How to make CATV Signal streght meter ?!

[csaba911]

I was thinking to create a RF signal strength meter from a dead VCR tuner. :idea:
Using a PIC or c51 to change the frequency and display it on the LCD.
I cant find any info how to control the tuner.

Any one have any experience with this :?:

Thanks
Steve

 

[Nigel Goodwin]

I was thinking to create a RF signal strength meter from a dead VCR tuner. :idea:
Using a PIC or c51 to change the frequency and display it on the LCD.
I cant find any info how to control the tuner.

Any one have any experience with this :?:

Thanks
Steve

There seems very little info available on the tuners themselves, you may have to open it up and find what PLL IC it uses, then try and find a datasheet for that.

 

[pebe]

You need the complete RF section of the VCR. The tuner, IF stages and demod. If you can get hold of a circuit you will need to identify the AGC (automatic gain control) line. When a signal is received, the demod produces a voltage that is fed back to the RF and mixer stages in the tuner in order to keep the demod output at a constant level. The voltage produced will be a measure of signal strength.

That voltage can be amplified to a suitable level with an op-amp and fed to the A/D section of your microcontroller and programmed to give a display.

 

[pebe]

Sorry! I've just re-read your post and realised I didn't answer your question.

I stated how to get the signal strength, instead of how to control the tuner's frequency.

 

[csaba911]

Thanks for the info, its help a BIT.
The real mystery is how to make the tuner to change frequency, I GUESS is I2C or other serial protocol is used to change, I tied to change the tuner supply voltage "+30v", it is working but very ruff. I collected more than 10 VCR for this project, any specific brand is better than the other tuner?
I think most of the tuner has the RF and IF on the same board.

It is not a stone age VCR's, 1-4 years old..

Anything else you can help, PLEASE...

STEVE

 

[Nigel Goodwin]

Thanks for the info, its help a BIT.
The real mystery is how to make the tuner to change frequency, I GUESS is I2C or other serial protocol is used to change, I tied to change the tuner supply voltage "+30v", it is working but very ruff. I collected more than 10 VCR for this project, any specific brand is better than the other tuner?
I think most of the tuner has the RF and IF on the same board.

It is not a stone age VCR's, 1-4 years old..

Anything else you can help, PLEASE...

STEVE

You need to find a tuner that you can get a datasheet for, I've had no luck at all finding one. One of the largest tuner manufacturers is Philips Components, but I've had no luck finding tuner data on their site.

 

[csaba911]

Ok
Now I have a bunch of useless VCR. :?

can some one send me a datasheet for this chips AN8560K and TD6359N

Thanks
STEVE

 

[pebe]

Ok
Now I have a bunch of useless VCR. :?

can some one send me a datasheet for this chips AN8560K and TD6359N

Thanks
STEVE

Do a search for TD6359N on Google. It will point you to the 'Chipdocs' site and you can do a free download from them.

 

[csaba911]

Thanks

Its only $95 access fee!

Are you working for them ?

STEVE

 

[pebe]

Sorry. It said 'download' and that's as far as I searched. I assumed it would be free.

If you know the manufacturer you can often get free downloads of data sheets from them.

 

[csaba911]

I did send email to Toshiba, if they helpful as before, I guess never have the datasheet for this IC. :!:

I always search google before I ask for help.
Thanks anyway.

STEVE