Narrowband with SPSGRF-868 module

Trilys · ‎2016-05-31

Posted on May 31, 2016 at 13:08

Hello,

I bought some X-NUCLEO-IDS01A4 for evaluation of the SPSGRF-868 module. I am not really pleased with the results. So far the best range I could get was 175 m in the same conditions in which I got 150 m with a competitor's Bluetooth 4.0 module, ie outside with a clear line of sight.

I am using the P2P demo software, with reduced datarate and FEC activated. Please see below the configuration pasted from the file spirit1_appli.h :

<code>

/*************************Uncomment the the protocol to be used****************/

//#define USE_STack_PROTOCOL

#define USE_BASIC_PROTOCOL

#if defined(USE_STack_PROTOCOL)

#define USE_STack_LLP /*Uncomment if LLP featured need to be used*/

#endif

/******************************************************************************/

#if defined(X_NUCLEO_IDS01A4)

#define USE_SPIRIT1_868MHz

#elif defined(X_NUCLEO_IDS01A5)

#define USE_SPIRIT1_915MHz

#else

#error SPIRIT1 Expansion Board is undefined or unsupported

#endif

#if defined(MCU_SLEEP_MODE) || defined(MCU_STOP_MODE)

#define RF_STANDBY

#endif

/* Exported constants --------------------------------------------------------*/

/* Radio configuration parameters */

#define XTAL_OFFSET_PPM 0

#define INFINITE_TIMEOUT 0.0

#ifdef USE_SPIRIT1_433MHz

#define BASE_FREQUENCY 433.0e6

#endif

#ifdef USE_SPIRIT1_868MHz

#define BASE_FREQUENCY 869.3e6

#endif

#ifdef USE_SPIRIT1_915MHz

#define BASE_FREQUENCY 915.0e6

#endif

#define CHANNEL_SPACE 25e3

#define CHANNEL_NUMBER 2

#define MODULATION_SELECT GFSK_BT1

#define DATARATE 19200

#define FREQ_DEVIATION 9600

#define BANDWIDTH 38400

#define POWER_DBM 11.6

#define POWER_INDEX 7

#define RECEIVE_TIMEOUT 2000.0 /*change the value for required timeout period*/

#define RSSI_THRESHOLD -120

/* Packet configuration parameters */

#define PREAMBLE_LENGTH PKT_PREAMBLE_LENGTH_04BYTES

#define SYNC_LENGTH PKT_SYNC_LENGTH_4BYTES

#define SYNC_WORD 0x88888888

#define LENGTH_TYPE PKT_LENGTH_VAR

#define LENGTH_WIDTH 7

#define CRC_MODE PKT_CRC_MODE_8BITS

#define CONTROL_LENGTH PKT_CONTROL_LENGTH_0BYTES

#define EN_FEC S_ENABLE

#define EN_WHITENING S_ENABLE

/* Addresses configuration parameters */

#define EN_ADDRESS S_DISABLE

#define EN_FILT_MY_ADDRESS S_DISABLE

#define EN_FILT_MULTICAST_ADDRESS S_DISABLE

#define EN_FILT_BROADCAST_ADDRESS S_DISABLE

#define EN_FILT_SOURCE_ADDRESS S_DISABLE//S_ENABLE

#define SOURCE_ADDR_MASK 0xf0

#define SOURCE_ADDR_REF 0x37

#define MULTICAST_ADDRESS 0xEE

#define BROADCAST_ADDRESS 0xFF

#define EN_AUTOACK S_DISABLE

#define EN_PIGGYBACKING S_DISABLE

#define MAX_RETRANSMISSIONS PKT_DISABLE_RETX

#define PAYLOAD_LEN 25 /*20 bytes data+tag+cmd_type+cmd+cmdlen+datalen*/

#define APPLI_CMD 0x11

#define NWK_CMD 0x22

#define LED_TOGGLE 0xff

#define ACK_OK 0x01

#define MAX_BUFFER_LEN 96

#define TIME_TO_EXIT_RX 3000

#define DELAY_RX_LED_TOGGLE 100

#define DELAY_TX_LED_GLOW 200

#define LPM_WAKEUP_TIME 100

#define DATA_SEND_TIME 50//30

</code>

I am using a still relatively large bandwith and data rate. The problem is that further reducing datarate and bandwith litterally kills the range. If I set the following settings :

datarate 9600

frequency deviation 4800

bandwidth 19200

all else stays equal

I do not even get a full meter of range !

Why does reducing datarate and bandwith kills the range ? Is it a hardware issue ? A software misconfiguration ?

Shouldn't this module be able to get around 1 km of clear line of sight range ?