Thanks Chris - by multichannel I mean , basically, surround sound. So stereo is two channels - but it woiuld be nice to, for example, broadcast 8 or 16 seperate signals to 8 or 16 seperate speakers each 100 metres apart .I have used the senheizer in ear montitors to do things like this but you can only go fifty metres. I often have to run several km of cables at events to speakers and I would love not to have to - of course they still need power but we;ve previously got round this with several low power low noise portable IP6 rated generators. I was wondering why Senheizers had a short distance range but good sound whereas my walkie talkies could go very far but had crap audio - youve answered the question tx.
On Thu, 30 May 2019 at 17:07, Chris Woolf <ch...@chriswoolf.co.uk> wrote: > Answering this specific question... > > On 30/05/2019 10:42, Augustine Leudar wrote: > > ... I had some walkie talkies that had a > > range of one KM with admitedly terrible audio (surely this could be > > improved) . Whereas Senheiser in ear monitors have a really short > distance > > range of around 40 metres and use much higher electromagnetic frequencies > > ((863 mhz) . Why is it something cant be done with the same sort of range > > as the walkie talkies but for.multichammel audio (according to wikipedia > > 30 - 400 mhz) ? > > Walkie talkies run on a 12.5kHz narrow band, and need ~50kHz of channel > space. Broadcast quality FM (as in radio mics) uses a channel space of > ~250kHz. Given than channel "skirts" are quite a bit wider multiple > local channels cannot sit close to each other, and are commonly spaced > ~500kHz apart. They also have to avoid numerical frequencies which would > cause intermodulation. Thus remarkably few analogue radio channels can > fit into a single (8MHz) TV channel space. The usual answer is ~12 at > best. Some claim more but range and mutual interference may suffer. With > digital modulation this can improve to ~20 because the effects of > interference are reduced. > > Range is directly related to bandwidth, transmission power, and RF > signal-to-noise limitations of the receiver. Narrow band with limited > audio bandwidth and restricted (audio) signal-to-noise is a much easier > task with a couple of AA cells than 20kHz audio with 100dB (companded) > dynamic range. Digital radio mics have been even harder to make that can > modulate something that equates to full broadcast bandwidth and dynamic > range into the the same 250kHz bandwidth as analogue, and with roughly > the same range/battery power. > > I've no idea what the .multichannel audio is - can you elaborate? And I > can't imaging that there is any spectrum clear in the 30-400MHz region. > > Chris Woolf > > > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, > edit account or options, view archives and so on. > -- Dr. Augustine Leudar Artistic Director Magik Door LTD Company Number : NI635217 Registered 63 Ballycoan rd, Belfast BT88LL www.magikdoor.net +44(0)7555784775 -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20190530/de617fc8/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
