I'm looking for a relatively simple (and hopefully inexpensive) OEM-style cellular modem that can work in conjunction with a PIC-based remote data-acquisition unit. Data transmission speed doesn't have to be very high at all, 2400 baud would be more than enough. The data only needs to be sent maybe twice a day, preferably by calling the cell-modem to wake up the PIC device and initiate transmission. I've looked into using 'smartphones', but the phone companies always insist on selling you an expensive internet-access subscription (that's where they really make their money). Non-'smart' phones require a Winders-based PC and drivers to serve as a modem. Yea, a PIC can be linked through and/or operated by one of those phones over USB or bluetooth, but the whole thing is *serious* overkill. As I intend to install twenty or thirty stations right off the bat, internet-access rates would just *destroy* the budget. I don't NEED an interactive web page at every site. I've seen a few such modems on the net, but they never list prices ... apparently they want to get you on the phone for the big sales speil. I'd be interested in hearing from anyone who's bought and used these things - price, performance and gotcha issues. Something like Global-Datas 'StarPoint' or OEM units are what I have in mind : http://www.arcelect.com/Global_Data_StarPoint_GSM-GPRS_cellular_modem.htm http://www.arcelect.com/Multitech_Digital_GSM-GPRS_Wireless_Cell-Cellular_modem.htm http://www.arcelect.com/Complete_Ready-to-deploy_OEM_Wireless_cellular_Modem.htm Any info helpful.
OEM Cellular Modems - Non-Internet - Models, Prices, Experiences ???
Started by ●January 7, 2008
Reply by ●January 7, 20082008-01-07
B1ackwater wrote:> I'm looking for a relatively simple (and hopefully > inexpensive) OEM-style cellular modem that can work > in conjunction with a PIC-based remote data-acquisition > unit.You can consider the following approach: connect to a regular cellphone via the hands-free connector. Make calls and generate a modem signal into the voice path with PIC. This is kinda partisan solution, however you don't have to care about the internets, OEM modems and subscriptions. It is simple enough to get the bit rate of 600bps via the voice path; it is possible to obtain much higher speed with some sophistication. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
Reply by ●January 7, 20082008-01-07
On Mon, 07 Jan 2008 15:27:17 GMT, bw@barrk.net (B1ackwater) wrote:>I'm looking for a relatively simple (and hopefully >inexpensive) OEM-style cellular modem that can work >in conjunction with a PIC-based remote data-acquisition >unit.Look here: http://pia.khe.siemens.com/index_products_systems-14200.htm Where are you located? What mobile network standards are available? Mit freundlichen Gr��en Frank-Christian Kr�gel
Reply by ●January 7, 20082008-01-07
On Mon, 07 Jan 2008 10:46:50 -0600, Vladimir Vassilevsky <antispam_bogus@hotmail.com> wrote:> > >B1ackwater wrote: > >> I'm looking for a relatively simple (and hopefully >> inexpensive) OEM-style cellular modem that can work >> in conjunction with a PIC-based remote data-acquisition >> unit. > >You can consider the following approach: connect to a regular cellphone >via the hands-free connector. Make calls and generate a modem signal >into the voice path with PIC. This is kinda partisan solution, however >you don't have to care about the internets, OEM modems and subscriptions. > >It is simple enough to get the bit rate of 600bps via the voice path; it >is possible to obtain much higher speed with some sophistication. > >Vladimir Vassilevsky >DSP and Mixed Signal Design Consultant >http://www.abvolt.comI finally found some data about the MultiTech MTCBA-G-F2-NAM / MTCBA-G-F4-NAM cell modems. They can be had for under $200 US and employ GSM/GPRS technology compatible with our local carrier. All that's needed is the appropriate SIM-card. I'd looked into using a hands-free connector also. Hands-free can PLACE the call, but ANSWERING a call would be more of a pain - you really need the "Ring Detect" output from a 'real' modem or something similar to tell the PIC board that someone wants a download. Bluetooth could likely be pressed into service, as well as a USB connection, but the abovementioned unit is conveniently set up for RS-232 and that's a breeze to connect to any microcontroller nowdays. Also comes in a nice industrial- looking box with flashing lights, screw-on connector for high-gain antennas and stuff to impress the client :-) I ordered an 'F2' to play with although it's soon to be discontinued, replaced by the 'F4'. I'm not sure what the big difference is. The F4s are only ten dollars more however so if I need 29 more units I won't go broke. As a lot of 'real' phones will cost you over $200 nowdays, the price of the MultiTech units ain't bad ... and they've got exactly the connectors you'd want. There's also a USB model ... I think my MikroPascal compiler can do those too. Anyhow, an 18x PIC with a serial EEPROM to hold the datasets and I'm in business. Easy to hang analog and digital sensors off of that, and I've ordered a s-EEPROM/RTC combo chip so I can timestamp the data too. The remaining obstacle was sending the data out ...
