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© 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.
TETRA Antenna Combiner
User Guide
RSI
Kingswear House
High Street
Cranbrook
Kent TN17 3EW
Tel: 0208 123 0028
Fax: 08707 051196
Email: sales@rsi-uk.com
www.rsi-uk.com
Issue 4.0
th
17
June 2009
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Table of Contents
Summary of Contents for RSI TETRA
- Page 1 © 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.
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Page 2: Table Of Contents
TETRA Antenna Combiner CONTENTS DISCLAIMER ........................3 WARNING.........................3 INTRODUCTION......................4 ......................... 4 ENERAL COMBINER DESIGN ....................6 ........................6 VERVIEW 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 SPECIFICATION......................8 MAINTENANCE ......................9 Radio Systems Information Ltd. -
Page 3: Disclaimer
If you have queries 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... -
Page 4: Introduction
The TETRA Antenna Combiner is designed to work with the Gemini survey tool allowing up to four TETRA class 3 (3W) radio terminals to be connected to a single antenna whilst meeting all ETSI requirements for isolation between radio terminals so that each may be operated independently with no degradation in performance caused by the other terminals. - Page 5 The combiner also includes a RECEIVE ONLY port with 0dB loss to the antenna. This is suitable for connecting to a measuring / monitoring receiver or similar and MUST NOT be attached to a TETRA terminal. The following diagram shows how the TETRA Antenna Combiner is connected: Antenna 12V DC Power...
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Page 6: Combiner Design
The maximum usable sensitivity of the receiver is about –110 dBm for 10 BER which with 18dB S/N ratio for TETRA requires a maximum interfering signal of –128 dBm. Therefore at least 62dB isolation is required between the ports at the receive frequency. -
Page 7: 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. -
Page 8: Specification
TETRA Antenna Combiner Specification Frequency: Tx 380-385MHz, Rx 390-395MHz Tx Insertion Loss: Model A: Ports 1 & 2: Ports 3 & 4: 11dB Model B: All Ports: 11dB Rx Gain: Configured to be identical to Tx path loss for each port Port to Port isolation (Tx Band): >60dB... -
Page 9: Maintenance
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...
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