[HN Gopher] LimeSDR
___________________________________________________________________
LimeSDR
Author : octopoc
Score : 75 points
Date : 2021-08-26 15:24 UTC (7 hours ago)
(HTM) web link (limemicro.com)
(TXT) w3m dump (limemicro.com)
| dang wrote:
| Some past related threads:
|
| _Investigating the Galileo Satellite Navigation System Outage
| with a LimeSDR_ - https://news.ycombinator.com/item?id=20464852 -
| July 2019 (41 comments)
|
| _LimeSDR Now Backed by the European Space Agency_ -
| https://news.ycombinator.com/item?id=16493727 - March 2018 (38
| comments)
|
| _LimeSDR Mini - An open, full-duplex, USB stick radio for
| femtocells and more_ -
| https://news.ycombinator.com/item?id=15318233 - Sept 2017 (46
| comments)
|
| _LimeSDR funded, some hours left to still get a discounted SDR_
| - https://news.ycombinator.com/item?id=11946239 - June 2016 (10
| comments)
|
| _LimeSDR GSM Base Station Demo_ -
| https://news.ycombinator.com/item?id=11931072 - June 2016 (27
| comments)
|
| _IoT wireless hacking - LoRa on the LimeSDR_ -
| https://news.ycombinator.com/item?id=11882491 - June 2016 (1
| comment)
|
| _Digital Video Transmission using LimeSDR and GNU Radio_ -
| https://news.ycombinator.com/item?id=11856912 - June 2016 (8
| comments)
|
| _LimeSDR: Flexible, Next-Generation, Open Source Software
| Defined Radio_ - https://news.ycombinator.com/item?id=11610521 -
| May 2016 (28 comments)
| nlh wrote:
| I was super into the ham world many many moons ago (DE K2KD), and
| my curiosity is definitely piqued with the arrival of SDRs.
|
| Dumb question(s): Is it possible to do "traditional" HF/VHF ham
| stuff with these mini SDRs? Is there a good software package that
| emulates the old-school rigs (but with fancy new features)? Are
| these radios powerful enough to drive an amp to get to something
| like 100W (or 1500W) on HF?
| cschneid wrote:
| Check out the Hermes Lite, it's an SDR with a transmit ability,
| and some other additional features. I think it's 10w by
| default, but a lot of people put that right into an amp to get
| up to 100+ watts.
| gorkish wrote:
| I immediately hit reply to suggest the Hermes Lite also;
| despite the crazy supply chain situation, there is a current
| manufacturing run going right now. With N2ADR's filter board,
| you have a complete 10W HF direct sampling transceiver. Add a
| hardrock PA and you can take that easily to 50W or 500W at an
| insanely low price point.
|
| I hand build a few of the early prototypes and have a couple
| of the production versions too. I cannot emphasize how
| underrepresented I think this radio is compared to a lot of
| the other SDR hardware out there. It compares favorably in
| performance and vastly exceeds the features of most amateur
| radio HF transceivers in the <= $2500 range.
|
| Because it speaks the OpenHPSDR protocol it can also run a
| digital predistortion algorithm called PureSignal that
| samples the PA output and distorts the input signal to
| correct for amplifier phase and power nonlinearity. Digital
| predistortion is relatively common in modern radios like
| cellular baseband, but to my knowledge PureSignal is the only
| open source implementation of such and the only
| implementation publicly available for an HF radio.
| superkuh wrote:
| Not without paying a bunch for bandpass filters and power amps
| to get it up high enough to actually drive your 100w amp. Most
| SDRs are just the transceiver without all the front-end parts
| you really need for a "usable" radio.
| jacquesm wrote:
| Yes, true, you'll need a bunch of intermediary stage amps as
| well, you won't drive 100W without something in the middle.
| Typically a set of usable stages would be an SDR, a very
| sharp bandpass filter, a 1W or so buffer, then something on
| the order of 5 to 10W and then into real power stages 50-100
| or so and if you want to go substantially higher than that
| you'll need yet another stage. And each of those will need to
| be perfectly regulated to avoid dumping a bunch of harmonics
| into the air.
