Hot!MRF89XA range not as expected

Author
leosw
New Member
  • Total Posts : 11
  • Reward points : 0
  • Joined: 2016/07/11 01:15:43
  • Location: 0
  • Status: offline
2017/08/18 00:07:30 (permalink)
0

MRF89XA range not as expected

Hello,
 
The Application Note AN1631 mentions a range around 700 meters for the MRF89XAM8A in even surface.
On this forum, Microchip's customers announced results around 80 meters in same conditions.
 
In our case, with FSK or OOK modulation, with a output power of +13 dBm and datarate at 20kpbs.
In fact, we used the default configuration from AN1340.
With this configuration we only had a 30m range.
 
You will find attached a picture of each receptor and one of the environment (the street on the middle).
 
Is there a specific configuration to reach the announced range?
 
Thanks,
 
Léo

Attached Image(s)

#1

9 Replies Related Threads

    PatAllen
    New Member
    • Total Posts : 6
    • Reward points : 0
    • Joined: 2008/07/08 12:28:51
    • Location: 0
    • Status: offline
    Re: MRF89XA range not as expected 2017/10/04 07:41:39 (permalink)
    4 (2)
    fwiw i managed to make 2000' in open field in OOK, making sure the modules where vertical.
    what really helped was to reduce data rate (13.1kbps), reduce preamble bytes (from 4 to 2) and reduce the sync word from 4 to 2, increase the amount of allowed errors on the sync word, and NOT use the imbeded crc calculation but a 8 bit "and" method.
    i also reduced the sensisitity up to the point the range started to lessens (flthreg) and came up with a much higher value in that register (less sensitive, less prone to environmental noise) than expected.
     
    hth
    post edited by PatAllen - 2017/10/04 07:43:59
    #2
    leosw
    New Member
    • Total Posts : 11
    • Reward points : 0
    • Joined: 2016/07/11 01:15:43
    • Location: 0
    • Status: offline
    Re: MRF89XA range not as expected 2017/10/05 07:14:12 (permalink)
    0
    Hi PatAllen,
     
    I just tried with your configuration. I haven't seen any change (40m).
     
    Here is my configuration:
     
    GCONREG    = 0x30; // CMOD_STANDBY | FBS_950 | VCOT_00 | RPS_SE1P1S1
    DMODREG    = 0x4C; // MODSEL_OOK | OOKTYP_PEAK | DMODE_PACKET | IFGAIN_0
    FDEVREG    = 0x0B; // FDVAL_33.3kHz
    BRSREG     = 0x03; // BRVAL_10kbps
    FLTHREG    = 0x13; // FTOVAL_9.5dB
    FIFOCREG   = 0x0F; // FSIZE_16 | FTINT_15
    R1CREG     =  125;
    P1CREG     =  100;
    S1CREG     =   20;
    R2CREG     =    0;
    P2CREG     =    0;
    S2CREG     =    0;
    PACREG     = 0x20; // PARC_3µs;

    FTXRXIREG  = 0xB8; // IRQ0RXS_FIFOEMPTY | IRQ1RXS_FIFOTHRESH | IRQ1TX_TXDONE | FIFOFULL_N | FIFOEMPTY_Y | FOVRRUN_N
    FTPRIREG   = 0x2B; // FIFOFM_AUTO | FIFOFSC_COMPLETE | TXDONE_COMPLETE | IRQ0TXST_FIFOTHRESH | RIRQS_LESS | LSTSPLL_CLR | LENPLL_EN
    RSTHIREG   = 0x00; // RTIVAL_0

    FILCREG    = 0x93; // PASFILT_321kHz | BUTFILV_100kHz
    PFCREG     = 0x30; // POLCFV_100kHz
    SYNCREG    = 0xAC; // POLFILEN_EN | BSYNCEN_EN | SYNCREN_ON | SYNCWSZ_16b | SYNCTEN_2
    RESVREG    =    0;
    RSTSREG    = 0x07; // RSSIVAL_3.5dB
    OOKCREG    = 0x00; // OOKTHSV_0.5dB | OOKTHPV_0 | OOKATHC_BR/8pi

    SYNCV31REG = 0x53;
    SYNCV23REG = 0x59;
    SYNCV15REG =    0;
    SYNCV07REG =    0;

    TXCONREG   = 0x70; // TXIPOLFV_200kHz | TXOPVAL_13dBm
    CLKOUTREG  = 0x3C; // CLKOCNTRL_DIS | CLKOFREQ_427kHz

    PLOADREG   = 0x10; // MCHSTREN_DIS | PLDPLEN_16B
    NADDSREG   =    0;
    PKTCREG    = 0x30; // PKTLENF_FIXED | PRESIZE_2B | WHITEON_ON | CHKCRCEN_OFF | ADDFIL_OFF
    FCRCREG    = 0x00; // ACFCRC_EN | FRWAXS_WRITE
     
    Of course, that seems correct to me, so I don't have any explanation.
    I just can confirm that no packet appears in the FIFO.
     
