POCSAG pager transmitter using RF22 board and Arduino

Feb 062016

Since putting this project on Youtube I’ve had a surprising amount of interest from across the world about the modifications I made to the original code from ON1ARF ( a radioamateur in België) to allow 1200 and 2400 bps pager transmissions as well as the default 512bps (I wanted to use the circuit to test commercial POCSAG pager receivers used at one site at my work).

The original code is here

https://github.com/on1arf/pocsag

To get 1200 and 2400 bps you must alter the radiohead libraries it depends on.

Two files must change – the first is RH_RF22.cpp. The code snippet is below (cut and paste this into your editor)


					header file for Arduino POCSAG RF22 tx


			
			// These are indexed by the values of ModemConfigChoice
// Canned modem configurations generated with
// http://www.hoperf.com/upload/rf/RH_RF22B%2023B%2031B%2042B%2043B%20Register%20Settings_RevB1-v5.xls
// Stored in flash (program) memory to save SRAM
PROGMEM static const RH_RF22::ModemConfig MODEM_CONFIG_TABLE[] =
{
    { 0x2b, 0x03, 0xf4, 0x20, 0x41, 0x89, 0x00, 0x36, 0x40, 0x0a, 0x1d, 0x80, 0x60, 0x10, 0x62, 0x2c, 0x00, 0x08 }, // Unmodulated carrier
    { 0x2b, 0x03, 0xf4, 0x20, 0x41, 0x89, 0x00, 0x36, 0x40, 0x0a, 0x1d, 0x80, 0x60, 0x10, 0x62, 0x2c, 0x33, 0x08 }, // FSK, PN9 random modulation, 2, 5

    // All the following enable FIFO with reg 71
    //  1c,   1f,   20,   21,   22,   23,   24,   25,   2c,   2d,   2e,   58,   69,   6e,   6f,   70,   71,   72
    // FSK, No Manchester, Max Rb err <1%, Xtal Tol 20ppm
    { 0x2b, 0x03, 0xf4, 0x20, 0x41, 0x89, 0x00, 0x36, 0x40, 0x0a, 0x1d, 0x80, 0x60, 0x10, 0x62, 0x2c, 0x22, 0x08 }, // 2, 5
    { 0x1b, 0x03, 0x41, 0x60, 0x27, 0x52, 0x00, 0x07, 0x40, 0x0a, 0x1e, 0x80, 0x60, 0x13, 0xa9, 0x2c, 0x22, 0x3a }, // 2.4, 36
    { 0x1d, 0x03, 0xa1, 0x20, 0x4e, 0xa5, 0x00, 0x13, 0x40, 0x0a, 0x1e, 0x80, 0x60, 0x27, 0x52, 0x2c, 0x22, 0x48 }, // 4.8, 45
    { 0x1e, 0x03, 0xd0, 0x00, 0x9d, 0x49, 0x00, 0x45, 0x40, 0x0a, 0x20, 0x80, 0x60, 0x4e, 0xa5, 0x2c, 0x22, 0x48 }, // 9.6, 45
    { 0x2b, 0x03, 0x34, 0x02, 0x75, 0x25, 0x07, 0xff, 0x40, 0x0a, 0x1b, 0x80, 0x60, 0x9d, 0x49, 0x2c, 0x22, 0x0f }, // 19.2, 9.6
    { 0x02, 0x03, 0x68, 0x01, 0x3a, 0x93, 0x04, 0xd5, 0x40, 0x0a, 0x1e, 0x80, 0x60, 0x09, 0xd5, 0x0c, 0x22, 0x1f }, // 38.4, 19.6
    { 0x06, 0x03, 0x45, 0x01, 0xd7, 0xdc, 0x07, 0x6e, 0x40, 0x0a, 0x2d, 0x80, 0x60, 0x0e, 0xbf, 0x0c, 0x22, 0x2e }, // 57.6. 28.8
    { 0x8a, 0x03, 0x60, 0x01, 0x55, 0x55, 0x02, 0xad, 0x40, 0x0a, 0x50, 0x80, 0x60, 0x20, 0x00, 0x0c, 0x22, 0xc8 }, // 125, 125

