jimyvr
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IPod May Replace/be Flight Data Recorder

Sat Feb 24, 2007 3:46 pm

http://www.flightglobal.com/articles...presti-launches-data-recorder.html

According to Flight Global website posted on 22FEB07, Apple Computer's popular iPod music player could become a flight data recorder (FDR) following an announcement by US light aircraft manufacturer LoPresti SpeedMerchants to introduce the device in the cockpit of its Fury piston aircraft.

[Edited 2007-02-24 08:00:34]
1000 - 01MAR07 | http://airlineroute.blogspot.com/
 
InbarD
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RE: IPod May Replace Flight Data Recorder

Sat Feb 24, 2007 3:52 pm

I hate ipods, although i guess they could be pretty usefull as a flight data recorder.
 
MCIGuy
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RE: IPod May Replace Flight Data Recorder

Sat Feb 24, 2007 3:56 pm

Makes sense really, memory keeps getting smaller and more reliable. I'm looking for hard drives and most forms of mechanical storage to go away in the not-too-distant future.
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TransWorldSTL
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RE: IPod May Replace/be Flight Data Recorder

Sat Feb 24, 2007 4:16 pm

If it improves the current system, then I'm all for it..

Does anyone know if/how often the current 'black boxes' are actually checked to see if they're functioning?
 
osiris30
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RE: IPod May Replace/be Flight Data Recorder

Sat Feb 24, 2007 5:12 pm

Well IPods would make pretty good CVR/FDRs.

They are solid state (well some of them, i.e. the nano's) and can therefore survive just about any impact if correctly secured. Additionally the Nano's are fairly rugged little devices.. I mean sure the screen may get wasted in accidents (not flight accidents I mean normal IPod accidents) but I've seen them run over by trucks and come out only marginally worse for the wear.

Franky I'm surprised commercial aviation hasn't been forced to replace all the tape based CVRs/FDRs with solid state digital ones. They have a much higher survivability factor, are less likely to fail, and won't degarde if submerged in water for extended periods of time.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
XT6Wagon
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RE: IPod May Replace/be Flight Data Recorder

Sat Feb 24, 2007 5:25 pm

Quoting Osiris30 (Reply 4):
Franky I'm surprised commercial aviation hasn't been forced to replace all the tape based CVRs/FDRs with solid state digital ones. They have a much higher survivability factor, are less likely to fail, and won't degarde if submerged in water for extended periods of time.

Tape has its own advantages in surviving in a condition that can be read. Certainly it would be a great advance to do a solid state recorder that does more channels of data and longer recording time, but I am hesitant to throw out the tape system. Certainly they must start recording more data, as currently they do too little. I'm sure we would be far safer for example if it recorded not only the position of the control surfaces, but the inputs at the controls. Right now you have no idea if the position of a control surface is the result of mechanical failure, computer failure, or pilot input. Its a wonder how FBW has been allowed at all with so little back checking available to the regulators to evaluate if in any given instance it was the pilot or the FBW system that failed to give the proper input to the control surface.

Oh and I think its borderline criminal how out of date the flight recorders have become. If they wait another 10 years before designing a new one... certainly that border is crossed.
 
rwessel
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RE: IPod May Replace/be Flight Data Recorder

Sat Feb 24, 2007 5:30 pm

Quoting Osiris30 (Reply 4):
Franky I'm surprised commercial aviation hasn't been forced to replace all the tape based CVRs/FDRs with solid state digital ones. They have a much higher survivability factor, are less likely to fail, and won't degarde if submerged in water for extended periods of time.

AFAIK, no one (at least in the west) has built a new CVR/FDR that isn't solid state in years.
 
osiris30
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 1:03 am

Quoting Rwessel (Reply 6):
AFAIK, no one (at least in the west) has built a new CVR/FDR that isn't solid state in years.

I was referring to retrofitting existing aircraft as well. I know that older aircraft still carry original equipment in some cases, and really that stuff should be upgraded. The solid state devices are probably cheaper these days anyway.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
jamesbuk
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 1:08 am

Has anyone thought about the fact the battery life is crap? well that the battery wears out after time. Or would it be adapted to be plugged in without a battery?

Rgds --James--
You cant have your cake and eat it... What the hells the point in having it then!!!
 
XT6Wagon
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 1:28 am

Quoting Jamesbuk (Reply 8):
Has anyone thought about the fact the battery life is crap? well that the battery wears out after time. Or would it be adapted to be plugged in without a battery?

