I am working on a Free-Space-Optics transceiver that uses the soundcard of a computer, a LED, a photodiode and a lens to transmit data over the air. At the moment I am trying to connect two transceivers with the help of GNU Radio. The GNU Radio tutorials and examples that I know of, all cover USB radio devices.
I already experimented with software called Minimodem which uses Audio Frequency Shift Keying for data transmission over the soundcard. GNU Radio offers a lot of useful blocks like Automatic Gain Control (helpful for changing signals due to light and weather conditions) etc., which is the reason I would like to use it for my experiments.
I understand that using the soundcard as the interface is a limiting factor for the achievable data rate.
I would appreciate advice of how to setup a reasonable flow graph in GNU Radio companion that enables a data transmission between the soundcards of two computers. Thank you!
You essentially need two out-of-tree modules for your soundcard in the Gnuradio. one sink(for transmitter) and one source(for receiver). If you already have some code that can send samples to your sound card, just create an oot module and put it in that module. if not, then write a C++ or Python code that can do this.
Related
I have one USRP B210 and E312 and all the message transferred between them are via the broadcast message.
Is there any way to transmit a unicast message (point to point) in GNURadio?
If yes, can you please help me with an example?
You're confusing GNU Radio with something it is not:
GNU Radio is a framework for designing signal processing flow graphs. It is especially useful for processing digital radio signals.
Whether a message is "unicast" or "broadcast" or whatever isn't anything that GNU Radio is concerned with. You'd typically just analyze a packet that you received to determine whether it was meant for you.
GNU Radio isn't something that you typically use to implement a network layer. Mostly, you do physical layer signal processing. As soon as you have packets of bits, you usually leave GNU Radio. Your problem arises from a misunderstanding of what GNU Radio does (and maybe, software defined radio in general).
I found a great library, gr-mac which can handle the broadcast and unicast messaging above the gnuradio.
https://github.com/jmalsbury/gr-mac
I hope it will be helpful to other new gnuradio users like me.
What is the procedure of implementing TDMA scheme on GNU radio using USRP?
I want to implement TDMA scheme using two USRPs as a transmitter and the third one as a receiver. The requirement is that first transmitter sends some data to the receiver for first 10 seconds and then after a delay of two seconds, the second transmitter sends some data to the receiver for another 10 seconds and this process continues to do so. Anyone who can help or provide with some useful links in order to implement this whole process in GNU radio software?
I am in the middle of implementing a TDMA radio. My design relies on GPS sync on the GR host platform. I use its time to sync my USRP using set_time_unknown_pps using an arg that is 2 seconds in the future.
My MAC block is purely message based, acting as a PDU broker between the application and PHY layer. PDU's to be transmitted are tagged with a tx_time command with time set an appropriate amount into the future. I've had to write several OOT blocks to handle tx_[sob,eob] tagging and other PHY details, but in the end packets come out exactly when they need to. The turn on latency for my B200mini appears to be about 1-2 us, which is fine for my timing requirements.
My advice is to start with simple MAC functions and test all the way along until you are confident with a block, then move down the transmit chain.
Anticipating your obvious question, I cannot release any of my code because it's not my code to release :-)
Here is a useful link, explaining how a TDMA system may be implemented in GNU Radio.
I have done projects using Arduino IDE.I have seen that many projects can be easily implemented using the IDE.Then, why should one learn register level programing? How important is it?
Can you do EVERYTHING with the Arduino library? If your project would need tight timing (for example to control a huge industrial apparatus), at the level of microsecond fractions, would Arduino still be a good choice? How about medical devices? How about performance - would you be able to design a BLDC controller using Vector Control in Arduino? How about battery life - would you be able to design a device that would run with a single CR2032 cell for a few years using Arduino? How about doing a network router? Does Arduino support threads?
Your question is like one of these:
who needs x-bit microcontrollers when we have y-bit microcontrollers at the same price?
who needs x programming language when we have y programming language?
who needs analog solutions when we have digital solutions?
who needs microcontrollers when we have microprocessors?
...
