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stewartjm

Best Dab+ Receiever Reception

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Just wondering what has the most sensitive receiver. I have a few DAB+ radios, as I am in a marginal area (90km), they vary differently in sensitivity. I would have thought that a well know brand combo unit would have better sensitivity to a "Warehouse" special. Wrong. The Cobolt special receives off the same antenna with 10-20 error rate, that is no break up. The Sharp occasionally gets service. A Kaiser Baas gets 30-40 off the same antenna, still ok. Then a bush does not even pick up signal. All with external antenna connected.

The Cobolt has the Frontier Silicon Venice 7 module.. http://www.frontier-silicon.com/products/modules/venice7.htm

Bush has the Quantek Q7+ module http://www.quantek-inc.com/Q7+.html

Not sure of the others, havent opened them

I know that the Silicon Chip magazine kit DAB+ uses the Frontier Silicon Venice 7. Quantek seems to be a chinese knock off, certainly seems more deaf.

Just wondering how other go in marginal areas?

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Be interesting to stick an attenuator between your antenna and your radios to reduce the signal even more and see where they give up.

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stewartjm,

Rather than trying to get the most sensitive radio, you will have much more success with a radio which has an external antenna connection. Then pick one of the fringe area antennas referenced in the link below;

See

Digital Radio Dab+ & Drm, What are they, what is happening here, which antenna to use

DAB+ Digital Radio Reception Issues is a new more appropriate strand for these posts as there are many references to types of radios etc.

AlanH

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Rather than trying to get the most sensitive radio, you will have much more success with a radio which has an external antenna connection.
...... The Cobolt special receives off the same antenna with 10-20 error rate, that is no break up. The Sharp occasionally gets service. A Kaiser Baas gets 30-40 off the same antenna, still ok. Then a bush does not even pick up signal. All with external antenna connected.

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Have been playing around with a Pure Move 2500 over last few days and it seems to have quite good receiver sensitivity.

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I bought a Bauhn DAB+ radio from Aldi last week for $30. I don't know if it's a good radio, or just a good spot where I live? I have no problems getting the Sydney DAB+ channels about 98km from the transmitter (North Side), just using the built in telescopic antenna.

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GlennP,

Are your days of listening to AM radio over?

AlanH

No, I only listen to the "digital" only stations on DAB+, usually Mix 80's, Zoo Super Digi, & sometimes The Crack. Even though the Sydney AM & FM stations aren't as clear as the DAB+ stations in Newcastle, I still prefer the warmth AM & FM seems to have over digital, & listen to the analogue station over the digital equivalent. When out & about in the car, at work, or just listening to the Newcastle stations, my preferred station is an AM one, & I have no problems listening to it, nor wish it was digital. I also prefer to listen to Super Radio Network programs on 2HD AM Newcastle than listen to it on 2SM digital. With a quality AM signal, I still think generally, it's much better than in digital. Yes with a poor AM signal & interference, digital is crystal clear (if it's not dropping out from poor signal too), but to me that interference just gives AM character & life.

I know this radio isn't a high quality one, but the FM stations sound better/warmer than their digital equivalents on this radio to my ears.

I've had it 2 weeks now & I spent the first 4 days listening to digital all day, then the new toy excitement wore off, & this morning was the first time I'd listened to digital in 3 days. Even though DAB+ works (for me), 100km's from the transmitter site, & well past the intended coverage area, I still don't think DAB+ is the best platform for digital radio in this country, DRM/DRM+ is.

I still stick by everything I've said about DAB+ digital radio, even though I'm now 1 of those "supposed" 1 million statistical people that CRA claim, own & listen to digital radio.

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GlennP,

I have always said that DAB+ is for high population density, because of its ability to carry lots of programs on one transmitter.

It is more appropriate for DRM+ to be used in regional areas and small area transmitters in areas of high population density.

DRM30 for remote and national coverage.

What will the ACMA/DBCDE selects for Newcastle and the Central Coast is yet to be decided.

So you are yet to hear 2HD in stereo with the high pitched sounds???

AlanH

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GlennP,

So you are yet to hear 2HD in stereo with the high pitched sounds???

AlanH

Not quite sure what you mean by "high pitched sounds"?

I have heard 2HD in AM stereo before it was turned off, & 2HD have a FM Stereo translator not far away. The FM Stereo is only fake stereo, as the studios are only wired in mono, but it sounds better than many "proper" FM Stereo stations around the country, & if you didn't know, you'd be hard pressed to tell it's not real stereo.

2HD & sister station NEWFM were set up technically very well, & are arguably the best sounding AM & FM stations in Australia. Austereo, DMG & ARN have all had top engineers checkout their setup, & have tried unsuccessfully to replicate NEWFM's sound quality. 2HD currently use a new (3 years old now), AM stereo transmitter run in mono (as the studios are only mono), so could relatively easily put fake stereo back on AM too if wanted, but not a lot of point, still sounds good in mono, & the TX runs out to about 12kHz before the audio drops off, making it sound good on a quality non-narrowband radio.

