AN4147 STMICROELECTRONICS | Alldatasheet

Document overview

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Technical content

Datasheet sections

  • 1 An overview of FCC regulations
  • 2 Application circuit
  • 3 Transmitter parameter
  • 3.1 Spurious RF conducted emission
  • 4 Receiver parameter
  • 5 Reference
  • 6 Revision history

August 2012 Doc ID 023516 Rev 1 1/14 AN4147 Application note Using the SPIRIT1 transceiver under FCC title 47 part 15 in the

315 MHz band

The SPIRIT1 is a very low power RF transceiver, intended for RF wireless applications in the sub-1 GHz band. It is designed to operate in both the license-free ISM and SRD frequency bands at 169, 315, 433, 868, 915 and 920 MHz. This application note outlines the expected performance when using the SPIRIT1 under FCC title 47 part 15 [ 2] in the 315 MHz band. There are no specific requirements in this band, no specific use and no channel spacing are defined. For details on the regulatory limits in the 315 MHz frequency band, please refer to the FCC Title 47 Part 15 regulations [2]. These can be downloaded from: http://wireless.fcc.gov/index.htm?job=rules_and_regulations.

1 An overview of FCC regulations

toys are not permitted. Data is permitted to be sent with a control signal.

  • A manually operated transmitter shall employ a switch that will automatically deactivate the transmitter within not more than 5 seconds of being released. A transmitter activated automatically shall cease transmission within 5 seconds after activation.
  • Periodic transmissions at regular predetermined intervals are not permitted. However, polling or supervision transmissions, including data, to determine system integrity of transmitters used in security or safety applications are allowed if the total duration of transmissions does not exceed 2 seconds per hour.
  • Intentional radiators which are employed for radio control purposes during emergencies involving fire, security and safety of life, when activated to signal an alarm, may operate during the pendency of the alarm condition.
  • In addition to the provisions of 15.205, the field strength of emissions from intentional radiators operated under this section shall not exceed the values in

Table 1. The field strength limits are specified at a distance of 3 meters.

  • The limits on the field strength of the spurious emissions in the Ta bl e 1 are based on the fundamental frequency of the intentional radiator. Spurious emissions shall be attenuated to the average limits shown in this table or to the general limits shown in section 15.209, whichever limit permits higher field strength.
  • The bandwidth of the emission shall be no wider than 0.25% of the center frequency. Bandwidth is determined at the points 20 dB down from the modulated carrier.
  • Intentional radiators may operate at a periodic rate exceeding that specified in point 1 and may be employed for any type of operation, including operation prohibited in point 1. In this case, the max field strength is different and is shown in the Ta bl e 2. The device operating in the condition described in this point shall be provided with a means for automatically limiting operation so that the duration of each transmission shall not be greater than 1 second and the silent period between transmissions shall be at least 30 times the duration of the transmission, but in no case less than 10 seconds.

Table 1. Field strength of emissions for normal working conditions

The field strength limits are specified at a distance of 3 meters. Table 2. Field strength of emissions for particular working conditions Table 1. Field strength of emissions for normal working conditions (continued) Table 3. Restricted bands defined in section 15.205

Table 4. Radiated and conducted emission limits defined in section 15.209 Table 3. Restricted bands defined in section 15.205 (continued)

2 Application circuit

Figure 2) by two header 5x2 connectors (J6 and J7). application. A graphical user interface (GUI) is developed to correctly program the SPIRIT1. correct functionality and verify the ETSI standard request. power amplifier (PA) and balun network for the receiver. switch. The daughterboard is designed to show the SPIRIT1 functionality in this condition. Figure 1. SPIRIT1 application daughterboard

Figure 2. SPIRIT1 application daughterboard plugged into the motherboard

Figure 3. Daughterboard schematic

3 Transmitter parameter

Tc = 25 ° C, Vdd = 3.0 V, f = 315 MHz, unless otherwise specified. short range devices are specified in field strength. Table 1. The calculated value of corresponds, applying the formula above, to a value of - 35 dBm at 3 m distance.

3.1 Spurious RF conducted emission

15.209, whichever limit permits higher field strength. spurious emission requirements. Figure 4. TX spurious emission below 1 GHz

Figure 5. TX spurious emission above 1 GHz

4 Receiver parameter

No specific requirements are defined for FCC compliance of the receiver in US FCC Title 47 Part 15 [2] in the 315 MHz band. No measurements were done for the receiver.

5 Reference

  1. SPIRIT1 datasheet 2. FCC title 47 Part 15: “Radio frequency devices”

6 Revision history

Table 5. Document revision history 06-Aug-2012 1 Initial release.