To be honest, personally (I write firmware for embedded devices),I see Arduino as a toy, nothing more.
Learning register level programming will help you learning how to read a datasheet, and also understanding how stuff works. It will give you more flexibility after you get the hang of it, plus you can optimize your code and write your own libraries.
By knowing how to read a datasheet it will be easier for you to develop device drivers and process algorithms.
What would you do if you cannot find an Arduino library for a certain sensor? If you were using register level programming, you could easily write your driver, by already knowing how to interpret the technical files ;).
Try it out, you will forget Arduino in the first weeks!
Best regards,
Alex Tofan
I've got quite a fun challenge / work assignment. I'm to monitor a couple of 5V light bulbs (warning lights) on a machine standing far out in no man's land. I'm looking for an affordable device with an input which allows me to hook into the light bulb circuit to tell whether it's lit or not.
Requirements:
GPRS
Inputs for at least two light bulbs
Programmable in C or something similar.
Bonus (not required, but it would be kind a nice):
Waterproof casing / chassis (I could make this my self, but it would be nice if I didn't have to)
Option to add other sensors like humidity, temperature and gps.
Any tips?
I'd recommend an arduino
Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It's intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.
Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by controlling lights, motors, and other actuators. The microcontroller on the board is programmed using the Arduino programming language (based on Wiring) and the Arduino development environment (based on Processing). Arduino projects can be stand-alone or they can communicate with software on running on a computer (e.g. Flash, Processing, MaxMSP).
there's an article here on hooking one up with gps
http://www.arduino.cc/playground/Tutorials/GPS
and for more information on the arduino platform in general, and where to buy
http://www.arduino.cc/
Edit: just noticed you were looking mainly for GPRS and not GPS - doh, however, quick look on google brings up this: http://www.libelium.com/squidbee/index.php?title=New_GPRS_module_for_Arduino_%28Hilo_-_Sagem%29 which is a GPRS module for the arduino :]
Have you looked at Arduino?
in fact, what you are asking already exists: many companies which produces electrical component for the industry provides a rail-mounted GPRS modem for remote signaling.
here is one example, made by phoenix contact
another one from another company
the tele-control range of product from wago
telit is well-known for its GSM chips, and provides a complete module with GPRS and programmable in python.
you can find some fancier systems including GPS and linux-based, here for example
there are countless other solutions...
I would buy the Terminus from Janus RC it is based on a telit module. It is a cell modem with 9 GPIO and you can program it using python.
Interface
9 Bi-directional CMOS I/Os
Power Monitor
1 ADC
ITU-T V.24 serial link through UART
Python Script Support
Integrated Python script interpreter (V1.5.2+)
2 MB of non-volatile memory
1.2 MB of RAM reserved for Python engine usage
Powerful built-in libraries makes accessing hardware easy
As a hobby project to keep myself out of trouble, I'd like to build a little programmer timer device. It will basically accept a program which is a list of times and then count down from each time.
I'd like to use a C or Java micro controller. I have used BASIC in the past to make a little autonomous robot, so this time around I'd like something different.
What micro controller and display would you recommend? I am looking to keep it simple, so the program would be loaded into memory via computer (serial is ok, but USB would make it easier)
Just use a PIC like 16F84 or 16F877 for this. It is more than enough.
As LCD use a 16 x 2 LCD. It is easy to use + will give a nice look to your project.
LCD
The language is not a matter. You can use PIC C, Micro C or any thing you like. The LCD's interface is really easy to drive.
As other components you will just need the crystal and 2 capacitors as oscillator + pull up resister. The rest of the components depend on the input method that you are going to use to set the times.
If you are using a computer to load the list then you will need additional circuit to change the protocols. Use MAX 232 to do that. If you want to use USB, you need to go ahead and use a PIC with USB support. (18F series)
(source: sodoityourself.com)
This is a set of nice tutorials you can use. You can purchase the products from them as well. I purchased once from them.
I would go with the msp430. An ez430 is $20 and you can get them at digikey or from ti directly, then sets of 3 microcontroller boards for $10 after that. llvm and gcc (and binutils) compiler support. Super simple to program, extremely small and extremely low power.
