Dab radio

[siliconmix]

i go to a lot of boot sales .i have noticed a lot of Dab radio's for sale , some of them quite good brand names.why is this  ? .what's your experience with dab ?

[grumpydoc]

In the UK? Rubbish - but then we chose the wrong standard, used too low bit rates and transmitted at too low a power - I live about 25 miles from a large city and can't get anything without a fairly high gain antenna which is then too directional to get all the transmitters.

[G7PSK]

What I think of DAB radio is not repeatable in a forum of polite people like this one. It is one of those things that was introduced for political reasons and no other.

[Monkeh]

I've never had a problem with mine. I can pick up a signal damn near anywhere, and my radio is both good sounding and lasts 12+ hours on battery.

[G7PSK]

I have a radio built in 1959 and the battery will last for months with it playing at least 6 hours a day.

[Zero999]

My brother and I bought a DAB radio for my mum's birthday. She thinks it's great and. I think it sounds good too. I know a good FM signal will give better sound quality than DAB but in my experience it's easier to get a good DAB signal so it generally sounds better.

[Monkeh]

I have a radio built in 1959 and the battery will last for months with it playing at least 6 hours a day.

And it won't sound as good, have a headphone amplifier, preset stations, line input..

[G7PSK]

I have a radio built in 1959 and the battery will last for months with it playing at least 6 hours a day.

And it won't sound as good, have a headphone amplifier, preset stations, line input..

I actually think that the tone is better than many modern radios and it does have an earphone out put as well as the car aerial input, and as I don't do a lot of station jumping and find part of the enjoyment of using a radio is turning the dial to tune, presets are not something I find that I want. It also has a bigger speaker than modern portables which gives a better sound.

[siliconmix]

having a large speaker and surrounded by a good quality wood makes a lot of difference.roberts realised this .

[Hydrawerk]

What is your opinion on DAB+ radio? What is the quality of sound like??
http://en.wikipedia.org/wiki/Digital_Audio_Broadcasting

DAB+ is approximately twice as efficient as DAB due to the adoption of the AAC+ audio codec, and DAB+ can provide high quality audio with bit rates as low as 64 kbit/s. Reception quality is also more robust on DAB+ than on DAB due to the addition of Reed-Solomon error correction coding.

Is this true? Can the sound be CD-like even at  low bitrate of 72 kbits/s?
Does anybody use this Panasonic RF-D10? http://www.panasonic.com/au/consumer/audio/portable-am-fm-radio/rf-d10gn.html

[Hydrawerk]

http://www.amazon.co.uk/PANASONIC-RF-D10-HIGH-QUALITY-PORTABLE/dp/B00KVFMNKE/ref=cm_cr_pr_product_top
http://www.amazon.de/Panasonic-RF-D10EG-W-DAB-Digitalradio-wei%C3%9F/dp/B00IAV90NO
Some customers from Germany say that the sound is not good and it is disturbed by some hum and noise. Like some design fail. I wonder how bad it really is.

[Fraser]

I bought a DAB radio purely out of curiosity and realised that in the UK it is compromised by the decision to use low bit rates on some channels. I believe BBC Radio 4 uses a better rate though as it was deemed appropriate to the music played.

The bad things that I have noticed with many DAB radios are:

1. They gobble batteries
2. They often do not have an external antenna port
3. The designs generally look like cheap 'trannies' from many years ago !
4. Sensitivity is often poor with the in-built antenna.
5. There are plenty of really cr*p DAB radios on the market that disappoint.

I own a very neat Sony DAB radio that actually works well but it eats batteries so they included a mains adapter for this compact PORTABLE radio    I also bought a PURE ONE DAB radio in as new condition from a charity shop for GBP5. It works OK but the design looks really cheap and nasty.

It is as though DAB radio manufacturers employed AMSTRAD designers for all their radio cases and had little confidence in the technology. A very poor implementation of Digital Radio in the UK.

I often listen to British Forces Radio so DAB offers me something not available via FM. My general radio listening is still FM though. The British Government have placed any plans to decommission FM analogue transmissions on hold and no surprises there.

Anyone remember Worldspace digital radio ? It has died and the company went into liquidation. Hillarious stories of how to deal with the defunct satellites have followed. NASA threatening all manner of action and demanding de-orbiting for which there is no money available.

I believe the USA has XM satellite radio that is satellite direct to car/home and I think it is still operating. I bought some of the active antennas for XM and they are a VERY sophisticated design with high quality pre-amplification. They are designed for use on boats, cars and trucks so have an excellent polar plot.

I just checked and they are now called SiriusXM Satellite radio.

http://www.siriusxm.com/

Digital radio can be done well but UK deployed DAB falls short of the mark.

[m100]

It's not hi-fi but then again FM in the UK is also knobbled by compression etc. Internet streams or a DVB-T / DVB-S feeds are just about the only way to get something approaching an acceptable bitrate.

For those that want a radio that is easy to setup and tune, is not susceptable to aerial location, automatically changes the time on a clock radio for daylight saving and is a bit of technology can be easily operated by a technophobe 80 year old then IMHO there is no equal.   (p.s. i'm not the 80 year old technophobe!)

