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HD Radio Receiver Sensitivity

7

700WLW

Guest
Could two receivers have the same problem, or maybe it is IBOC's poor coverage, to quote:

"I called Radiosophy the other day to get an update on their new radio. While on the phone we discussed the B.A.'s sensitivity problems which some of their units are suffering from as well. The new radio will also use DSP like the B.A. but will not suffer from the poorly shielded display problems which have effected the receptor HD's perceived poor sensitivity issue. I was told that operation in a moving vehicle might not be what one hopes for, but the radio does contain an internal antenna as well as a switch which allows an external antenna to be used. At this point the radio will only be sold directly by Radiosophy, although they are looking for retailers and it should be available by the end of November, barring any other production problems. The fact that the radio can be used both in the house and in the automobile makes this radio very desirable, as far as I'm concerned. I had the chance to play with one at NAB. I thougth it was more sensitive than the BA. It was easy to work with and if they ever get that car adapter set up that would be REAL nice." :D
 
To quote, referring to the Radiosophy MultiStream HD :

"I want one for the sole purpose of the car adaptor. It runs on 12v, so no step up or step down is needed. My car is wide enough to hang a dipole in the back seat - should suffice for FM."

:D
 
To quote, referring to the Radiosophy MultiStream HD:

"Any thoughts about FM sensitivity? If you could draw a conclusion, how does this radio compare with the B.A.? From my conversation they appear to acknowledge the Receptors deficiencies and have addressed them. I was told that a full second generation chip has not appeared yet (which might explain why Tivoli has delayed their HD radio) even though they did use the latest first generation chip. The price is excellent especially when you add in that the radio can be used both at home and in the automobile. I was told not to expect miracles when the radio is used in a car without an external antenna. Of course the company is in South Dakota where there are very few HD signals in the air. It will be interesting to see what the radio can do in a more urban environment."

Let's see - both the B.A. and Radiosophy need external antennas, preferably mounted outside. Now, along with the lack of portable HD radios, for the forseeable future, do you think average consumers are going to buy HD radios ? Also, just think of all the HD radios that have probably been returned, and will be, because of lousy reception, new chips or not ! :D
 
To quote, off one of radio-info's boards:

"Just picked up the "Accurian" HD radio at Radio Shack in Pasadena. $199.00 with a $20.00 rebate. So far, seems to work well, although I live very close to Senior Road. The only AM I know of that runs HD is Disney's KMIC, and I can't get enough of a signal for the HD to kick in."

Texas Tuner

:D
 
ElCheapo said:
You must be the king of beverage antennas. Glad I'm not as obsessed with this as you! :D
Click to expand...

You are the one that keeps signing on at every reply - you are now dominating the board ! Good point - consumers aren't going to buy table-top receivers that require beverage antennas, especially, that need to be mounted outside ! :D
 
To quote:

The Perfect HD Antenna

I just thought it was worth a *slightly* misleading teaser headline to encourage people to experiment. For indeed I *have* found the perfect HD antenna...for me!

I decided to get the JVC KD-HDR1 car unit for use at home in part because it had external antenna input (of course) and an infrared remote. Decent price, too.

I soldered up a little motorola-to-F connector pigtail and attached a dipole I had (that had a balun with F connector). I could get all the local HD stations *except* the local NPR affiliate's HD channels. The reason I bought the radio! I have a nice hill between me and their transmitter, but I get enough signal to get nice, steady stereo on an old Pioneer tuner hooked up to an old Bic "Beambox" antenna. I'm only 4 miles away! Humph!

So I hooked up the beambox to the JVC, then an old ratshack powered antenna, then an omnidirectional Antennacraft FMSS, then a directional ratshack 15-2163. Nada.

So I sulked for a couple of days but then I went to the hardware store and Ratshack. I got:

- an 8-foot length of 1/2" copper tubing
- a 1/2" PVC "T" pipe coupler
- 2 1" long #10 machine screws
- 2 #10 wingnuts
- 4 #10 washers
- 1 300 Ohm to 75 Ohm antenna balun with F connector

Total cost about $15

So I cut 2 3-foot lengths of the copper pipe, stuck 'em in the coupler, and marked a spot to drill through each piece of pipe about 3/4" from the edge of the coupler. I drilled, put the pipes back in the coupler, put the screws through with washers and then fastened the two tails of the $4 balun with the wing nuts. Hooked it up to the JVC with a 6-foot length of coax.

BANG! All three NPR affiliate HD channels.