| trothamel wrote:
| That's correct, though getting those is possible, and
| something of a fun project. I've found the stuff 60dbmco ( ht
| tps://www.ebay.com/sch/60dbmco/m.html?_nkw=&_armrs=1&_ipg=...
| ) makes to be useful for this .
|
| You're probably not saving any money this way, but you do
| learn a lot.
| jacquesm wrote:
| Before you start pumping out that kind of power I'd invest in a
| spectrum analyzer (which are surprisingly affordable today) to
| ensure that the signal that goes out is clean.
|
| Those mini SDRs when used for transmission will output a ton of
| harmonics because they are almost by definition not going to
| have any filtering on their output because that would limit
| their usability. When used for reception that is not a problem,
| if you start using them for transmission it's a completely
| different matter.
|
| Keep in mind that a power stage that responds well to a
| particular signal absent filtering is going to respond quite
| well to the main harmonics too!
| drmpeg wrote:
| That's for sure. Here's what an Ettus B210 (now $1472, not
| cheap) looks like with a fundamental at 145 MHz. 3rd harmonic
| is only 10 dB down. Power was 0 dBm (with a 20 dB pad on the
| analyzer input).
|
| https://www.w6rz.net/harmonic.png
| jacquesm wrote:
| That's even worse than I thought it would be. A cheap one
| will likely not do better. At least they picked the HAM
| bands smart so harmonics tend to end up in the next HAM
| allocated frequency range up. But SDRs being what they are
| there are no passive components on board to ensure the
| signal stays 'in its lane'.
| gmiller123456 wrote:
| As far as transmitting, it's not really practical. Receiving,
| yes. What I normally do is look for signals using my SDR, and
| when I want to make a contact, use my FT991A. Even though the
| 991 has a SDR in it, the dedicated ones have a much wider
| bandwidth, and the better display and UI of a computer make
| things a lot easier.
| ehttwljlq34y wrote:
| Biden needs to be removed _immediately_.
|
| He has murdered dozens of American citizens and was laughing
| about them yesterday.
|
| Fucking evil piece of shit.
| moftz wrote:
| I haven't used a LimeSDR but I have used the mini version which
| is just about the same hardware minus the extra TX/RX channels.
| It's a great little device that covers a massive spectrum with a
| decent bandwidth as well. Comparable devices from Ettus are much
| more expensive. I'd love to own one for ham stuff but haven't had
| much time for that hobby lately. The Lime rep did give me a mini
| PCB on a keychain once, coolest trinket I've ever gotten at a
| conference.
| ngz00 wrote:
| Any suggestions on where to start to use this as a LTE uplink
| that reads from an SD card and uploads images? I'd like to
| replace my expensive faulty game camera subscription.
| myself248 wrote:
| Using an SDR is the most painful and power-hungry way to
| replicate what already exists as cheap, optimized, small,
| commodity LTE modems.
|
| Use the SDR for standards that don't exist as finished silicon
| yet.
| themulticaster wrote:
| In addition to what myself248 said:
|
| In case you aren't familiar with the details of consumer RF
| standards (including IEEE 802.11, but especially LTE or
| anything cellular related) or don't have some prior RF
| knowledge: To put it mildly, LTE is not an easy standard to
| implement on an SDR, especially if it's your contact with SDRs.
| Even GSM is nowhere near a simple stack.
|
| If you want to get a feeling for what kind of cellular projects
| are possible using SDRs _from a hobbyist /free software
| perspective_, have a look at the Osmocom (Open Source Mobile
| Communications) projects [1] as well as Harald Welte's blog [2]
| (one of the main Osmocom contributors). The Osmocom projects
| are focused on the carrier side of LTE/GSM networks AFAIK.
|
| Another warning: While cellular technology involves lots of
| networks, it is completely different from the standards and
| terminology used in the Internet. For example, citing the
| description for OsmoHNBGW: "An Open Source implementation of a
| HNB-GW (HomeNodeB-Gateway), implementing the Iuh, IuCS and IuPS
| interfaces. It aggregates the Iuh links from femtocells
| (hNodeBs) and presents them as regular IuCS and IuPS towards
| MSC and SGSN (such as OsmoMSC and OsmoSGSN). It uses M3UA as
| signaling transport." The description totally makes sense to an
| insider, but if you only dabbled with TCP/IP, routers and
| switches so far, be prepared for learning a whole new world of
| networking terms.
