When flight testing in the room, the flight controller's GPS is lost and it automatically switches to A mode. At this time, data can not be sent using "sendVirtualStickFlightControlData" method. The connection with the transmitter has not expired.
Although data transmission outdoors was successful, I do not know the reason why indoor communication does not go well.
Data can only be sent when the aircraft status indicator is flashing green light slowly.
Is there a relationship with GPS when doing data communication?
The drone you are using is "Phantom 3 standard".
MobileSDK
Virtual stick definitely works indoors.
It seems that the main culprit is wireless interferences.
For a P3 standard, you are looking at wifi interferences.
It's a real issue when working in indoor dev environment.
You can check if there is a lot of wifi network with any wifi diagnostic application like this app on Android: https://play.google.com/store/apps/details?id=com.farproc.wifi.analyzer&hl=en
Now for solution, the best of best is a conductive setup, but it's really not trivial to do and will void your warranty.
Non-intrusive solution would be controlling the bands (keeping your wifi at 5Ghz, leave 2.4 free for the P3). This could help but doesn't guarantee to solve it all.
I hope this helps.
Related
I want to build something with Raspberry Pi Zero and write in Go,
I never tried bluetooth before and my goal is;
Sending a dynamic packet which it will change every second, an iOS app will expand this message and with a button, client will send a message back without a connection.
Is Bluetooth Advertising what I am looking for and do you know any GoLang library for it? Where should I start?
There are quite a lot of parts to your question. If you want to be connection-less then the BLE roles are Broadcaster (beacon) and Observer (scanner). There are a number of "standard" beacon formats out there. They are summarized nicely on this cheat sheet
Of course you can create your own format as these are using either the Service Data or Manufacturing Data in a BLE advertisement.
On Linux (Raspberry Pi) the official Bluetooth stack is BlueZ which documents the API's available at: https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc
If you want to be connection-less then each device is going to have to change it's role regularly. This requires a bit of careful thought on how long each is listening and broadcasting as you don't want them always talking at the same time and listening at the same time.
You might find the following article of interest to get you started with BLE and Go Lang:
https://towardsdatascience.com/spelunking-bluetooth-le-with-go-c2cff65a7aca
I am building an Android App to control power outlets with a smartphone. The app features an Android Wear app so people can control their lights right from their wrist.
When the user wants to control a light I send a String action via the MessageApi from the smartwatch to the smartphone, which receives this action in a WearableListenerService and sends the appropriate network signal to the power outlet/gateway in an AsyncTask.
This works fine as long as the phone has not been in idle for too long. However if the phone is still on the table for too long and doze kicks in Wear actions do execute very slow or sometimes not at all. I guess this is in part intended behavior however it is not practical in my case as the user cant wait that long for his lights to turn on if he wants to enter a dark room.
I am aware that doze completely cuts the networking for everything except FCM/GCM if you are not on the doze whitelist. But even when my app is on this whitelist and the networking part works actions can take a long time to execute on the phone.
So my specific question is:
Whats the recommended way to handle this scenario, where an action from a wearable device needs to be done via network on the connected smartphone which is in doze mode?
Is there a way to exit doze for a quick amount of time to execute calculations triggered by the wearable companion app faster?
I know the AlarmManager has a new method that works even in doze mode, but will this fix the processing delay too? Firing an alarm after receiving a MessageEvent from MessagApi seems like a workaround to me.
Or maybe is an AsyncTask just the wrong way to handle background networking and thats where the delay comes from?
Actually, there are a few options that you can do to handle Doze's effects as given in Adapting your app to Doze. You may want to consider the following options:
If your app requires a persistent connection to the network to receive messages, you should use Google Cloud Messaging (GCM) if possible.
GCM is optimized to work with Doze and App Standby idle modes by means of high-priority GCM messages. GCM high-priority messages let you reliably wake your app to access the network, even if the user’s device is in Doze or the app is in App Standby mode.
To help with scheduling alarms, Android 6.0 (API level 23) introduces two new AlarmManager methods: setAndAllowWhileIdle() and setExactAndAllowWhileIdle(). With these methods, you can set alarms that will fire even if the device is in Doze.
However, please note that with these methods, neither setAndAllowWhileIdle() nor setExactAndAllowWhileIdle() can fire alarms more than once per 9 minutes, per app.
Please try going through Optimizing for Doze and App Standby for a more detailed information or discussion.
In addition to these given documentations, the same options in handling Doze were also given and discussed in Diving into Doze Mode for Developers which might also help.
Im using MCP25625 which is MCP2515+integrated MCP2551 and trying to send messages in a loop.
For some reson I dont see any signal at all on CANH, CANL lines.
SPI communication works correctly
I use software reset procedure
There is clear 20Mhz sinewave from Crystal
There is TXCAN signal
At the moment there is nothing at all connected to CANL,CANH, just the probe.
I also tried to run in LOOPBACK mode and it works, but in the NORMAL modethere is nothing coming out.
Seems like transciever is broken? I changed 2 chips already, so it shouldnt be the problem.
Any suggestion guys?
Schematics
have you considered the modes of operation of the CAN transceiver?
In your schematic, the pins value is not clear.
If you have connected it to the MCU, Please pull it to LOW to select the normal operation mode for the transceiver (it is different configuration then the CAN controller settings, hence might cause some confusion!).
Controlling it by MCU is a good choice as it gives more control to prevent network communication from being blocked, due to a CAN controller which is out of control.
