For the next Auto Nav Kit

[JPV123]

This may have to wait for the next ique remodel but an external antenna should be able to plug into the auto nav kit (as well as the unit itself). This way less messy wires exposed and easier in and out with the unit. The OEM car kits for cell phones are that way why not the ique.

[Robertp366]

Generally a great idea. But that would automatically add at least one more connector to the antenna chain - like adding an extension cable. Genberally RF connectors cost 2 to 3 dB in signal, and that is a big deal with the low power og the GPS signals. You'd sort of give up all the gain of the Gilsson antenna over the Garmin.... The connector loss is one of the reasons that it's better to get a too long cable than a too short one and an extension.

While we're at it. I'd like to seperate the power plug and the speaker. In fact, for a permanent installation version, drop the power plug altogether and put in a voltage converter and a big power noise/spike filter.

Robert

[JPV123]

I agree, We need a permanent install version of the auto nav kit. Maybe with an external line output to hook up to a stereo that has an aux input (like mine has). I know the ique has it but I hate plugging things in and out all the time. I also Hate messy exposed wires. I was thinking of splicing into the speaker lines on the auto nav kit and get a speaker to line converter so I can hook it up to my stereo. I did that with my cell phone kit. This is for a convertible, so I need something to overcome the wind noise when the nice weather is here.:D

[PDA Paul]

One wish. Speaker in the mount so I can cut the wire for custom install.

Paul

[Robertp366]

Well, while we are on wishes for a 'permanent' mount version auto kit, how about an interrupt line, active when Betty speaks, to mute the stereo - again like my cell phone mount does.

BTW - an aux input would be nice for the mp3's, it'd be NFG for Betty - you'd have to switch source to que all the time to get nav directions and you'd have no stereo.

But you can already do this - just get a mini stereo to RCA cable from Radio Shack. It's just like the one that the iPod uses. Then in the auto mount Betty will give you nav directions from the speaker and the MP3's will play from the headphone jack through your stereo.

Or just get an iPod like I did :D 40 GB of music is much better than 100 MB on an SD card. My iPod has 'only' 5000 songs from 320 CD's ('cause that's all I own) that'll play for 14 days 18 hours without repeats. Its only half full, but I use 192kbps ACC encoding to get audio far superior to FM or even XM radio.

Robert

[Bokkie]

Originally posted by Robertp366
Or just get an iPod like I did :D 40 GB of music is much better than 100 MB on an SD card. My iPod has 'only' 5000 songs from 320 CD's ('cause that's all I own) that'll play for 14 days 18 hours without repeats. Its only half full, but I use 192kbps ACC encoding to get audio far superior to FM or even XM radio.

Robert

Robert, describe the main difference for me between ACC and MP3 encoding. Is ACC proprietery to Apple (iPod)? Can you hear a difference in the sound quality between ACC and MP3? Hifi reviews often go hyper-critical at the dB-low-band-filter-attenuation-phase-offset-distortion-wave-form-modulation level that only an oscilloscope can measure?! Me, I don't carry oscilloscopes as I'm of the old school that noise goes in both lugs, brain has a stab at it, and if my foot jerks in response, then that's a result!:D

[jonasolof]

Originally posted by PDA Paul
One wish. Speaker in the mount so I can cut the wire for custom install.

Paul

Can be done as it is. Mount a small cell phone hands free speaker anywhere. Unsolder the speaker connection in the speaker/power combo and run the leads to your new speaker. Then dismount the plug part from the combo and run the balck and red + a 1 amp fast fuse fuse to 12 V. A filter in between wouldn't hurt.

The electronics in/out from the speaker combo is so basic that there are lots of ways it can be adapted for fixed installations if one bothers.

You can get rid of the speaker/power combo completely by

- providing 5 V 700- 1000 mA via a switching circuit. Costs about 25 USD. See posts by signature JohnVa

- amplifying the audio output from the cradle with any amp/speaker that takes a ear plug signal as input. There should be cheap DIY circuits that one could use.

The "antenna connector in the cradle" could be done like on the Ericsson T39 etc. But for many other uses it would be awkward to have the ext ant connector on the rear of the iQue. I don't think they'll do it. They will rather try to improve the internal antenna.

