Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

LimeSDR

limemicro.com

Post reply on HN
Print view View original

121–130 of 130 posts

Re: LimeSDR

#121

Post by plugger »

stefan_ wrote: post #29
octopoc wrote: post #16

Earlier quoted context omitted.

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.

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.

Or put the unit in a faraday cage to carry out testing. I believe a lot of people do this to allow them to play with transmission while not breaking any laws.

Re: LimeSDR

#122

Post by plugger »

7kay wrote: post #93
stefan_ wrote: post #29

Earlier quoted context omitted.

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.

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.

I'm not too sure about that. Having a HAM radio license would allow you to transmit on bands licensed for HAM usage. A lot of the stuff that people want SDRs for (especially for transmitting) lies outside of those bands.

Re: LimeSDR

#123

Post by plugger »

iNate2000 wrote: post #49
octopoc wrote: post #7

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/publ…

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 h…

> That document (DA 18-980) talks about "importing two-way VHF/UHF radios... used primarily for short-distance, two-way voice communications."

I thought it was more along the lines of going after Baofengs, not CB radios, hence the calling out of VHF/UHF radios specifically.

Re: LimeSDR

#124

Post by toomuchtodo »

TaylorAlexander wrote: post #115
toomuchtodo wrote: post #76

Earlier quoted context omitted.

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/

Sounds like a good idea. Thanks for the suggestion.

Hope it helps.

Re: LimeSDR

#125

Post by jmrm »

atonse wrote: post #9

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 aro…

If you want to play without spending too much money or time, yo always can get a chinese DVB-T USB receiver or similar with a RTL chip. It cost less than 50 bucks and usually works well without too much configuration AFAIK. Don't expect an incredible SNR or wideband, but it's pretty good for tinkering.

Re: LimeSDR

#126

Post by jmrm »

Blackthorn wrote: post #2

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.

I find totally rare that these devices works at 5kHz. instead of 5MHz or 500Khz (for example). At 5kHz you would need in theory huge antennas to being able to transmit and receive the signal correctly, and hundreds of kHz frequencies are totally achievable even with the most basics mid 1900s telecom systems.

If you know the data to send, and you are totally sure the data is sent electromagnetically at 5kHz, you can modulate in as sound in a computer and play it in a PA system connected to a long cable,

Re: LimeSDR

#127

Post by jmrm »

nlh wrote: post #14

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?

AFAIK that radios aren't usually that powerful (at least, legally to non-commercial use), and usually amplifies the modulated signal from the machine, they doesn't have an input of a direct signal to amplify and send.

Anyway, I think you can send signals in baseband from the computer or the SDR and let the radio modulate it.

Re: LimeSDR

#128

Post by slobiwan »

slobiwan wrote: post #96
jjwiseman wrote: post #62

Earlier quoted context omitted.

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…

How do you get that footprint plot? I'm using dump1090-fa and don't see it

To answer my own question, in case others are interested: https://discussions.flightaware.com/t/how-do-you-create-a-co...

Re: LimeSDR

#129

Post by unwiredben »

I've got a LimeSDR Mini. I mainly use it as an ATSC 1.0 signal generator from time to time for testing TV tuner code at work, and it does a good job, as long as I'm running it on a PC with a high-bandwidth USB 3.0 port. I've had issues going through hubs.

Re: LimeSDR

#130

Post by mrjeeves »

tibbon wrote: post #85
ohazi wrote: post #71

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 downconver…

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 ha…

Argh, I'm jealous.

I've been looking for suitable SDRs in the ~£180 range for a few months now, and nowhere has one suitable for 5G NR or 4G LTE available. HackRF seems to be pretty crippled in mobile networking, and Pluto seems to not work at all on srsRAN/srsLTE.

I doubt you'd be willing to let go of your full-size LimeSDR for £180, though, and I don't blame you based on its demand level.

Post reply on HN