There is plenty of memory technologies that are not dependant on energy to maintain thier data.
 
osiris30
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 2:48 am

Quoting Jamesbuk (Reply 8):
Has anyone thought about the fact the battery life is crap? well that the battery wears out after time. Or would it be adapted to be plugged in without a battery?

My IPod spends a good deal of it's time teathered  Wink.. the only time you would need a battery in this scenario is when all electrical systems fail.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
LimaNiner
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 3:52 am

Quoting Osiris30 (Reply 10):
the only time you would need a battery in this scenario is when all electrical systems fail.

Exactly! Think of the battery time as the time the device continues to record *after* power has gone. Of course, there won't be much data to record if there isn't any power -- unless the sensors are battery-backed, too...

And since these things are dirt cheap, replacing them every year or two shouldn't be a burdensome expense...
 
RobertS975
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 6:58 am

I dunno... my teen daughter is on her third iPod in a couple of years. It is nothing more than a small hard drive... drop one off the kitchen table and it is history. I would hate to see it try to survive a high G crash!
 
awthompson
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 7:49 am

Only one problem...

IPODS record information on a magnetic HARD DISK and are therefore not entirely solid state! I am referring to my IPOD which is the 30GB Ipod video. I don't know about the Nano.
 
jbmitt
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 7:59 am

The nanos and shuffles are on flash drives.
 
jbguller
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 8:30 am

If the aircraft have a glass cockpit, would it come complete with OSX and iTunes?

If it does, I'm getting one...!
 
cancidas
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 11:02 am

that's a really good idea... NTSB must like this idea, would make it easier investigating small airplane crashes. the weight would be minimal on a small airplane, all they would need is some shielding to make it crash-proof.
"...cannot the kingdom of salvation take me home."
 
Baron52ta
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 11:55 am

In reference to the black boxes they are removed and inspected on each major service rotation with most airlines I can't say that is true of all of them though.But of course the B/B's on British aircraft record approx 2000 different sensors where as America only requires about 30 and on older planes not even that.
It makes sense that they finally have decided to try flight recording devices in light, and GA planes. I don't care for Apple Mac but great move on their part.
 
Electech6299
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 12:35 pm

Quoting RobertS975 (Reply 12):
t is nothing more than a small hard drive... drop one off the kitchen table and it is history.

That refers to the compact hard disk volumes, which currently are pretty much anything over 1-2 gigabyte. I hope they're referring to the flash memory versions, but it's not clear from the article. If they want to use the integrated voice recorder, they'll need well over the 2-gig threshold to get a useful amount of data. Hopefully they are including improved voice recording and digital storage. The data on a current tape FDR would probably only occupy about 100 kilobytes, or possibly even less, in a simple ASCII format. The CVR would be significantly larger, depending on the sample rate...No need for a 30-gig hard disk, tho- the music library of a teen has far more data than the NTSB wants to sift through after a crash.

Quoting Jamesbuk (Reply 8):
Has anyone thought about the fact the battery life is crap?

From the article:

Quote:
The iPod FDR would work with the patented iPod Dock Connector port on the bottom of the iPod

Battery life for routine play is irrelevant in this case, if there's no dock power then there's no data to record.

Then again, I suppose they might want to continue voice recording after a power (or FMS) failure...so a 2-hour battery would be useful. I'm sure they could throw in a little button cell just for kicks...the stored data (on flash memory or hard disk) has no need for power, so longevity is not an issue.

I personally see much more promise for unregulated GA and corporate aircraft than commercial ops. The airliners need a quite different package of features...

(now, to spill my ignorance of modern avionics...The FDR data is not used during routine maintenance of an airliner, is it? It seems that this device is touted as more of a FMS/performance history, with data recording as an added feature, than as a data recorder to replace the FDR/CVRs of airliners)
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osiris30
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 12:48 pm

Quoting RobertS975 (Reply 12):
I dunno... my teen daughter is on her third iPod in a couple of years. It is nothing more than a small hard drive... drop one off the kitchen table and it is history. I would hate to see it try to survive a high G crash!



Quoting Awthompson (Reply 13):
Only one problem...

IPODS record information on a magnetic HARD DISK and are therefore not entirely solid state! I am referring to my IPOD which is the 30GB Ipod video. I don't know about the Nano.



Quoting Jbmitt (Reply 14):
The nanos and shuffles are on flash drives.

 checkmark  As Jbmitt stated, the nanos adn shuffles are solid state units. I wouldn't suggest using a hard-disk based IPOD for this purpose.