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GlennP,

The quality of the sound of a radio station depends on the following;

The technical quality of the equipment used. It sounds as if 2HD is analog from microphone to transmitter input if they are wired for mono.

The critical thing for station "sound" is the setup of the audio processor.

These devices usually split the audio up into either octave or 1/3 octave bands according to the price. Each band contains a compressor with controls for the amount of compression, the attack and decay times and may also have some pre-emphasis on the output. This pre-emphasis was proposed when the original AM stereo was standardised to increase the level of the high frequencies because of the high frequency rolloff in nearly all receivers. The amount of high frequency boost is similar to that used in FM pre-emphasis in Australia with some low frequency boost added because of the majority of AM radios having small speakers.

After all this there still has to be a peak limiter to prevent overmodulation of the transmitter.

Tuning of so many variables on the audio processor is an art not a science and is not only related to the expected receiver and human hearing but also to the sounds being processed. So the processor settings for 2NEW should be different to 2HD. This is not only because its FM but also to the type of programs transmitted.

Fake stereo can never produce a signal which comes from the left or right. The best demonstration of this is the Beatles "Yellow Submarine" where the singing is only in one channel and the music is in the other only.

Considering that nearly all AM radios roll off at around 4 kHz the transmitter being able to produce sidebands out to 12 kHz either side of the carrier is mostly irrelevant.

There are many in the AM radio audience who have high frequency hearing loss and imbalance in the sensitivity of the left to right ears which has build up over many years that the better sound is also being assessed by such ears.

Hearing losses in the production area of radio stations is not uncommon, due to the ability to listen to loud monitoring sounds. I know some.

AlanH

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& the TX runs out to about 12kHz before the audio drops off, making it sound good on a quality non-narrowband radio.

I'm sorry, Glenn, I simply can't believe this anymore. I thought I measured audio out to 9, 10, 12, even 15kHz once on AM, but the DTV Forum Master corrected my mistaken belief. HE KNOWS the secret regulations, and they only permit audio to 7.5kHz. Praise the DTV Forum Master!!

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GlennP,

The quality of the sound of a radio station depends on the following;

The technical quality of the equipment used. It sounds as if 2HD is analog from microphone to transmitter input if they are wired for mono.

The critical thing for station "sound" is the setup of the audio processor.

These devices usually split the audio up into either octave or 1/3 octave bands according to the price. Each band contains a compressor with controls for the amount of compression, the attack and decay times and may also have some pre-emphasis on the output. This pre-emphasis was proposed when the original AM stereo was standardised to increase the level of the high frequencies because of the high frequency rolloff in nearly all receivers. The amount of high frequency boost is similar to that used in FM pre-emphasis in Australia with some low frequency boost added because of the majority of AM radios having small speakers.

After all this there still has to be a peak limiter to prevent overmodulation of the transmitter.

Tuning of so many variables on the audio processor is an art not a science and is not only related to the expected receiver and human hearing but also to the sounds being processed. So the processor settings for 2NEW should be different to 2HD. This is not only because its FM but also to the type of programs transmitted.

Fake stereo can never produce a signal which comes from the left or right. The best demonstration of this is the Beatles "Yellow Submarine" where the singing is only in one channel and the music is in the other only.

Considering that nearly all AM radios roll off at around 4 kHz the transmitter being able to produce sidebands out to 12 kHz either side of the carrier is mostly irrelevant.

There are many in the AM radio audience who have high frequency hearing loss and imbalance in the sensitivity of the left to right ears which has build up over many years that the better sound is also being assessed by such ears.

Hearing losses in the production area of radio stations is not uncommon, due to the ability to listen to loud monitoring sounds. I know some.

AlanH

Yes 2HD is analogue all the way from microphone to the TX input, the studios used to be in stereo, but were re-wired many years ago & to save money were only done in mono by not needing more cables for a stereo signal. The TX ran in AM Stereo for quite some time (again in fake stereo) with only a mono input. The TX is over the road from the studios, & both the TX power supply & audio cables (all owned by 2HD), run from the studios, under the 4 lane divided hwy to the TX site.

NEWFM is analogue all the same as 2HD, all NEWFM broadcast equipment (except for parts that have been repaired with new parts), are the original ones, installed when they started broadcasting 23 years ago.

You don't have to tell me about processing, I've seen, & been into detail about this at 2HD/NEWFM with staff, yes NEWFM processing is different to 2HD as is the 2HD FM translator, both stations use next to no processing. The NEWFM Optimod is the main reason for their awesome sound, newer ones (including their newer backup one), can't replicate it's settings & resultant output.

