rashel gereldine cleavland
Shane Rouse
How to Decode POCSAG Transmissions with Free Software
POCSAG is a digital paging protocol that is widely used by emergency services, hospitals, and other organizations. It allows sending alphanumeric messages to pagers or other receivers. POCSAG transmissions can be captured with a radio scanner or a software-defined radio (SDR) device and decoded with free software.
In this article, we will show you how to decode POCSAG transmissions with OpenPoc, OpenEar, and PDW, three free software applications that can run on Windows. We will also explain what POCSAG is and how it works.
What is POCSAG?
POCSAG stands for Post Office Code Standardisation Advisory Group, the name of the committee that developed the protocol in the 1970s. POCSAG is a digital paging protocol that uses frequency-shift keying (FSK) to modulate binary data on a carrier wave. POCSAG transmissions consist of batches of codewords, each containing 32 bits of information. A codeword can be either an address codeword or a message codeword. An address codeword indicates the recipient of the message, while a message codeword contains part of the message text.
POCSAG transmissions can have different data rates: 512, 1200, or 2400 bits per second (bps). The higher the data rate, the shorter the transmission time and the higher the bandwidth requirement. POCSAG transmissions are usually sent on VHF or UHF frequencies allocated for paging services.
How to Decode POCSAG Transmissions with OpenPoc
OpenPoc is a cross-platform POCSAG decoder written in FreePascal/Lazarus. It can decode POCSAG transmissions at any data rate and display the messages on a console or a graphical user interface. OpenPoc requires a radio scanner or an SDR device and a sound card to decode POCSAG transmissions.
To use OpenPoc, you need to download and install it from its SourceForge page[^1^]. Then, you need to connect your radio scanner or SDR device to your computer's sound card input and tune it to a frequency where POCSAG transmissions are sent. You also need to adjust the volume and the squelch settings of your radio scanner or SDR device to ensure a clear signal. Next, you need to run OpenPoc and select the sound card input as the source. You can also choose the data rate and the display mode of OpenPoc. Finally, you can start decoding POCSAG transmissions by clicking on the Start button.
How to Decode POCSAG Transmissions with OpenEar
OpenEar is a Windows application that can decode various digital modes, including DMR, TETRA, P25, ADSB, and POCSAG. It can also demodulate AM, NFM, and WFM signals. OpenEar can use an SDR device or a sound card as the source of input.
To use OpenEar, you need to download and install it from its GitHub page[^3^]. You also need to download and install osmocom-rtlsdr driver[^2^] if you are using an SDR device. Then, you need to connect your SDR device or your radio scanner to your computer and tune it to a frequency where POCSAG transmissions are sent. You also need to adjust the gain and the bandwidth settings of your SDR device or radio scanner to ensure a clear signal. Next, you need to run OpenEar and select the source of input as either RTL-SDR or SoundCard. You also need to select POCSAG as the mode of decoding and choose the data rate. Finally, you can start decoding POCSAG transmissions by clicking on the Play button.
How to Decode POCSAG Transmissions with PDW
PDW is a Windows application that can decode POCSAG, FLEX, ACARS, MOBITEX, and ERMES transmissions. It can use a sound card or a serial port as the source of input. PDW can also filter messages by address or text and save them to a file or send them to another application.
To use PDW, you need
51082c0ec5