|
| If you _are_ familiar with RF /cellular engineering and/or if
| you're trying to do this on a corporate budget then you
| probably already know what I mentioned above, and your project
| can certainly be realized for $$$.
|
| If you're looking for a one-off DIY solution then you could use
| something like a u-blox SARA-R4 [3] modem (for NB-IoT/low
| bandwidth). Similar boards with higher bandwidth also exist.
|
| [1] https://osmocom.org/projects
|
| [2] https://laforge.gnumonks.org/blog/
|
| [3] https://www.sparkfun.com/products/14997
| marcodiego wrote:
| LTE, GSM... Does it means it is now easier to build an entirely
| free device that can be used as a cellphone?
| themodelplumber wrote:
| You mean with proper licensing? That might be the tricky part;
| use of the rf spectrum is probably monitored and regulated,
| depending on where you're at in the world.
| IshKebab wrote:
| I got a LimeSDR when they first made them. Unfortunately the
| whole SDR software ecosystem is pretty terrible. Even with
| something as popular and widely supported as RTL-SDR most of the
| software is unusuable (with some happy exceptions). It also
| doesn't help that there is an absolute mountain of SDR software
| out there, but 99% of it is "this is cool, I'm going to write...
| eh nevermind" type stuff. There's so much ( https://www.rtl-
| sdr.com/big-list-rtl-sdr-supported-software/ ) that I can't even
| find the one good one I found last time I used an RTL-SDR.
|
| I guess that is what happens if you play with software written by
| uber-nerds for uber-nerds.
|
| Anyway in conclusion I would NOT recommend getting a LimeSDR
| unless you are really really into SDR and it's your only hobby,
| or better yet, your job.
| jandrese wrote:
| The LimeSDR Kickstarter made these grand promises of running a
| repo full of usable apps for your board. Many years later that
| repo is still quite spartan.
|
| I've generally had pretty good luck with my LimeSDR, but I
| don't try to push it too hard. The documentation can be
| frustratingly minimal in so many places and the USB
| implementation on my board is touchy (it must be plugged into
| exactly the right port on my computer or the device enumerates
| incorrectly and is unusable).
| platz wrote:
| as an early limesdr buyer i completely agree
| tzs wrote:
| The couple of times I've had something I wanted to do that needed
| an SDR more powerful than than an RTL-SDR and decided I wanted a
| LimeSDR or LimeSDR mini...the lead time on them has been such
| that it would not arrive in time for the project I wanted it for.
|
| Right now, both LimeSDR and LimeSDR mini orders place now don't
| ship until Feb 28 2022, except for the LimeSDR PCIe which ships
| Sep 29 2021. (You might be able to get the USB LimeSDR sooner
| from Sparkfun. They say they might have some coming in early
| October).
|
| Projects where I'll need something like that are rare enough that
| I can't really justifying buying one just in case another such
| project comes up.
| touisteur wrote:
| It is very depressing indeed. Has eBay or second hand given
| good results on this to anyone?
|
| I guess we'll have to wait for
| https://www.crowdsupply.com/krakenrf/krakensdr but I can't
| imagine the price will be very light-hobby-adapted.
| syedkarim wrote:
| We are shooting for a price of $299 for KrakenSDR.
| touisteur wrote:
| Oh thanks for your answer, that's very interesting! For
| someone wanting to upgrade from rtl-sdr that seems a good
| step up.
|
| While you're here, I'm particularly interested whether
| you're aiming for something more ambitious some day or 100%
| focused on kraken? I'm thinking coherent 32/64 rx channels
| or more? Also, is there a way to assemble two krakens and
| synchronize them somehow so as to have 10x coherent rx? :-)
|
| There's probably a better channel of communication for such
| questions ...
|
| Thanks again for jumping in with a correction.
| syedkarim wrote:
| We have plans to offer a few different versions of
| KrakenSDR. The entry level version will likely be the
| current version with 5 tuners. We are laying out an idea
| for 8 tuners, integrated CPU, and pre-set antennas;
| basically a turnkey system for remote operations. We can
| definitely produce more exotic beasts, but I don't think
| there is much of a market for a Kraken with a hundred
| heads.
