Apr 19, 2007, 9:59 AM
Post #1 of 19
19 April, 2007
For your reference,
There's a research project going on at The Parachute Club of Finland at the moment. We evaluate the possibility to create a highly dedicated GPS for the skydiver community, combining GPS receiver, short-range radio, altimeter, 3D accelerometer, microprocessor with large storage capacity and USB interface.
The GPS will feature practically zero acquisition time since it stores the raw receiver data, along with the NMEA one, for further processing (satellite fix) on the ground.
The collected data (tracks) could be then viewed on standard computer using built-in device keypad similar to a TV remote control, so one does not even need to touch PC mouse or keyboard.
If interested, please visit the project site at www.DropZoneGPS.com
Briefly, the main features of the device:
* High Resolution Differential GPS (DGPS) * Zero Acquisition Time * Collision Warning Alarm * Formation Recorder (incl. orientation) * G-Meter * Standard Logbook * Built-in Flash Memory (no card required) * USB / Wireless Operation * Track Browser Keypad * FREE 3D Graphical Viewer
Resolution 0.5 m (differential) Frequency band 2.4 GHz Output power 1 mW Range approx. 100 meters Memory capacity 8 MB Data format NMEA / raw Interface USB / IEEE 802.15.4 (uses one device as a dongle) Battery 3 x AA type Size 10 x 40 x 60 mm Weight 50 g (w/batteries) Target price 95 EU
after reading website www.dropzonegps.com I have few questions in mind.
First of all I would like to ask, who is running this project from Parachuting Club of Finland? I can see we share the DZ but this is very first time I hear your name or DropZoneGPS-project.
My second question is about photo in your site. According "Legal notice" of your site: ******** Intellectual Property (IP) Rights
The material contained on this website is protected by copyright. ...clip... ...you must not use, copy, modify, transmit, store, publish or distribute the material on this website, or create any other material using material on this website, without obtaining the prior written consent of Polar Laboratories. ********
That is correct, the only photo in your site is protected by copyright laws. But I am the copyright owner, not you.
Dear all, be careful with this YuriT. Perhaps he is honest man but he has no right to use my photo and I never heard of him.
You can also make your own conclusions if you combine following details: -YuriT has registered Apr 19, 2007 to DropZone.com and this is his only post -Domain Name DROPZONEGPS.COM has registered 19-Apr-2007 -Domain name POLARLABS.FI website is alias for DROPZONEGPS.COM
But if you, Yuri are the man, you contact me and we have a word concerning use of my photos.
Planning 2 versions of the device, simple the NMEA-only and full-blown raw/DGPS one. Sampling rate for non-DGPS version is 5 Hz, for DGPS could be as high as 1 KHz since raw receiver data (pseudo-ranges) is stored on flash disk and then processed offline on the ground workstation. Actual altitude is fused from pressure sensor and GPS data.
Obviously, it's not well suited for the BASE jumps for the reason you've just mentioned.
The GPS will feature practically zero acquisition time since it stores the raw receiver data, along with the NMEA one, for further processing (satellite fix) on the ground
Can you explain how you plan to use DGPS in this situation? From the sounds of it, this system you are developing will only work there at your DZ. If I am not mistaken, what you are doing is using inverted DGPS.
Also, I am assuming that the receivers you are using are all differential ready receivers and you are using a reference station some where off of the coast?
Receivers are differential only relatively to each other, so to log formation you need at least 2 skydivers in this formation. In formation of 1 person it will not work :)
I think there maybe a misunderstanding of the technology here. In order for Differential GPS to work, there needs to be a ground based receiver station located several hundered kilometers away from the roving receiver(s) in order to avoid the same timing errors. As long as there is a stationary surveyed station and one roving or moving receiver, the correct distance apart, DGPS can work. The ground based station measures all the timing errors,corrects for them and transmits the corrections to the roving receivers. Since GPS receivers don't transmit information they are linked to a seperate radio transmitter, hence the need for differential ready GPS receivers. That simplistic explanationis how it(DGPS) is used the world over for maritime operations.
I am wondering,are you are actually talking about using true DGPS or perhaps WAAS?
It's a DGPS but in bit different matter which you can find on Google. One just logs (raw) data from all receivers in formation and then you can get relative distance between divers much better than absolute one and draw nice 3D OpenGL picctures. You don't need any ref station, another receiver is this base station.
What you are describing isn't DGPS, from what you have said, the closest thing I can assume you are trying to do is use something similar to Inverted DGPS, but even that is a stretch. With all the receivers on the individual jumpers, it means that they will all have the same timing errors as found on any GPS receiver.
Again, I am only assuming that your post processing the data from all of the receivers on the jump is similar to the collecting of data in a mapping application such as ArcGIS(Arcview), where you'll be able to compile information to "see" the formation.Is this correct?
Is this something completely new and still being developed? Perhaps you could explain in a bit more detail about this different DGPS since as you say it cannot be found on Google and it apparently isn't differential.
Yo, you compile data on the ground reading raw file from flash disk and then "see" the formation. Google lists the most common terms to describe diff positioning (DGPS), but there's many other techniques to get the same result. Timing errors are the same, but we want to know relative distances between divers not the absolute ones. The abs position comes from standard NMEA stream.
you compile data on the ground reading raw file from flash disk and then "see" the formation.
Ok, nothing really new. Several applications(ArcGIS) have been doing that for some time now with Paralog being specifically made for skydivers.
Google lists the most common terms to describe diff positioning (DGPS), but there's many other techniques to get the same result.
Granted and they range from simplistic to somewhat technical. I am familiar with this slightly beyond that. So perhaps a better explanation is in order because you haven't made it clear how you can say you are using DGPS other than just stating it in your original post. I am beginning to suspect you are really relying on WAAS(WADGPS) or in your case(Finland) EGNOS. Please do tell what this different technique is that doesn't require a base station/beacon or survey quality equipment to obtain DGPS accuracy.
but we want to know relative distances between divers not the absolute ones. The abs position comes from standard NMEA stream.
So you want to overlay the data to "see" where everyone is at? Again, there are several programs that do just that. However,if you are using a standard GPS reciever on all the jumpers, they will all have a margin of error that varies from receiver to receiver in the NMEA stream anyways. Are you saying that you will use/build a receiver that is different from a standard GPS receiver that has the ability to "talk" to the other receivers on the other jumpers via raido wave to compile the relative data?
Again, if you would just explain in detail how this supposedly will work, it would clear up a lot of these questions.