[Robertp366]

I'm CTO for a satellite data transmission VPN service company, and one of our customers uses a lot of video and audio data, so I've done a lot of research on compression formats. I've been able to generate a lot of test files for my iQue and iPod and try them out on my own car stereo system. [Alpine 9815, aux 4ch 200W per amps, 200W subwoofer amp, 12 ch Dennon Speakers]. The following is my personal opinions and results:

ACC is an apple iTunes/iPod porpriatery format. It's primarily the stereo portion of the audio codec from MP4 (DVD/ 5.1 format) combined with some DRM (digital rights management) code to keep stuff from the iTunes store out of the file sharing networks such as Kazaa. Generally, MP4 - or ACC is superior audio compression to MP3. It's a constant loss frequency adaptive variable bit rate compression that reduces bit use on low frequency sounds without increasing losses so it can use a few more bits at the high end. As a result, the base is less 'boomy' and the highs (like violins or cymbals) cleaner. While most rock music does OK with the boominess of MP3, many other music types don't sound as good as they should.

The Que also decodes the microsoft propriatery format WAV, used for audio on most MS internal sounds. Generally WAV is slightly better sounding than 64 Kbps MP3, but except for the push from Redmond, its not a player in the compressed music world. Especially because of the onerous DRM baggage that MS adds.

Comparing MP3 and ACC as used for music at the Apple iTunes store, lower bit rate ACC give equal performance to higher bit rate MP3. For example, 128 kbps ACC compression sounds as good as 192 to 256 Kbps MP3 (depends on music content). Note that the iQue can only play MP3's and WAV's - it does not have the decoder for ACC or MP4-audio like an iPod does.

Here's a link that has a lot of detail on the precevable differences:

http://www.recordstorereview.com/misc/aacmp3.shtml

Because of the limitations of the audio circuits in the iQue, I've never found MP3's higher than 96 Kbps to sound any better, and for most anything except full orchestra classics, 56 to 64 Kbps is as good as it gets. So you can carry more music if you do MP3 encoding specifically for the Que at 56 to 64 Kbps. An average song will be about 1 to 1.2 MB.

Much of the internet streaming radio music is at 56 Kbps MP3. And if you use an FM modulator like an iRock to link the Que to your radio, 56 Kbps fills the FM link bandwidth anyway. Hardwire link to an accessory input will be good at 96 Kbps, and above that the limitations of the Que kick in.

But I do 192 K bps on my iPod, and 256 Kbps for the big classic orchestrations like Wagner, and with a hardwire link AUX input I get breathtaking sounds.

Sorry for being so long winded. All my posts tend to. Long ago one of my bosses told me: "Robert, when I ask for the time, I don't need to know how to build a chronometer." :p

Robert

[jonasolof]

Robert, it's a pleasure to read what you write.

[Robertp366]

Jonas

Well of course from a fellow chronometer lover.:D

BTW did you know that the GPS system adjusts for the general relativity time dilation of signals climbing the earth's gravity well to the sats. It's the only macro application of General Relativity ever; all the others have to do with neutrino decay rates and a few astromomical things (gravitational lenses, perihelion precession...)

You, Anders, Bokkie, Lycestra, my favorite Schrodenger Cat, and others share my affliction. What's one word when there are so many thousands of others......

Really, though, I love to experiment and measure stuff. Don't have to have a good reason. I just enjoy playing with different toys than the other children.


By the way, today's experiment is aluminum and steel plates on my car's back shelf (Gilsson and Garmin antennas). Got a 6 by 18 inch piece of each and some good tin snips. Already measured the antennas on the steel roof......


Robert

[Bokkie]

Originally posted by Robertp366
Really, though, I love to experiment and measure stuff...

Robert, thanks for a very good explanation about the sampling rates. A lot of it went straight over my head, but that's a fair result for being intellectually 'small' in comparison.:D

So on the iQue a smaller sampling rate is better than a big 'un. And all those points will be academic anyway when I enter the iPod arena.

On the subject of chronology, if you ever get the chance to visit Greenwhich, home of 0 longitude, the clocks by John Harrison H1, H2, H3, and H4 will leave you filled with awe and total admiration for the man that started it all. Other clock makers there were and many since, and if you want to bring atomic clocks back to earth with a thud, compare them to what an old man in the 18th century produced.

They represent the human face of GPS.

[Robertp366]

Let's see If I can do something really really hard (for me) - make this simple. :D

An original CD holds 600 M Bytes, or 4.8 G bits. Songs are recorded at about 500 K bits per second, and end up about 50 M Bytes each.