So I checked the rest of the channels and all was pretty good. Oddly, I lost HD on another station -- one that had been the strongest. So I took a chance and shortened the arms of the dipole tubes down to 2' 8", closer to the theoretical optimum for a dipole aimed at the middle of the FM band. Tada! I was then able to get that channel back by rotating the antenna.

So, sometimes it may be possible to fix a problem by just throwing more copper at it.

I will now proceed to paint this work of art black and admire it.

:D
 
Now you just need to set up a production line and begin advertising "HD-compatible" antennas.
It would be as funny as when they used to market "color TV antennas" specially designed to make your colors clear and sharp, even given the limitaitons of NTSC....as if the colors were in some other frequency band, or your old 3-element B&W antenna wouldn't work as well.

Marketing is everything. A good line of BS could make you rich, as millions of new listeners will be striving for the best possible
(or any at all) HD reception. If you can't make 'em happy, sell them something else that MIGHT help.

Use some kind special color for the paint, and claim that's part of the secret. People will believe it.
Maybe wrinkle-finish in bright red! No, one of the flashy new paints that change color by viewing angle!
And cheapen it up somehow...the market won't stand for real copper pipe, copper flashing on a piece of conduit is enough for the public.
 
Tom Wells said:
Now you just need to set up a production line and begin advertising "HD-compatible" antennas.

Use some kind special color for the paint... Maybe wrinkle-finish in bright red! No, one of the flashy new paints that change color by viewing angle!
Click to expand...

You just may have something there... I hear in Chicago since "Pride FM" debuted--there's quite a market for "designer dipoles" to "add fab" to those BA HD radios tuned to the 103.5 HD-2 stream :D
 
To quote, referring to the RS Accurian HD:

"But will it work in Rural Morgan County Indiana, 25 to 35 miles from all the Metro Stations... Keep in mind that the station I want to pick up is 30 miles away at about 1000 feet Haat, and 13,500 watts, and im trying to pick up the HD-2 of that station, which is less powerful than the primary channel, and im kinda in the shadow of a big hill. We do pickup the analog here quite well on a regular radio, but not quite city grade. I had a Boston Acoustics, but sent it back, I couldnt get any HD stations at all, and couldnt really afford it anyway. I too am really wanting to try out the Accurian, but if I cant pick up the only station I want, it wouldnt do me any good."
 
It sounds like the wide bandwidth required is making the previous radio reference designs inadequate. No matter what the label is on the front of the radio, it is probably based on 3 or 4 reference designs - which may date from the 70's. You don't slap a 350 kHz ceramic filter in there, tack on IBOC decode circuitry, and go to production. There is this little thing called the gain / bandwidth product that will get you.

The IBOC contingent had better get on the ball and start designing some really good receivers from scratch to compensate for this problem. Old techniques like stagger tuning the IF, dual conversion, etc. might yield some decent sensitivity figures AND have bandwidth wide enough to accomodate HD.

I am very much afraid - if this isn't done and done quickly - HD radio will suffer from a public perception that it is no better than analog: because demonstrations inside steel frame construction stores will render it analog only. And - if the only listeners that can hear HD are within 20 to 25 miles of the transmitter or closer, MOST metro area suburbs will not be able to get HD - and that is where the affluent live who could afford receivers.

The HD radio folks had also better partner with antenna makers such as Radio Shack - it may turn out their decision to stop selling their medium fringe 6 element yagi was ill-timed, as HD radios could really benefit from it. Also - it sounds like the AM radios could really benefit from their loop antenna.

Bottom line - HD will make DX'ers out of suburban listeners.
 
rbrucecarter5 said:
It sounds like the wide bandwidth required is making the previous radio reference designs inadequate. No matter what the label is on the front of the radio, it is probably based on 3 or 4 reference designs - which may date from the 70's. You don't slap a 350 kHz ceramic filter in there, tack on IBOC decode circuitry, and go to production. There is this little thing called the gain / bandwidth product that will get you.

The IBOC contingent had better get on the ball and start designing some really good receivers from scratch to compensate for this problem. Old techniques like stagger tuning the IF, dual conversion, etc. might yield some decent sensitivity figures AND have bandwidth wide enough to accomodate HD.

I am very much afraid - if this isn't done and done quickly - HD radio will suffer from a public perception that it is no better than analog: because demonstrations inside steel frame construction stores will render it analog only. And - if the only listeners that can hear HD are within 20 to 25 miles of the transmitter or closer, MOST metro area suburbs will not be able to get HD - and that is where the affluent live who could afford receivers.

