I am scientist working on a project related to wireless communications.
In my project I need to have access to the phone signal strength, or Binary error rate, or anything that indicates the quality of the received signal.
I know that it is possible to do so on Android using SignalStrength, but I just don't have any idea how fast it is updated.
Can anybody please tell me what is the update time of such variable ?
Many thanks in advance.
G.
Related
We're trying to have time-keeping as close to real-time as possible. Since our network doesn't support PTP, I'm using NTP. We have an NTP-server with GPS at disposal, and we're syncing about every minutes.
Though we still experience a little drift - of course. But some of our hardware drifts more than others. The best drifts about 1/10th of a ms where as other drift as much as 1.5ms.
We would like to hit around 0.25ms 90% of the time.
Does anyone know if it is possible to change the crystal on the board to a more accurate crystal, or have an idea how to make the clock drift less?
Best regards.
First I want to point out that I'm very new to Raspberry Pis. I have bought a Raspberry Pi Zero for my project, because Arduino did not have enough horsepower.
My Project involves an I2C sensor and audio output (I2S). The audio is generated on the Raspberry and that is why I need the computational power.
Now I'd like to know what would be a good choice for the operating system. I don't really need anything else but the I2C and I2S and some math to generate the sound. The project is going to have the Raspberry embedded in the system and is battery powered, so it should be able to survive sudden power loss.
I found something relating to Real Time Operating systems, but I'm not sure if I need it to be exactly real time since I can buffer the generated sound data. But I do need the system to be fast, and as light as possible as the sound generation is rather heavy process.
I understand this is sort of vague question and I'm happy with any information I can get and if you could just point me in the right direction, that would be appreciated.
I have two questions regarding GPS sampling on iPhone:
1.Is it possible to use CLLocationManager (or any other method) for location readings based on GPS alone without WiFi or Cellular network affecting it?
2.Given a stationary device, is it possible to control the sampling rate? Can I use CLLocationManager to get nonstop location readings from GPS in nanoseconds resolution? If not, what's the best resolution I can get?
regarding number 1, apparently, you cannot directly control gps data. having said that: if you have speed > 0 AND high accuracy, then you can infer that your data has a high probability of having come from a gps reading.
as far as i know, gps fixing is not measured in nanoseconds, but rather in seconds. what you mean exactly by resolution (reading frequency?) is a bit unclear. but, if it is frequency, most navigational software (google, for example) refreshes location every second or so.
hi frequency position updating is very costly in terms of storage cost (server side), query times (server side), battery use (iphone) and heats the phone up bigtime. i would be going in the opposite direction, especially for stationary devices (sending a heartbeat every 5 minutes or so is usually more than enough).
reference on CLLocationManager
I am about to start on a huge new project which will rely on the use of an Arduino connected to third party electronics (in this case an electromyography board I have already built).
I have a good idea of how to transmit data between the Arduino and the iPhone or iPad using protocols like OSC and an Ethernet shield.
What I am hoping to achieve is to effectively analyse an incoming analog signal and recognise the gestures employed to create that signal. So what I am essentially talking about is waveform analysis, whether it is on the iPhone side or on the Arduino side. Are there any libraries or previous methods of analysing or recognising gestures? This is going to be a large research project, so I am really looking for a push in the right direction.
This, I understand, might be a vague question so if anybody wants me to shed some light on the matter I will be more than happy.
Is there is a way to determine an iPhone's exact location (indoors, and to a distance of just a couple of feet) via use of radio/antenna's or some other infrastructure located around premises (i.e a hospital, shopping mall, school). Will appreciate any ideas/direction (technologies, research) as for how to overcome this limitation.
If you mean for an area you have control over (setting up a location network for a specific school/hospital) as opposed to generic location, you'd be able to triangulate your position based on wifi signal power for APs with known locations.
If you wanted it to be a generic solution, and you know there would be multiple APs in/around the buildings you wanted, you could triangulate all wifi signals while you have GPS outside the building, and then reference those locations when you lose gps accuracy. The first part is something that many wardriving applications already do.
Here's an article describing a commercial technology for this purpose in high-level detail: link
And here's a link to a SO page where people have started discussing possible methodologies: link
Use the GPS and hope that you got good coverage.
Other than this, you can deploy several wifi hotspots that can measure the signal strength for each packet and do a triangulation to calculate the iPhone position with regards to three or more of these hotspots based on the signal strength each of them measured.
A quick search for "signal triangulation" on the internet reveals a Wi-Fi Based Real-Time Location Tracking technology from Cisco. I have not used it, so I can't vouch for it; and I suspect it's rather expensive. There might be other solutions as well.
The alternative would be to buy several wifi routers or access points and flash them with your own version of the firmware. You can probably use OpenWRT or DD-WRT as a base for this.