| structural wrote:
| Components for producing SDRs are impacted by the overall
| semiconductor shortage very significantly, too: keeping stock
| of what are fairly niche products is difficult when times are
| good, but with component lead times in the 52-80week ranges
| (and still increasing), there's absolutely no room to adapt to
| what customers might want a year from now. It really sucks for
| everyone.
| scrps wrote:
| Not sure your exact use-case but if you are frequency-limited
| by the RTL and you feel like soldering, you can mod a
| SUP-2400[0] to be a 4.5GHz downconverter for the RTL[1].
|
| [0]: https://www.solidsignal.com/zinwell-directv-b-band-
| converter...
|
| [1]: https://www.kd0cq.com/2016/04/part-ii-the-mod-receive-up-
| to-...
| rtkwe wrote:
| It's tough for small groups or hobbyists to do because building
| and keeping stock is a considerable investment and risk so a
| lot of times they'll do batches constantly.
|
| Also if you've had multiple projects that would want to use it
| why not order it knowing you'll probably have a similar idea in
| the future?
| octopoc wrote:
| One of my concerns with using an SDR is that the FCC basically
| requires DRM[1]:
|
| > ...importers and marketers should ensure that [two-way radios]
| are properly certified and labeled as FCC-compliant and cannot be
| easily modified to operate outside its grant of certification.
|
| So if you use an SDR for LoRa, you have to make it hard for users
| to modify the code to emit a different frequency.
|
| [1]: https://docs.fcc.gov/public/attachments/DA-18-980A1.pdf
| iNate2000 wrote:
| That document (DA 18-980) talks about "importing two-way
| VHF/UHF radios... used primarily for short-distance, two-way
| voice communications."
|
| In other words: cheap walkie-talkies that don't comply with FCC
| regulations.
|
| Such radios typically max out at 5w.
|
| The LimeSDR claims 10dBm - which I believe means about
| 10milliwatts.
|
| In other words, that FCC memo is concerned with radios being
| sold that are something like five hundred times as powerful as
| a LimeSDR. And therefore much more likely to interfere with
| other transmissions.
| birktj wrote:
| This is probably true, meaning you can't really have a FCC
| certified tx-capable SDR. However in order to legally use the
| tx-capabilities of an SDR you probably have to be a ham anyway.
| And hams don't need their equipment to be FCC certified if I am
| not mistaken.
| stagger87 wrote:
| > However in order to legally use the tx-capabilities of an
| SDR you probably have to be a ham anyway.
|
| You can transmit in the ISM bands without a license. There
| are still power restrictions which most SDRs won't exceed
| anyways.
| syedkarim wrote:
| Yes, a general user/consumer can transmit in the ISM band
| without a license, but they are still required to use
| intentional transmitters which have been certified by the
| FCC.
| stagger87 wrote:
| > but they are still required to use intentional
| transmitters which have been certified by the FCC.
|
| For a hobbyist experimenting with an SDR, this wouldn't
| apply.
| stefan_ wrote:
| But this is a fully generic SDR. Can this even be certified as
| some consumer product?
| octopoc wrote:
| I mean if you used an SDR in your consumer product. Let's say
| you make a dual purpose LoRa / WiFi radio to put in vehicles
| for a fleet management solution. If you use an SDR, you'd
| have to lock it down with DRM to prevent end users from
| repurposing it.
| rfdave wrote:
| Well, it would also cost at least 10x what a dual purpose
| LoRA/WiFi radio would cost if it were built out of LoRa
| parts from Semtech and an ESP-32.
| stagger87 wrote:
| Using an SDR for this kind of product would be horribly
| cost and time inefficient. You would design it with off the
| shelf WLAN and LoRa ICs.
|
| > If you use an SDR, you'd have to lock it down with DRM to
| prevent end users from repurposing it.
|
| Not any more so than a product you designed that didn't use
| an SDR as its core.
| stefan_ wrote:
| Yes, but the same applies to your WiFi router even if it
| has hardware filters. Its simply a certification
| requirement.
