tone decoder

[grounded]

another phase of the finished project
http://www.picbasic.co.uk/forum/showthread.php?t=5757
will be the the wireless video transmitting .
using a 1.2 ghz RX/TX the receiver will always be powered up and the transmitter power up when needed.
what I need is A output @ the receiver WHEN IT IS receiving . to use as a input on a 12f629

What I 'm looking @ is using a NE567 tone decoder chip @ the receiver audio output, set for X freq. and feeding the transmitter audio input using "Freqout" from the 16f676 on my main board with the filter diagram in the PBP manual which also says
"FREQOUT works best with a 20MHz or 40MHz oscillator. It can also work
with a 10MHz oscillator and even at 4MHz, although it will start to get
very hard to filter and be of fairly low amplitude."

I'm using the enternal 4MHz clock

I guess what I'm asking is
1. will this work?
2. is there a better way?
3. how would you do it?
4. can this be done PIC to PIC without the decoder

as always thanks

[skimask]

1. will this work?
2. is there a better way?
3. how would you do it?
4. can this be done PIC to PIC without the decoder
If I smell what you're cooking here...
1- It might, won't know 'till you try it...of course it'll be too late then :)
2/3- If it was me, I'd use the FFT on the Rx end, but that would cost a licensing fee, so a '567 might not be too bad an idea.
4- If you can get a clean enough audio output, COUNT may be able to pick up the FREQOUT'd audio and you could COUNT the audio coming across watching for the right frequency. The book says PBP will COUNT up to 25Khz at 4Mhz oscillator.

[Melanie]

Well, if you are trying to determine if you've got VIDEO being received, wouldn't it be sensible (and easiest) to detect the FRAME sync-pulse component of a video signal?

[grounded]

thanks
and please explain with a little more detail for us non profess. hobbist

[skimask]

thanks
and please explain with a little more detail for us non profess. hobbist

To get video, among other things, you have to have Horizontal Sync and Vertical Sync pulses.
If those sync pulses come at the right intervals (depends on frame rate, resolution, video standards, etc), then you've got video coming thru.
Google it or something. You find references all over...

[Melanie]

OMG... this isn't going to become a training course in video for the hobbyist...

Here's THREE solutions...

1. Detect the Video as a whole. In the same way you would strip the audio modulation component from a Radio Carrier, you can strip the video component. Couple of Capacitors, a Resistor and a Diode. Noise (when a carrier is not present can simply be filtered away), and when video is present, you simply look for a decent voltage from your Detector.

2. Detect the Frame Pulses. The Frame Pulse is the start of each picture. The repetition rate is slow enough even for a handicapped (frequency challenged 10F PIC) to cope with. However, different cameras and standards mean that the Frame Rate could be as slow as 5fps or as fast as 120fps. Still, you're looking for a repetitive, slow pulse...

3. Detect the Line Sync. Build a sync-stripper and detect the LINE sync (my choice). You can build a sync stripper with not much more than one Transistor. The presence of LINE sync means you've definately got sensible video (in some cases Frame Pulses on their own with no other video information are used to keep a carrier link open, and since in some cases the Frame is phase-locked to the supply mains you have to make sure you're not simply detecting supply mains hum).

Now, armed with all these choices you can go and learn something about video detection and sync stripping...

[grounded]

I was going to post the below but after reading your post all I can say is
"Thanks you've giving me a reason to live" I'm gone googling
found out stripping video is not a safe search
Just to clear up.
The cam and transmitter are remote and or control by a motion sensor.
the receiver is (or will be) in my house.
the objective
simplest:
when the cam is active (because of motion) I need a indicator light to tell me
to turn on the TV and see what is being filmed.

or
down the road option
the slave board WILL turn on a tv /vcr record for x amount of time

so in a nutshell I need to know when that cam is active and sending video
and I can use that to do what ever.

I'm simple minded so simple is alway better for me.