If this checkbox is disabled, processing ( Advanced Clipper and Hard Limit output) is done with pre-emphasis, but signal that's sent to the output is de-emphasized, as it would be in an FM receiver. Make sure that this is enabled when using an FM transmitter. If you leave this disabled and feed the signal to an FM transmitter, the sound will lack highs. Pre-emphasize output Outputs a pre-emphasized signal.
This means that the increment of high frequencies in the US is higher than in the rest of the world, which also means that it is more difficult to broadcast loud highs. Pre-emphasis time The pre-emphasis setting for your region.įor most parts of the world this must be 50 μs, but in the US 75 μs is used.If you want to send pre-emphasized output to a transmitter, make sure that Pre-emphasize output is also enabled! If this checkbox is enabled, processing ( Advanced Clipper and Hard Limit output) is done with pre-emphasis.
So, if you don't hear enough highs on your FM station, this is where you should look first. If you don't configure pre-emphasis correctly, you'll get a very dull sound that lacks highs. To reduce hiss on the receiver, FM stations broadcast high frequencies a lot louder, and the receiver reduces this again. Lowpass frequency FM lowpass frequency.This overrules the global lowpass frequency for the FM output. Enabled Enables FM processing and features.Pre-emphasis time The amount of extra pre-emphasis to add to the FM pre-emphasis.In countries with BS412-like regulations, this setting can be useful though. And you definitely don't want to use this at high loudness levels. If you have a clipper at the transmitter site, you probably don't want to use this. This setting will adversely affect the audio quality.Īdds extra pre-emphasis to the FM clipper on top of the FM pre-emphasis, to protect the FM signal that is sent to the transmitter against overshoots, and de-emphasises it again before outputting. Don't use this unless you know what you are doing. Extra FM pre/de-emphasis (bad!) Perform extra pre-emphasis to protect the FM signal against overshoots after a lossy link.If you have multiple transmitters and want to synchronize the sound between them, see Synchronize FM transmitters. If you are planning to use Stereo Tool on an FM transmitter, please also read FM Output.
If the whole composite/MPX signal is generated from within Stereo Tool, the sound that can be generated is a lot better. While this works and still gives a reasonable sound, it makes it impossible to use Composite Clipping which gives several dB's of extra headroom for mainly the high frequencies, and features such as multipath distortion protection. Some people prefer to use Stereo Tool only for processing and use a separate RDS and stereo coder. Because of Pre-emp you often loose highs when enabling the FM processing settings ( Composite Clipping helps a lot against this), Stokkemask and multipath distortion protection can have some impact on the amount of stereo separation, and BS412 lowers the level a lot. Back to overview Documentation version 9.23Īll the settings to generate a compliant FM signal.Īll the settings that are related to the FM signal can be found here, such as pre-emphasis, stereo and RDS encoding, RDS texts, Stokkemask (ITU-R SM.1268) and ITU-R BS.412 compliance and multipath distortion protection.įM processing is more difficult that normal processing.