3 ms·

Wide-band WebSDR: Control a short-wave receiver over the web

54 points by SoulMan 11y ago

dest 11y ago
what's the periodic signal at 27 MHz?
- jdietrich 11y ago
  It's a local pager service that overloads the front end on the receiver.
jimmcslim 11y ago
Awesome! Keep meaning to get into SDR or ham somehow. There's chatter at 17.79MHz... but can't really make it out.
- jdietrich 11y ago
  If you're interested, it has never been cheaper or easier to get into the radio hobby. You can buy an RTL-based receiver with an upconverter on eBay for less than $50, that will receive on 100kHz to 1.7GHz. With a technician class license and a $30 Baofeng transceiver, you can start working UHF/VHF repeaters.
  - csirac2 11y ago
    I hate to be a buzz kill, but some of those Baofengs really need harmonic suppression filters installed. They're popular here in Australia, but I saw a friend put his on a spectrum analyzer and saw 2nd harmonic at ~-5dBc! I know they're only low power, so it's likely harmless, but it's stuff like this which makes it harder for amateur radio to retain the rights we have left on the spectrum, and raises the noise floor for everyone.
    - morganvachon 11y ago
      I agree, I've got a Baofeng UV-5R and while it's not a bad radio overall for the price, it's got the dreaded harmonic issue too. It sounds excellent on the band you're actually trying to transmit on, but I only use it as a backup since I don't want to cause issues on other bands. I'd say to the prospective new ham, spend just a few more bucks and get an Anytone or Tera radio. They are well made, full featured, and still half the cost of your average Yaesu or Icom radio. Barring that, look for well-kept used gear on eBay or at hamfests, or borrow a good radio from a local ham. There aren't many of us left, but I'd still say everyone knows someone who knows a ham.
      - fluxquanta 11y ago
        >They are well made, full featured, and still half the cost of your average Yaesu or Icom radio. They may not have the most features, but the Yaesu FT-252's are 5W, 2M handhelds for under $100. Plenty suitable for repeater work.
    - fluxquanta 11y ago
      Absolutely this. The lowest end Yaesu handhelds, for example, can be had for under $100 USD, provide better reliability with none of that QRM, and a high resale value. Stay away from the Woxuns or Baofengs, unless you want to just piss everyone off.
      - jimmcslim 11y ago
        Don't know if anyone if still watching these comments, but the thing that probably puts me off is the antenna requirements; that part seems to be quite DIY whereas I'm looking for something a bit easier but powerful enough to whet the appetite/be interesting (and preferably without some massive array in my backyard/on my roof!)
        csirac2 11y ago
        You don't need an insane antenna setup to start out. A lot of Amateur radio people love optimizing their antennas for efficiency, skywave propagation, frequency agility etc. but it's not required for basic operation especially in higher frequencies. All radios, regardless of brand, have essentially the same laws of physics driving their antenna requirements (well, some have fancy in-built antenna tuning capability but we're talking small budgets here). But perhaps I've misunderstood. The crazier antennas are generally down in HF frequencies, below ~30MHz. They're crazier because longer wavelengths put more physical demands on antenna optimization. Making an antenna which efficiently operates a 4MHz chunk of spectrum 144-148MHz means you can build something tuned at 146MHz and only suffer very small performance difference when moving <2% off either side of this range. That's a completely different story to HF freqs, Eg. operating 1.8-5.5MHz is <4MHz of spectrum but that <4MHz chunk represents a 300% increase in frequency moving from lower to upper end, a far cry from the 2% needed before. So, to summarize, you can definitely and easily start out without any DIY gear, just usin turn-key stuff. Make friends with other amateurs working the higher/easier frequencies. Even in HF, you can still go a long just by draping bits of old wire around the place, there's still a bit of an art to this but not so difficult to learn :)
mailslut 11y ago
An index of others also online at: http://www.websdr.org http://www.websdr.org
philcrump 11y ago
I help run one for the VHF/UHF Radio Bands, located in Surrey, UK. http://websdr.suws.org.uk/ http://websdr.suws.org.uk/
atlantageek 11y ago
Too bad they wont open source the software.
- dnet 11y ago
  A friend of mine recently open sourced a similar solution. - Code: https://github.com/simonyiszk/openwebrx https://github.com/simonyiszk/openwebrx - Short intro: http://www.rtl-sdr.com/openwebrx-an-multi-user-rtl-sdr-receiver-with-web-interface/ http://www.rtl-sdr.com/openwebrx-an-multi-user-rtl-sdr-recei...
god_bless_texas 11y ago
Every now and then you can hear US number stations kick off there.
- fapjacks 11y ago
  No idea why you're downvoted. It's absolutely true.
fapjacks 11y ago
Come join us in #priyom on Freenode[0] if you'd like to get into number stations! We have a channel bot hooked into our schedule (which has been created over a long time of listening to number stations and tracking transmission patterns) which posts links to this SDR when a number station is on. Just to make a guess, there are number station transmissions at least several times a day, some days as many as several an hour. It's a ton of fun and we're pretty friendly! Stop by and say hi! [0] http://webchat.freenode.net/?channels=priyom http://webchat.freenode.net/?channels=priyom

