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“HD did worse than ever,” according to Pew.

Kmagrill said:
Well, maybe the Lucent guys should have foreseen the IF problem. Then again, a lot of markets don't have 10.4 or 11 mHz spaced stations, so it may not be a huge issue, though in some places it certainly could be. This problem may fade over time as digital quadrature detection, software defined radios find their way into the market, replacing the standard radios with 10.7mHz IF stages. In a few years it's very likely that almost all receivers will abandon the traditional mixer/IF amps in favor of DSP due to lower cost and superior performance.
Click to expand...

I like the approach in the Sony CXA1129 chip - change the IF frequencies. I haven't looked specifically at that chip to see if their unique approach would solve HD problems. Their FM section is dual conversion, with the first IF at 30 MHz. So far so good - that would put the sum component above the FM band in the first IF. The second IF is 150 kHz - and implemented in a 9 pole low pass filter. Kind of ingenious, because the lower sideband is eliminated completely by having it cut off at zero Hz. Nine poles makes for a really selective FM on the high end. Enough so that the analog tuned SRF-59 is hard to deal with.

The problem I see with digitizing the entire FM band is the frequencies involved. Silicon has kind of hit a wall - speed wise. That is one of the reasons for multiple cores in Intel microprocessors, the clock can't go much faster, so you have to parallel and pipeline to get more speed. Semiconductor complexity is following Moore's law, but the speeds are not. When it comes to bandpass filtering, a good rule of thumb is that you need a gain / bandwidth product about 100 times the frequency of operation, or about 10 GHz for FM. A level above the current state of the art in semiconductor design. Which is why cell phones (and base stations) are triple conversion, by the way. To get to where they can digitize the signal, they have to convert it way down to something they can digitize in current semiconductor technology and DSP algorithms. If you use a good old superhet design and an IF frequency of 20 MHz for FM, you can probably digitize the 20 MHz directly in a 2 GHz DSP and solve the IF imaging problem. Otherwise, you are going to be making compromises - serious ones - somewhere.

As for Sony - they have an incredible IC. Maybe pair their IC with HD decoders and you wouldn't have the mixer product problem. But Sony won't sell that IC to anybody. Silabs has one with 10.7 MHz filtering on the chip, but if you look inside it is probably a very conventional analog filter of some sort - not a direct sample IF. Not at the price they are selling it.
 
rbrucecarter5 said:
I like the approach in the Sony CXA1129 chip - change the IF frequencies. I haven't looked specifically at that chip to see if their unique approach would solve HD problems. Their FM section is dual conversion, with the first IF at 30 MHz. So far so good - that would put the sum component above the FM band in the first IF. The second IF is 150 kHz - and implemented in a 9 pole low pass filter. Kind of ingenious, because the lower sideband is eliminated completely by having it cut off at zero Hz. Nine poles makes for a really selective FM on the high end. Enough so that the analog tuned SRF-59 is hard to deal with.
As for Sony - they have an incredible IC. Maybe pair their IC with HD decoders and you wouldn't have the mixer product problem. But Sony won't sell that IC to anybody. Silabs has one with 10.7 MHz filtering on the chip, but if you look inside it is probably a very conventional analog filter of some sort - not a direct sample IF. Not at the price they are selling it.
Click to expand...

After reading about this Sony chip, I wonder if Sony has ever made a radio with both the CXA1129 chip and a built-in speaker...unless the chip cannot drive the speaker. I found nothing from Google search. The ICF-38 radio has the older 1029 chip that I think drives a speaker.
 
local oscillator said:
Following yesterday's rebuttal to the Pew Report by Struble in Radio World, a certain "Michigan broadcaster" commented that the publication has been "in the tank" for HD Radio, to which editor Paul McLane took exception: http://www.rwonline.com/article/ibiquity-pew-data-isnt-accurate/218396. Thoughts?
Click to expand...

McLane points to one article RW published as a rebuttal to the claim of bias. Really? ONE article? I don't know whether to laugh or vomit...
 
ddsparxx said:
After reading about this Sony chip, I wonder if Sony has ever made a radio with both the CXA1129 chip and a built-in speaker...unless the chip cannot drive the speaker. I found nothing from Google search. The ICF-38 radio has the older 1029 chip that I think drives a speaker.
Click to expand...

I think there is one - there was some discussion of it on one of the technical forums I visited. It has the chip, it has a separate audio amplifier IC. As I remember the review wasn't kind to the radio - it was pretty poor quality, but with alignment and some care they got it up to acceptable standards. That chip, mounted on a PC board, in a radio case large enough for a decent size ferrite bar antenna would be hard to pass up. I'll check around and see if I can find the model number.
 
If you read RW's coverage of IBOC over time, you can see how they've shifted positions. Originally they were cheerleaders - then, in the late '90s and early-to-mid '00s, there was a critical bent.

Why things have become so stenographic with regard to the iBiquity perspective more recently is puzzling. I definitely don't see them as outright shills...nor do I see them as doing due journalistic diligence regarding claims made by proponents.
 
My biggest disappointment in life was the loss of the Motorola Semiconductor invention: the "Symphony Chipset" which had some terrific AM improvements - but then, to gain on the cell industry, Moto dumped their Semiconductor division to "ON Semi" and the big bucks and wonderful future the Symphony chipset had went right down the toilet. If I ever win the lottery, I want to resurrect the Motorola Symphony Chips: DSP, noise reduction, adjustable bandwidth, stereo AM, great selectivity, add other bands onto it, software updates, and so on...damn I wish somebody would use it - sounds close to Sony's little gem - less any HD monkeybusiness.
 
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