    Thanks,
     
    Léo
    #3
    rmh
    Starting Member
    • Total Posts : 13
    • Reward points : 0
    • Joined: 2009/08/31 15:22:34
    • Location: 0
    • Status: online
    Re: MRF89XA range not as expected 2017/10/05 11:16:54 (permalink)
    3 (2)
    read DS70651A about mounting the module on a pcb. You need a groundplane under the module.
    the antena must be outside of the pcb
    i have a range of 300m with +10dBm
    default configuration
    https://mega.nz/#!4QMExACb!wp47E-9fJBwV0OwLtd1XIFXEWS7LbtqWyJfhKqcO0VM
     
     
    #4
    rmh
    Starting Member
    • Total Posts : 13
    • Reward points : 0
    • Joined: 2009/08/31 15:22:34
    • Location: 0
    • Status: online
    Re: MRF89XA range not as expected 2017/10/05 11:19:53 (permalink)
    3 (2)
    first picture is ok, but the second one has a pcb under the antena
     
    #5
    PatAllen
    New Member
    • Total Posts : 6
    • Reward points : 0
    • Joined: 2008/07/08 12:28:51
    • Location: 0
    • Status: offline
    Re: MRF89XA range not as expected 2017/10/10 09:40:51 (permalink)
    3 (1)
    pcb antenna really needs to be clear, and i found out that it is somehow directionnal, ie, unit has better range when it is vertical.
    maybe you have other sources of  disturbance at this frequency. do you have a spectrum analyser ?
    if not try to use a 3rd module programmed in direct rf mode and monitor noise/data on the direct data pin at the chip itself. try to reduce the sensitivity up to the point where noise figure reduce (random transitions). this will be your best adjustment for noise floor for your test at your location.
    hth
    #6
    PatAllen
    New Member
    • Total Posts : 6
    • Reward points : 0
    • Joined: 2008/07/08 12:28:51
    • Location: 0
    • Status: offline
    Re: MRF89XA range not as expected 2017/10/10 13:05:43 (permalink)
    0
    defenitively try to use a much lower data rate 0x03 seems pretty high imho
    i use 0x0e for having about 70usec bit periods in brsreg register
    the poly filter, which is absolutely required for ook, doesnt seems to accept high data rate properly (work in progress with the tech support themselves)
     
    #7
    Vit
    New Member
    • Total Posts : 8
    • Reward points : 0
    • Joined: 2015/12/11 07:19:06
    • Location: 0
    • Status: offline
    Re: MRF89XA range not as expected 2017/10/12 07:42:26 (permalink)
    0
    Hi to all,

    please I need an advice. I tried to send a packet to another module, but without any success.
    Can somebody please provide me register settings for Tx and for Rx modules? I tried to apply several procedures, but without success. I think I have a bug in the registers (Fdev, BRS, Vtune, BW or something similar)
    #8
    rmh
    Starting Member
    • Total Posts : 13
    • Reward points : 0
    • Joined: 2009/08/31 15:22:34
    • Location: 0
    • Status: online
    Re: MRF89XA range not as expected 2017/10/12 13:56:43 (permalink)
    0
    hi vit,
    i had a lot of problems to get the modules working with each other.
    i must also switching to rx after a tx , listen [rx] to an answer, [do tx is needed] and goto sleep mode.
    i am not working in OOK mode, but in fsk.
    i use max pramble and max syncword to dont get a wrong packet.
    its a little time ago that i wrote the software for it, with several work arrounds.
    i write in asm, i dont know if i can help you.
    i dont know if this subject fits to this thread. else pm, ore make a new thread
    rmh
    #9
    Vit
    New Member
    • Total Posts : 8
    • Reward points : 0
    • Joined: 2015/12/11 07:19:06
    • Location: 0
    • Status: offline
    Re: MRF89XA range not as expected 2017/10/12 22:37:25 (permalink)
    0
    Hi rmb,
    Please could you provide me register settings for Tx and for Rx?
    I have 12 units of MRF89XAM8A and I would like to create a small net for sensors in my house.
    I measure temperature, light, door lock, window lock etc. Every sensor works well. I have the RS485 network which works very well, but I need some sensors connect via RF and here is the problem.
     
    thanks, Vit
    #10
    Jump to:
    © 2017 APG vNext Commercial Version 4.5