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Original question:

CC430F5137: Huge decrease in transceiver range when using wider channel band

CC430F5137: Continuation: Huge decrease in transceiver range when using wider channel band

Kieran Nicholas
Prodigy 20 points
Part Number: CC430F5137
Other Parts Discussed in Thread: TEST2, CC1101

We are a data company based out of the UK who use a data collection device which utilises RF transmission. The device is an instrumented mouthguard which transmits data using an ST Electronics low powered transceiver component. During use, this RF transmission is captured by a receiver plugged into a PC nearby.

This set up is certified for FCC and CE, with the caveat that during compliance testing, the frequency band had to be made wider for the FCC regulations:

 

CE

FCC

Base Frequency

868 MHz

921 MHz

Frequency Deviation

20 kHz

229 kHz

Channel Bandwidth

100 kHz

541 kHz

In the past we have used an ST chip on the RX side, however, we have now switched to using the CC430F5137 by Texas Instruments.

Using our CE settings, the transition has been seamless, and the performance is almost identical to what was achieved with the ST chip. However, in the US where we use the FCC settings, the range at which the product can work has decreased massively. The table below displays this.

 

CE

FCC

ST CHIP

100m range

100m range

TI CHIP

100m range

5m range

Last time I asked about this, I was pointed towards the SmartRF studio.

Below is a table containing our CE register settings (good range), our FCC register settings (bad range), and RF studio recommended settings for FCC. 

Register Setting

CE Settings

FCC Settings

RF Studio FCC

IOCFG1

0x09

0x09

0x09

IOCFG0

0x06

0x06

0x06

PKTLEN

0x3D

0x3D

0x3D

PKTCTRL1

0x06

0x06

0x06

PKTCTRL0

0x05

0x05

0x05

ADDR

0x01

0x01

0xAA

CHANNR

0x01

0x02

0x02

FSCRTL1

0x0C

0x0C

0x0C

FREQ2

0x21

0x23

0x23

FREQ1

0x62

0x6C

0x6C

FREQ0

0x76

0x4E

0x4E

MDMCFG4

0xCA

0x2A

0x2A

MDMCFG3

0x83

0x83

0x83

MDMCFG2

0x13

0x13

0x13

DEVIATN

0x35

0x71

0x71

MCSM0

0x10

0x10

0x10

F0CCFG

0x16

0x16

0x16

AGCCTRL2

0x43

0x43

0x43

WORCTRL

0xF0

0xF0

0xFB

FSCAL3

0xE9

0xE9

0xE9

FSCAL2

0x2A

0x2A

0x2A

FSCAL1

0x00

0x00

0x00

FSCAL0

0x1F

0x1F

0x1F

TEST2

0x81

0x81

0x81

TEST1

0x35

0x35

0x35

TEST0

0x09

0x09

0x09

BSCFG

0x6C

0x6C

Not present

MCSM1

0x30

0x30

Not present

FSTEST

0x59

0x59

Not present

F1F0THR

0x07

0x07

Not present

IOCFG2

0x29

0x29

Not present

FREND1

0x56

0x56

Not present

FREND0

0x10

0x10

Not present

AGCCTRL1

0x40

0x40

Not present

AGCCTRL0

0x91

0x91

Not present

MDMCFG1

0x22

0x22

Not present

MDMCFG0

0xF8

0xF8

Not present

FSCTRL1

0x08

0x0C

Not present

FSCTRL0

0x00

0x00

Not present

From these settings I can't see anything that should be resulting in the decreased performance.

  • 0
    TI__Expert 4940 points

    Hi Kieran,

    would it be possible you to post an image of the RF section of your design and share the type of antenna you are using?

  • 0 in reply to Diego P
    Prodigy 20 points

    The hardware setup is a guard transmitting data wirelessly to a receiver module.

    The radio on the guard module uses an S2-LP chip from ST for the radio interface.  It is has a PCB printed aerial and is designed to work in both EU and US frequencies.

    The receiver module comprises a commercially available panStamp NRG3 board, and an external aerial.  The panStamp board mounts a TI C430F5137 microcontroller, and the radio has been designed to work in both EU and US frequencies. 

    For the purpose of comparison, an experimental receiver was also constructed using a S2-LP development board and an ST microcontroller.  This was to compare performance of radio on the TI C430F5137 microcontroller to the S2-LP.

  • 0 in reply to Kieran Nicholas
    TI__Expert 4940 points

    Hi Kieran,

    I did some testing with your FCC settings with CC1101 (the RF core inside the CC430) and they worked.

    I did notice you have CHANNR set to 0x2 which would actually set the RF frequency to 921.4 MHz, because the base frequency is 921 MHz and the channel spacing is set to 200 kHz in the MDMCFG1 register. If your transmitter is transmitting at 921 MHz and the CC430 is set to 921.4 MHz this can be the cause of bad range. In my testing I used CHANNR set to 0x0.

    Could you test with CHANNR set to 0x0?