09-24-2021, 08:37 PM
rfeenstra,
The shortest answer is yes and no.
1) The stations that are still doing wideband AM are generally the larger stations, though this is by no means a given. A standard envelope detector can take full advantage of these stations, but for most radios, the audio bandwidth is limited by the bandpass of the IF chain, usually about 4 KHz or so, since most radios were made to be able to separate stations, and not worry about hi-fi audio.
That being said, there were a number of high-end 1930's sets that had variable bandwidth that, when set to wide band/hi-fi would do a fine job and sound nearly as good as FM on a local signal. There are still a few radios out there that will take advantage of broadband AM, such as some of the CCranes and the Superadio III.
2) Our old radios are completely useless and will not see any advantage to I-BLOCK (IBOC/HD.) The stations using I-BLOCK all have a very narrow AM bandwidth, because the sidebands are used for the digital signal. In fact, a decent hi-fi AM radio will actually see a degradation of what AM audio they do have, since the wider IF bandwidth passes the digital signal, which comes out as a sort of a hiss that vaguely reminds one of the noise an old dial-up modem used to make. Oh, and 5KHz audio on I-BLOCK stations is a pipe dream, it's closer to 3.5.
The shortest answer is yes and no.
1) The stations that are still doing wideband AM are generally the larger stations, though this is by no means a given. A standard envelope detector can take full advantage of these stations, but for most radios, the audio bandwidth is limited by the bandpass of the IF chain, usually about 4 KHz or so, since most radios were made to be able to separate stations, and not worry about hi-fi audio.
That being said, there were a number of high-end 1930's sets that had variable bandwidth that, when set to wide band/hi-fi would do a fine job and sound nearly as good as FM on a local signal. There are still a few radios out there that will take advantage of broadband AM, such as some of the CCranes and the Superadio III.
2) Our old radios are completely useless and will not see any advantage to I-BLOCK (IBOC/HD.) The stations using I-BLOCK all have a very narrow AM bandwidth, because the sidebands are used for the digital signal. In fact, a decent hi-fi AM radio will actually see a degradation of what AM audio they do have, since the wider IF bandwidth passes the digital signal, which comes out as a sort of a hiss that vaguely reminds one of the noise an old dial-up modem used to make. Oh, and 5KHz audio on I-BLOCK stations is a pipe dream, it's closer to 3.5.