RobertS975: Get her a nano, they last ALOT longer than the hard disk based ones (and they look way cooler too :P )
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
lincoln
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 1:05 pm

Quoting Jamesbuk (Reply 8):
Has anyone thought about the fact the battery life is crap? well that the battery wears out after time. Or would it be adapted to be plugged in without a battery?

I don't know -- I can go at least 10 hours or so on a single charge with my ~18 month old 5th generation iPod (Whatever the drive time from CLE to GRR and back is) .

My experience with the iPod's durability though...er...it fulfills its intended purpose well enough, but I wouldn't trust irreplaceable data to it, especially data that would only really be important in a critical/harsh environment. The things aren't designed to be subject to large amounts of heat or vibration. They don't do well when compressed, and they're particularly sensitive to water/humidity intrusion (the later I know from a 'small' incident with my previous iPod).

The OS running in the thing is also crap. It's a very limited purpose OS, not intended for real-time operations and it doesn't multitask (at least for substantial values of multitask) -- because that wasn't a design criteria for a music player. I've had to reboot my iPod more times in the past month than I have my Windows XP PC.

Can you use an iPod as a FDR/CDR? Can you use a forklift as an elevator? The answer to both of those is a qualified "yes". Is either a particularly good idea? My personal feeling is "no".

Quoting Cancidas (Reply 16):
that's a really good idea... NTSB must like this idea, would make it easier investigating small airplane crashes. the weight would be minimal on a small airplane, all they would need is some shielding to make it crash-proof.

You know for no reason in particular, the following scene played out in my mind when I read that paragraph:

Inside an NTSB laboratory, a technician takes the iPod from a crash scene, miraculously recovered intact and plugs it into a computer. The wrong computer, as it turns out, because before our tech has a chance to correct the mistake, all of the flight data has been overwritten by iTunes auto syncing the '80s pop music collection from his PC.

Lincoln
(Hey, I love both of my iPods -- and I've given the iTunes music store hundreds of dollars over the past few years -- I'm also a 'right technology for the right job' person -- and I don't feel that the iPod was intended to be anything more than an entertainment device)
CO Is My Airline of Choice || Baggage Claim is an airline's last chance to disappoint a customer || Next flts in profile
 
osiris30
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 1:22 pm

Quoting Lincoln (Reply 20):
The things aren't designed to be subject to large amounts of heat or vibration.

Heat yes, vibration not so for the solid state ones. My nano has been so abused it would make most folks cry. The key here is a lot of people have disk based iPods. I purposely went solid state because I know full well if I got a disk one, it would be deader than dead by now.

Quoting Lincoln (Reply 20):
They don't do well when compressed, and they're particularly sensitive to water/humidity intrusion (the later I know from a 'small' incident with my previous iPod).

In the event of a total soaking they just need to hold their data for recovery, not actually work. You are expecting that after a crash the iPod would need to work. That's just the wrong way to look at it. It merely needs it's data to survive.

Quoting Lincoln (Reply 20):
Inside an NTSB laboratory, a technician takes the iPod from a crash scene, miraculously recovered intact

See above. The NTSB would disconnect the guts and treat them in the same special way they treat all other CVRs/FDRs. You don't really think any aircraft falling from 35K feet has the FDRs and CVRs survive in WORKING condition do you?
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
Electech6299
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 1:35 pm

Quoting Lincoln (Reply 20):
Can you use a forklift as an elevator?

Well, you might have some weight and balance issues, and wouldn't get as much attitude control as I'd prefer, but if you think it can be done, ...  Wink

Let's rephrase that...Can you use a forklift engine and gear mechanism as a limited use (building) elevator? Or to make it simpler, electric motors are used to drive (battery-operated) forklifts, do they have any place on an elevator mechanism? Only the data storage and retrieval hardware and interface appears to be duplicated, the firmware is not mentioned and the unit is sold as an FDR, not a music player. Do you seriously think this device will have a headphone jack?

Quoting Lincoln (Reply 20):
The OS running in the thing is also crap. It's a very limited purpose OS, not intended for real-time operations and it doesn't multitask (at least for substantial values of multitask) -- because that wasn't a design criteria for a music player.

The function here would not require multitasking either- only the OS of the platform to which the FDR is connected needs to do that. The Ipod FDR is only used as the data storage device. As to the interface, I like the Ipod dock better than the USB interface, otherwise I'd say a standard USB flash drive would do the same thing. (Personally, for reliability, not much beats a good old RS-232!)

