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RSI TETRA User Manual Download Page 7

TETRA Antenna Combiner 

 

Radio Systems Information Ltd. 

 

Page 7 

2.1.4  Blocking from out-of-band transmitters 

Broadcast transmitters for radio around 100MHz and TV starting at 480MHz with power levels in 
the  megawatts  have  the  potential  to  overload  the  combiner  receiver  and  cause  blocking  even 
though they are operating far from the TETRA frequency. 
 
The combiner includes a spectrum defining filter to provide at least 20dB attenuation to external 
signals below 300MHz and above 470MHz. 
 
 
 
 
 
 
 
 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

 

Summary of Contents for TETRA

Page 1: ...i uk com www rsi uk com Issue 4 0 17 th June 2009 Copyright 2009 Radio Systems Information Ltd All Rights Reserved Neither the whole nor any part of the information contained in this manual may be adapted or reproduced in any material form except with the prior written approval of RSI Gemini is a trademark of Radio Systems Information Ltd ...

Page 2: ...ge 2 CONTENTS DISCLAIMER 3 WARNING 3 1 INTRODUCTION 4 1 1 GENERAL 4 2 COMBINER DESIGN 6 2 1 OVERVIEW 6 2 1 1 Blocking 6 2 1 2 Wideband noise 6 2 1 3 Intermodulation products 6 2 1 4 Blocking from out of band transmitters 7 3 SPECIFICATION 8 4 MAINTENANCE 9 ...

Page 3: ...ueries regarding its accuracy please contact RSI at the address shown on the title page With a policy of continual improvement RSI reserves the right to alter specification without notice Warning WARNING On NO account should a TETRA terminal be connected to the Receive Only 5 th Port as serious damage WILL occur WARNING The 5 dB attenuator switches should not be operated while the TETRA units are ...

Page 4: ...ss in the transmit path The remaining 2 terminals have 11dB loss in the transmit path Model B passive design with all terminals having 11dB loss in the transmit path Note that 11dB is the difference as proposed by PITO normally applied to degrade a vehicle antenna to give the same performance as the antenna on a body worn handportable radio terminal The Model A contains a front panel mounted fan f...

Page 5: ...minals the combiner will simulate the following Port 1 Port 2 Port 3 Port 4 Model A 5dB switches in for ports 3 4 Class 3 Vehicle Radio Class 3 Vehicle Radio Class 4 Handportable Radio Class 4 Handportable Radio Model B 5dB switches in for all ports Class 4 Handportable Radio Class 4 Handportable Radio Class 4 Handportable Radio Class 4 Handportable Radio External attenuators may be added between ...

Page 6: ...y have wideband noise extending for several MHz into the receive band Therefore a co located receiver will receive in band noise The ETSI specified level greater than 5 MHz away from the carrier is less than 100 dBc which equates to 66 dBm for a 3W transmitter en 300 392 2 para 6 4 2 3 The maximum usable sensitivity of the receiver is about 110 dBm for 10 2 BER which with 18dB S N ratio for TETRA ...

Page 7: ...round 100MHz and TV starting at 480MHz with power levels in the megawatts have the potential to overload the combiner receiver and cause blocking even though they are operating far from the TETRA frequency The combiner includes a spectrum defining filter to provide at least 20dB attenuation to external signals below 300MHz and above 470MHz ...

Page 8: ...o Tx path loss for each port Port to Port isolation Tx Band 60dB Port to Port isolation Rx Band 65dB Antenna to Port isolation Tx Band 60dB PA 3rd order intercept 2 x 3 watt 58dBm Blocking 30dBm 1dB change in 80dBm wanted interferer 1MHz away LNA noise figure 3dB at 2dB gain VSWR 1 5 1 Antenna Port Connectors BNC Receiver Only 5 th Port TNC Power Supply Model A 11 15V 15A Model B 11 15V 1A Dimensi...

Page 9: ...k the survey vehicle in an open area away from any buildings and at least 250m from any TETRA base transmitters 2 Put each TETRA radio into engineering mode so that the RSSI is displayed 3 Connect the survey antenna direct to the TETRA radio antenna Make a note of the RSSI and the serving base LAC 4 Connect the survey antenna to the Combiner antenna port connect the TETRA radio to the relevant por...

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