[AndyC_772]

I was pleasantly surprised by the DAB radio that came with my car. Quality seems pretty decent, coverage is much better than expected, and most importantly of all, there's a far wider choice of stations available.

For that reason alone, it's made the difference between listening to the radio and not listening to it.

I wouldn't buy one for home use, though. Not when I have broadband, several Logitech Squeezeboxes, and hundreds of streaming stations to choose from.

[Hydrawerk]

Thanks. Any opinions on Panasonic RF-D10? I like it, because there are not many radios with 10 direct preset buttons. I like separate controls for volume and tuning. The volume knob is probably a rotary encoder. So no danger of noise from a damaged potentiometer as on my Olympia ATS-803A.
But I miss the audio input port on RF-D10.

[SeanB]

So the Worldspace receiver I have is now teardown material. No wonder it would not work at a cursory power up.........

[Fraser]

http://en.wikipedia.org/wiki/1worldspace

[Hydrawerk]

That's weird.

The final fate of the original Worldspace satellite radio service still remains a mystery. Despite the company's very public insolvency and the liquidation of all of its various commercial entities in 2008-2009, the company's Afristar and Asiastar satellites remain in geostationary orbit. Currently, the channels WRN 1 and WRN 2 can be received on Afristar with audio.

[Fraser]

The last I read on the satellites was that they are a big liability for someone.

The company that owned the satellites has long gone with huge debts. There is no money to de-orbit them. NASA are very concerned about abandoned satellites as they have to be regularly maintained in order to keep them in the correct position. There was much talk about possibly selling the satellite hardware for use by another company. That fell through.

NASA were left with a pair of orphaned and abandoned satellites that could cause all manner of trouble in the future if they became unresponsive to commands due to lack of position maintenance. No one wanted to pick up the huge bill for either maintaining or de-orbiting the pair. I believe that they were placed into sleep mode with ESA or NASA using their remaining fuel to maintain orbit until a decision could be made as to their fate.

This matter has raised questions as to whether companies owning and operating a satellite should place a de-orbiting fund in Bond in case they go bust. You can't just abandon a satellite if you no longer want it. It must be placed into a safe graveyard or brought down to burn up.

Aurora

[German_EE]

I wonder why deorbiting two satellites would cost a lot of money? All they need to do is send the commands to the engines so that the satellites slow down and then gravity does the rest.

[SeanB]

Where the bits will land requires careful monitoring during lowering burns, then final orbits require tracking from all around the world along with a lot of orbital calculations as to trajectory and where it will finally reenter and when. All needs guys with expensive equipment, PHD degrees and such, a lot of overtime for them all, and an insurer with a big set of brass ones to insure just in case it karks out during this and ploughs into somewhere expensive a few orbits later. If you do not really care you just command it to orient in plane of orbit and fire main engines till fuel exhaustion, then fire all manoeuvring rockets in order after rotating to scrub velocity and drop into an extremely elliptical orbit, then use momentum control to maintain solar panels at maximum drag at the perigee until it drops low enough that it does not rise up again.

Will land somewhere between 30N to 30S, and you take the chance that as most is 70% water, 10% desert and only 5% what is densely inhabited. Hey, it might not land on you, I know it will land on me.

[Precipice]

I wonder why deorbiting two satellites would cost a lot of money? All they need to do is send the commands to the engines so that the satellites slow down and then gravity does the rest.

I was wondering about the impulse you'd need to bring something back to earth from geosynchronous orbit. Turns out, it's too much, you just park them in a junk orbit that nobody cares about.
http://en.wikipedia.org/wiki/Graveyard_orbit

[Fraser]

@Precipice,

Regret that is not really true. NASA and we care !

The Graveyard for satellites seemed a good idea at one time but it has since been established that the graveyard is a bit of a time bomb for other satellites.

the issue is that the satellites degrade over time and bits come off. That combined with being hit by micro meteorites that knock more bits off the shell leads to many lethal scrap particles that can fall back into orbits used by live satellites that are in turn damaged by colliding with the junk.

NASA are very concerned about the long term effects of all the 'parked' junk satellites that are in graveyards. I know of at least one satellite worth many millions that was taken out by particles that originated from the graveyard. Expensive and very inconvenient for the satellites users.

We now have a large target in the form of the space station that is also vulnerable to collisions with graveyard junk.

It is better to de-orbit a satellite if such is feasible and safe but there must be enough fuel left on board to achieve this manoeuvre as has already been stated.

Aurora

[Precipice]

Even for GEO?
LEO, sure, it's a timebomb, but isn't GEO so huge and sparse that if you can get to 100Km above, then you're as close to safe as you can be? (as in, safer than trying to deorbit your way back to the atmosphere, at (reading that Wikipedia page) over 100 times the delta-V.)

If your GEO junkyard stuff hits the ISS, things have gone very, very wrong!

[Fraser]

I am no expert on satellite disposal so cannot answer.

This page indicates that NASA are worried about Satellite Graveyards and it highlights the issues of old satellites not being adequately functional to achieve de-orbit or Graveyard parking.

http://www.tethers.com/OrbitalDebris.html

It's getting crowded up there !

Aurora