"DAB sounds worse than FM" wrote in message
...
Agamemnon wrote:
"DAB sounds worse than FM" wrote in message
...
X-posted to uk.rec.audio hopefully to attract Jim Lesurf's attention.

Look at the encoder and transmitter technical specifications

http://www.transmittersrus.com/inovo_222.htm

(pre-emphasis defeated):
"PROOF" mode: ±0.5dB, 10Hz-15kHz
222-00 (NRSC): ±1dB, 10Hz-9.7kHz
222-01 (Euro MW): ±1dB, 10Hz-8.7kHz
222-02 (US SW): ±1dB, 10Hz-6.2kHz
222-03 (Int'l SW): ±1dB, 10Hz-4.85kHz


Then they're mis-selling their product.

They are doing nothing of the kind otherwise they would not be
allowed to sell it by OfCom.


I accept that they're not mis-selling, but only because of what hwh said:

"When digital filters became practical,
brickwall filtering was introduced, but in may cases well above 4,5
kHz. When the adjacent channel is not used anywhere near, that is not
a problem."

In general, assuming adjacent channels are in-use, then 4.5kHz is the
maximum audio bandwidth.


http://www.st-andrews.ac.uk/~www_pa/...rt9/page4.html

"The AM wave essentially carries two copies of the modulation
pattern - one in each transmission sideband. As a result, it
occupies a Transmission Bandwidth, . i.e. it takes up twice as much
bandwidth as the original information. This represents one of the
main disadvantages of AM modulation."


http://www.transmittersrus.com/blyth_ambt101.htm

Maximum SWR:1.5 at carrier (minimum return loss from aerial between
-10kHz and +10kHz of carrier 10dB)

Audio Filter:10 kHz switched capacitive filter (other cut-of
frequencies readily available)

Audio Response 10H0z to 10kHz:+0.5dB, -1dB Ref 1kHz

Modulation System:Pulse Width Modulation (PWM)


In general, assuming adjacent channels are in-use, then 4.5kHz is the
maximum audio bandwidth.


"MW frequency response = 50Hz-10 KHz (US) -9KHz (UK). Capable of up
to 20KHz
or better frequency response if no adjacent channels are present."

because it fails to take the double-sideband nature inherent in
envelope AM transmission.

Twaddle.

You can have virtually any frequency response you like on medium
wave. From the tech speacs above you can see that in PROOF mode its
up to 15kHz, and you can always go higher. Weather the tuner lets
you decode it is another thing. Solution. Build your own.


Broadcast MW uses envelope AM. MW receivers use envelope detectors.
Envelope AM is inherently double-sideband, so the maximum audio
bandwidth will be 4.5kHz.

Nope. If the transmitter is fed with a 9kHz audio signal, which is
perfectly legal 9kHz is what you get out from a compatible receiver.

See below for decoder circuit diagrams and response plots.

http://www.geocities.com/rbrucecarter/amaudio.htm

"High frequency interference is a problem at night. AM frequency
response is not limited (unlike FM, which is severely rolled off
above 15 kHz). Even though AM stations are allocated on 10 kHz
channels, the FCC does not require that the audio frequency response
be limited to less than 10 kHz. High frequency response can extend to
20 kHz or even beyond. At night, however, distant stations will be
present on adjacent frequencies, and audio from those stations will
mix with the high frequency audio, producing noise. a.. The 10 kHz
spacing of AM stations causes another problem. The channel spacing is
close enough that the carrier frequencies from adjacent channels are
audible. These carriers produce audible tones in the audio - 10 kHz
in North America, and 9 kHz in Europe and much of the rest of the
world. Because AM propagates much farther at night, the problem
becomes worse. In almost every case, there will be a carrier below
and above the desired station. Not only will both carriers contribute
to a 10 kHz whistle, but they will be at slightly different
frequencies. The FCC allows AM stations to deviate (20 Hz from their
assigned frequency, so the two carriers will mix together, creating
an even more annoying warbling 10 kHz whistle tone. "
"The high pass filter will remove the pilot difference frequencies as
well as the stereo pilot, while allowing bass frequencies of 50 Hz
and above to pass unaltered. Because FM radio also rolls off below 50
Hz, the listener should not notice any difference between AM and FM
in bass response. High frequency noise and the 10 kHz pilot tones are
removed by the low pass filter. This filter also limits the high
frequency response of the AM audio to 8 kHz, so the listener may
notice a difference compared to FM. Because high frequency noise only
occurs on distant stations in the daytime - the listener should be
able to listen to local AM stations with the filter section switched
out the circuit. "


In general, assuming adjacent channels are in-use, then 4.5kHz is the
maximum audio bandwidth.


Yet again you've just got everything wrong so, obviously, no
apology will be forthcoming.


It is you who have got everything wrong.

I'm still waiting for your apology.


You wouldn't take the test, so I owe you no apology whatsoever, and
I'd like to know whether you've donated the agreed £10 to the
Tsunami appeal?

I took the original test and I got them all right even though it was
not completely fair on me as I pointed out at the time. Your second
test was completely unscientific and deliberately weighted against me
as can be seen from the EBU
Technical Review which details how a genuine scientific test should be
carried out.

I'm still waiting for your apology.


You admitted that you only identified the CD-original sample by viewing
the sample's frequency response and you've admitted that you keep Dolby

You downright DECEITFUL LIAR !!!!

I said nothing of the kind. What I told you was that is was easy to work out
the original since the difference in frequency responses is clearly audible.

Digital switched-on, which helps to identify the MPEG-encoded samples.
This test was therefore declared null and void.

POPPYCOCK. I did nothing of the kindwith the original samples you posted.

You are a downright DECEITFUL LIAR !!!!


You then refused to take a test where the bandwidths of the samples were
all similar due to lowpass filtering. Therefore, just like a football

Because you are a CHEAT ! That is not how official scientific listening test
are conducted and that is why you still owe me an apology.

team that doesn't turn up to a match forfeits the game, you fail the test,
and owe the tsunami appeal £10, as agreed.

You will never receive an apology, because I have nothing to apologise
for.

You're a technical incompetent and a known and regular troll and buffoon.

CHEAT, LIAR, CHARLETON !


Goodbye.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

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