Hi Mike, Thanks! I'll start searching the web for POCSAG. By the way, I'm not based in the USA, but in Argentina. I understand that I will not have access to commercial frequencies, but I was thinking on "modifying" a standard pager to receive on a custom frequency. The question is: which frequency? And supposing I can find a "free" range, will I need FCC (or our local equivalent) clearance? Will I need a license? I'd like to cover at least 50 Km (that is a little over 30 miles), so I will need a fairly powerful transmitter... Look, I could build a custom receiver and let pagers alone, but I will never build such a good-looking, small, lightweight, low-power unit like the commercial pagers. Using PICs and standard LCDs, I will end up with a big, ugly, heavy case, 3 standard battery cells or a custom battery, lasting just a few days, etc. Standard pagers use custom VLSI chips, and custom LCDs and use just a single AAA battery cell, that lasts for over 20 days. Again, thank you for your help. Regards, Andres Tarzia Technology Consultant, SMART S.A. e-mail: atarzia@smart.com.ar -----Original Message----- From: Mike Cornelius [mailto:mike@BYTETHIS.COM.AU] Sent: Thursday, September 02, 1999 23:57 To: PICLIST@MITVMA.MIT.EDU Subject: Re: [OT] Pager Transmitter Hi Andres, This is actually quite simple, the standard paging protocol is known as POCSAG, do a web search and you should be able to find details. Basicly paging transmissions consist of a preamble (512 alternating bits from memory) followed by a number of codewords which consists of 21 bits of data followed by 11 bits of CRC (This may not be exactly right as it's been 4 years since I looked at the protocol). Actual RF transmision is simple FM FSK. A 1 is FC +4.6Khz A 0 is FC - 4.5Khz. The encoding side of things for your app could be done with a 12C508, I can help you with code if you like, although I don't actually have code for POCSAG specificly but I do have something very similar (in fact it would have been POCSAG but I needed more bits per codeword). The transmission side is pretty easy too, there are plenty of rf modules out there you could use or build your own. In terms of licence regs I'm not sure about regs in the USA but in Australia there are a number of options depending on whether you need in house or wide area coverage. Naturally enough though you won't be able to use the same freq as an existing wide are provider. Regards, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mike Cornelius Internet: mike@bytethis.com.au Byte This Interactive Phone: +61 2 9310-2157 PO Box 1342 Strawberry Hills FAX: +61 2 9319-3948 NSW 2012 Australia URL: http://www.bytethis.com.au ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > -----Original Message----- > From: pic microcontroller discussion list > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Andres Tarzia > Sent: Thursday, 2 September 1999 12:12 > To: PICLIST@MITVMA.MIT.EDU > Subject: [OT] Pager Transmitter > > > Hi all! > > I am designing a PIC-based alarm system. The instrusion detection is easy. > The local alarm is very easy too. > > But I'd like to include some form of remote alarm. I was thinking about a > regular pager as the alarm receiver, but I don't know how to transmit data > to it. Does anybody knows how to send an alert to a pager? Please, without > using the phone. I mean a Pager Transmitter like the one that carrier > companies have, only smaller. Provided that one can build/adquire the > equipement, is it legal? Does the FCC allows you to transmit in the Pager > frequencies? Or are they restricted? Do you need some kind of licence? > > Thank you for your help. > > Regards, > Andres Tarzia > Tecnology Consultant, SMART S.A. > e-mail: atarzia@smart.com.ar >