I'am developing a server for a GPS Tracker that can send pictures taken by a camera connected to it, inside a vehicle.
The problem is that I follow every step in the manual and I can't still decode the bytes sent by the tracker into a picture:
I receive the picture in packages separated by the headers and "tails", each one. When I receive the bytes I convert them into hexadecimals as the manual expecifies, then I have to remove the headers and "tails" and apparently after joinned the remain data and saved as a .jpeg, the image should appear, but it doesn't.
the company name is "Toplovo" from China. Have anyone else solve something similar?
Are the line feeds part of your actual data? Because if so I doubt that's supposed to happen.
Otherwise, make sure you're writing the file in binary mode. In some languages this matters. You didn't really specify, but make sure you're not in text mode. Also make sure you're not using any datatypes unsuited for hexidecimal values (again, we don't even know what language you're using, so, it's kind of hard to give specific suggestions.)
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Is there a way to request Data from this Sensor, at the moment it continuously sends the data and I can't change anything (and don't know how to change). I tried with the ublox Software but that did not help me. I found the Datasheet with the list of commands but did not find the right one and don't know how to use them either.
I am currently implementing a web app with the goal of keeping track of the location of all the packages in a company I am working for. Our plan is to have a barcode for each package and scan that barcode at the different sectors of the company, indicating where they are. The problem is that I have no idea where to start. I've done some research on Google but haven't found much. My main questions are:
How do barcodes work in the first place?
How do you program with barcodes? Is there a specific language I should use? Do I have to buy anything?
How do you read barcodes and enter them in your program and how do you generate them in the first place?
Any hints on how I should proceed with my implementation?
I look forward to hearing back from you as I need to implement this as soon as possible.
This is a pretty broad question, but I'll do my best to answer:
How do barcodes work in the first place?
Essentially, for this type of project, you can think of the barcodes you're going to be implementing as merely serial numbers. If you really want to know how barcodes work, Wikipedia has a pretty good write up - but essentially, at this level, just think of them as a serial number, encoded in such a way that a machine can read it.
In your web app, you'd be taking a number (say, 42) that has no meaning on its own, and associating with a package and a location.
How do you program with barcodes? Is there a specific language I should use? Do I have to buy anything?
You don't really "program" with barcodes per se... Again, it's just a machine readable implementation of some kind of information. In terms of "specific language", just build your web app as you already are, and add, say, an extra integer field. The integer doesn't mean anything on it's own - it's just going to be what's printed in the barcode. In this use case, you don't even have to have a barcode per se - you could just write it on the box! The usefulness of barcodes comes in speed and accuracy of data entry - you'd be having a computer device scan the barcode and type it in instead of a human.
How do you read barcodes and enter them in your program and how do you generate them in the first place?
It doesn't sound like you're at the point where you're doing any kind of machine vision or anything, so the most common entry method would be to buy a basic USB barcode scanner, like a Symbol LS2208. Use the manual that comes with it (or you can download the manual) to configure it as a keyboard emulation device - that way, your user would just select a field in the web app, scan, and the scanner would type out whatever was stored in the barcode (in the example above, the number 42).
As far as generating, depending on your volume, you have lots of options. For low volumes, you can find a generator online and print them out onto Avery label-type sheets using an inkjet or laser printer. You could also find a barcode font and print right from, say, Word, onto a label sheet. For higher volumes, you could purchase specialized software and use a label printer, or you can even write this yourself. Personally, I have a Zebra LP2844 with a network interface, and I wrote some custom PHP to send commands in the printer's native language (EPL2) over a socket to print onto roll labels.
EDIT: You'd probably want to use either Code128 or Code39. These are two different "symbologies" (types of barcode) that are appropriate for what it sounds like you're doing. They're 1-dimensional (like UPC codes and not like QR codes), so a cheap reader can decode them, and they're pretty flexible and VERY common.
Any hints on how I should proceed with my implementation?
Just think of barcodes, the way that it sounds like you want to use them, as arbitrary serial numbers that don't mean anything on their own. For example, doing this sort of box tracking in a previous warehouse environment, we printed THOUSANDS of unique serial numbered barcode labels. Those labels didn't have ANY value until they were attached to a box and a picker started to put stuff into that box. They were just numbers. Just remember to keep them unique.
I'm starting to work with the Google Tango Tablet, hopefully to create (basic) 2D / 3D maps from scanned areas. But first I would like to read as much about the Tango (sensors / API) as I can, in order to create a plan to be as time efficient as possible.
I instantly noticed the ability to learn areas, which is a very interesting concept, nevertheless I couldn't find anything about these so called Area Description Files (ADF).
I know the ADF files can be geographically referenced, that they contain metadata and an unique UUID. Furthermore I know their basic functionalities, but that's about it.
In some parts of the modules ADF files are referred to as 'maps', in other parts they are just called 'descriptions'.
So what do these files look like? Are they already basic (GRID) (2D) maps, or are they just descriptions?
I know there are people who already extracted the ADF files, so any help would be greatly appreciated!
From Tango ADF Doco
Important: Saved area descriptions do not directly record images or
video of the location, but rather contain descriptions of images of
the environment in a very compressed form. While those descriptions
can’t be directly viewed as images, it is in principle possible to
write an algorithm that can reconstruct a viewable image. Therefore,
you must ask the user for permission before saving any of their
learned areas to the cloud or sharing areas between users to protect
the user's privacy, just as you would treat images and video.
Other than that there doesn't seem to be much info about the file internals - I use a lot of them, but I've never been compelled to look inside - curious yes, but not compelled
Without any direct info from the project Tango folks anything we provide would be merely speculation. I'm with Mark, not much compelling reason to get details. My speculation: probably contains a set of image descriptors, like SIFT, and whatever other known device settings are available, like GPS location, orientation (gravity), time(?), etc.
