4 ms·

More information about proposed amateur TV experiments [video]

30 points by lightlyused 5y ago

drmpeg 5y ago
Unfortunately, no amateur radio television below 420 MHz here in the US.
- tantalor 5y ago
  Why is that unfortunate.
  - drmpeg 5y ago
    We won't be able to make two-way contacts with European stations.
    - tantalor 5y ago
      Why not
      - drmpeg 5y ago
        420 MHz (and above) is generally line of sight propagation. The frequencies mentioned in the article (29.25 and 51.7 MHz) are able to reflect/refract off the ionosphere and allow much longer propagation paths.
- edrxty 5y ago
  There's no restriction on type of emission in the 10 and 6m bands, just the bandwidth (which once again, is a dumb carry over from the pre-digital era...fight me OM). The way the bandwidth limitation is worded for non-phone emissions is pretty subjective so you can probably make something work, it just won't be super high quality.
  - themodelplumber 5y ago
    Can 500KHz bandwidth be worked out for RBTV? That could be fun to play with.
    - drmpeg 5y ago
      That's actually pretty wide. A popular rate for DVB-S2 is 333 ksyms/s or 400 kHz with 0.2 rolloff.
  - drmpeg 5y ago
    The way I read it, it's 3 (or maybe 6) kHz on 10m and 20 kHz on 6m. The article is using 80 kHz.
themodelplumber 5y ago
In a related video, there's a nice capture of a great moment, a 156km distance over-the-air digital amateur TV feed (at 27:40): https://youtu.be/GqFLtLBgIo0 https://youtu.be/GqFLtLBgIo0
8bitsrule 5y ago
I'd guess they'd appreciate signal reports from anyone who can't transmit (yet). Esp. from anyone with access to a big antenna! The mentioned Aug 15 description: [https://ei7gl.blogspot.com/2021/08/new-amateur-tv-activity-proposed-for.html https://ei7gl.blogspot.com/2021/08/new-amateur-tv-activity-p...] "From what I understand, it will be DVB-T digital TV operating on 29.250 MHz with a 300 kHz bandwidth." Didn't find a mention of transmit power... found this online: "Full licence Maximum UK licence power of upto 400 watts can be used and all UK amateur radio band allocations available." Would be useful to know for anyone considering listening in N. America. A YT video about building a RX system (40m): [https://www.youtube.com/watch?v=lfSi7vTQK44 https://www.youtube.com/watch?v=lfSi7vTQK44]

30 points by lightlyused 5y ago

drmpeg 5y ago

Unfortunately, no amateur radio television below 420 MHz here in the US.

tantalor 5y ago
Why is that unfortunate.
- drmpeg 5y ago
  We won't be able to make two-way contacts with European stations.
  - tantalor 5y ago
    Why not
    - drmpeg 5y ago
      420 MHz (and above) is generally line of sight propagation. The frequencies mentioned in the article (29.25 and 51.7 MHz) are able to reflect/refract off the ionosphere and allow much longer propagation paths.
edrxty 5y ago
There's no restriction on type of emission in the 10 and 6m bands, just the bandwidth (which once again, is a dumb carry over from the pre-digital era...fight me OM). The way the bandwidth limitation is worded for non-phone emissions is pretty subjective so you can probably make something work, it just won't be super high quality.
- themodelplumber 5y ago
  Can 500KHz bandwidth be worked out for RBTV? That could be fun to play with.
  - drmpeg 5y ago
    That's actually pretty wide. A popular rate for DVB-S2 is 333 ksyms/s or 400 kHz with 0.2 rolloff.
- drmpeg 5y ago
  The way I read it, it's 3 (or maybe 6) kHz on 10m and 20 kHz on 6m. The article is using 80 kHz.

themodelplumber 5y ago

In a related video, there's a nice capture of a great moment, a 156km distance over-the-air digital amateur TV feed (at 27:40): https://youtu.be/GqFLtLBgIo0 https://youtu.be/GqFLtLBgIo0

8bitsrule 5y ago

I'd guess they'd appreciate signal reports from anyone who can't transmit (yet). Esp. from anyone with access to a big antenna! The mentioned Aug 15 description: [https://ei7gl.blogspot.com/2021/08/new-amateur-tv-activity-proposed-for.html https://ei7gl.blogspot.com/2021/08/new-amateur-tv-activity-p...] "From what I understand, it will be DVB-T digital TV operating on 29.250 MHz with a 300 kHz bandwidth." Didn't find a mention of transmit power... found this online: "Full licence Maximum UK licence power of upto 400 watts can be used and all UK amateur radio band allocations available." Would be useful to know for anyone considering listening in N. America. A YT video about building a RX system (40m): [https://www.youtube.com/watch?v=lfSi7vTQK44 https://www.youtube.com/watch?v=lfSi7vTQK44]