On 6/15/2012 6:55 PM, glen herrmannsfeldt wrote:> Randy Yates<yates@digitalsignallabs.com> wrote: > > (snip, I wrote) >>> [...] >>> and at least a start (I haven't bought one yet) on digital >>> radio, how long before the complete conversion of broadcast >>> to digital? > >> I presume you're talking of Ibiquity, AKA HD Radio? > > I believe so. There are both AM and FM versions, with presumably > different technologies. And there is also Sirius/XM, which I > presume is also digital. > > I suppose before it gets very popular, a new technology might > come along, and everything shift over. > > There is the story about the beginning of FM radio, they were > in the 30MHz or so band, and selling (slowly) radios. > > Then when the standard came out at 88-108MHz (as I understand it, > influenced by AM radio broadcasters) all the old radios were useless.39-44 MHz FM was a temporary standard before WWII, and the transmitters went silent during the war. They briefly returned after the war, but by then emerging radar technology made the 88-108 band commercially practical. http://userpages.bright.net/~geary/fm/fm.html Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Analog RF to DSP
Started by ●June 14, 2012
Reply by ●June 18, 20122012-06-18
Reply by ●June 18, 20122012-06-18
On 6/18/2012 1:51 PM, Jerry Avins wrote:> On 6/15/2012 6:55 PM, glen herrmannsfeldt wrote: >> Randy Yates<yates@digitalsignallabs.com> wrote: >> >> (snip, I wrote) >>>> [...] >>>> and at least a start (I haven't bought one yet) on digital >>>> radio, how long before the complete conversion of broadcast >>>> to digital? >> >>> I presume you're talking of Ibiquity, AKA HD Radio? >> >> I believe so. There are both AM and FM versions, with presumably >> different technologies. And there is also Sirius/XM, which I >> presume is also digital. >> >> I suppose before it gets very popular, a new technology might >> come along, and everything shift over. >> >> There is the story about the beginning of FM radio, they were >> in the 30MHz or so band, and selling (slowly) radios. >> >> Then when the standard came out at 88-108MHz (as I understand it, >> influenced by AM radio broadcasters) all the old radios were useless. > > 39-44 MHz FM was a temporary standard before WWII, and the transmitters > went silent during the war. They briefly returned after the war, but by > then emerging radar technology made the 88-108 band commercially > practical. http://userpages.bright.net/~geary/fm/fm.htmlI should add that someone gave me an obsolete low-band Meissner and I tried to make a down-converter front-end for it. I learned about bandwidth from that. The Meisner's IF wasn't wide enough to accommodate a "modern" 10.7 MHz signal. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●June 18, 20122012-06-18
Jerry Avins <jya@ieee.org> wrote: (snip, I wrote)>> There is the story about the beginning of FM radio, they were >> in the 30MHz or so band, and selling (slowly) radios.>> Then when the standard came out at 88-108MHz (as I understand it, >> influenced by AM radio broadcasters) all the old radios were useless.> 39-44 MHz FM was a temporary standard before WWII, and the transmitters > went silent during the war. They briefly returned after the war, but by > then emerging radar technology made the 88-108 band commercially > practical. http://userpages.bright.net/~geary/fm/fm.htmlYes, 5MHz wouldn't have been enough for very long. Almost surprising that 20MHz is still enough. But converter boxes won't be quite as convenient as for TVs. For home use, maybe, but not for portable radios. I have a Sony Watchman battery powered TV that someone gave me a few years ago. Not so portably if you have a line powered converter box to go with it. -- glen
