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prop am modulation ota, over the wire. — Parallax Forums

prop am modulation ota, over the wire.

IncVoidIncVoid Posts: 40
edited 2017-02-08 16:02 in Propeller 1
Sorry to bump an old thread, with a new post.
I couldn't find this in the prop manual, or the hydra book.
so reading this post/discussion.

I know this is talking about FM mod. but my understanding is the ctrB gets AM modulated by ctrA, if I said this right, in the tv driver.

http://forums.parallax.com/discussion/137751/demo-new-fm-broadcast-code-using-chip-s-video-mixer-method-explanation/p1
kuroneko wrote: »
pedward wrote: »
The datasheet says the broadcast carrier frequency is generated by ctrb, I just followed the datasheet.
Got it. One of the less often referred to (by me) parts of the documentation :)
so I guess it is in the "propeller datasheet" pdf from the prop tool.

yeah, got an rtl-sdr and yup its all over the place.(cog modulation of video on channel 2 or 3)

Now instead of barewire antenna, if you put it on coax directly into the tv antenna, would that shield all that junk going out on the air?

I got a few cheap b&w crts, but they don't have rca jacks. so I have no way to get the ntsc into them.

I haven't looked into hacks to add an rca jack to them after the ntsc gets demodulated off of the channel frequency, if that's how to say it. Is it safe if done via coax with no antenna?

Comments

  • Mark_TMark_T Posts: 1,981
    There was never any intention to put this on the air, just (a hack?) to drive a TV set as a monitor, via the aerial socket - its an
    alternative to digital VGA.
  • IncVoidIncVoid Posts: 40
    I don't want the signal on the air. That is bad. But using the rca or coax, connected to the antenna on the old b&w, will it be enough to keep all the harmonics off the air, and let the tv still get the channel. I guess I'll have to try it and report back and let everybody else know heh.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    Use channel 3 (60 MHz). You'll get less jitter than you would on other channels. And don't worry so much about RF escaping. It won't propagate far enough to be concerned about.

    -Phil
  • IncVoidIncVoid Posts: 40
    You're the man Phil. I couldn't ask for a better reply short of C.Gracey Himself. Thank you. Can Close topic.
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