|
| That doesn't have anything to do with LimeSDR. This is
| already not a product that is certified for anything. It
| exists in a very gray zone where anyone using it for
| transmission is likely in violation of the law unless they
| obtained a development/testing license in the specific band
| they are using.
| 7kay wrote:
| The easiest way to leave the gray zone would be to get a
| ham radio license. Although this might vary from country
| to country, generally you are allowed to use selfbuilt
| transmitters in specific frequency ranges, which also
| includes noncertified hardware.
| vdqtp3 wrote:
| > likely in violation of the law...development/testing
| license
|
| Or they just have a ham radio license
| amelius wrote:
| No WiFi support?
| rfdave wrote:
| WiFi is hard to support, it's very complex from a signal
| processing and timing perspective.
| amelius wrote:
| And probably also the protocol.
| nuand wrote:
| Wifi is a pretty difficult protocol, but fortunately Linux
| ships with mac80211. So all that is needed is an SDR based
| PHY such as https://github.com/Nuand/bladeRF-wiphy/ .
| cepher wrote:
| Does anyone know if this is more appropriate than the PlutoSDR
| for hobbyists? Seems like they have similar specs and are around
| the same price.
| ohazi wrote:
| I haven't played with the Pluto, but I do have a USRP, which
| uses the Analog Devices front-end, and it's leagues more
| reliable than the LimeSDR.
|
| I would absolutely go for the Pluto if it'll work for your
| application. I guess the main limitation is USB2 for getting
| the captured signal out, so you wouldn't be able to use it for
| crazy high bandwidth applications.
| ohazi wrote:
| I wish them luck, but judging by the ~week I spent trying to get
| a LimeSDR mini to work, their product is so half baked that it's
| basically not fit for purpose, and if you're considering getting
| one, I'd recommend something with an Analog Devices front-end
| instead.
|
| The PLL would fail to lock at random frequencies and
| temperatures. You'd try to scroll through e.g. the 2.4 GHz ISM
| band and would randomly get downconverted signal or baseband
| noise on every other click. Two minutes later, the set of bands
| you could capture would be entirely different. There was no
| consistency whatsoever.
|
| When I went to their forums to see if other people had
| encountered the same issue, it turned out that basically none of
| the LimeSDRs even pass their own self tests [1]. I don't know how
| they're still selling these devices... they don't work.
|
| I returned it, paid ~4x more for a USRP, and could not be
| happier. The hobby is playing with radio modulation schemes, not
| debugging a defective piece of silicon.
|
| [1] https://discourse.myriadrf.org/t/new-limesdr-mini-
| loopback-t...
| azinman2 wrote:
| Which USRP do you use? And what do you do specifically with it?
| ohazi wrote:
| A B205.
|
| Mostly playing around with high spectral efficiency digital
| modulation techniques like PSK/QAM and OFDM using GNU Radio.
| Trying to shovel as much data as I can between two links with
| as little power as possible. I'd like to experiment with
| below-the-noise-floor communication, but haven't gotten there
| yet.
|
| It's sort of silly, because you can do all of this in
| simulation, but it's more fun with real hardware. Eventually
| I'd like to be able to build a (solar?) drone with a radio
| system resembling a cell tower and do ground-drone-ground
| relay experiments, but I'm _extremely_ not there yet.
|
| I also wanted something that could transmit after I got a ham
| radio license (out of boredom during the pandemic, shortly
| after they started doing testing online), but haven't really
| used it that much, as I don't really have a good antenna set
| up. For data experiments, a wire or a PCB trace works well
| enough.
|
| I also do a lot of embedded Wi-Fi / Bluetooth stuff at work
| and would like to use this for packet captures, but haven't
| needed to yet. It's completely overkill for something like
| that though.
| garaetjjte wrote:
| I bought LimeSDR Mini back at crowdfunding campaign and didn't
| have good experience too. Janky middleware, problems with
| tuning, randomly occuring errors. I haven't used it in quite a
| while and I hoped these are all software problems they would
| fix eventually, sad to hear it is still broken.