Else, connect it to ground to ensure normal operation mode specifically for the build in transceiver.
I have referred the data-sheet's of MCP25625, MCP2515 and TJA1050 to bring out this conclusion.
TJA1050 has pin-S for selecting high-speed mode and silent mode. Both modes are similar to normal mode and standby mode respectively of the transceiver of MCP25625.
Also, pin-S configuration in TJA1050 is similar to pin-STBY configuration in MCP25625.
0(LOW) for high-speed/normal mode of TJA1050/MCP25625-Transceiver
1(HIGH) for silent/standby mode of TJA1050/MCP25625-Transceiver
Hope this helps.
At the moment there is nothing at all connected to CANL,CANH, just the probe.
Hope you have connected the termination resistor? It is on the schematic, but ...
I am trying to collect GPS location every 5 seconds from a smart phone by using socket.io.
I notice that when users pick up a phone call, socket.io will stop emitting messages. When users switching tabs in the browser, socket.io will stop emitting messages too.
Does anyone know how to solve this problem?
Thanks very much!
Your best bet would be to package the website in a native app. Use a service such as http://build.phonegap.com or Intel XDK. There are configuration options to keep your app alive in the background. As for it disconnecting during phone calls, this is a carrier limitation. If the user was connected to WIFI, most phones will that for data while simultaneously on a call.
Some networks (such as Verizon) do not have the capability to do voice and data at the same time. Thus, when a call is made, data is suspended until the call is finished. AT&T does not have this limitation.
The operation of background tabs will vary by mobile browser and is likely done for battery conservation reasons. It is unlikely there is a work-around to keep the background tab running (because that would defeat the whole battery management purpose).
I'm planing to start some sms based application and currently in feasibility study part. In my application client have to sms their problem to the server and we have to analyse the problem and take reasonable action. Also We have to find the tentative location through which tower they have been connected. I have seen about silent sms feature but not understand. Is any body have experience on how to detect location of sms creator (not in android or iphone). Please help me on determining whether it is possible or not to find the location. If possible then how?
In short this is not possible.
an SMS message weather in PDU mode or text mode does not carry the information to match the source location to the message in any way shape or form.
With reference to the article you linked to in your opening post, I'm sorry to say that there's so much B$$l S$$t in that post that I can smell it from here.
In all the years Iv'e worked with GSM systems, both as a network maintenance engineer and later as a developer writing software to use these systems, not once have I heard of anything such as an 'LMU' or an 'E-OTD' in fact the only acronym that article really got correct was 'BTS' oh and the bit on passing the data over the signalling channel.
As for the silent SMS, well that part actually is true. The special type of SMS they refer to is actually called a Ping-SMS and it exists for exactly the same reason that a regular PING on a TCP/IP network exists, and that's to see if the remote system is alive and responding.
What it's NOT used for is the purpose outlined in the article, and that's for criminal gangs to send it to your phone and find out where you are.
For one, the ONLY people that can correctly send these messages are the telephone operator themselves. That's not to say that it's impossible to send one from a consumer device by directly programming a PDU if you have the necessary equipment and know how. You could for instance pull this stunt off using a normal GSM modem, a batch of AT commands and some serious bit twiddling.
However, since this message would by it's very nature have to go through your operators SMSC and most operators filter out anything from a subscriber connection that's not deemed regular consumer traffic, then there's a high chance this would fail.
You could if you had an account, also send this message using a web sms provider that allowed you to directly construct binary messages, but again they are likely to filter out anything not deemed consumer grade messages.
Finally, if you where to manage to send an SMS to a target device, the target device would not reply with anything anywhere near a chunk of location based info, cell tower, GPS or otherwise. The reason the SMS operators (and ultimately the law enforcement agencies know this info) is because EVERY handset that's attached to the GSM network MUST register itself in the operators MSC (Mobile switching centre), this registration (Known as ratching up) is required by the network so it can track what channels are in use by which device on which towers so that it knows where to send paging and signalling info.
Because of the way the PING SMS works it causes the destination device to re-register itself, usually forcing the MSC to do a location update on the handset which causes a re-registration.
Even then, all you get in the MSC is an identifier of the cell site the device is attached too, so unless you have a database in the organisation of all cell sites along with their exact lat/long co-ordinates, it's really not going to help you all that much.
As for the triangulation aspect, well for that to work you'd need to know at least 2 other transmitters that the device in question can see, and what's more you'd need that device to report that info back to someone inside the network.
Since typically it's only the Ril (Radio interface layer) on the device that actually keeps track of which transmitters it can see, and since the AT commands for many consumer grade GSM modems have the ability to query this information disabled, then it's often not easy to get that info without actually hacking the firmware in the device in question.
How does Google do it? well quite easy, they actually have commercial agreements with network providers that pass the details of registered towers to their back-end infrastructure, in the apps themselves, they have ways of getting the 'BSS List' and sending that list back to Google HQ, where it's cross referenced with the data from the network operator, and the info they have in their own very large transmitter database and finally all this is mashed together with some insane maths to get an approximate location.
Some GSM Modems and some Mobile phone handsets do have the required AT commands enabled to allow you to get this information easy, and if you can then match that information to your own database you can locate the handset your running from, but being able to send a special SMS to another device and get location info back is just a pipe dream nothing more, something like this is only going to work if your target device is already running some custom software that you can control, and if your device is running software that someone else is controlling, then you have bigger problems to worry about.