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long distance radio mics and audio links


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I'm part of a team running a RSL radio station for a couple of days at a large event.


We are having a few problems with ideas about how to have link ups around the site.


Basically we would like to be able to go around the large 150 acre site and carry out interviews with the various activities taking place on the site.


We are looking for some kind of high powered radio mic? but don't know where to be able to hire something like this from. From previous experiments things like a normal radio mic with a receiver but with a direction Yagi antenna haven't worked.


Some of our ideas include:

> Having another base station in the middle of the activities with radio mics and pa with a link back to the studio - but how could this link be done pref wirelessly?


> Using mobile phones and adapting a handsfree kit?


> Using the mobile internet to have a link on wirelessly sending audio over IP?


> Using a audio/video sender that claims a 5km link (http://www.maplin.co.uk/Module.aspx?Module...16&doy=19m5)


Any ideas, thoughts, advice kindly welcomed.


Many Thanks


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Well, first off the FAQ on the Maplin sender says it will NOT work with just audio--you'd have to provide some kind of video sync source as well. It also uses a parabolic antenna with a quoted 10 degree -3dB point so somebody would have to be up a tower pointing it pretty accurately at the source. I have to admit to be sceptical.


You won't really find such things as "high power radio mics" off the shelf. The legal power for radio microphones is limited by the Radiocommunications Agency and obviously manufacturers make their gear to fit in with those powers.


What you'll need to create (if it has to be wireless) is the sort of thing you see being used at sporting events: a conventional mic plugged into a backpack-style transmitter. If you ever watch golf you will have seen guys holding a "furry hamster" mic, with a backpack of electronics and a big whip antenna on top. This sort of thing can be rented from various broadcast hire companies that specialise in sports work. As a start, I'd give BBC Resources a call and see what they can do and it might also be worth contacting HANDHELD AUDIO and ask their advice.


Be warned though, you're not talking about cheap kit and there WILL be licence fees involved.



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Thanks for the reply Bob.


I'm also very sceptical of the Maplin audio/video sender mainly because I haven't heard of one with more than 10mW of power but having someone up a tower isn't a problem we've got to mount our transmission antenna on the mast anyway.


That's exactly the kind of thing we were thinking about the golf style body transmitter packs - I think these are about 1W rather than the 30mW radio mic. I did try and contact BBC resources but they tell me that all their outside broadcast work has been sold out to SIS which are a rather large company who don't seem very interested in hiring us one system.


Thanks for the link to Handheld Audio there link system looks ideal and very well priced!


License fees have been fairly horrible for all radio stuff it's about £2k on license fees so far!

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:slapforehead: Duh. I knew about the BBC Resources thing because some good friends lost jobs through that sell out. Too much Queensland sun rots the brain--but I'm not complaining. SISLink used to be an okay company but have probably suffered from too much growth. Hopefully Handheld can either help or recommend somebody.





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Having worked on a few radio OBs, one thing to bear in mind is that a lot of "live" interviews around site aren't live at all. Reporter goes off with a MD recorder or whatever, starts off the interview with "Thanks Mike" or something along those lines and ends with "Back to you, Mike" and the presenter in the OB studio (called Mike...) plays out the recorded clip as live with appropriate intro & outro.


Not quite the same as doing it live but 99.9% of the listeners won't be able to tell the difference if it's done well. And it needn't cost you a penny!

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Shez - great idea we might end up doing something along those lines maybe with an MD as you say no cost and I doubt anyone would realise. Maybe use a MP3 recorder, could then chuck it straight into audition and edit it before going out on the air.


Big Dave - thanks for the post I've emailed The Wireless Works might give them a call tomorrow they look like exactly the right company and they're only in Godalming, just hopefully it doesn't turn out too expensive!


Any more bright ideas or companies providing solutions greatly appreciated!




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I don't know what you maximum transmission distance will need to be over your 150 acre site, but we have had great success with standard radio links equipment fitted with an omni receive aerial.


In the most recent usage we had a small 6U rack with 12V battery, inverter, link transmitter, radio mic and small mixer. We then had a small mast (think lightweight windup stand) with the transmit aerial fixed to the top. The receive omni aerial was then mounted back at the studio approx 50 foot above ground.


As the gain on the omni aerial was not as good as a standard directional aerial, we also installed a couple of hi-gain directional aerials in the direction of the common OB locations.


The kit we used ran on the 800 - 960MHz range and has to be licensed, but there are deals for short term use so the cost is not too prohibitive.


If you want any further info feel free to PM me.


To answer some of the OPs points:

Using mobile phones and adapting a handsfree kit?

If you are happy with the low quality and call costs this can be ok. Bear in mind you need to be careful with echo cancellation.


Using the mobile internet to have a link on wirelessly sending audio over IP?

Hmm... If you are thinking GPRS internet - forget it! If you have site wide wi-fi coveredge you may be ok. You need a minimum of 20kbps bandwidth with relatively low latency for this to work.


Other comments:

Using a handheld radio may work, but I understand that it is not permitted to use de-regulated bands for broadcast.


If the site has other services being installed (power?) think about getting some tie lines pulled in. We have effectively run balanced audio signals over nearly 500m of mic cable run in a ditch (yes a ditch! - not my choice - and no I don't recommend it), without any special equipment.


As for recorders look at the Zoom H4


Hope this helps



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The recorded method sounds like a good one !


Dont forget if you go down the "Live" link up methods u have two other things to worry about


1) Talk back or some kind of monitoring system for the interviewer to use to listen to the studio output for cues etc.


2) if the event is going to played out live over the PA then it will be very difficult to conduct an event whilst the delayed PA output is also heard.

tried it , very very off putting .


Recorded idea sounds like the cheapest and most fool proof to me !



Matt :)

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u have two other things to worry about


1) some kind of monitoring system (snip)


2) if the event is going to played out live over the PA (snip)


Did you actually read the original post? :)


This is for a radio RSL.


So monitoring/cueing is easy - just listen to the broadcast. And it isn't going out live over the PA.

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