    // { 0x2b, 0x03, 0xa1, 0xe0, 0x10, 0xc7, 0x00, 0x09, 0x40, 0x0a, 0x1d,  0x80, 0x60, 0x04, 0x32, 0x2c, 0x22, 0x04 }, // 512 baud, FSK, 2.5 Khz fd for POCSAG compatibility
    { 0x27, 0x03, 0xa1, 0xe0, 0x10, 0xc7, 0x00, 0x06, 0x40, 0x0a, 0x1d,  0x80, 0x60, 0x09, 0xd5, 0x2c, 0x22, 0x07 }, // 1200 baud, FSK, 4.5 Khz fd for POCSAG compatibility
    // { 0x27, 0x03, 0xa1, 0xe0, 0x10, 0xc7, 0x00, 0x06, 0x40, 0x0a, 0x1d,  0x80, 0x60, 0x04, 0x32, 0x2c, 0x22, 0x07 }, // 512 baud, FSK, 4.5 Khz fd for POCSAG compatibility
    // 2400 bps
    { 0x27, 0x03, 0xa1, 0xe0, 0x10, 0xc7, 0x00, 0x06, 0x40, 0x0a, 0x1d,  0x80, 0x60, 0x13, 0xa9, 0x2c, 0x22, 0x07 },// 2400 baud, FSK, 4.5 Khz fd for POCSAG compatibility
    
    // GFSK, No Manchester, Max Rb err <1%, Xtal Tol 20ppm
    // These differ from FSK only in register 71, for the modulation type
    { 0x2b, 0x03, 0xf4, 0x20, 0x41, 0x89, 0x00, 0x36, 0x40, 0x0a, 0x1d, 0x80, 0x60, 0x10, 0x62, 0x2c, 0x23, 0x08 }, // 2, 5
    { 0x1b, 0x03, 0x41, 0x60, 0x27, 0x52, 0x00, 0x07, 0x40, 0x0a, 0x1e, 0x80, 0x60, 0x13, 0xa9, 0x2c, 0x23, 0x3a }, // 2.4, 36
    { 0x1d, 0x03, 0xa1, 0x20, 0x4e, 0xa5, 0x00, 0x13, 0x40, 0x0a, 0x1e, 0x80, 0x60, 0x27, 0x52, 0x2c, 0x23, 0x48 }, // 4.8, 45
    { 0x1e, 0x03, 0xd0, 0x00, 0x9d, 0x49, 0x00, 0x45, 0x40, 0x0a, 0x20, 0x80, 0x60, 0x4e, 0xa5, 0x2c, 0x23, 0x48 }, // 9.6, 45
    { 0x2b, 0x03, 0x34, 0x02, 0x75, 0x25, 0x07, 0xff, 0x40, 0x0a, 0x1b, 0x80, 0x60, 0x9d, 0x49, 0x2c, 0x23, 0x0f }, // 19.2, 9.6
    { 0x02, 0x03, 0x68, 0x01, 0x3a, 0x93, 0x04, 0xd5, 0x40, 0x0a, 0x1e, 0x80, 0x60, 0x09, 0xd5, 0x0c, 0x23, 0x1f }, // 38.4, 19.6
    { 0x06, 0x03, 0x45, 0x01, 0xd7, 0xdc, 0x07, 0x6e, 0x40, 0x0a, 0x2d, 0x80, 0x60, 0x0e, 0xbf, 0x0c, 0x23, 0x2e }, // 57.6. 28.8
    { 0x8a, 0x03, 0x60, 0x01, 0x55, 0x55, 0x02, 0xad, 0x40, 0x0a, 0x50, 0x80, 0x60, 0x20, 0x00, 0x0c, 0x23, 0xc8 }, // 125, 125

