Radio Data System (RDS) > MRDS1322
MiniRds New version
Jan:
An audible noise from the minirds unit is impossible by principle (the antialias and bandpass filter is passive). For example noise at 5 kHz is below -100 dB (referenced to the 75 kHz FM deviation). So there are another possible reasons:
1) Distortion in the exciter or
2) too high RDS signal level, that causes 1) and distortion in receiver or
3) individual unit failure? Can send you another unit if necessary.
Before you release any strong allegation an appropriately strong argument base must exist. How did you assured that the deviation caused by RDS is below 7.5 kHz as required by standards? In other words I hope you have tried to adjust the RDS level and you are not injecting the RDS signal to Left or Right audio input.
Marcel_TNT:
Well, i never measured with any equipment... first i tought it was normal the noise because just like a stereo encoder some noise is normal to apear, you can't compare a mono exciter with a stereo one at blanck noise level! But i saw at a friend the pira32 rds and i noticed his blank was crystal clear on fm thats why i tought the noise could be eradicated by a more expensive rds(pira 32) and asked you about new model!
Aldo i also cannot compare my situation with of that of my friend because i don't know what pilot level he has from the pira 32... thats why i needed to be asured by you that Minirds is same at noise as pira32 rds.
I think most probable cause could be pilot level because if i raise it then the noise becomes louder and louder, and another thing is if i turn the receiver on mono mode then the noise is not audible no more!
In any case the mini rds does his job more than expected for that money it costs, not to mention the stereo encoder from your schematic... it takes the exciter to another level... all sounds can be hared, excelent separation and it doesen't cut off a thing!
Jan:
If RDS noise varies with pilot level, then the noise surely does not come from the minirds. In my opinion both pilot and RDS injection is too high into the exciter. Hobby FM equipment is usually much sensitive than professional equipment, i.e. all modulation signals must be kept on low level to prevent overmodulation and distortion.
Some people are able to do things that one is amazed, for example connect RDS signal to audio Left or Right channel before stereo encoder or to a limiter and then wonder that it does not work as expected... :P
Marcel_TNT:
Very true, i also seen some crazy stuff done! I usualy do stuff by the law except for the sound (the input of the exciter) i alwais modified the input in my crazy desire to reach the loudness of sound of the legal radio stations from my country but how can one do batle with their sound processors of over 10.000 euro or more.... is true i made some progress but also lost some things in the sound and surton distortion apeared!
Another thing i wanted to ask you... i see you sell the rds ic programmed so i can build the MiniRds at home, but the MiniRds i purcesed from you had a Pic not Mrds!
Jan:
Yes, it is a pic based.
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