Apologies as my reply was somewhat rushed. The command is to run a second instance of stereo tool so that the configurations don't conflict with each other. You can create a .bat or .cmd file with the above lines. I use task scheduler to automatically launch them and run them hidden from view.
I can hear artifacts inside the "studio" aka living room when RDS is enabled. There's a sort of pulsating electronics sound. But outside the studio - dead air is just dead air. No weird sounds. No buzzing, no nothing. Except text that displays instantly.
Kage, I am running 2 instances of Stereo Tool. 7.50 for audio processing and 5.02 to handle the RDS. 5.02 has a much simpler interface and is easier to figure out. In 5.02 I have the RDS Volume turned all the way down to 0.50%. I can't hear the pilot tone. I use a dummy input (muted mic from my webcam) and output to the same sound card outputting the processed audio. Windows volume level set to 72.
Use a bat or cmd file so they don't conflict:
set USERPROFILE=C:\Second\ "C:\Program Files (x86)\Stereo Tool 2\StereoTool.exe"
I have a cheap 5w HLLY transmitter with RDS working flawlessly, scrolling text and all. No modification was required. I guess this can work with any transmitter.
Bruce, I'm trying to contact the manufacturer to see about getting just the main board with pre-emphasis disabled. Either buying one new or sending mine in. I contacted Yue Lan at www.czhfmtransmitter.com, but she doesn't seem to understand what I'm talking about. Perhaps it's a language barrier thing. I'm going to keep working on this.
Regarding the metal plate. I'm not too happy that it's missing. I purchased the transmitter new on ebay.
Sorry that your board got ruined. I appreciate the words of caution. Are you going to repair your transmitter? If not, how much to buy the metal plate off of yours?
mbruce thank you for the instructions and words of caution. I should have asked to borrow your picture before posting it. I will try this and post back.
As a temporary work around, stereo tool 7.5 has a calibration setting under the FM Output option. I believe this can be used to add de-emphasis before all the processing and compression occurs. One can cross reference this information regarding the De-Emphasis Response Table with the db limits that can be set in the calibration screen. Then, turn pre-emphasis back on in the processing. I tried this with good results and can get louder audio without the distortion coming through the radio.
Should look something like this, but I need to re-do my calculations to get more accurate results as the table gives different setpoints than whats in this program.
Thanks for the info Kage and mbruce. Instead of replacing the capacitors, can I just remove them and jumper them to complete get rid of pre-emphasis? Also, where are the capacitors located in relation to the chip. Are they on the underside of the board (opposite side of the metal plate covering the chip) or do I need to remove the metal plate?
Thanks for the advice Kage, but I cracked open the unit and didn't see any capacitors or resistors on the inputs. Therefore, I believe my transmitter uses an active filter. To combat this problem, I completely removed pre-emphasis from my audio processing and am just using what's built into the transmitter. This, at least, removes one of the variables, although I have no way of knowing if my transmitter is set up to 50 or 75 microseconds.
Unfortunately, I still can't seem to achieve peak modulation. When I look at a stereo with VU meters, the needles only peak about halfway or slightly above. Commercial radio stations peak higher. If I try to turn up the input, it results in a loss of stereo separation, loudness and quality. As a result, I turned the hard limiter way up to compensate for the quietness. Do you think the highs and the pre-emphasis could still be a problem after I removed it from my audio processor or could something else be going on here?