At least in the market in which we live, that being Minneapolis and St. Paul, 
Minnesota, the quality of HD broadcasts is still pretty good.  There has been 
some of the quantity over quality move, though.  There are cases where an HD 
channel is used to give an AM band talk format to the FM band.  One of our 
stations carries four programs on one frequency and none sound that great.  The 
bandwidth used for each can be varied, though, so it is possible for a talk 
format to be allocated less bandwidth than a music source using the same FM 
frequency.  To my knowledge, one can only carry one HD program on an AM signal. 
 We had two HD AM stations here for some time but right now we do not have any. 
 The way AM HD works, the coverage area is very small, and it takes very little 
interference to prevent a radio from locking on to an HD signal.  
Interestingly, it is sometimes possible to receive an AM HD signal at night 
from some distance away by skip.  It is not uncommon to be able to get two HD 
signals here from Chicago, some 400 miles away.  When they lock in they sound 
great, but they don't stay locked in for long, as a rule.

There is apparently some limited experimentation with AM signals that are only 
HD, that is, with no analog signal.  This let's them use less AM bandwidth and 
also put all of the power into the HD signal.  That means, of course, that the 
signal is completely unlistenable with an analog AM radio but the HD coverage 
area is much larger from what I here.

We are hearing on our news here in the United States that there is quite a heat 
wave in Australia.  Is that the case where you are?

Best regards,

Steve Jacobson

-----Original Message-----
From: all-audio@groups.io <all-audio@groups.io> On Behalf Of Dane Trethowan
Sent: Sunday, December 30, 2018 10:18 AM
To: all-audio@groups.io
Subject: Re: [all-audio] Sangean HDT-20 AM/FM/HD Tuner

An interesting inside into the world of HD again.
In Australia - in and around the capital cities - we use DAB - Digital Audio 
Broadcast - rather than HD.
I won’t go into the differences now suffice to say that when I got my first DAB 
radio I would spend hours listening to DAB broadcasts.
Things have moved on and those who define what we hear on DAB consider quantity 
over quality so the audio on DAB now has gotten to the point of being 
unlistenable, I fact many Internet streams from the same sources that broadcast 
DAB are far better.
The average bit rate of a DAB broadcast is only 32K where as it was twice that 
but not as many stations.

> On 31 Dec 2018, at 3:01 am, Steve Jacobson <steve.jacob...@visi.com> wrote:
> Dane and others,
> I purchased one of these tuners a year or so ago and have been generally
> happy with it.  The reviewer mentions experimenting with antennas, and I
> created a larger loop for AM reception and it added a good deal to the
> sensitivity of the AM section of this tuner.  However, I would agree with
> the reviewer that the supplied loop does a better than average job for that
> type of loop which is likely due to the tuner's sensitivity.
> One of the reasons there is a lot of comment about audio quality is that one
> cannot make any assumptions about how tuners work because of the
> complexities of the circuits inside.  For example, I also have a Teac HD
> radio and have connected it to my stereo using the headphone jack.  It has
> great audio when the signal is strong and on HD signals.  However, if an FM
> analog signal is even of medium strength, that radio reduces the high
> frequency response and does not have a stereo signal.  It also seems to
> reduce the low frequency response some.  The Sangean does a pretty nice job
> of maintaining frequency response, something I appreciate.  I would rather
> choose to lower the high frequencies if I found the noise to bother me.
> However, the Sangean uses a very narrow FM bandwidth when stations are not
> real strong.  While selectivity is super and signal to noise is very good,
> the analog audio is annoyingly distorted on signals that I believe would
> still be very listenable with a wider bandwidth.  This tuner seems to be
> very resistant to the effects of overload from strong signals.
> Since we have lost all of our AM HD stations in my area, I also don't
> understand why the Sangean tuner doesn't allow a wider bandwidth to be used
> on AM analog only signals.  The Sangean tuner has a very nice extended low
> end on AM, though.  I appreciate that.
> So my bit of frustration is that there are some artificial limits being
> imposed by the engineers designing some of these tuners that I just don't
> really understand.  Still, I find the Sangean tuner to be very enjoyable on
> HD signals and to be a good overall tuner.
> Best regards,
> Steve Jacobson
> -----Original Message-----
> From: all-audio@groups.io <all-audio@groups.io> On Behalf Of Dane Trethowan
> Sent: Sunday, December 30, 2018 5:40 AM
> To: all-audio@groups.io
> Subject: [all-audio] Sangean HDT-20 AM/FM/HD Tuner
> Hi,
> I know those in the USA are interested in HD radio as I would be myself if
> we had those radio standards in Australia.
> We don't so I can only be as envious as hell and wish I could move to the
> States tomorrow <smile>
> The following link is to a review of the Santean Hdt-20 AM/FM HD radio
> component tuner.
> I've read the review and the tuner is one of those things I'd very
> definitely like to own and put to use in my lounge or on my Hi-Fi system in
> the Den.
> I would be most interested in comments from others.
> I know there are people on list who own HD Radio sets, does anyone own the
> Sony set which is mentioned in this review which seems to be held in very
> high regard.
> Anyway here's the link
> https://nam05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fradiojayal
> len.com%2Fsangean-hdt-20-am-fm-hd-tuner%2F&amp;data=02%7C01%7C%7C5b640d0a283
> 7470bfe9408d66e4b803e%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636817667
> 881891178&amp;sdata=0GiY%2BdiCAu%2FoZp7fpTQvY6S%2FcvuwROJY5YdbarhgyvU%3D&amp
> ;reserved=0

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