Wireless Transmitter

[Mostafa]

hi

recently i decided to make a wireless transmitter. here i will explain my conception:

initially by using ADC module of a 16F877A , PIC samples speaker's output of my computer at the rate of 128Kbps and then some coding techniques will be executed on ADC results. then by using a digital modulator module, i will send the signals and then in the receiver side, i will demodulate this signals by using a digital demodulator module.

with best regards.

[Ioannis]

So?

Ioannis

[dhouston]

I'm not at all clear about what you hope to do but most inexpensive RF modules have low baseband data rates (3-4kbps), making any realtime transfer of continuous data difficult.

128Kbps means 16K samples per second with 8-bit resolution. It takes about 25µS minimum for an ADC sample so you can do the sampling (and maybe the encoding).

You will need good quality FSK transmitter and receiver and probably quadrature encoding to transmit this type of data rate.

The result will be really crappy sound - you need much higher sampling rates to get good sound quality.

[skimask]

hi
recently i decided to make a wireless transmitter. here i will explain my conception:
Just like you do here?
http://www.picbasic.co.uk/forum/showpost.php?p=16649&postcount=2


initially by using ADC module of a 16F877A , PIC samples speaker's output of my computer at the rate of 128Kbps
Good luck getting a PIC16F877A, or any PIC to sample ANYTHING at 128kbps


and then some coding techniques will be executed on ADC results.
What 'techniques would those be?


then by using a digital modulator module, i will send the signals and then in the receiver side, i will demodulate this signals by using a digital demodulator module.
There's a lot of those out there. Why not use the ones you used in the above linked post?

[Mostafa]

hi
is there any link for this project ?

best regards

[Archangel]

Hi Mostafa,
If I understand correctly, you want to digitize an audio signal, send it wireless for a short distance and then decode it back to audio? Question: why go through all this brain damage and expense when you can send audio in analog format very easily and cheaply via an FM transmitter? FM units are available on the cheap from many "hobbiest suppliers" or you can roll your own, also wireless mic's are available, here's a source:
http://www.ramseyelectronics.com/hk/default.asp?page=amfm
or
http://www.dak.com/reviews/2030story.cfm?Ref=G&PM=WM&type=GSrch&Srh=wireless_mic
or these
http://www.discovercircuits.com/W/wirelessmic.htm

[RussMartin]

In all sincerity, I have to echo Joe S's question. Another straightforward and economical solution would be:

http://www.linxtechnologies.com/Products/RF-Modules/HP3-Series-Multiple-Channel-Radio-Frequency-Module/

The audio will be what we old farts call "communication quality"--about as good as you hear on a land-line telephone.

Perhaps I don't completely understand your project?

[Mostafa]

thanks Joe

also i think analog modulations is easier but i want to experience digital communication.

thanks
with best regards

[Normnet]

See sparkfun wireless Nordic (http://www.sparkfun.com/commerce/categories.php?cPath=16_114)

Norm

[Mostafa]

hi Normnet
thanks, but this majules are not FREE.
best regards

[dhouston]

There is just no way that you can sample fast enough for good quality audio.

You might look at Roman Black's PicSound page at http://www.romanblack.com/picsound.htm.

[Mostafa]

hi

thanks all.

ultimately i decided to use the MC3361 (narrowband FM IF) as receiver and MC2833 (FM transmitter) as transmitter.

is it a good idea?

best regards, Mostafa

[Ioannis]

Yeah, I think the best. No program overhead and good audio quality.

Go ahead.

Ioannis