The HD radio folks had also better partner with antenna makers such as Radio Shack - it may turn out their decision to stop selling their medium fringe 6 element yagi was ill-timed, as HD radios could really benefit from it. Also - it sounds like the AM radios could really benefit from their loop antenna.

Bottom line - HD will make DX'ers out of suburban listeners.
Click to expand...
But HD promoters claim DXers are illegals, and should not be allowed.
 
SUPERCASTER said:
But HD promoters claim DXers are illegals, and should not be allowed.
Click to expand...

All this time I thought we were supposed to be anachronisms. Whenever receiver manufacturers or stations run into coverage problems - who are the first people they contact for the solution? But if we are all anachronisms - then I guess they can solve their lousy coverage problems on their own this time. Lets see how far IBOC stations reach with a dipole crumpled up on the floor, or with a two inch ferrite bar antenna. My guess is - they won't even make ten miles, let alone the 25 some HD radio people are claiming. Especially in steel frame construction.
 
To quote, referring to the RS Accurian HD:

"Just picked up one of the new "Accurian" HD table radios from Radio Shack. $175 after rebate. Sound is good for a table radio.. not quite up to the sound of the more expensive "Boston" HD-Radio. The Am-HD worked right out of box with supplied (Cheep Plastic) antenna after some tweaking of direction. The FM-HD worked ok with supplied dipole-again required some tweaking of antenna direction. All this in the basement. AM-HD sounds as good as regular FM on this radio...Ultra critical listeners will hear a very slight harshness on the high end. Now if they can get the price down to $59.95 they would have a winner."

First of all, there is no guarantee of getting the rebate back, and those darn dipoles sure will be a selling point ! Seeing the price come down to $59.95 - keep dreaming, maybe on clearance ! :D
 
To quote, referring to the Jvc Kd-hdr1:

"Antenna and Ignition noise"

"I put this unit in my car the other day, 1996 Nissan. Looking to buy another one for another car. Love the HD!! Fantastic unit, but I know from experience that the antenna on the car is really sub-par, and I get a lot of "noise" when the car is running. It's kind of like a popping sound that increases when I use the accelerator. The problem was there with the factory radio. Does anyone know of a good aftermarket antenna that would boost the signal. It's getting really hard to find aftermarket antennas. Also, need advise on what I need to do to clean up the interference."
 
Ignition noise is chased by the following measures....
1. A real, stand-up antenna, not a windshield antenna.
2. Resistor spark plugs.
3. Resistor wires.
4. Ground strap from hood to firewall.
5. Ground strap from firewall to radio chassis. (most dashboards aren't metal anymore).
6. Power filter with inductance (coil) in 12v line.
7. .01 mfd capacitor from 12v lead to radio case, after the in-line filter.
8. Ground strap from engine block to firewall.
9. .01 mfd capacitor from 12v side of coil to engine block.
10. Ground strap from firewall to base of antenna/and/or fender antenna is mounted on.

Manufacturers may use some of these measures, but not all. Add as many as needed.

Corvettes used to have ignition wire sheaths to limit ign noise propagation, since the hood was fiberglass.

Oh, and DO NOT use antenna amplifiers. They almost always add to the problem, and often introduce new problems as well.
 
To quote:

"Accurian HD Antenna Trick"

"I found that plugging in the AM Loop antenna (INTO ITS PROPER SPOT), and let it hang beside my dressor, in addition to rabbit ears actually helped out a little with FM HD as well. I now can get an NPR station in HD from 60 miles away... It also brought in the HD-2 of WRZX-Classic Alternative. I usually only get TWO HD-2 stations here, WNOU-Dance and WHLK-Americana. This may or may not work for everybody. I dont know why this would effect reception, but it does. I unplug it, and loose the HD-2s of the stations in question..."

"I had a similar experience with the Boston Acoustics unit. I moved the AM antenna and all the HD FMs dropped out."

HD Radio - what a pathetic joke ! BTW, another poster here, stated that the Accurian HD heats up - that is good ! :D
 
700WLW said:
HD Radio - what a pathetic joke ! BTW, another poster here, stated that the Accurian HD heats up - that is good !
Click to expand...
Perhaps the Accurian is a better toaster, coffee maker, or food warmer, then a radio.
 
"Microwave Oven. Cuts out my HD signal"

"Okay, does this mean I have a poorly shielded microwave, or is this a common problem when someone fires up the Microwave in the next room? Another important question is, do Microwave transmissions in general effect HD reception? This could be a serious problem for someone living in an apartment complex with people running microwaves all the time. And what if you live near a Microwave STL????? This troubles me a bit when thinking of the future of HD."
 
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