IMHO, this is just Apple/Micron trying to get into the market before AMD, Toshiba, or Samsung do. Flash memory is cheap, useful for many things, and there is little difference in the hardware that supports it. So take an existing bare-bones platform (music player), take out the unnecessary hardware (headphone jack) and software (music file processing capability, data library, etc...), add a minimal data-writing framework, partition for voice/data, and voila! A customized, portable unit that does all you need.

The only serious competition would come from a platform that uses a connection other than the Ipod jack. Use of a standard (non-proprietary) connector would open the door to all kinds of standard device manufacturers...

So I agree that a packaged Nano would make a poor FDR, but a customized storage device and voice recorder (which this article refers to) using Apple's interface doesn't sound all that bad...
Send not to know for whom the bell tolls...it tolls for thee
 
osiris30
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RE: IPod May Replace/be Flight Data Recorder

Sun Feb 25, 2007 2:14 pm

Quoting Electech6299 (Reply 22):
(Personally, for reliability, not much beats a good old RS-232!)

Actually RS-232 itself is a pretty poor communication system. Give me something with differntial signalling any day for binary data.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
awthompson
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RE: IPod May Replace/be Flight Data Recorder

Mon Feb 26, 2007 7:41 am

Quoting XT6Wagon (Reply 5):
Tape has its own advantages in surviving in a condition that can be read. Certainly it would be a great advance to do a solid state recorder that does more channels of data and longer recording time, but I am hesitant to throw out the tape system. Certainly they must start recording more data, as currently they do too little. I'm sure we would be far safer for example if it recorded not only the position of the control surfaces, but the inputs at the controls. Right now you have no idea if the position of a control surface is the result of mechanical failure, computer failure, or pilot input. Its a wonder how FBW has been allowed at all with so little back checking available to the regulators to evaluate if in any given instance it was the pilot or the FBW system that failed to give the proper input to the control surface.

Egyptair 990 of 31st Oct 1999 was one of the best recent examples of where pilot control input data would have brought the investigation to an unarguable conclusion. The 767 went into a dive from the cruise and although it was largely believed that this was the action of a suicidal/terrorist pilot, it could not be conclusively proven that the dive was not caused by a control anomaly with the suspect pilot trying to counteract the dive as the Egyptian authorities put forward.

Quoting Osiris30 (Reply 21):
In the event of a total soaking they just need to hold their data for recovery, not actually work. You are expecting that after a crash the iPod would need to work. That's just the wrong way to look at it. It merely needs it's data to survive.

Thats what I was thinking in all of this. Surely the most rugged devices do not continue to record throughout severe high speed impacts, that is not the issue. It is only important that the data can be recovered later even though the recording mechanism is destroyed.

I can understand how tape is better. Part of the tape could be damaged whilst other stretches of tape are still readable. Damage to an actual hard disk surface or to flash drive memory chips could render ALL of the data completely gone.
 
Electech6299
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RE: IPod May Replace/be Flight Data Recorder

Mon Feb 26, 2007 10:29 am

Quoting Osiris30 (Reply 23):
Quoting Electech6299 (Reply 22):
(Personally, for reliability, not much beats a good old RS-232!)

Actually RS-232 itself is a pretty poor communication system. Give me something with differntial signalling any day for binary data.

Assuming raw binary data over a cable, sure...I was thinking along the lines of direct connection to the interface computer and formatted data, since the article is talking about a plug-in device. So use whatever signal works best from the sensor to the interface computer, and from the computer to the Ipod any reliable communication protocol would work without fear of interference. RS-232 is just conductors and framework anyway, you can use whatever signaling mode you want once the framework is established.

IMHO, the defining line is the software and memory requirements. The more direct hardware communication and the fewer drivers involved, the better. I suppose either asymmetrical or differential signaling would work, might be a slight power savings using differential, but the big advantage of differential (data transfer rate) is wasted considering the data requirements.

We operate a variety of test equipment at my office, from 20+ years old to 2006 model. A few instruments we got in 2003-2004 hyped a "plug & play" USB interface, but they have given us nothing but trouble, including lost data and compatibility issues with different laptop manufacturers (or operating systems, not sure which). In contrast, the 1972 model time-lapse instruments we have still run just fine off of RS-232, even considering having to use a port emulator and non-existent DOS support on WinXP. The only advantages to the modern instruments are battery life, ergonomics, case size, and software support.