I got the ADF file, basically coded binaries and seems difficult to decode.
I will be happy to share the file if anyone is still interested.
first question I've asked and I'm not sure how to ask it clearly, or if there will be an answer that I want to hear ;)
tl;dr: "I want to import a file into my application at work but I don't know the input format. How can I discover it?"
Forgive any pending wordiness and/or redaction.
In my work I depend on an unsupported (and proprietary) application written in Pascal. I have no experience with pascal (yet...) and naturally have no source code access. It is an excellent (and very secret/NDA sort of deal I think) application that allows us to deal with inventory and financial issues in my employer's organization. It is quite feature-comprehensive, reasonably stable and robust, and kind of foistered (word?) on us by a higher power.
One excellent feature that it has is the ability to load up "schedules" into our corporate system. This feature should be saving us hundreds of hours in data entry.
But it isn't.
The problem is, the schedules we receive are written in a legacy format intended for human eyes. The "new" system can't interpret them.
Our current information (which I have to read and then re-enter into the database by hand) is send in a sort of rich-text flat-file format, which would be easy to parse with the string library of probably any mainstream language.
So I want to write a converter to convert our data into a format that the new software can interpret.
By feeding certain assorted files into the system, I have learned a little bit about what kind of file it expects:
I "import" a zero-byte file. Nothing happens (same as printing a report with no data)
I "import" an XML file that I guess might look like the system expects. It responds with an exception dialog and a stacktrace. Apparently the string <?xml contains illegal characters or something
I "import" a jpeg image -- similar result to #2.
So I think that my target wants a flat-file itself. The file would need to contain a "document number" along with {entries with "incident IDs" and descriptions and numeric values}.
But I don't know this for certain.
Nobody is able to tell me exactly what these files should look like. Someone in the know said that they have seen the feature demonstrated -- somewhere out there is a utility that creates my importable schedules. But for now, the utility is lost and I am on my own.
What methods can I use to figure out the input file format? I know nothing about debugging pascal, but I assume that that is probably my best bet. Or do I have to keep on with brute force until I can afford a million monkey-operated typewriters? Do I have to decompile the target application? I don't know if I can get away with that, let alone read the decompiled source.
My google-fu has failed me.
Has anyone done something like this before or could they point me in the right direction? Are there any guides on this subject?
Thanks in advance.
PS: I am certain that I am not breaking any laws at this point, although I will have to check to find out if decompilation would get me into trouble or not, and that might be outside of my technical competence anyway.
If you have an example file you can try to take a hexdump utility and try to see if there things you can identify. Any additional info that you have (what should in the file) helps with that. Better even, if you know a program that can edit the file, you can use the editor to make minimal changes and then compare the file before and after.
IOW standard tricks of binary file format reverse engineering.
...If you have no existing files whatsoever, then reverse engineering the binary is your only option, and that is not pretty. Decompilation of native binaries is a black art that requires considerable time and skill. Read the various decompilation FAQs on the net.
First and for all, I would try to contact the authors of the program. Source code are options 1,2,3 and you only go with other options if there is really, really, really no hope whatsoever of obtaining source or getting normal support.
Am trying to write a piece of code which will allows the user to type text into a textbox which then gets saved on the server. When the user types some more text in the textbox, I want only the difference to be sent to the server.
Is there a difference algorithm for JS which I can use to send only information about the difference. So it should be able to tell the difference between two text boxes essentially.
It could also be language agnostic and I can port it.
Thank you for your time.
UPDATE
In simple words. I have a text area which keeps saving the text in the box every X seconds. Now to save bandwidth I only want it to send the difference from the last saved revision (which I can say put in a variable. Initially this will be empty). Now the JS has to check the difference between the last revision and the current state of the textbox and generate a change list to send to the server.
UPDATE 2
Something like www.etherpad.com
Google DiffMatchPatch has a Javascript implementation, I've used it with much success.
http://code.google.com/p/google-diff-match-patch/
The Python difflib module does this and more. It's very flexible but might be challenging to port to Javascript.
Regarding your update, I'm first wondering why you need to worry about bandwidth. Unless your users are typing a lot of text into an edit box (which has its own usability issues) then there just aren't that many bytes to send. Send the whole text box each time you autosave. Users can't type fast enough to really notice the use of bandwidth.
Or, you could meet halfway. Every time you autosave, check to see whether the user has only added new text to the end compared to the last time. If so, send an "append" type update with just the new text. If the user has gone back and edited anything else, then send a "replace" type update where you send the whole text. This takes care of the common append-only case without severely complicating your implementation.
Instead of calculating a diff between 2 texts, which is difficult,
you could always, while people are editting, record the keystrokes and the caret position in the textbox. If you send this over every now and then (and clean the buffer), the server can playback the exact same sequence.
This code-smells of premature optimization. Perhaps you should implement your solution first and then see about optimizing your transfer rates using diffs. How much text are you looking at? Because the request and response packets are going to be more or less the same size with only a few bytes difference for your message, so the savings could be very minimal.
At the very least, complete your solution without optimization and profile your network traffic using tools like Firebug and then test to see how much worse the performance is with what you would consider to be the maximum text block that could be sent.
Finally, you could always use the TypeWatch JQuery plugin to listen for change events in the textbox. You can set a delay so that once the user finishes typing and the delay elapses, the callback function is triggered. This means that the text will only be sent when the user types something, and only when they are finished typing. This will be significantly more efficient than repeatedly polling the server.
Depends on how far you are ready to go.
You would like to check deltav algorithm, it is used by svn in particular: http://svn.apache.org/repos/asf/subversion/trunk/notes/svndiff