MP3 is a compression scheme that throws out a lot of those bits, while trying to retain as much of the true music as possible. It's called a "lossy" compression because when reconstructed, the music is not identical to the original. There are "lossless" compressions that make perfect reconstructions - we use .sit and .zip compressed files all the time - but they rarely do more than 2 to 1 compression. MP3 and ACC can give us 5 to 1 compression with good results, and as much as 15 to 1 is OK for a lot of music. Pure spoken voice can be compressed at least 100 to 1.

All these compressions -MP3, ACC, WAV - do very well on voice pieces - speaking has a lot of redundant information - so the losses tend to be at the high frequencies. This makes violins for example sound 'muddy'. And the loss of highs makes the 'attack' side (the begining of the sound) of low frequencies like drums not as sharp, so they soound 'boomy' instead of clean. This will be true of virtually any 'lossy' compression method.

The benefit is in reduced file size. A typical 4 minute song is 50M Bytes in original CD form - 12 on a CD. MP3 and ACC can make the same song, still sounding almost as good as an FM radio, as small as 1 to 2 M Bytes. So that extra 256 MB you have on your new $300 512 MB SD card can hold either 4 original songs or 100 compressed ones, or something in between.

You can choose the sound quality of music files you compress, or 'rip' with most of the encoders by choosing the bit rate of the compressed file. The factors that can affect your choice are 1) the kind of music - symphony is harder to compress than a Gregorian Chant, for example; 2) the quality of the decoder that will uncompress it. We often do not have a choice here; the iPod decoder is built in, as is the Que's, either as hardware or s/w. Que and PC's can use other programs with different software decoders, adn that can make a difference; 3) the quality of the audio system - end to end - that will play the decoded music. The weakest link principle applies here. Use an FM link from iPod or Que to any stereo and that's the limit (unless you have really bad speakers). Often the speakers are the limiting factor, which is why audiophiles always say spend as much as you can on speakers and get a cheap amp; 4) the environment you will be listening to the music in - a windy convertible won't let you hear much of the flute solo in the death passage of "Tristian und Isolde"; and 5) your ability or interest in discerning the differences in your music quality. The author in the referenced link

http://www.recordstorereview.com/misc/aacmp3.shtml

is very discerning in hearing small differences, more that I can most of the time. Often it takes a direct comparison of original vs compressed to hear a difference. But he gives a very complete guide.

Just remember: lower rates gives you more songs in limited storage, and higher rates gives you better music.

This is a pretty compressed summary. Was it too 'lossy' -did I loose you still?

Robert

[Robertp366]

And now a technical note on sampling rates:

It takes at least two samples to perfectly reproduce a sine wave at any frequency. A 'lossy' sampling can be as low as 1.2 samples, which gives a signal that is 50% wrong. For any higher frequency the sample approaches 100% wrong. And each sample takes several bits to reproduce the amplitude (volume) - CD players typically use 12 bits per sample. Really good 'lossy' compression schemes reduce the amplitude data to less than 1.1 bits per sample.

So what can we get from a 56 K bps MP3? There's two stereo channels of 28 K bps each. Or about 24 K samples per second. This will reproduce a signal of 22 khz with 50 % error (distortion). A cheap amp, by comparison may have 0.2% distortion at 22 khz. A cheap speaker is easily 50% distortion at 22 khz. Young ears can hear well to 28 khz, and can discern the effect on music quality up to 35 khz. Spend some time with 8 inch howitzers and 2000 pound bombs, or get a front row seat at a Stones concert, and you have more limited ears.

A higher rate MP3 will give better music. An ACC compression is slightly better than an MP3. I personally can tell the difference for just some of my music between a 128 K bps ACC and a 128 K bps MP3. I can just preceive a difference at 192 K bps ACC vs 128 Kbps ACC. For me anything higher is a waste of bits.

But that's with my best audio system - at home with studio Dennon amps and monitor speakers in a sound controlled listening room. My car's system is really good, but the noise background is worse. The trade off I ended up with is 192 K bps ACC becaue I have a 40GB iPod, and at that compression I still can put every CD I own (about 300) on it with space to spare. In the 128 MB space I leave on my Que's 512 MB SD card, I stick to 56 K bps MP3. And I have to change the music a lot to keep from being bored. But that's still more music than the $300 12 disk changer I could have gotten, 'tho that would be full bandwidth CD quality.

Robert

[jonasolof]

I'd say it's complex but not complicated