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2. General 

 

2.0

 

Product Overview 

The N920BT is a high-performance embedded wireless data transceiver.  
Operating in the 902 - 928 MHz ISM band, this frequency-hopping spread-
spectrum module is capable of providing reliable wireless data transfer 
between almost any type of equipment which uses an asynchronous serial 
interface.  The small-size and superior RF performance of this module make 
it ideal for many applications.  
 
While a pair of N920BT modules can link two terminal devices (“point-to-
point” operation); multiple modules can be used together to create a 
network of various topologies, including “point-to-multipoint” and 
“repeater” operation. Multiple independent networks can operate 
concurrently, so it is possible for unrelated communications to take place in 
the same or a nearby area without sacrificing privacy or reliability. 
 

1.1  Features

 

Key features of the N920BT include: 

  transmission within a public, license-exempt band of the radio 

spectrum

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 – this means that it can be used without access fees 

(such as those incurred by cellular airtime). 

 

a serial I/O data port  with handshaking and hardware flow 
control, allowing the N920BT to interface directly to any 
equipment with an asynchronous serial interface. 

 

ease of installation and use – the N920BT module uses a 
subset of standard AT style commands, very similar to those 
used by traditional telephone line modems. 

  all units in a system are physically identical, and can be 

configured as a master, repeater or slave using the AT 
command set. No hardware modifications are required 

  Selectable pseudo-random hopping patterns, intelligently 

designed to offer the possibility of separately operating 
multiple networks while providing security, reliability and 
high tolerance to interference. 

  32-bit of CRC error detection and auto re-transmit to provide 

accuracy and reliability of data. 

                                                           

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 902-928 MHz, which is license-free within North America; may need to be factory-

configured differently for some countries.

 

Summary of Contents for n920BT

Page 1: ...Manual n920BT 900 MHz Spread Spectrum OEM Transceiver Revision 0 10 September 5 2013 17 2135 32nd Ave N E Calgary Alberta T3K 4Z4 Phone 403 248 0028 Fax 403 248 2762 www microhardcorp com Microhard Sy...

Page 2: ...IONAL WARRANTY Indemnification The Purchaser shall indemnify Microhard Systems Inc and its respective directors officers employees successors and assigns including any subsidiaries related corporation...

Page 3: ...nnas require installation preventing end users from replacing them with non approved antennas Antennas not listed in the tables must be tested to comply with FCC Section 15 203 unique antenna connecto...

Page 4: ...ights ii n920BT Regulatory Requirements iii CONTENTS IV 2 GENERAL 1 2 0 PRODUCT OVERVIEW 1 2 1 OUTPUT POWER LEVEL 2 3 INSTALLATION 4 3 0 OVERVIEW 4 3 1 ESTIMATING THE GAIN MARGIN 4 3 2 ANTENNAS AND CA...

Page 5: ...e transmission within a public license exempt band of the radio spectrum1 this means that it can be used without access fees such as those incurred by cellular airtime a serial I O data port with hand...

Page 6: ...sensitive receiver can operate with very low power levels so it is recommended that the lowest power necessary is used using excessive power contributes to unnecessary RF pollution Ideally you should...

Page 7: ...used for this transmitter must be installed to provide a separation distance of at least 23 cm from all persons with the maximum allowable antenna gains of 1 5 dBi Quarter Wave 2 dBi Rubber Ducky 5 1...

Page 8: ...wledge of the equipment being deployed The following four factors make up a system gain calculation 1 Transmitter power 2 Transmitter gain transmitting antenna gain minus cabling loss between the tran...

Page 9: ...ystem gain and path loss Referring to the same example suppose the path loss is 100 dB the gain margin would be 40 dB which is more than adequate for reliable communication Path loss is a very complic...

Page 10: ...rocedure for installing cabling and antennas for use with the N920BT module 3 2 1 Internal Cabling The most common method for installing the module is to run a cable from the module s MMCX connector t...

Page 11: ...The most effective protection against lightning is to install two lightning surge arrestors one at the antenna the other one at the interface with the equipment The surge arrestor grounding system sho...

Page 12: ...suitable Choose a Yagi with enough gain to ensure adequate gain margin When deploying the Yagi point the antenna towards the intended target ensuring the antenna elements are perpendicular to the grou...

Page 13: ...the maximum power setting of 30dBm Example 2 What is the maximum power the N920BT can be set to comply with FCC and IC given the following equipment given a Yagi Ant Gain 12dBd and cable and connector...

Page 14: ...dBd 900MHz Yagi Directional Antenna Bluewave RPTNC Pigtail Patch Antennas MHS031440 8dBi 900 MHz Patch Antenna RPTNC Pigtail MHS031430 12 5dBi 900 MHz Patch Antenna RPTNC Pigtail Omni Directional MHS0...

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