| Prcmaker wrote:
| Unfortunately, I agree with this. I was an early backer on the
| mini, and got it with the aluminium case. While the case looked
| great, it mechanically interfered with the antennae, meaning
| they didn't actually make a connection. Their support taught me
| how to screw in an antenna, ignoring the actual problem, before
| deciding my issue was too hard and ignoring me. I got
| eventually got in some antennae from Ossmann, but when other
| hardware/software issues cropped up, my enthusiasm for the
| device had already waned too much to want to put in effort. I
| got some basic things working eventually, but never
| outperformed cheaper devices.
| tibbon wrote:
| I've got the LimeSDR standard size one, and I've never been
| able to make good use of it. Thinking of throwing it on eBay
| soon.
|
| Software support is far more limited than I'd prefer compared
| to other SDRs too, which someone at DEF CON told me was because
| they pissed off the community and copied of a lot of things
| from another SDR project. I don't know how true it is, but I
| can see that support on all sides is pretty half baked.
| atonse wrote:
| SDR is one of those technologies I still want to play with that I
| feel will open up this incredible new world to my curious mind.
| All of a sudden, the invisible waves around us that we often
| tangentially know about but never think about (because we can't
| see, smell, or hear them), become a whole sixth sense to explore.
|
| I really hope for some free time to play with this, and to expose
| this invisible world to those around me (especially my kids), in
| a way that has been much less accessible in the past.
|
| Even things like ceiling fan remotes, door sensors, wifi, a
| garage remote, a car key, ISS video feeds, data from stuff in
| SPACE, weather data, I mean, we're bombarded with it every day
| all the time and we just don't realize it.
|
| Anyway, just had a wide-eyed moment, as I do every time I read
| about another thing that makes SDR just a bit easier to access.
| WrtCdEvrydy wrote:
| The best one is the ADS-B Out from airplanes, you can map the
| planes around you with a $20 widget.
| CSSer wrote:
| This sounds really cool. When you say 'around you', what kind
| of radius are we talking?
| ambientenv wrote:
| You may be able to find out more information, including
| instructions on assembling your own ground station, at
| Flightaware - https://flightaware.com/adsb/piaware/build/
| rtkwe wrote:
| Hard to answer that it depends on so much; the quality of
| the rx you're using, the antenna and your local environment
| (open field? wooded area? valley? top of a hill?).
| sosborn wrote:
| It really depends on the environment around you. I live
| deep in valley, so my range is pretty limited to line of
| sight.
| jjwiseman wrote:
| As others have said, it depends on terrain, your antenna,
| the altitude of the aircraft, etc. But generally, 50-60
| miles is pretty easy with almost any setup.
|
| I have an ADS-B antenna mounted on my roof that feeds into
| a filter and an amp, and I get less than 50 miles in some
| directions (because of mountains) and more than 150 miles
| in other directions (over the ocean).
|
| Here's a map of my coverage (any altitude), with range
| rings every 50 miles:
| https://www.flickr.com/photos/wallofhair/51403416502
|
| My coverage for altitudes up to 10,000 feet:
| https://www.flickr.com/photos/wallofhair/51404165241
|
| It's radio, so nothing's guaranteed. Those maps show the
| maximum ranges at which I picked up any aircraft in that
| direction over a couple months, so they're kind of a best-
| case, showing when conditions possibly happened to be
| perfect. I also have a dead zone just around my house,
| because my gain is configured to prioritize range. Lots of
| tradeoffs in RF.
|
| There's a site (with an impossible-to-remember name) that
| can predict antenna range for you (it's not obvious how to
| use it; Try "New panorama", then "Up in the Air"):
| http://www.heywhatsthat.com/
|
| Here's what it shows for me. The blue ring is 40,000 feet
| altitude and the orange ring is 10,000 feet altitude:
| https://www.flickr.com/photos/wallofhair/51404944889
| slobiwan wrote:
| How do you get that footprint plot? I'm using dump1090-fa
| and don't see it
| TaylorAlexander wrote:
| It's very fun! I use it to monitor for low flying aircraft
| around a farm where I am doing some drone experiments. The
| legal drone limit in my area is 400 feet above ground level
| and near the hills some aircraft fly pretty low, so I'm
| going to ground the drone any time an aircraft is nearby
| that is not above 10kft.
