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

21–30 of 130 posts

Re: LimeSDR

#21

Post by jacquesm »

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?

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!

Re: LimeSDR

#22

Post by touisteur »

tzs wrote: post #17

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 t…

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.

Re: LimeSDR

#23

Post by stagger87 »

birktj wrote: post #19
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…

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.

> 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.

Re: LimeSDR

#24

Post by jacquesm »

superkuh wrote: post #15
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?

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.

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.

Re: LimeSDR

#25

Post by ronsor »

Blackthorn wrote: post #13
ronsor wrote: post #6

Earlier quoted context omitted.

At 5000 Hz, you could probably just rig up a sound card with a mic input.

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.

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.

Re: LimeSDR

#26

Post by WrtCdEvrydy »

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…

The best one is the ADS-B Out from airplanes, you can map the planes around you with a $20 widget.

Re: LimeSDR

#27

Post by rfdave »

octopoc wrote: post #16
stefan_ wrote: post #10

Earlier quoted context omitted.

But this is a fully generic SDR. Can this even be certified as some consumer product?

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.

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.

Re: LimeSDR

#28

Post by stagger87 »

octopoc wrote: post #16
stefan_ wrote: post #10

Earlier quoted context omitted.

But this is a fully generic SDR. Can this even be certified as some consumer product?

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.

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.

Re: LimeSDR

#29

Post by stefan_ »

octopoc wrote: post #16
stefan_ wrote: post #10

Earlier quoted context omitted.

But this is a fully generic SDR. Can this even be certified as some consumer product?

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.

Re: LimeSDR

#30

Post by cepher »

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.
Post reply on HN