DEI Headquarters Inc. DEI547 Manuel D’Utilisation

 
 
 
 

 
 
 
 
 

Wednesday, May 12, 2004 
 
TUV Product Services 
10040 Mesa Rim Road 
San Diego, CA  92121 
 
RE: FCC ID EZSDEI487 
 
 
Dear Sir or Madam, 
 
This letter is to address the following for the 547T Transceiver:  
 

1.  System transmission frequency range 
2.  Data transmission duty cycle description 
3. Manuals 

 
 

1.  This transmitter is a single frequency device. It has a crystal controlled PLL oscillator which 

generates the RF carrier. The crystal based oscillator can maintain a center frequency of 
433.92MHz within a +/-35KHz tolerance. The receiver operated by this transmitter is a single 
band receiver tuned to 433.92MHz and only capable of receiving this frequency. 

 
 

2.  The 547T is a data transmission device. Its protocol consists of the following worst case condition 

for duty cycle credit calculation: 

 
a) 17 preamble bits: 9 x 300us HI bits and 8 x 300us LO bits = 2.7ms ON time out of 5.1ms total time.   
 
b) There’s a 3ms gap between the preamble bits and the data bits. 
 
c) 57 data bits of 300us or 600us each, they are random. Worst case of 600us HI bits and 300us LO 
will be used. So, 29 x 600us and 28 x 300us LO = 17.4ms HI out of 25.8ms total time. 
 
c) There’s a 60ms gap between the end of the data bits and the beginning of the next frame. 
 
d) Total worst case word = 2.7ms + 17.4ms = 20.1ms ON time out of 93.9ms 
(5.1ms+3ms+25.8ms+60ms) 
 
So for a worst case 100ms frame we have: 
 
20.1ms ON out of 93.9ms + 3.3ms ON out of 6.1ms = 23.4ms out of 100ms = 23.4% ON time  
OR a -12.62dB FCC duty cycle credit.