Every communication that is made without cable, everybody can listen but not everybody can understand. So, when I call someone with my phone, or send a sms my cellp phone send information, I want that my pc know this (I know that both have to the same frequency). Or some site or material to start with it. I have an android.
It's like make a operator communication, just that is my cell phone with my pc and not my cell phone with the operator
Please have a look at OpenBTS. It is an (experimental) open source implementation of a BTS (base transceiver station), the network node that handles the radio communication. Similar OpenBSC.
What you want to do is huge. You will need special hardware.
Related
I have to write a BLE application on an embedded device and there are some features where I'm not sure if BLE supports that or whether I've to create some wrapper around everything or if it's maybe not possible at all. The gerenal descriptions of Bluetooth and BLE I found around the internet usually only cover the overall functionality but don't go in too much detail. If this post gets too complex I'll split it up into different smaller ones.
I use the STM32 BlueNRG-MS chip
1. Discoverability (resolved)
The user has to be able to disable the BLE function in case there are several devices in reach. I see that there are functions aci_gap_set_discoverable() or aci_gap_set_non_discoverable() but altough I set it to not discoverable I can still see it in the LightBlue App on my mobile. How would I correctly disable the BLE functionality of a device to make sure no one can see it or connect to it?
Update: Okay that has been a mistake from my end, if I call the aci_gap_set_non_discoverable() function it is actually undiscoverable. So that's fine.
2. Only accept connections of paired devices
I'd like to achieve a behavior such that, if you have an unpaired phone you have to set the BLE device into a pairing mode in order to connect. If the phone has already been paired, the BLE device shall accept the connection request regardless of whether it's currently in pairing mode or not. Is this what the whitelist should be there for or do I have to do this manually by saving the address of the device after successful pairing? If whitelist is the right approach, I read that newer phones cause issues with whitelisting because they change their address on a regular basis, how can I handle this? That's actually where I thought I'm gonna work with the "discoverability".
3. Automatically reconnect
I'm not sure if this topic has to be handled on the BLE device or on the mobile phone. E.g. my phone is paired with my car's radio, so whenever the phone is in the car it automatically connects - how is this done? It's still the phone that acts as central device I assume?
I want to develop a mobile app that listens for broadcasts by a BLE device. My idea generally is patterned on the game "I spy".
In a room full of objects, there should be a numerous Bluetooth beacons. The beacons will have a button and when the button is pressed, it would send a broadcast. One person goes in the room to solve the puzzle so there won't be the need to consider if the broadcast reaches multiple phones.
When the button is pressed, the app should check the clue given and read the corresponding beacon's ID and then alert the user whether they're correct or not.
I would like this to happen without having the user's phone pair with all BLE beacons.
For the beacon, i'm thinking to use something along the lines of an Adafruit LE Friend or flora wearable. This would be soldered to a CR 2025 or similar battery. Do I also need an Arduino or can this be standalone?
I'm thinking that it could be standalone but I have no experience here
For your use case, the flora wearable is the more suitable choice because you can just solder a battery to it and get it to work (the Adafruit LE Friend requires a PC as it is a USB dongle). You will need to do some reading on basic Bluetooth Low Energy (BLE) concepts, and I recommend that you focus on the following:-
Advertising/Broadcasting: This is what your BLE peripherals such as the flora will be doing. These devices will be sending adverts when a button is pressed or a command is sent.
Scanning/Observing: This is what the app developed on mobile phones will do. Your apps will be continuously scanning for those LE adverts and display relevant information to users when those adverts are read.
Luckily these are relatively easy BLE concepts and there are already many examples for both advertising and scanning.
For more resources, I recommend having a look at the following:-
Bluetooth Low Energy: A Primer
Getting Started with Bluetooth Low Energy
Introduction to BLE
I hope this helps.
I want to find a solution to broadcast voice over WiFi for the people in a march. Since Android and IPhone is the most popular devices among the people in the march, it would be great if i can find a solution for audio broadcast over wifi with limited budget.
I know that people in occupy movement use different app on their cell, but it is not suitable in a march in my city. As the authority in my country may temporarily shutdown the data over mobile network to disable the app.
If i can develop an app to gather the broadcast message (SSID) from a powerful wifi AP with a long-length directional antenna, I should able to deliver message among the people in the march. Is it a possible solution?
Also, is it possible to modify the AP to allow any device to join the AP without further acknowledgment and broadcast message to all devices in that network?
Any idea or opinion is welcome.
Many Thanks.
This will be difficult, especially with a large number of users. Since you only need to send audio in one direction, that will at least be a bit easier.
First, you're going to want to put that AP in the middle of the crowd with an omnidirectional antenna. Perhaps, in a backpack or something. Each phone on that network needs to "hear" when other phones are transmitting, or it will be a mess. Even though your application is one-way, 802.11 isn't.
Now, when you write your application, use UDP packets sent to the broadcast address. No need for TCP packets, as they will clog up your network anyway.
Use a simple voice codec, such as AMR. The codecs available vary from platform to platform. See this document for a list on Android: http://developer.android.com/guide/appendix/media-formats.html
Honestly, the easiest solution would be to go buy a small FM transmitter, since many phones have receivers in them anyway.
Im writing application that communicate (via serial port) with electronic device which i designed myself.
When my PC application starts - it opens available COM ports one by one and it sends some string ("What are you?" for example).
My device is programmed, to reply to that "magic question" with own ID (for example: "I am evil device for supervising employees").
When my PC software receive that "magic reply" it starts working normally and its not searching other ports anymore.
Of course im not using stupid questions in data transmission, its just example.
Question is - can i send strings like on all (not busy) ports, to discover my device?
If I can - how that "question" string should look? Are there any normalized standards?
This is not first project like this on my desk, but now im developing solution for little industry and i need to pay more attention what my application is doing, because there may be other devices connected to COM ports and I do not know how they can react.
Im sorry, if i made some language mistakes, english is my third language.
Thanks in advance for replies.
After Alvin Wong confirmed my concerns I thought about it again and redesigned my device discovery functionality, because I don't want to abandon that idea.
I will send unique-complicated-ID every 1-5 seconds from device.
When my PC starts - it will try to open sequentially all available ports and will listen for that ID for few seconds.
If application receive that ID - it will be confirmation, that port number/name is correct and I my connection is established.
No, you wouldn't want to do that.
When you are using COM serial port, you have no idea what is plugged into the port. It could be nothing, your device, a modem, a mouse (though I believe nobody uses this anymore...) or whatever you can't even imagine.
Imagine if it is connected to another computer (probably a Linux/router), sending things may lead to execution of "that command", thus creating unexpected effects (though your program may not notice). Or if it is some badly-programmed device, it may trigger a bug in the firmware, thus failing the device and making it malfunction.
In short, in the worst case, you can cause a catastrophic event.
Serial (RS232 or UART I assume) communications don't have a designated transfer protocol (in contrast to USB which has one) to identify a device, so it isn't fail-safe. The user must make sure he selected the correct port. This is probably one of the reasons why hardware manufacturers choose USB, and one of the reasons why USB is so popular, even to computer idiots.
we want to route the call to ip network instead of GSM network. for that purpose first we are connecting our mobile phone to a PC through bluetooth. So we want to transfer the real time audio data to that PC over bluetooth. Could you please help..
If you can trick the mobile phone to function as a bluetooth headeset [profile] -- which I doubt any phones would support because phones are, well, the consumers of such headset devices -- then you could use it like any other "headset" device. (It would be much more feasible to just purchase a headset or plug in a microphone.)
As far as "where the real time audio data is stored?" -- well, that just won't go anywhere. The "data" (perhaps already in an encoded/delta form) is briefly (like milliseconds!) "stored" in a few small buffers / integrated circuits in the radio circuitry. This circuity will vary based upon phone/radio module used and is not accessible from a PC.
Happy doing productive things.