Lime SDR (and Pluto, Too) Sends TV

If you have experienced software defined radio (SDR) using the ubiquitous RTL SDR dongles, you are missing out on half of it. While those SDRs are inexpensive, they only receive. The next step is to transmit. [Corrosive] shows how he uses DATV Express along with a Lime SDR or a Pluto (the evaluation device from Analog Devices) to transmit video. He shows how to set it all up in the context of ham radio. An earlier video shows how to receive the signal using an SDR and some Windows software. The receiver will work with an RTL SDR or a HackRF board, too. You can see both videos, below.

The DATV Express software has plenty of options and since SDR if frequency agile, you ought to be able to use this on any frequency (within the SDR range) that you are allowed to use. At the end, he mentions that to really put these on the air you will want a filter and amplifier since the output is a bit raw and low powered.

If you are old enough to remember when a TV transmitter was a big box full of circuitry, seeing video pour out of a little circuit board is pretty amazing. What’s more, is that on transmit and receive you can do an impressive amount of processing in software that would have been very advanced using traditional hardware.

Oddly enough, the RTL SDR was originally made to receive TV anyway. You can actually do the transmit with nothing but a Raspberry Pi, and [Corrosive] mentioned he’ll do a video about that soon.

21 thoughts on “Lime SDR (and Pluto, Too) Sends TV

  1. So very irresponsible to not even mention the fact transmitting without a license unless into a non radiating load is illegal in the US and most other developed countries.

    If you want to do cool shit like this, and others, do it right and go get your amateur radio license. Instead of being a turd and doing it illegally and not really knowing wtf you are doing, harming, interfering with, etc.

    1. Everyone knows that because there’s not one single article about ham radio that doesn’t have a million comments about legalities and regulations. I swear this is the most rigid and neurotic hobby–the airwaves are practically dead, the FCC doesn’t care about anything except protecting Verizon and co’s monopoly, no harm will come from a few competent, licensed citizens experimenting. Not like they allow you to do much of anything anyway.

      Everyone here knows a license is needed and most of us already have one, it doesn’t have to be disclaimered every time. This is a tech forum and assumes at least a basic level of knowledge. Otherwise–speeding on the highway is a way more unethical violation of the law than pirate radio.

      1. Part 5 (Experimental) licenses aren’t that hard to get. Easier to get if you can get it sponsored by a 4-year degree granting institution, a museum, an aquarium, or a “recognized” scientific organization. Even if not, “product development” is an accepted reason to receive a license, though I think you may have to submit some paperwork to suggest that’s what you’re really doing. It’ll be easier still if you request the ISM bands only. Enforcement is kind of like shoplifting – you aren’t likely to get caught but the penalties are pretty significant if you do.

    2. You are the reason your hobby sucks. I question whether I should even get a license these days, just for the fact that I don’t want to deal with people like you. The FCC can go shove it.

      I have a RIGHT to private communications, as far as I’m concerned. Encryption should not be banned.

    3. You are the reason your hobby sucks. I question whether I should even get a license these days, just for the fact that I don’t want to deal with people like you. The FCC can go shove it.

      I have a RIGHT to private communications, as far as I’m concerned. Encryption should not be banned.

      1. Is encryption allow on ISM bands for those who hold amateur licenses ?

        Because I can totally understand why it would be against the spirit of the global amateur radio bands, where encryption would provide nothing but a hindrance to the communal nature of the medium.

        1. No, encryption is not allowed in any licensed amateurr radio transmission with a few exceptions, basically RC aircraft or satellite control signals, where the code is considered identical to the transmission

          1. That said, almost all of the ISM bands are outside amateur frequency allocations, so the others are subject to different rules that I couldn’t tell you about.

