AFSK Paging Link

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AFSKAudio Frequency-Shift Keying Paging Link
AFSKPaging Waterfallthmb.jpg
Frequencies 72 MHzMegaHertz (MHz) 10^6 Hz72,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
72,000 kHzKiloHertz (kHz) 10^3 Hz
,76 MHzMegaHertz (MHz) 10^6 Hz76,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
76,000 kHzKiloHertz (kHz) 10^3 Hz
,450 MHzMegaHertz (MHz) 10^6 Hz450,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
450,000 kHzKiloHertz (kHz) 10^3 Hz
,460 MHzMegaHertz (MHz) 10^6 Hz460,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
460,000 kHzKiloHertz (kHz) 10^3 Hz
,850 MHzMegaHertz (MHz) 10^6 Hz850,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
850,000 kHzKiloHertz (kHz) 10^3 Hz
,928 MHzMegaHertz (MHz) 10^6 Hz928,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
928,000 kHzKiloHertz (kHz) 10^3 Hz
72,000 kHzKiloHertz (kHz) 10^3 Hz
72 MHzMegaHertz (MHz) 10^6 Hz
928,000 kHzKiloHertz (kHz) 10^3 Hz
928 MHzMegaHertz (MHz) 10^6 Hz
Frequency Range 72 MHzMegaHertz (MHz) 10^6 Hz72,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
72,000 kHzKiloHertz (kHz) 10^3 Hz
- 928 MHzMegaHertz (MHz) 10^6 Hz928,000,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
928,000 kHzKiloHertz (kHz) 10^3 Hz
Mode NFMNarrowband Frequency Modulation
Modulation AFSKAudio Frequency-Shift Keying
ACFAutoCorrelation Function
Bandwidth 9 kHzKiloHertz (kHz) 10^3 Hz9,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
0.009 MHzMegaHertz (MHz) 10^6 Hz
kHzKiloHertz (kHz) 10^3 Hz
0.009 MHzMegaHertz (MHz) 10^6 Hz
kHzKiloHertz (kHz) 10^3 Hz
0.009 MHzMegaHertz (MHz) 10^6 Hz
Location Worldwide
Short Description Pager signals such as POCSAG can be re-modulated at the transmitter site to use FMFrequency Modulation-modulated tones, as the FSKFrequency-Shift Keying waveform (not spectra) is usually a pulse train. Mostly used as uplinks at transmitter sites through cross-band operations.
I/Q Raw Recording
Audio Sample

POCSAG as a waveform, not spectrum, is read as a pulse train, which means the raw data can be sent through a simple modem that can mimick the mark and space tones of Bell 202, Lojack, or any other type of modulation that it was designed for. Some systems can contain cross-band operations, while others can have multiplex transmissions with rapidly-changing mark and space tones on one given frequency.



Samples[edit]

examples of simple cross-band operations of AFSKAudio Frequency-Shift Keying links with Bell 202 tones:






Examples of multiplex operations from a Chicago transmitter with its own set of mark and space tones recorded from a handheld scanner:



Decoding Software[edit]

PDW: But you will need to create a demodulation method and feed the incoming bits to PDW itself so that the demodulated POCSAG pulse train waveform can be read.

Additional Links[edit]

http://vocaroo.com/i/s1miV3hCCCfC

Additional Images[edit]