    // OOK, No Manchester, Max Rb err <1%, Xtal Tol 20ppm
    { 0x51, 0x03, 0x68, 0x00, 0x3a, 0x93, 0x01, 0x3d, 0x2c, 0x11, 0x28, 0x80, 0x60, 0x09, 0xd5, 0x2c, 0x21, 0x08 }, // 1.2, 75
    { 0xc8, 0x03, 0x39, 0x20, 0x68, 0xdc, 0x00, 0x6b, 0x2a, 0x08, 0x2a, 0x80, 0x60, 0x13, 0xa9, 0x2c, 0x21, 0x08 }, // 2.4, 335
    { 0xc8, 0x03, 0x9c, 0x00, 0xd1, 0xb7, 0x00, 0xd4, 0x29, 0x04, 0x29, 0x80, 0x60, 0x27, 0x52, 0x2c, 0x21, 0x08 }, // 4.8, 335
    { 0xb8, 0x03, 0x9c, 0x00, 0xd1, 0xb7, 0x00, 0xd4, 0x28, 0x82, 0x29, 0x80, 0x60, 0x4e, 0xa5, 0x2c, 0x21, 0x08 }, // 9.6, 335
    { 0xa8, 0x03, 0x9c, 0x00, 0xd1, 0xb7, 0x00, 0xd4, 0x28, 0x41, 0x29, 0x80, 0x60, 0x9d, 0x49, 0x2c, 0x21, 0x08 }, // 19.2, 335
    { 0x98, 0x03, 0x9c, 0x00, 0xd1, 0xb7, 0x00, 0xd4, 0x28, 0x20, 0x29, 0x80, 0x60, 0x09, 0xd5, 0x0c, 0x21, 0x08 }, // 38.4, 335
    { 0x98, 0x03, 0x96, 0x00, 0xda, 0x74, 0x00, 0xdc, 0x28, 0x1f, 0x29, 0x80, 0x60, 0x0a, 0x3d, 0x0c, 0x21, 0x08 }, // 40, 335
};
		
				
					RH_RF22.cpp
					view raw

Also the header file RH_RF22.h must change so the modemconfig table has values that reflect the changed modulation schemes.