There are many ways to do this, and a number of people have already given pretty good suggestions AVR or PIC are good starting points for a microcontroller to work with that doesn't require too much in the way of complicated setup (hardware & software) or expense (these micros are very cheap). Honestly I'm somewhat surprised that nobody has mentioned Arduino here yet, which happens to have the advantage of being pretty easy to get started with, provides a USB connection (USB->Serial, really), and if you don't like the board that the ATMega MCU is plugged into, you can later plug it in wherever you might want it. Also, while the provided programming environment provides some high level tools to easily protype things you're still free to tweak the registers on the device and write any C code you might want to run on it.
As for an LCD display to use, I would recommend looking for anything that's either based on an HD44780 or emulates the behavior of one. These will typically use a set of parallel lines for talking to the display, but there are tons code examples for interfacing with these. In Arduino's case, you can find examples for this type of display, and many others, on the Arduino Playground here: http://www.arduino.cc/playground/Code/LCD
As far as a clock is concerned, you can use the built-in clock that many 8-bit micros these days provide, although they're not always ideal in terms of precision. You can find an example for Arduino on doing this sort of thing here: http://www.arduino.cc/playground/Code/DateTime. If you want something that might be a little more precise you can get a DS1307 (Arduino example: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1191209057/0).
I don't necessarily mean to ram you towards an Arduino, since there are a huge number of ways to do this sort of thing. Lately I've been working with 32-bit ARM micros (don't do that route first, much steeper learning curve, but they have many benefits) and I might use something in that ecosystem these days, but the Arduino is easy to recommend because it's relatively inexpensive, there's a large community of people out there using it, and chances are you can find a code example for at least part of what you're trying to do. When you need something that has more horsepower, configuration options, or RAM, there are options out there.
Here are a few places where you can find some neat hardware (Arduino-related and otherwise) for projects like the one you're describing:
SparkFun Electronics
Adafruit Industries
DigiKey (this is a general electronics supplier, they have a bit of everything)
There are certainly tons more, though :-)
I agree with the other answers about using a PIC.
The PIC16F family does have C compilers available, though it is not ideally suited for C code. If performance is an issue, the 18F family would be better.
Note also that some PICs have internal RC oscillators. These aren't as precise as external crystals, but if that doesn't matter, then it's one less component (or three with its capacitors) to put on your board.
Microchip's ICD PIC programmer (for downloading and debugging your PIC software) plugs into the PC's USB port, and connects to the microcontroller via an RJ-11 connector.
Separately, if you want the software on the microcontroller to send data to the PC (e.g. to print messages in HyperTerminal), you can use a USB to RS232/TTL converter. One end goes into your PC's USB socket, and appears as a normal serial port; the other comes out to 5 V or 3.3 V signals that can be connected directly to your processor's UART, with no level-shifting required.
We've used TTL-232R-3V3 from FDTI Chip, which works perfectly for this kind of application.
There are several ways to do this, and there is a lot of information on the net. If you are going to use micro controllers then you might need to invest in some programming equipment for them. This won't cost you much though.
Simplest way is to use the sinus wave from the power grid. In Europe the AC power has a frequency of 50Hz, and you can use that as the basis for your clock signal.
I've used Atmel's ATtiny and ATmega, which are great for programming simple and advanced projects. You can program it with C or Assembly, there are lots of great projects for it on the net, and the programmers available are very cheap.
Here is a project I found by Googling AVR 7 segment clock.
A second vote for PIC. Also, I recommend the magazine Circuit Cellar Ink. Some technical bookstores carry it, or you can subscribe: http://www.circellar.com/
PIC series will be good, since you are creating a timer, I recommend C or Assembly (Assembly is good), and use MPLAB as the development environment. You can check how accurate your timer with 'Stopwatch' in MPLAB. Also PIC16F877 has built in Hardware Serial Port. Also PIC16F628 has a built in Hardware serial port. But PIC16F877 has more ports. For more accurate timers, using higher frequency oscillators is recommended.