No, fake (or Pseudo) stereo can't produce a signal that comes from the left or right, all three inputs to the TX can be fed with a mono (Left + Right) channel feed, but slightly delaying one of the feeds to either Left or Right, thus making all three channels on the carrier almost identical (Mono L+R & Stereo Left (L+R) - Right (L+R)). That results in what? The stereo channels being slightly out of phase with each other stopping them from cancelling each other out, running a 19kHz pilot tone make the receiver think there is stereo there, so it sends the mono channels to each speaker, fooling both the radio receiver & the un-witting listener into thinking it's a stereo broadcast, or it can be done by electronically sending some frequencies to the left channel & some to the right channel, thus again fooling the listeners ears into thinking there is stereo audio. But then how is that different from Parametric Stereo & Spectral Band Replication in DAB+ Digital radio that you keep mentioning? Don't tell me that's not fake.

Most AM radios don't roll off at 4kHz, that's somewhat a myth, it's not a sharp rolloff anyway. As you should know, only half the transmitted bandwidth is recoverable in audio, so technically with our 9kHz spacing that equates to 9kHz audio. But US (& others) radios can legally recover 10.2kHz audio being on 10kHz spacing, so why would nearly all AM radios roll off 6kHz early? Most reasonable quality radios have a frequency response better than 5kHz. While it mightn't be legal, if your not interfering with others, run your TX out past the 18kHz bandwidth & most listeners can hear 9+kHz audio.

There's many listeners in the FM audience that suffer hearing loss, so the extra audio frequencies available on FM are a waste, & of no use to them anyway.

Again there's many in FM radio production that suffer hearing loss, (yes I know some too), but that's no excuse for the generally poor audio quality most FM station transmit these days.

Edited by GlennP

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Glenn,

There are quite a number of stations which are totally digitial except for the DAC to the AM transmitter. Some FM transmitters digitally generate the subcarrier modulation. Quite a few ABC studio complexes are purely digital and for example Local radio, ABC Radio National, ABC FM and JJJ, ABC Jazz, ABC dig are all transmitted in stereo on DAB+ This is real stereo.

One of the reasons why MLXXX complains of digital radio sound is the use of processing is much more obvious.

Which model of Optimod is 2NEW using?

The difference between the fake stereo you describe and Pseudostereo on DAB+ is that the control signal sent to the receiver varies the gain between the left and right channels and can also change the delay to steer the sound around. In your fake stereo, you cannot have sound only from the left channel for example, but pseudostereo can. In addition good encoders can measure the reverberation in the signal being encoded to allow the reverberation to be recreated. It can also be steered by the stereo control signal as well. I do not know of any receivers using this function.

AM HF rolloff

In the USA the density of stations is much greater than here. As you would be aware a 10 kHz audio bandwidth causes the higher frequencies to occupy upto half of the adjacent channel on each side. When another station is much closer to yours in distance then there is interference between theirs and your high frequencies causing an intolerable noise. In addition the carrier also causes a 10 kHz whistle. To overcome this problem it is more reliable for receiver manufacturers to limit the IF bandwidth to +/-5 kHz for the US market. In fact it is usually a little less so that they do not have to install a deep notch filter at 10 kHz. The density in Europe became so high most stations converted to FM.

You will notice that the top of the range tuner amplfiers/ Home theatre Amps mention the frequency range of FM but not AM. The above is the reason why. This is why AM radio has been relegated to talk radio.

Get a walkman type radio and compare the sound from AM and FM.

http://search.murata.co.jp/Ceramy/CatsearchAction.do. Other than professional AM off air receivers and specific wideband AM tuners have you seen any radio with a notch filter (usually requires a pot core inductor). HD on the MF band has been a failure in the USA, there is very few transmitters using it because it uses 30 kHz bandwidth for the compatible analog digital transmission mode. In the all digital mode this reduces the bandwidth to 20 kHz.

Alanh

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Getting back to best Dab+ receiver reception I have a Sangean Dpr34 and decided to do some DX on a trip from Sydney to Canberra. I had it looked on Novanation channel 9b using the headphones for an antenna. On the M7 I had a couple of dropouts around Richmond Rd exit, and then again around Horsley Park on the M7. From there reception was solid to the Douglas Park exit where reception dropped out all together. From there I had no reception to Pheasant Nest, where it was very patchy. Reception became very strong at Hill Top due to excellent line of site to Sydney. After this all reception of Sydney digital radio was lost.

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Did not try of the way down but on the way back to Sydney I had Canberra digital radio tuned on the Sangean and had continous reception to Lake George where it dropped out. Once past Lake George it was patchy to the Collector turn off and then no signal to Mt Gray where there was some signal but not enough to get above the Digital Cliff. There was no signal beyond Mt Gray so this was the extreme limit of Dxing on my portable radio.

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Thanks. I read your more detailed report in the Canberra DAB+ trial postings.

I've also had good reception to Gearys Gap, where you drop below the ridge and drive past Lake George, just using a portable radio inside the cabin of the car. My radio has a separate aerial - yours would probably do better if you could separate the antenna from the audio signal. I expect a dedicated DAB+ radio would do better and approach the FM coverage from Black Mountain tower. Pity they are so expensive (and using an iphone and tunein app is so convenient :-)

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