USRP and GPS antennas)
Hi, Thanks for finding time to answer while commuting :) Quickly checking LC_XO webpage ( http://www.jackson-labs.com/index.php/products/lc_xo): "The unit includes internal 3.3V to 5V DC-DC power supplies and filters, and can provide 5V at up to 50mA to external customer circuitry, as well as to the external GPS antenna." This seems compatible with the Trimble antenna recommended for N-series but maybe I am missing something. Best, Temir ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com
[USRP-users] Re: Bias power on E312's RX ports (was: USRP and GPS antennas)
The only thing I can think of off the top of my head is RF gain differences. Sent from my iPhone > On Dec 14, 2021, at 4:09 PM, Temir Karakurum wrote: > > > Hi, > > Thanks for finding time to answer while commuting :) > Quickly checking LC_XO webpage > (http://www.jackson-labs.com/index.php/products/lc_xo): > "The unit includes internal 3.3V to 5V DC-DC power supplies and filters, and > can provide 5V at up to 50mA to external customer circuitry, as well as to > the external GPS antenna." > This seems compatible with the Trimble antenna recommended for N-series but > maybe I am missing something. > > Best, > Temir > ___ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com
