We’re rewarding the question askers & reputations are being recalculated! Read more.

Hot answers tagged

10

After much googling and mashing together various answers, I got it working. Here's the AT command sequence. You can test this from start to finish, you'll just need to confirm the APN of the carrier you're using. // My comments are here Command to send is here Expected responses are here // See if the SIM900 is ready AT ...


6

These things are all PIFA (planar inverted F) antennas. They all perform exactly the same, though they have to be carefully designed to fit into the enclosure and have the correct resonances. The basic idea is to add cuts in such a way that the path the current takes through the antenna cause it to resonate at a lower frequency than the overall size would ...


5

How are you powering that GSM module? [...] from the usb port Using a PC USB port for power is likely to be a problem, for the same reason I explained in my answer here to someone who (initially) also used a power supply with a similar current capability. The supplier's website from that earlier question mentioned that the power supply should be ...


4

I'm actually also working on a SIM900 and had the same problem. One possible cause of the problem is that the SIM900 already has made a connection. Try re-starting the sim900 before issuing the commands. Also I set the APN settings with the AT+CSTT= command Below the in/output of my serial connection: For testing purposes use this. Be sure to have the ...


3

For custom client headers use the AT+HTTPPARA command with HTTPParamTag set to USERDATA. It is described in Simcom AT Commands Manual.


3

Your question: what are thing i need to learn to do this How the modem access the web server Learning how a client send a request to a web server. HTTP request is the most easiest way. Other ways are FTP, email, etc. Making sure your modem (GSM/GPRS module) has TCP/IP stack or not. Things are easier if it has TCP/IP stack because the TCP/IP command will ...


3

I solved the problem. :) The problem was with Extra "Space" in header. sprintf(DataToSend, "GET %s HTTP/1.1\r\n Host: %s\r\n\r\n", PATH, HOST); I removed that space: sprintf(DataToSend, "GET %s HTTP/1.1\r\nHost: %s\r\n\r\n", PATH, HOST); and then problem get resolved. here is the response from server: HTTP/1.1 200 OK Date: Fri, 19 Jun 2015 03:38:14 GMT ...


3

I'd contact ntp.org. They have a pool of public NTP servers with DNS anycast for geographic proximity and are generally able to give good suggestions. You might be asked to use a subdomain (e.g. Debian uses "debian.pool.ntp.org") so if a malfunction in your devices causes a traffic storm this can be reflected without affecting the rest of the pool.


2

Rolling your own NTP server is quite easy, You can install NTPD on almost any modern computer running Linux. Add a domain name and you are done. An alternate solution would be to use your cellular provider's timing servers, via the cellular network's control plane messages. This is a bit more complicated solution, but also more accurate.


2

My best guess: the Host header's value should be a host name, not a URL. In your example, it should probably be exqure.com instead of http://exqure.com. In terms of code, the offending line would be: SIM300SendDATA(0,"/httptest.php?data1=value1","http://exqure.com") ...which should probably be changed into: SIM300SendDATA(0,"/httptest.php?data1=value1","...


2

There are some cellular providers that have implemented posisioning services on their networks, so you can get the latitude and longitude using some special AT commands. The problem with this option is that is very dificult to get information or support about this feature.


2

Try the following: Suspend the PPP connection by sending the +++ escape sequence: (wait one second) +++ (wait one second) If the modem comes back with OK, you are back in command mode. If it comes back with NO CARRIER, then this method will not work as it has hung up. Assuming it comes back with OK, you can now send your AT+CSQ command (or any others). ...


2

I assume by 'soundsystem' you mean either a PA (sound reinforcement) system, or a hi-fi system? The practical answers will depend on exactly what equipment you have but methods could include: use balanced audio connections wherever possible make sure all cables are correctly shielded and equipment is correctly grounded (earthed) make any unbalanced ...


2

Solution I am just posting the solution if anyone needs it. Everyone seems to downvote the problem instead of giving solutions. First of all, remove all the jumpers [see the picture] Then add two Male to Female cable to the S-TX and S-RX [Here S stands for SIM900, you can find the pins after removing the jumpers.] Short the grounds of both arduino and ATK-...


2

There isn't much information in your question, but I'll explain one common way you can solve this type of problem. In short: You need to get more troubleshooting data, and then use your critical thinking skills to find the cause of the problem by using that data. Remember that responses like "HTTP 400 Bad Request" come from the HTTP server. Therefore you ...