          2. This is not correct. Encryption is not allowed when operating under amateur radio regulations (in the US) with the noted exceptions. There are overlaps between ISM and amateur radio frequency allocations in many bands. If you operate in conformance to FCC rules under part 15 (ISM), it doesn’t matter whether you have an amateur radio license or not (and encryption is legal). If you are operating under part 96 (Amateur Radio) then encryption is generally not allowed.
            While operating in part 15 generally requires properly certified transmitters, there is an exception for operating transmitters you have constructed as a hobbyist that technically conform to part 15 (up to 5 devices, CFR 47 15.23, Home Built devices) before they get certified. You cannot sell these devices without getting them certified. Note that this also does not allow you to operate purchased transmitters that are not FCC certified under any circumstances using part 15 rules. Certified devices can be identified by a label with an FCC label and FCC ID of the device (or included module). You can google the FCC ID to make sure it is legit.

            Getting an amateur radio license is an excellent way to familiarize yourself with the basics of RF design and operation and can be really useful in the field. It in no way precludes you from operating under ISM (part 15) rules.

        2. Yeah I misread the question, amateur radio licensing has nothing to do with the ISM bands in general, they happen to overlap in a few spots but the license won’t affect what you can do with ordinary ISM transmissions

    4. It’s perfectly legal to operate an unlicensed, home-built transmitter as long as it “does not cause interference to any licensed radio communications” and “accept[s] any interference that it receives.”

      Quote:
      Hobbyists, inventors and other parties that design and build Part 15 transmitters with
      no intention of ever marketing them may construct and operate up to five such
      transmitters for their own personal use without having to obtain FCC equipment
      authorization. If possible, these transmitters should be tested for compliance with the
      Commission’s rules. If such testing is not practicable, their designers and builders are
      required to employ good engineering practices in order to ensure compliance with the
      Part 15 standards.
      Section 15.23

      Home-built transmitters, like all Part 15 transmitters, are not allowed to cause
      interference to licensed radio communications and must accept any interference that
      they receive. If a home-built Part 15 transmitter does cause interference to licensed
      radio communications, the Commission will require its operator to cease operation
      until the interference problem is corrected. Furthermore, if the Commission determines
      that the operator of such a transmitter has not attempted to ensure compliance with the
      Part 15 technical standards by employing good engineering practices then that operator
      may be fined up to $10,000 for each violation and $75,000 for a repeat or continuing
      violation.
      Section 15.5
      47 U.S.C. 503

      Operating a prototype of a product that is ultimately intended for market is not
      considered “personal use.” Thus, a party that designs and builds a transmitter with
      plans to mass produce and market a future version of it must obtain an experimental
      license from the FCC in order to operate the transmitter for any purpose other than
      testing for compliance with the Part 15 technical standards. Information on
      experimental licenses may be obtained from the contact point listed in the Additional
      Information section of this bulletin. FCC authorization is not required in order to test
      a transmitter for compliance with the Part 15 technical standards.
      Section 15.7
      47 CFR Part 5

    5. Actually unlicensed radiation of RF energy (which may be either intentional or unintentional) is allowable in the US as long as the RF energy is below limits set in FCC rules part 15. True enough, that is often a rather small amount of energy, so operating under licensed conditions is often the more pragmatic choice for real world applications. Of course, the rules vary depending on the country where the prospective transmitter is to be located. Disregarding rules risks significant financial forfeiture when the offender is caught, not to mention careless operation could interfere with licensed communication systems, causing safety risks.

    6. Whilst I acknowledge Hackaday is U.S.-centric, U.S. jurisdiction stops just off shore. There are many jurisdictions who care little about RF radio above cell base station frequencies.

      Your complaint is baseless as the article mentioned “context of ham radio” and “on any frequency … that you are allowed to use” which to the average Hackaday reader signal there are licencing / permit requirements.

      My employer designs military equipment for non-aligned countries and not once have we had to modify equipment for any customer for as other many countries have neither the wherewithal, or staff and equipment to chase spurious – notwithstanding the United Nations has donated impressive amounts of technology to Developing Countries.

    1. It’s on my list of things to do I don’t do a lot with analog TV because I live north of the A line and generally don’t have enough bandwidth at the frequencies I have transmitters for to do a TV there.

      With digital I can transmit at 1mhz of bandwith or less vs 4-6 MHz analog.

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