SINUS RDS PROJECT

[radium98]

why does the rds signal and stereo signal be in phase ? or lock as a pll.

[radium98]

@sinus private email ? seen

[sinus trouble]

Nice work Albert!

An interesting observation with bugs in the software, I have never noticed them? But i dont have many radios that support RDS at my disposal.

I like the switchable sync circuit you have shown!

[sinus trouble]

why does the rds signal and stereo signal be in phase ? or lock as a pll.

RDS and STEREO will would probably work un-synced? But can sometimes cause strange glitches in data and sound.

[radium98]

Thank you sinus

[Albert H]

why does the rds signal and stereo signal be in phase ? or lock as a pll.

RDS and STEREO will would probably work un-synced? But can sometimes cause strange glitches in data and sound.

Without synchronisation, you can get some weird burbles and whistles. Since adding sync is so easy, it seems silly to omit it!

[Albert H]

Here's a quick Veroboard layout for the "Sinus RDS Coder". This is the basic one without synchronisation, with simple transistor buffer and chopper. You have to pick your capacitors in parallel with you 150µH coil, to get the best 57kHz resonance. You DON'T have to use 150µH, you can use 220µ (a much more common value), but then your total capacitance has to be about 35.4 nF - you still have to select your capacitors!

I've left out the programming inversion transistor, so that it can be directly programmed with one of the cheap USB to "RS232" adaptors. If you're going to use "real" RS232, you'll have to add the extra transistor, and its base resistor. I used 2N3904 transistors. I get them for around 1p each (buying them in thousands from the Far East). They're easily replaced with BC548, BC108, 2N3706, 2SC1815 or pretty much all small medium gain NPN transistors - just check that you connect them the right way 'round!

Programming the PIC is easy enough - just make sure that you set the oscillator mode to "crystal".

RDS-Mini.png

I'll put up a PCB version shortly. I've also got another improved, more comprehensive version that I'll put up here later or tomorrow.

[sinus trouble]

Nice neat version Albert!

Certainly better than my first attempt.

20140820_202842.jpg

[Albert H]

This is what my Veroboard looks like:

RDS Proto.jpg

[sinus trouble]

I like it Albert!

Did you experience any issues writing to the RDS via USB interface? I experimented with both Pull up and down resistors and found the Pull down option quite sketchy and would occasionally not write data.

I found the data input was happier in a 'High' initial state.

[teckniqs]

Are they both the same circuit on your Veroboards? ....Only I notice Albert's seems to have a few more components and a diode.

[sinus trouble]

Are they both the same circuit on your Veroboards? ....Only I notice Albert's seems to have a few more components and a diode.

Correct Teck!

I believe Albert has added the diode for polarity protection and a 100uF cap for some extra smoothing/filtering of the DC.

Both units most likely operate the same? its just a question of builder preference and application.

[Albert H]

Teck - my Veroboard has a series 1N4148 diode on the way in to the 78L05 regulator to prevent me blowing things up by reversing the supply. Sinus is right - I added the 100µF cap to keep the supply rail clean.

[radium98]

And a ferrite ring at entrance ,that is very delicate and sensitive clean ,in such kind of signals images/smilies/icon_e_wink.gif

[Albert H]

I like it Albert!

Did you experience any issues writing to the RDS via USB interface? I experimented with both Pull up and down resistors and found the Pull down option quite sketchy and would occasionally not write data.

I found the data input was happier in a 'High' initial state.

Thanks

I used a cheap 6-way 5 Volt USB to "RS232" adaptor (£0.68 on Ebay). It has the Prolific chip inside it, and works well. You might need to set your RDS software that you use to send the data to the PIC to 9600 Baud send rate.

I've been experimenting with a return data path from the PIC back to the laptop, so that I can read the existing configuration in a PIC, and save it as a file for later upload to another RDS board. This should be fairly easy - there's enough space left in the PIC for the additional bit of code. I'll make it available to all when I get it working.

My latest version of the board includes a 12F629 as a clock generator, deriving 4.332MHz from the rock, then 57 kHz (to drive the chopping transistor), 38kHz (for the switches in a stereo coder), 19kHz (for the stereo pilot). The extra outputs require a transistor and a couple of resistors each. I've added a slowed reset at power-up - it guaranteed that the PIC started cleanly. It's just an extra resistor and capacitor.

[sinus trouble]

Thanks

I used a cheap 6-way 5 Volt USB to "RS232" adaptor (£0.68 on Ebay). It has the Prolific chip inside it, and works well. You might need to set your RDS software that you use to send the data to the PIC to 9600 Baud send rate.

Cheers Albert! Its great to hear your feedback, Also a relief to know that someone else has succeeded too! Not just some lucky fluke on my part!

[sinus trouble]

I've been experimenting with a return data path from the PIC back to the laptop, so that I can read the existing configuration in a PIC, and save it as a file for later upload to another RDS board. This should be fairly easy - there's enough space left in the PIC for the additional bit of code. I'll make it available to all when I get it working.

My latest version of the board includes a 12F629 as a clock generator, deriving 4.332MHz from the rock, then 57 kHz (to drive the chopping transistor), 38kHz (for the switches in a stereo coder), 19kHz (for the stereo pilot). The extra outputs require a transistor and a couple of resistors each. I've added a slowed reset at power-up - it guaranteed that the PIC started cleanly. It's just an extra resistor and capacitor.

Excellent work once again Albert!

It will be a pleasure to see any developments you discover!

[Albert H]

Here we go....

Better RDS.png

The dual op-amp can be a TL072, but I found that the LM358 gave me cleaner signals (probably because of the filtering effect of the slower slew rate). I've also got a Veroboard version, but haven't drawn it up yet.

[radium98]

it is an old part of the pira erds1.1 the one using the lpt port and use 12c805 and can generate all 3 clocks and the 1.1875

[Albert H]

Nope. The code for the 12F629 is actually the frequency generator for a completely different project, just repurposed. The code for the 16F628A is the "Mon RDS" code from the French developer - it's been around for a while. The Mon RDS code has a couple of (minor) bugs. I'm looking to fix it at the moment.

The data connection is one-way RS232 at the moment, but may be upgraded to bidirectional if I can get the code to work.