2

Theoretically, you can design a multi-band antenna and use it for both GSM and 433MHz receiver. To combine the two radios to the same antenna you would need a diplexer, which could be implemented using a low-pass filter feeding the 433MHz receiver and a high-pass filter feeding the GSM radio. However, if you have enough space, I strongly recommend that you ...


2

"Active antennas" include an amplifier to improve reception. This works well with things that only receive. GPS receivers and television receivers only receive. It is fairly easy to include an amplifier to make reception better. GSM has to transmit as well as receive. It is much more difficult to make an active antenna if you have to be able to transmit ...


2

(x)G is actually pretty meaningless. Since multiple technologies get called 3G and 4G, even though they are completely different and achieve different data rates. For example 3G speeds range from 144Kbps to 21.6Mbps. The providers of the 144Kbps network still call it 3G though. It doesn't really have anything to do with a service level. If your signal is ...


2

This 4 band and Class 12 Modem chip is capable of supporting low bandwidth applications up to 85.6kbps up and down stream. Packets are kept small to reduce retry sizes when not received. Signal to Noise Ratio must increase above some threshold to achieve error free communication at fastest rates. This is often when the RSSI starts > -80dBm with a -105 dBm ...


1

If you want (or need) reliability, then you should stick with a commercial modem. If you use an Arduino with a modem module, then you will end up writing software for the Arduino and for your computer. That makes for more opportunities for problems and program errors. Use a commercial module, and you only have to write software for the computer. This is ...


1

The most common problem with such GSM modules is that they draw current in surges. The transmitter is the only thing that draws a lot of current, it only transmits sporadically. When the transmitter kicks in, the module will draw around 2A. If the connections are poor, or the power supply weak, the voltage will drop when the transmitter goes on. If it ...


1

From the GSM module voltage specification, it sounds like it was made for a single cell Li-ion battery, with 4.2V max and 3.3V minimum for that logic level. I would be willing to bet that the module has some internal voltage regulation that is going to be able to accept 4.2V and even a bit above and bring it down closer to the 3.3V at which it is likely ...


1

All GSM/GPRS/LTE module I've worked with are fine when supplied from a single li-ion cell. As you see the range is from 3,3 to 4,2V. Li-ion cells never (should) get above this voltage, so you are okay to power it directly from a li-ion cell.


1

Something to try: Adjusting the cable length and antenna mounting seems to affect the noise you are measuring, but that doesn't necessarily mean that the noise is coming from the RF. When the cable length or counterpoise (adding aluminium sheet) changes, the load (complex impedance) presented to the output of the RF module will change. This can cause the ...


1

Does folding the PCB the way I have mentioned (In the middle) affect the performance due to any interference in the radiating arm? The fold will have an impact but it'll be small in comparison to the other issue you have. The antenna is tuned to be stuck to a piece of plastic (2 mm thick ABS in the datasheet). Sticking it to piece of grounded metal (the ...


1

You go on about interference but that is not an issue. To have what is called interference in the RF world, you need something else transmitting a signal, the signals then influence each other and disturb reception of these signals. What you are doing will affect the radiation pattern and impedance of the antenna. For both non-flexible and flexible ...


1

SIM908 does actually support post even though it is poorly documented: AT+HTTPINIT AT+HTTPPARA="CID",1 AT+HTTPPARA="URL","http://108.167.133.20/.../index.php" NB*** AT+HTTPDATA=, ****NB Wait for DOWNLOAD response then send data (bytes needs to be exact) AT+HTTPACTION=1 AT+HTTPREAD=1,100000


1

If I'm not wrong, for the same power higher frecuencies have a lower reach Irrespective of frequency, the power radiated from an antenna is the same (if the power input to that antenna is constant). This means that at some arbitrary distance from a transmitting antenna, the same power density is present (watts per square metre) irrespective of frequency. ...


1

The serial connection uses the pins D0 through D3. RX and tX are selectable by jumper on the GPRS module. In addition, you will need ground and power. The GPRS module uses the Vin from the Arduino connector (on the same row of pins as reset, 3V3 and 5V) for power. It also uses the 3V3 to power the LCD. Finally, D5 can be used as a reset on the SIM9000, ...


1

Increase C41, I think. Try double or quad mounting this component to see the effect (you can use the switcher harmonic as a proxy, if you have anything able to measure it). You also need some inductance on the cable side of C42, this will help, particularly if you add another low impedance capacitor across C42. You could also try adding some small ...


Only top voted, non community-wiki answers of a minimum length are eligible