4 ms·

"In the transmitter the fidelity is limited by the bandwidth of the modulator, and in the Receiver by the bandwidth of the IF stage." This applies to heterodyn

"In the transmitter the fidelity is limited by the bandwidth of the modulator, and in the Receiver by the bandwidth of the IF stage." This applies to heterodyne systems with the bandwidth limitation coming from deliberate filtering. My understanding is the channel width, set out in the broadcast standard and license, is the bottleneck and not so much the limitations of the electronics. FM must be under 150khz (5 times the maximum source bandwidth of 15khz, then doubled for upper and lower sidebands) and MW-AM must be under 9/10khz (limiting the source to around 5 kHz). So without the transmitter broadcasting outside its allocation, I don't understand how changing the receiver could improve the audio quality. I could be wrong. Do you have a source on 15khz audio bandwidth over MW-AM?

Johnythree 3y ago
There is no direct connection between the channel spacing, and the allowed TX bandwidth. If the bandwidth is wider than the channel spacing (for AM BC), all that happens is that adjacent stations hear a little "monkey chatter". And that is minimised because most stations are arranged on a geographic grid which prevents a local station having another local on an adjacent channel. In Australia the local Government ABC stations most definitely do transmit 15KHz wide audio. A quick search turned up this article from September 1980 ETI magazine which discusses stations having 30KHz total bandwidth. https://imgur.com/a/gVpSwoo https://imgur.com/a/gVpSwoo Whatever, just tuning around with a high-end SDR shows many stations at 20KHz bandwidth. The Commercial stations have a problem in that they use aggressive audio processing in order to maximise their coverage, given their licensed power output. So as soon as the commercials decided to concentrate on talk shows, they wound down their bandwidth.

Johnythree 3y ago

There is no direct connection between the channel spacing, and the allowed TX bandwidth. If the bandwidth is wider than the channel spacing (for AM BC), all that happens is that adjacent stations hear a little "monkey chatter". And that is minimised because most stations are arranged on a geographic grid which prevents a local station having another local on an adjacent channel. In Australia the local Government ABC stations most definitely do transmit 15KHz wide audio. A quick search turned up this article from September 1980 ETI magazine which discusses stations having 30KHz total bandwidth. https://imgur.com/a/gVpSwoo https://imgur.com/a/gVpSwoo Whatever, just tuning around with a high-end SDR shows many stations at 20KHz bandwidth. The Commercial stations have a problem in that they use aggressive audio processing in order to maximise their coverage, given their licensed power output. So as soon as the commercials decided to concentrate on talk shows, they wound down their bandwidth.