RF22 headerfile

typedef enum { UnmodulatedCarrier = 0, ///< Unmodulated carrier for testing FSK_PN9_Rb2Fd5, ///< FSK, No Manchester, Rb = 2kbs, Fd = 5kHz, PN9 random modulation for testing FSK_Rb2Fd5, ///< FSK, No Manchester, Rb = 2kbs, Fd = 5kHz FSK_Rb2_4Fd36, ///< FSK, No Manchester, Rb = 2.4kbs, Fd = 36kHz FSK_Rb4_8Fd45, ///< FSK, No Manchester, Rb = 4.8kbs, Fd = 45kHz FSK_Rb9_6Fd45, ///< FSK, No Manchester, Rb = 9.6kbs, Fd = 45kHz FSK_Rb19_2Fd9_6, ///< FSK, No Manchester, Rb = 19.2kbs, Fd = 9.6kHz FSK_Rb38_4Fd19_6, ///< FSK, No Manchester, Rb = 38.4kbs, Fd = 19.6kHz FSK_Rb57_6Fd28_8, ///< FSK, No Manchester, Rb = 57.6kbs, Fd = 28.8kHz FSK_Rb125Fd125, ///< FSK, No Manchester, Rb = 125kbs, Fd = 125kHz FSK_Rb_1200Fd4_5, ///< FSK, No Manchester, Rb = 1200bs, Fd = 4.5kHz, for POCSAG compatibility // FSK_Rb_512Fd4_5, ///< FSK, No Manchester, Rb = 512bs, Fd = 4.5kHz, for POCSAG compatibility FSK_Rb_2400Fd4_5, ///< FSK, No Manchester, Rb = 2400bs, Fd = 4.5kHz, for POCSAG compatibility GFSK_Rb2Fd5, ///< GFSK, No Manchester, Rb = 2kbs, Fd = 5kHz GFSK_Rb2_4Fd36, ///< GFSK, No Manchester, Rb = 2.4kbs, Fd = 36kHz GFSK_Rb4_8Fd45, ///< GFSK, No Manchester, Rb = 4.8kbs, Fd = 45kHz GFSK_Rb9_6Fd45, ///< GFSK, No Manchester, Rb = 9.6kbs, Fd = 45kHz GFSK_Rb19_2Fd9_6, ///< GFSK, No Manchester, Rb = 19.2kbs, Fd = 9.6kHz GFSK_Rb38_4Fd19_6, ///< GFSK, No Manchester, Rb = 38.4kbs, Fd = 19.6kHz GFSK_Rb57_6Fd28_8, ///< GFSK, No Manchester, Rb = 57.6kbs, Fd = 28.8kHz GFSK_Rb125Fd125, ///< GFSK, No Manchester, Rb = 125kbs, Fd = 125kHz OOK_Rb1_2Bw75, ///< OOK, No Manchester, Rb = 1.2kbs, Rx Bandwidth = 75kHz OOK_Rb2_4Bw335, ///< OOK, No Manchester, Rb = 2.4kbs, Rx Bandwidth = 335kHz OOK_Rb4_8Bw335, ///< OOK, No Manchester, Rb = 4.8kbs, Rx Bandwidth = 335kHz OOK_Rb9_6Bw335, ///< OOK, No Manchester, Rb = 9.6kbs, Rx Bandwidth = 335kHz OOK_Rb19_2Bw335, ///< OOK, No Manchester, Rb = 19.2kbs, Rx Bandwidth = 335kHz OOK_Rb38_4Bw335, ///< OOK, No Manchester, Rb = 38.4kbs, Rx Bandwidth = 335kHz OOK_Rb40Bw335 ///< OOK, No Manchester, Rb = 40kbs, Rx Bandwidth = 335kHz } ModemConfigChoice;

RH_RF22.h

view raw

the rest can then be used as normal – remember to alter the main Arduino sketch code to select these new bps rates.

NB: I am based in the UK/Europe; we always use wide deviation for POCSAG signals (although much other PMR traffic is now on narrow deviation).

If your country’s Communications Ministry requires narrow deviation to be used you will have to recalculate the modem settings using the spreadsheet referred to in the library files. (Its not as bad as it might seem; I had to use it to get the 1200/2400bps settings and I am not an RF nor a coding expert by any means)

6 Responses to “POCSAG pager transmitter using RF22 board and Arduino”

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Joseph says:

2016/04/11 at 10:52

Hello,

I have tried to make the arduino and the pager communicat by using your modification. Please can you send me the configurating file of the pager.
Sorry if i disturb you.

Thank you

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Jumbo says:

2017/01/02 at 01:29

i use si4463 test ok! thank you!

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  Mike says:
  
  2019/03/17 at 13:17
  
  What settings are needed for this 463 To transfer to the seat?
  
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Scott says:

2017/07/03 at 03:42

I am interested in using this setup to control a mobile radio in the 70cm band. Does anyone think its possible to have the arduino key the radio via 5v relay and then send data over the radios data port?

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Israel Sanchez says:

2018/11/25 at 16:40

hola que tal
quisiera saber como esta conectado el arduino
la configuracion de los pines
bueno realmente todo, ya que necesito replicar algo como lo que usted hizo.
le agradeceria mucho si hace un video mas explicativo, donde muestre como usar la libreria y compilar el codigo en el IDE de arduino y ver su funcionamiento.

saludos desde mexico!

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Mike says:

2019/03/17 at 13:17

What settings are needed for si4463 to transfer to the seat?

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