Hi Zach,
When they designed the FM broadcast band system, they wanted to have a very quiet background sound level, even better than the fairly low noise (high frequency hiss) that FM provides. So they decided to emphasize (boost) the audio high frequencies when they transmit, then allow the receiver to cut the audio high frequencies back down to normal. When the highs are cut, then the hiss is also cut. The Americans, who started FM broadcasting first, chose an agressive emphasis curve so that the hiss was reduced very much during de-emphasis by the receiver. The recorders and microphones at that time didn't have much high audio frequency level anyway.
Years later, the Europeans decided to broadcast FM too, but noticed that the high audio frequencies frequently overmodulated the transmitter when they were emphasized so much. They realised that recording machines and microphones had improved very much over the years since the Americans developed the system and produced high audio frequency levels that were much higher than the system could support. So they chose a less agressive emphasis curve (less high audio frequencies boost).
Therefore the North American and European curves are different. An American radio will sound muffled in europe, and a european radio will sound too bright in America.
Your radio has the agressive American de-emphasis curve where the high audio frequencies are cut quite a lot. (The datasheet has the european curve). However, your simple transmitter doesn't have any pre-emphasis to balance the sound so the radio will play it very muffled, similar to your home stereo having its treble tone control turned all the way down.
When they designed the FM broadcast band system, they wanted to have a very quiet background sound level, even better than the fairly low noise (high frequency hiss) that FM provides. So they decided to emphasize (boost) the audio high frequencies when they transmit, then allow the receiver to cut the audio high frequencies back down to normal. When the highs are cut, then the hiss is also cut. The Americans, who started FM broadcasting first, chose an agressive emphasis curve so that the hiss was reduced very much during de-emphasis by the receiver. The recorders and microphones at that time didn't have much high audio frequency level anyway.
Years later, the Europeans decided to broadcast FM too, but noticed that the high audio frequencies frequently overmodulated the transmitter when they were emphasized so much. They realised that recording machines and microphones had improved very much over the years since the Americans developed the system and produced high audio frequency levels that were much higher than the system could support. So they chose a less agressive emphasis curve (less high audio frequencies boost).
Therefore the North American and European curves are different. An American radio will sound muffled in europe, and a european radio will sound too bright in America.
Your radio has the agressive American de-emphasis curve where the high audio frequencies are cut quite a lot. (The datasheet has the european curve). However, your simple transmitter doesn't have any pre-emphasis to balance the sound so the radio will play it very muffled, similar to your home stereo having its treble tone control turned all the way down.
