| iceamplifiers |
Hey Hey,
I'm considering a short range radio transmitter & receiver to use instead of a guitar lead. My interest is primarily for fun and to stop me tripping over. There are no specifics yet... but it’s quite logical to assume min bandwidth is 70Hz --> 7.5 kHz and range is less than 50 Meters also the transmitter will have to be battery powered.
I didn't pay too much attention in communications lectures and it was some time ago. If any of you know of websites on which I could begin researching or books that are particularly useful I would appreciate it.
I've been through my old university comms texts; they're great on the theory (maths), and sadly rather easy on the practical implementation...
I know this is probably not legal in the UK... but I am only considering... :D
James |
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| karlw |
The company I work for, Lectrosonics, makes systems for guitar and also for voice. I'm not an engineer, but I can give you a couple of pointers:
1. The audio bandwidth you need is greater than what you supposed in your post. For electric guitar, we have measured meaningful signals down to about 40Hz and up to about 15kHz. Admittedly, you could "get away" with less than that, but you'd be missing things that are very easily transferred by even a cheap cable.
The reason for this is that there are "extra-musical" sounds from an electric guitar on the low end, particularly if you do things like mute the strings at the bridge and go "chunka chunka chunka" as is done so often with rock and metal. Also, the upper harmonics give the sound "sparkle" and help to define the attack on the notes. Without transmisson of signals above 10kHz, the effect would sound a little "dull". this would be most noticeable with a clean guitar sound.
2. How the signal is handled between transmitter and receiver is important. Most wireless systems use a compandor to reduce the dynamic range before transmission and expand it in the receiver, to overcome channel noise. Part of this is because the government specifies how much power we can use (in mW) and how much deviation you can have in your FM system. The result is that due to the companded signal, the sound tends to be a tad "mushy" and distorted by the time it makes it to your amp.
Since you are only *considering* a system, you might want to look at a really wide-band FM system with, say, 150kHz of deviation. Most likely, you could get away without a compandor. However, you would indeed be breaking the law.
-Karl |
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| pinkmouse |
| You can buy them these days pretty cheaply, especially as you really want a diversity system to avoid signal drop out, adding extra complications. |
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| IDerrington |
Hi,
Im also looking at building myself a wireless audio transmitter for my guitar to amp.
My design is based around the 2.4GHz transmitter and receiver pair from Nordic.
Im am only halfway there. I am posting schematics and layouts on my website http://www.kandi-electronics.com. Have a look and see what you think. If you see any errors in the schematics let me know.
Regards
Iain |
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