54 points by SoulMan 11y ago

dest 11y ago

what's the periodic signal at 27 MHz?

jdietrich 11y ago
It's a local pager service that overloads the front end on the receiver.

jimmcslim 11y ago

Awesome! Keep meaning to get into SDR or ham somehow. There's chatter at 17.79MHz... but can't really make it out.

jdietrich 11y ago
If you're interested, it has never been cheaper or easier to get into the radio hobby. You can buy an RTL-based receiver with an upconverter on eBay for less than $50, that will receive on 100kHz to 1.7GHz. With a technician class license and a $30 Baofeng transceiver, you can start working UHF/VHF repeaters.
- csirac2 11y ago
  I hate to be a buzz kill, but some of those Baofengs really need harmonic suppression filters installed. They're popular here in Australia, but I saw a friend put his on a spectrum analyzer and saw 2nd harmonic at ~-5dBc! I know they're only low power, so it's likely harmless, but it's stuff like this which makes it harder for amateur radio to retain the rights we have left on the spectrum, and raises the noise floor for everyone.
  - morganvachon 11y ago
    I agree, I've got a Baofeng UV-5R and while it's not a bad radio overall for the price, it's got the dreaded harmonic issue too. It sounds excellent on the band you're actually trying to transmit on, but I only use it as a backup since I don't want to cause issues on other bands. I'd say to the prospective new ham, spend just a few more bucks and get an Anytone or Tera radio. They are well made, full featured, and still half the cost of your average Yaesu or Icom radio. Barring that, look for well-kept used gear on eBay or at hamfests, or borrow a good radio from a local ham. There aren't many of us left, but I'd still say everyone knows someone who knows a ham.
    - fluxquanta 11y ago
      >They are well made, full featured, and still half the cost of your average Yaesu or Icom radio. They may not have the most features, but the Yaesu FT-252's are 5W, 2M handhelds for under $100. Plenty suitable for repeater work.
  - fluxquanta 11y ago
    Absolutely this. The lowest end Yaesu handhelds, for example, can be had for under $100 USD, provide better reliability with none of that QRM, and a high resale value. Stay away from the Woxuns or Baofengs, unless you want to just piss everyone off.
    - jimmcslim 11y ago
      Don't know if anyone if still watching these comments, but the thing that probably puts me off is the antenna requirements; that part seems to be quite DIY whereas I'm looking for something a bit easier but powerful enough to whet the appetite/be interesting (and preferably without some massive array in my backyard/on my roof!)
      - csirac2 11y ago
        You don't need an insane antenna setup to start out. A lot of Amateur radio people love optimizing their antennas for efficiency, skywave propagation, frequency agility etc. but it's not required for basic operation especially in higher frequencies. All radios, regardless of brand, have essentially the same laws of physics driving their antenna requirements (well, some have fancy in-built antenna tuning capability but we're talking small budgets here). But perhaps I've misunderstood. The crazier antennas are generally down in HF frequencies, below ~30MHz. They're crazier because longer wavelengths put more physical demands on antenna optimization. Making an antenna which efficiently operates a 4MHz chunk of spectrum 144-148MHz means you can build something tuned at 146MHz and only suffer very small performance difference when moving <2% off either side of this range. That's a completely different story to HF freqs, Eg. operating 1.8-5.5MHz is <4MHz of spectrum but that <4MHz chunk represents a 300% increase in frequency moving from lower to upper end, a far cry from the 2% needed before. So, to summarize, you can definitely and easily start out without any DIY gear, just usin turn-key stuff. Make friends with other amateurs working the higher/easier frequencies. Even in HF, you can still go a long just by draping bits of old wire around the place, there's still a bit of an art to this but not so difficult to learn :)

mailslut 11y ago

An index of others also online at: http://www.websdr.org http://www.websdr.org

philcrump 11y ago

I help run one for the VHF/UHF Radio Bands, located in Surrey, UK. http://websdr.suws.org.uk/ http://websdr.suws.org.uk/

atlantageek 11y ago

Too bad they wont open source the software.

dnet 11y ago
A friend of mine recently open sourced a similar solution. - Code: https://github.com/simonyiszk/openwebrx https://github.com/simonyiszk/openwebrx - Short intro: http://www.rtl-sdr.com/openwebrx-an-multi-user-rtl-sdr-receiver-with-web-interface/ http://www.rtl-sdr.com/openwebrx-an-multi-user-rtl-sdr-recei...

god_bless_texas 11y ago

Every now and then you can hear US number stations kick off there.

fapjacks 11y ago
No idea why you're downvoted. It's absolutely true.

fapjacks 11y ago

Come join us in #priyom on Freenode[0] if you'd like to get into number stations! We have a channel bot hooked into our schedule (which has been created over a long time of listening to number stations and tracking transmission patterns) which posts links to this SDR when a number station is on. Just to make a guess, there are number station transmissions at least several times a day, some days as many as several an hour. It's a ton of fun and we're pretty friendly! Stop by and say hi! [0] http://webchat.freenode.net/?channels=priyom http://webchat.freenode.net/?channels=priyom