Our most recent instruments communicate from a CAT5 jack with a variety of adapters (USB, 1394, 9-pin serial, 5-pin RS-232, or direct interface with the NIC.) But the communications interface still utilizes RS232 framework, and is backwards-compatible to the 1980s model instruments from that manufacturer. Some of the permanent monitoring stations we read data from utilize fiber optic data transfer (via translators), but interface using the same RS-232 chip installed in our portable monitor. So I suppose I'm a firm believer in RS-232.
Send not to know for whom the bell tolls...it tolls for thee
 
Electech6299
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RE: IPod May Replace/be Flight Data Recorder

Mon Feb 26, 2007 10:40 am

Quoting Awthompson (Reply 24):
I can understand how tape is better. Part of the tape could be damaged whilst other stretches of tape are still readable. Damage to an actual hard disk surface or to flash drive memory chips could render ALL of the data completely gone.

Consider that a flash drive chip weighing 0.2kg can hold the data of a 3-5 kg spool of tape, and has no moving parts to damage it, and can be protected far more securely than tape, I'm more a fan of the flash memory. Anything that could manage to damage the surface of a flash disk would likely have destroyed the entire tape reel. (An actual hard disk, on the other hand, shouldn't be used in anything more sensitive than a camcorder IMHO...)

And for all who didn't read the article before posting....this isn't about replacing the FDR/CVR in airliners. How many tape reels are used now on private planes? This is a developing market.
Send not to know for whom the bell tolls...it tolls for thee
 
bingo
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RE: IPod May Replace/be Flight Data Recorder

Mon Feb 26, 2007 10:45 am

Quote:
So I suppose I'm a firm believer in RS-232.

Ill drink to that  bigthumbsup  I manage an "information store" thats just shy of 1 petabyte in size. All our configs are done via RS-232. Why? Its simple and secure!

Its scary to think that NTSB might one day pull a FDR out of a wreck only to get the "Sad MAC Icon"....  Sad
 
lincoln
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RE: IPod May Replace/be Flight Data Recorder

Mon Feb 26, 2007 11:06 am

Quoting Bingo (Reply 27):
Ill drink to that I manage an "information store" thats just shy of 1 petabyte in size. All our configs are done via RS-232. Why? Its simple and secure!

 Wow!...wow. And I was impressed when I pulled my first terabyte array out of the box.

I owe most of my living to RS-232 as it remains the domininat communications layer for A/V gear (projector/plasma/LCD control, control of a/v switching and routing, audio mixer control, video conferencing codec control etc., etc. and it it pretty hard to, er, 'cluck' up, but I would never use it for anything mission critical -- for that, I much prefer RS-422 or RS-485 because the balanced line makes it much less susceptable to errors due to noise on the line-- the same reason balanced audio is less susceptable to noise than its unbalanced counterpart.

All three are well understood and have long proven track records. While the dock connector has been reverse engineered (and clearly there would need to be an outboard interface box of some type to collect all of the sensor data and feed it down the iPod cable) it is certainly not as well understood.
CO Is My Airline of Choice || Baggage Claim is an airline's last chance to disappoint a customer || Next flts in profile
 
bingo
Posts: 278
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RE: IPod May Replace/be Flight Data Recorder

Mon Feb 26, 2007 11:50 am

Quote:
All three are well understood and have long proven track records. While the dock connector has been reverse engineered (and clearly there would need to be an outboard interface box of some type to collect all of the sensor data and feed it down the iPod cable) it is certainly not as well understood.



Some of the companies I've worked for have made good money producing special milspec converters for RS232 and a number of other “old” interfaces. Unless youre doing A/V and high throughput stuff like youre doing, I don’t really see a need for much more. The majority of the stuff I do is just static configs of these storage area networks. Once the configs are loaded, short of a physical security breach there is no getting to them. It’s reliable, easy and cheap. Give me a laptop with a serial port and I’m in business. I'm never more than 8ft from my work  Smile

You’ll find a good number of free SDKs and script kiddies out there that will write code for the I-Dock system, so this came as no surprise to me to see the FDR idea being proposed. I thought it was pretty cool the first time I jumped into a Diamond Star with a G1000. It had this cute little SD Card Reader that let me do some pretty cool things. I guess this is just the next step in the evolution....
 
Electech6299
Posts: 606
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RE: IPod May Replace/be Flight Data Recorder

Mon Feb 26, 2007 12:27 pm

Quoting Bingo (Reply 29):
I thought it was pretty cool the first time I jumped into a Diamond Star with a G1000. It had this cute little SD Card Reader that let me do some pretty cool things. I guess this is just the next step in the evolution....

