Quick question: How did this guy add RDS to a Chinese transmitter?

[BlackBeard]

Recently, I found this video on YouTube:

It shows how a latvian guy managed to add a RDS signal to a cheap 30w chinese transmitter. The transmitter features the Quintec QN8066 chip which is better than the CZH/CZE transmitters that normally use BHxxxx and BFxxxx chips. A spectrum analysis of the 30w transmitter's output can be found here:
A comparison of the IC chips can be found here: https://darkliferadio.proboards.com/thr ... w-question
I'm talking about this transmitter: https://a.aliexpress.com/_m0JLIJe
It's quite impressive as there's no datasheet for the QN8066 chip although other Quintec chips feature an RDS option. The RDS encoder he used looks like the small white squares with the Pira chip that also feature DSP. They were sold by Pcbwizard, the infamous RadioMaster and hf-electronics.nl.

I know that it's still not good but I was just curious how the guy managed to add RDS to this cheap transmitter.

My guess would be that he inserted it by finding the two pins where the MPX runs through. Then he soldered a chinch cable to them so that the RDS signal is simply mixed with the stereo MPX so that the RDS's subcarrier is not synced with the pilot tone.

What do you think?

Just one additional question: Can you deactivate the 19kHz pilot on the small white Pcbwizard-DSP-Stereo-RDS coder? Can you deactivate the pilot on the Engima coder?

[3metrejim]

Looks like he managed to find a modulation input - I think the chip you mentioned still has the oscillator on the outside, so it is possible. As far as the encoder being used, it looks more like a Vincent Bruinink type (Mini RDS). It's not meant to have a very clean signal, it's similar to the monRDS - more of a toy. The Pira encoder is meant to be a lot better.

The Vincent and the MonRDS don't have pilot sync. Also it isn't the RDS coder that generates the pilot, they use the pilot from a stereo coder (19kHz) to synchronise their own 57kHz carrier, so there is no pilot to disable. On the Pira, you can disable the pilot sync if you are only broadcasting mono - not sure how it would react with sync enabled but no sync present. Having the RDS carrier synced to the stereo pilot is meant to reduce noises in stereo reception for some stereo decoders, but it can also work without sync (and has to if you broadcast mono only).

[3metrejim]

Just had a look at the QN8066 data sheet. It already does RDS, so not sure what he's done (or why). There is nothing on the data sheet for extra inputs anyway.

Data sheet here: https://vrtp.ru/index.php?act=Attach&ty ... &id=913773

[3metrejim]

Sorry for number of posts, can't edit after so long.

Anyway, I've managed to answer why the RDS doesn't come from the tx even though it's capable. That is just it's control software doesn't support it (or the instructions are only in mandarin?).

Where the cable is placed is in the RF path, so somehow the 57kHz rds carrier is being mixed with the rf and will appear above and below the carrier and may be a little messy. It must survive the fm demodulation process ok to work though - I'm not sure of the maths behind that, but it seems to work. I wouldn't be trusting the cleanliness of the transmission though.

[BlackBeard]

Sorry for number of posts, can't edit after so long.

Anyway, I've managed to answer why the RDS doesn't come from the tx even though it's capable. That is just it's control software doesn't support it (or the instructions are only in mandarin?).

Where the cable is placed is in the RF path, so somehow the 57kHz rds carrier is being mixed with the rf and will appear above and below the carrier and may be a little messy. It must survive the fm demodulation process ok to work though - I'm not sure of the maths behind that, but it seems to work. I wouldn't be trusting the cleanliness of the transmission though.

Thank you again for your detailed reply!

So you managed to find the datasheet, great! I should've looked on Yandex as well, there it's actually shown.

So you mean that the chip is capable of generating RDS but only the using the control software, right? As it's not possible to reprogram that chip because you'd need to unsolder it, he did it this way. Makes sense.

I already expected the signal to be pretty unclean Interesting idea though.

[radionortheast]

There is no mpx I tried every pin, the rds level will be really low throught the input jack to the cheeky 8066. I did manage to get a bit higher pilot level on my 7watt one, by bypassing some the caps surface mount devices by tracing it back from the 3mm input jack, i’m not sure why it should work. On the unformentioned website were videos are uploaded, in the videos they get it to work on certain transmitters by putting it thought the audio input jack at the highest level, so to stand any chance of it working, you would want the volume out from your computer to highest level and the pilot at highest level. I had a hard time seeing if the rds was there, I only had a combined fm/dab radio, they have signal processing in them, unlike a bulky older tuner you won’t see the rds indicator come up straight away.