| toomuchtodo wrote:
| I highly recommend not relying on SDR ADS-B reception
| alone and also checking online data systems for ADS-B
| that also use multilateration to track aircraft using
| their transponder when they aren't ADS-B capable.
| Otherwise you might be operating under the assumption
| there are no contacts in your working airspace when there
| is aircraft present but not announcing their location.
|
| https://flightaware.com/adsb/mlat/
| ericbarrett wrote:
| You need both data sources--a number of planes are
| "delisted" from the commercial trackers and won't show
| up, but they still broadcast ADS-B. You can find partial
| lists of such registrations through a keen Google search.
| [deleted]
| toomuchtodo wrote:
| https://www.adsbexchange.com/ does not blacklist or
| delist aircraft tail numbers fwiw.
| BuildTheRobots wrote:
| 160 miles with a PS6 rtlsdr and an antenna I bodged out of
| coax. Its painfully easy. Also have a nosy at POCSAG -
| there's still a little bit left in the UK.
| tjohns wrote:
| It depends on your location, antenna, and the aircraft's
| elevation, but in the bay area I'll often pick up aircraft
| all the way out to Sacramento. Sometimes quite a bit
| further.
|
| Of course, the higher the aircraft the further you can
| "see" them. Most of the traffic I see is within 45 miles
| (especially low flying GA traffic), but I'll still pick up
| the occasional high altitude aircraft at 100+ miles out.
| sliken wrote:
| Similarly you can map out lightning strikes with similar
| tools/methods.
| gmiller123456 wrote:
| Can you provide some resources about this?
| ambientenv wrote:
| There is the Blitzortung.org site -
| https://www.blitzortung.org/en/cover_your_area.php -
| which has some interesting information.
| gmiller123456 wrote:
| Thanks, but that link appears to be about dedicated
| modules. I already have a HackRF One and an RSPDuo, the
| person I was replying to seems to indicate it was
| possible to use a typical SDR.
| opwieurposiu wrote:
| SDR made me understand how much RF noise my desktop computer
| emits. Lots of spikes between 400-500mhz. Could be my monitor
| also, as scrolling text seems to emit the most noise.
| cschneid wrote:
| There's a fun toy I just got called 'TinySA' (tiny spectrum
| analyzer). For $60, plus an adapter + some wire (another $20
| maybe), you can get a live battery powered little receiver that
| shows noise across the whole spectrum from less than 1mhz
| through 350mhz.
|
| A really basic loop of wire is a directional antenna, so you
| can narrow down exactly what is causing issues too.
|
| I'm doing it to find noise issues for my ham radio setup, but
| it can be generally fun. Not quite an SDR, but to find noise
| sources it's pretty amazing for so cheap.
| tzs wrote:
| My Samsung monitor does that.
|
| It's bad enough that I lose several channels on my Samsung TV
| when my Samsung monitor is on if the TV antenna is in the same
| room as the monitor.
| jareklupinski wrote:
| interesting... I guess I never scrolled while looking at
| wideband noise :) I'm going to see if I can determine what
| is/was displayed on the screen by filtering/machine learning
| the noise, fingers crossed
| themodelplumber wrote:
| Same here with the monitor, I have an old Dell 24" from 2006
| that I somehow keep around. I've learned not to expect much if
| my ham radio is within 3 feet of it. Probably fixable with some
| clip-on parts but for now it's easier to scoot the chair
| over...
| easton_s wrote:
| https://www.drti.com/
|
| https://web.archive.org/web/20161106083817/http://www.drti.c...
|
| The true master of SDR....
| rektide wrote:
| still havent used mine. supposedly theres not as much software
| thats ready for limesdr, that this is a mire rareified pick than
| many ither options.
| Blackthorn wrote:
| Does anyone know of a solution that can go down to the 5khz
| range? Older (...and even newer) gym equipment uses the gymlink
| protocol for heart rate monitors instead of low power Bluetooth
| and friends, and very few monitors support it anymore. I wanted
| to try to make a converter but couldn't find anything to output
| in that frequency.
| ThrowawayR2 wrote:
| The only thing I can think of that goes that low out of the box
| is the old Ettus Research USRP1, B100/B110, or E100/E110 SDRs
| combined with both a LFRX daughtercard and LFTX daughtercard,
| which are DC - 30 MHz.
