This preamble is a series of alternating zeros and ones with a length of at least 576 bits long.Īfter the preamble is transmitted the information is transmitted in batches. If Fc is the carrier frequency then a 0 is represented by Fc+4.5kHz and a 1 is represented by Fc-4.5kHz.Ī base station transmits a preamble before the actual message (if needed) to wake up any receivers that are not currently decoding information. POCSAG uses frequency shift keying of 4.5 kHz for its signaling of ones and zeros. This example code is meant for pagers that use the POCSAG protocol. There are several standards for pagers, the newest one being FLEX and an older one called POCSAG. You can use these components and the functions built here to send one way pages to any POCSAG pager. This example program assumes you already know LabVIEW programming, are familiar with Modulation Toolkit and have previously used the USRP. This made the next message start in a new batch, which also spills over into the next frame. In the first batch, the message that started in Frame 2 spilled over into Frame 3 but didn't fill it completely, so an idle codeword finished it off. In this visual you can see the Preamble, Synchronization codeword, and two messages competing for the same space (Frame 3). Block Diagram and Front Panel of POCSAG functions
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |