Pager message sent 4 times on some frequencies

[mrDevGit]

Hi

Love the RPITX. However, on some frequencies the message is sent (or received?) 4 times. Some pagers show 4 seperate messages others just show one and flag as a duplicate.

When I send the same pager a message via the HackRF One, it is sent once, as expected.

My setup: Pi 4 15cm Dupont wire on GPIO4

Pagers affected: All above 400mhz as far as I can tell. lower frequencies receive the message once as expected.

Any thoughts?

Thanks

Example output:

echo -e "1234567:Test 123" | sudo ./pocsag -f "929162500" -b 3 DEBUG DATA = I=0 P=0x1e730a8 T=0 L=35 DEBUG DATA = I=1 P=0x1e74150 T=35 L=17 DEBUG DATA = I=2 P=0x1e74228 T=52 L=17 DEBUG DATA = I=3 P=0x1e74348 T=69 L=17 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 dma PI4 using channel 7 channel 7 CBSize 24006 UsermemSize 12003 Using mbox device /dev/vcio. 816204 Size NUM PAGES 200 PAGE_SIZE 4096 BufferSize 12003 , cb 24006 user 12003 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Info:NTP find offset -121309 freq -909944 pps=0 ppm=-13.884644 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Info:NTP find offset -121309 freq -909944 pps=0 ppm=-13.884644 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 Info:NTP find offset -121309 freq -909944 pps=0 ppm=-13.884644 Peri Base = fe000000 SDRAM c0000000 RPi4 GPIO detected Running on Pi4 PLLC_DIG0=006bd422 PLLC_DIG1=0002401a PLLC_DIG2=00400000 PLLC_DIG3=00000002 PLLC_ANA0=00000000 PLLC_ANA1=0011c000 PLLC_ANA2=00d00000 PLLC_ANA3=00000052 PLLC_DIG0R=006bd422 PLLC_DIG1R=0002401a PLLC_DIG2R=00400000 PLLC_DIG3R=00000002 PLLA_ANA0=00000000 PLLA_ANA1=0011c000 prediv=1 PLLA_ANA2=00d04000 PLLA_ANA3=00000052 GNRIC CTL=0000636d DIV= 636d VPU CTL=00000214 DIV= 4000 SYS CTL=00000040 DIV= 0 PERIA CTL=00000040 DIV= 0 PERII CTL=00000040 DIV= 0 H264 CTL=00000244 DIV= 1000 ISP CTL=00000244 DIV= 1000 V3D CTL=000002d4 DIV= 1000 CAM0 CTL=00000200 DIV= 0 CAM1 CTL=00000200 DIV= 0 CCP2 CTL=0000636d DIV= 636d DSI0E CTL=00000200 DIV= 0 DSI0P CTL=00000000 DIV= 0 DPI CTL=00000200 DIV= 0 GP0 CTL=00000005 DIV= 2000 GP1 CTL=00000200 DIV= 0 GP2 CTL=00000200 DIV= 0 HSM CTL=0000636d DIV= 636d OTP CTL=00000091 DIV= 4000 PCM CTL=00000296 DIV= ff504a PWM CTL=00000200 DIV= 0 SLIM CTL=0000636d DIV= 636d SMI CTL=00000200 DIV= 0 SMPS CTL=0000636d DIV= 636d TCNT CTL=00000000 DIV= 9c4 TEC CTL=00000000 DIV= 0 TD0 CTL=00000200 DIV= 0 TD1 CTL=00000200 DIV= 0 TSENS CTL=00000091 DIV= 10000 TIMER CTL=00000291 DIV= 36000 UART CTL=00000296 DIV= fa00 VEC CTL=00000000 DIV= 0 PULSE CTL=00000091 DIV= 1b000 PLLT CTL=00000000 DIV=???????? DSI1E CTL=00000200 DIV= 0 DSI1P CTL=00000098 DIV= 0 AVE0 CTL=00000000 DIV= 0 CMPLLA=00000000 CMPLLC=0000022a CMPLLD=00000000 CMPLLH=0000636d EMMC CTL=00000296 DIV= 3000 EMMC CTL=00000296 DIV= 3000 EMMC CTL=00000296 DIV= 3000 PLLA PDIV=1 NDIV=60 FRAC=194181 3249.999962 MHz DSI0=0 CORE=13 PER=256 CCP2=0

PLLB PDIV=1 NDIV=55 FRAC=582542 3000.000092 MHz ARM=2 SP0=6369911 SP1=256 SP2=256

PLLC PDIV=1 NDIV=34 FRAC=432885 1858.292839 MHz CORE2=0 CORE1=0 PER=2 CORE0=256

PLLD 21037 PDIV=1 NDIV=55 FRAC=582544 3000.000092 MHz DSI0=0 CORE=5 PER=4 DSI1=0

PLLH PDIV=0 NDIV=256 FRAC=256 13824.013184 MHz AUX=0 RCAL=0 PIX=6369911 STS=6369911

Info:NTP find offset -121309 freq -909944 pps=0 ppm=-13.884644 Pi4=1 Xosc = 54000000 Freq PLL no 5= 929159345 Found PLL solution for frequency 1858.3MHz : divider:1 VCO: 3716.6MHz Pll Fix Divider Use PLL Prediv Master PLLC Locked Info:NTP find offset -121309 freq -909944 pps=0 ppm=-13.884644 Pi4=1 Xosc = 54000000 Freq PLL no 6= 750010435 PCM prediv = 153 PCM clk=4085 / 98 FSK Origin fsel 0 FSK burst end Tx

[mfalkvidd]

https://github.com/F5OEO/rpitx/blob/master/src/pocsag/pocsag.cpp#L574 sets int REPEAT_COUNT = 4;

I guess you'll want to add -t1 to the command line to only send once?

Also, since you seem to have missed this part of the readme:

[mrDevGit]

Thanks! I am very very new to this.... how do i create a band pass filter? Could you point me at a link? Stupid question in the spirit of learning: Is that a software of hardware filter?

[mfalkvidd]

Thanks for asking. It is a hardware filter. They can be bought pre-made, example https://www.ebay.com/itm/164586150463 or built do-it-yourself: https://alicja.space/blog/designing-lna-with-bandpass-filter/

Without it, rpitx will send on many other frequencies (other than the intended frequency), often including military and cellular frequencies which can cause lots of problems.