Not to borrow from your user name, but... Bingo!  Wink

If Garmin units can be certified for flight use, (not to mention Garmin systems have been accessed after a fatal incident to provide essential detail on the flight) then I can't see why an Ipod would be any worse off...
Send not to know for whom the bell tolls...it tolls for thee
 
osiris30
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RE: IPod May Replace/be Flight Data Recorder

Mon Feb 26, 2007 12:40 pm

Quoting Electech6299 (Reply 25):
RS-232 is just conductors and framework anyway, you can use whatever signaling mode you want once the framework is established.

At the risk of going off topic I wanted to reply to a couple of points here. Firstly I don't disagree you can run whatever protcol you want over RS-232. My preference for differential signalling is just in terms of reliability in adverse conditions (such as power fluctuations on driver or receiver for example). Easily overcome with an error correcting/checksumming protocol, but I've always been a believe in do the least amount of work necessary to make it work and odds are it will work better for longer.

Quoting Electech6299 (Reply 25):
but the big advantage of differential (data transfer rate) is wasted considering the data requirements.

See above. Rs-232 is basically TTL signalling. If both ends of the signalling aren't on the same ground reference weirdness can happen. I base this on real world goings on recently with 28vdc supplied hardware. It's the ability to survive those weird conditions better that makes me a fan of differential. Add to that some circuits are so low power now they need a driver just to do traditional 5v TTL anyway, why not go differential.

Quoting Electech6299 (Reply 25):
But the communications interface still utilizes RS232 framework, and is backwards-compatible to the 1980s model instruments from that manufacturer.

Yes that's the big advantage of rs-232. Everything under the sun can support it.

Quoting Electech6299 (Reply 26):
Consider that a flash drive chip weighing 0.2kg can hold the data of a 3-5 kg spool of tape, and has no moving parts to damage it, and can be protected far more securely than tape, I'm more a fan of the flash memory. Anything that could manage to damage the surface of a flash disk would likely have destroyed the entire tape reel. (An actual hard disk, on the other hand, shouldn't be used in anything more sensitive than a camcorder IMHO...)

Agreed fully and basically exactly what I was going to say, but found my self too lazy to post  Smile
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
Electech6299
Posts: 606
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RE: IPod May Replace/be Flight Data Recorder

Mon Feb 26, 2007 1:12 pm

Quoting Osiris30 (Reply 31):
At the risk of going off topic I wanted to reply to a couple of points here. Firstly I don't disagree you can run whatever protcol you want over RS-232. My preference for differential signalling is just in terms of reliability in adverse conditions (such as power fluctuations on driver or receiver for example). Easily overcome with an error correcting/checksumming protocol, but I've always been a believe in do the least amount of work necessary to make it work and odds are it will work better for longer.

I think it's quite on-topic...considering that Ipod agrees with you and uses balanced pair digital data transmission (like all USB-style interfaces). I just consider that a potential weakness, you consider it a strength. Power fluctuations I'm afraid you have the edge...as you say, RS-232 doesn't resume and reconnect as conveniently after a power loss/fluctuation without sufficient safeguards in place, and the data is more likely to be corrupted.

Quoting Osiris30 (Reply 31):
If both ends of the signalling aren't on the same ground reference weirdness can happen. I base this on real world goings on recently with 28vdc supplied hardware.

Absolutely, hence the need for a single ground point. Musicians know this (or sound engineers, anyway)  Wink and a lot of industrial controls tech are learning it the hard way. (Yes, as an amateur sound engineer I also know the reasoning behind balanced cables) As I said, however, for a directly docked device, it really won't matter (unless there is excessive interference in the computer case, which is another whole problem in itself)

Quoting Osiris30 (Reply 31):
Add to that some circuits are so low power now they need a driver just to do traditional 5v TTL anyway, why not go differential.

Yes, the power savings can help, but the Ipod will require a 5v power source anyways. If you're going to use a balanced signal to save power and then engineer a separate power wire into the same bundle, that seems to defeat your "simplest method".

Hmm...on second thought, the RS-232 interface does not natively include a means to power the supported device either, unless you use a non-standard multi-pin interface. The Ipod dock does provide power. So I guess the Ipod digital dock is a decent interface after all, going by existing connection technologies. I still think it depends too much on software and drivers.... Where's the competition with a 9-pin serial RS-232 with integrated power? Hello? AMD?  Smile
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