|
| The SDRs themselves can occasionally be found on eBay and the
| daughtercards are still sold directly by Ettus Research or
| themselves occasionally can be occasionally found on eBay.
| octopoc wrote:
| I think it's pretty easy to make circuitry to shift a radio's
| frequency. If you did that with LimeSDR you'd still get the
| same bandwidth but it would be shifted into a different range.
| lxe wrote:
| Try an upconverter like this https://www.nooelec.com/store/ham-
| it-up.html or https://airspy.com/spyverter-r2/
| ronsor wrote:
| At 5000 Hz, you could probably just rig up a sound card with a
| mic input.
| Blackthorn wrote:
| I need to output the 5khz, not input it. Would I be able to
| do that with a sound card in a small form factor? The idea is
| to have a small box that can convert my heart rate monitor to
| something that the gym equipment can understand.
| ronsor wrote:
| I believe attaching an antenna to the card's output could
| work. For small form factor, a USB sound card and a
| Raspberry Pi is a possibility.
| jpindar wrote:
| I've used a cell phone as an audio signal generator for
| testing transmitters. There are apps for sending a
| continuous signal, and I assume it would be easy enough to
| write one for sending a modulated signal.
|
| BTW, this is one reason why I won't buy a phone without an
| audio jack.
| jquast wrote:
| Ham It Plus can go upconvert as low as 300Hz, compatible with
| any SDR you just shift the frequency in software
| https://support.nooelec.com/hc/en-us/articles/360005812474
| Blackthorn wrote:
| Guess I didn't make it clear and that's my bad. I need to
| output 5khz, not input. The input is a more modern Bluetooth
| protocol.
| user-the-name wrote:
| Why not just use audio out then?
| jquast wrote:
| sorry maybe we misunderstand each other, I just got my
| license last year but this FAQ link reads, "Is the Ham It
| Up capable of transmitting as well as receiving? Even on
| lower frequencies? -- Yes, it is bidirectional, so you can
| transmit and receive on any frequency within range,
| provided that you have a compatible transceiver, like the
| HackRF One. "
| moftz wrote:
| 5KHz is pretty low, it would be difficult finding anything in
| the ham category because no ham bands are that low. You would
| need to probably build your own receiver. The good news is that
| 5KHz is super low frequency and could easily be received with a
| crystal detector. Antenna connects to an LC resonator centered
| at 5.3KHz, pass the result of this through a diode and then
| into a microcontroller. Many have analog input pins and analog
| comparators built-in that can trigger an interrupt. You would
| need to figure out what voltage level you expect to see from
| the detector when a heart beat signal is sent and then apply
| that voltage to the other side of the comparator. Some
| microcontrollers even have a real analog voltage output that
| could allow you to adjust the voltage through software. The
| microcontroller would then trigger an interrupt and do
| something every time a heart beat signal is received (send it
| through serial to a PC, compute heart rate, display something
| on a LED screen, etc).
|
| If you need to broadcast at 5.3KHz, that's pretty easy too.
| There are numerous designs out there for a basic CW transmitter
| (https://makerf.com/posts/ten-minute-transmitter). You may have
| trouble finding a crystal centered at your 5.3KHz frequency.
| platz wrote:
| The multichannel components LimeSDR used are more constructed for
| streaming video applications, but they dont have good sensitivity
| in the HF range.
|
| I wish I had gotten a hackRf instead, which also had better
| tooling support
| stagger87 wrote:
| This doesn't seem right, you might be thinking of a different
| product. The LimeSDR uses the LMS7002 IC as an all in one dual
| channel RF to bits chip. The chip specifically is targeting
| broadband wireless communications applications. Data sheet
| linked below.
|
| https://github.com/myriadrf/LMS7002M-docs
| platz wrote:
| The issue is not with the chip itself, but with with the
| choices made for the board construction
| https://wiki.myriadrf.org/LimeSDR_HF_Performance
| stagger87 wrote:
| I was more specifically responding to your comment that it
| was constructed for "streaming video applications". I don't
| think the SDR is targeting this application.
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