Reply by ●January 7, 20082008-01-07
On Mon, 07 Jan 2008 19:48:50 +0100, Frank-Christian Kruegel <dontmailme@news.invalid> wrote:>On Mon, 07 Jan 2008 15:27:17 GMT, bw@barrk.net (B1ackwater) wrote: > >>I'm looking for a relatively simple (and hopefully >>inexpensive) OEM-style cellular modem that can work >>in conjunction with a PIC-based remote data-acquisition >>unit. > >Look here: > >http://pia.khe.siemens.com/index_products_systems-14200.htm > >Where are you located? What mobile network standards are available?GSM/GPRS ... AT&T/Cingular.>Mit freundlichen Gr��en > >Frank-Christian Kr�gelThe AC-45 looks interesting ... I'll have to see what it costs. I ordered a MultiTech MTCBA-G-F2-NAM (soon to be replaced by the 'F4') to experiment with. These units are under $200 US, needing only a SIM-card from the local carrier. Convenient RS-232 as well. Draws 10 mA in standby mode however ... and my app is to be solar powered. The Siemens says 25 mA in "idle mode". Anyway, with units like these, it should be easy to interface any microcontroller. Prices seem to have dropped considerably since the last time I checked on these things. Anything from DTMS to SMS to TCP and several other data transmission options will be availible depending on how much you want to spend on the monthly service. I'm encouraged. I thought I'd have to bluetooth to a Winders 'smartphone' - lots of places to go astray there - but it looks as if a PIC plus s-EEPROM/RTC chip, the cell modem and a serial cable is all I need. The cells really seem superior to the olde-tyme method of dedicated high-powered radio links. Effectively unlimited range, no special licences and, due to volume & competition, CHEAP.
Reply by ●January 7, 20082008-01-07
On 2008-01-07, B1ackwater <bw@barrk.net> wrote:> I'm looking for a relatively simple (and hopefully > inexpensive) OEM-style cellular modem that can work > in conjunction with a PIC-based remote data-acquisition > unit.If you intend to use this on AT&T, be advised that they probably won't provision your account with the necessary feature to place modem calls (CSD) unless you pay an additional monthly fee.
Reply by ●January 8, 20082008-01-08
On Mon, 07 Jan 2008 21:33:19 -0600, John Temples <usenet@xargs-spam.com> wrote:>On 2008-01-07, B1ackwater <bw@barrk.net> wrote: >> I'm looking for a relatively simple (and hopefully >> inexpensive) OEM-style cellular modem that can work >> in conjunction with a PIC-based remote data-acquisition >> unit. > >If you intend to use this on AT&T, be advised that they probably won't >provision your account with the necessary feature to place modem calls >(CSD) unless you pay an additional monthly fee.As expected, alas. Of course they ARE in it for the money after all ... I'll just have to find out if adding the CSD option is cheaper than the "full internet" package they sell for their smartphones. Well ....... there's always the OTHER option for people who need to move data, but not MUCH data ... just use DTMF tones. I've got a nice DTMF decoder I could use at the base station - and my PIC can produce the necessary tones at the remote end. 16 baud ... what the hey - it's cheap ! :-)
Reply by ●January 9, 20082008-01-09
Hi B1ackwater, I looked for a similar modem, and eventually settled for a GSM-based module: TER-GX110 (see http://www.roundsolutions.com/uk_products.htm). This device has an RS232 port, which is easily interfaced to a microcontroller. It supports both GPRS (for "internet" connection), and SMS (text messages with up to 160 chars). If your data set is small enough for transmission via SMS, you can omit the internet service plans. Just use a prepaid SIM card without monthly fees ("pay as you go") and send an SMS upon receiving incoming calls as trigger. Regards, Marc
Reply by ●January 9, 20082008-01-09
In article <4d63ac14-e1a7-425f-a483-1c238dcb6867@j78g2000hsd.googlegroups.com>, jetmarc@hotmail.com writes:> > This device has an RS232 port, which is easily interfaced to a > microcontroller. It supports both GPRS (for "internet" connection), > and SMS (text messages with up to 160 chars). > > If your data set is small enough for transmission via SMS, you can > omit the internet service plans. Just use a prepaid SIM card without > monthly fees ("pay as you go") and send an SMS upon receiving incoming > calls as trigger. >Just one minor point in case someone's thinking of sending binary data via SMS and that is that it's actually 160 _7-bit_ characters, or only 140 _8-bit_ characters per SMS message. Simon. -- Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP Microsoft: Bringing you 1980's technology to a 21st century world
Reply by ●March 5, 20082008-03-05
