Operating Manual L400 400–480 MHz Narrowband Modem Revision 0.20, June 4, 2009 Model: L400 Microhard Systems Inc. #17, 2135 – 32nd Ave N.E. Calgary, Alberta T3K 4Z4 Phone: (403) 248-0028 Fax: (403) 248-2762 www.microhardcorp.
Warranty Microhard Systems Inc. warrants that each product will be free of defects in material and workmanship for a period of one (1) year for its products. The warranty commences on the date the product is shipped by Microhard Systems Inc. Microhard Systems Inc.’s sole liability and responsibility under this warranty is to repair or replace any product which is returned to it by the Buyer and which Microhard Systems Inc. determines does not conform to the warranty.
L400 Regulatory Requirements PLEASE READ THIS SECTION CAREFULLY WARNING: To satisfy FCC RF exposure requirements for mobile transmitting devices, a separation distance is based on the above them ranging from 39 cm to 305 cm between the antenna of this device and persons during device operation. To ensure compliance, operations at closer than this distance is not recommended. The antenna used for this transmitter must not be co-located in conjunction with any other antenna or transmitter.
Contents Warranty ....................................................................................................................................................................... ii Warranty Diclaims ........................................................................................................................................................ ii Indemnification......................................................................................................................................
2. General 2.0 Product Overview The L400 is a high-performance embedded wireless data transceiver. Operating in the 400 - 480 MHz band, this narrowband 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.
TDMA (time division multiple access) support, allowing multi-slave access in point-to-point mode. roaming ability, allowing repeaters and slaves to resynchronize with a new master if the synchronization pulse from the original master is lost. While the typical application for the L400 is to provide a short- to midrange wireless communications link between DTEs, it can be adapted to almost any situation where an asynchronous serial interface is used and data intercommunication is required. 2.
L400 Operating Manual: Chapter2 General 3
3. Installation 3.0 Overview Qualified and experienced personnel must carry out the installation, removal or maintenance of all antenna components. The L400 complies with FCC part 15 at the modular level for operation in the license-free 400 to 480MHz depending on the country of operation there maybe some band restrictions. This chapter provides guidelines for installing and deploying equipment which incorporates the L400 module. 3.
Figure 1 Gain Calculation The power level has been set to 30dBm (1W) on the transmitter, and the receiver sensitivity for the L400 is -108dBm. System gain would be calculated to be: 30 - 2 + 6 + 3 - 2 + 108 = 143 dB. Base Height (m) Mobile Height (m) Distance (km) Figure 2 System Deploying When deploying your system, care must be taken to ensure the path loss (reduction of signal strength from transmitter to receiver in dB) between equipment does not exceed the system gain (140 dB in the above example).
Once the equipment is deployed, you can verify the signal strength by entering into Command Mode and reading Register S123. This register provides the average signal strength in dBm. The minimum strength for communication is roughly -108dBm. For consistent reliable communication, you should try to deploy the equipment such that signal strength exceeds -95dBm. 3.
3.2.2 WARNING: Direct human contact with the antenna is potentially unhealthy when the L400 is generating RF energy. Always ensure that the L400 equipment is powered down during installation. WARNING: Never work on an antenna system when there is lightning in the area. Installing External Cables, Antennas and Lightning Arrestors Qualified and experienced personnel must carry out the installation, removal or maintenance of all antenna components.
WARNING: The L400 can only be used with any antennas listed in Appendix A and this the antenna separations shown in Appendix A. Factors to take into consideration when choosing a cable are: • price; • bend radius limitations (the lower performance cables generally can bend more sharply) • performance requirements; and, • distance between the equipment and the antenna. WARNING: Be careful with dBi vs dBd gains on antenna specifications.
A. Antenna / Separations Impedance (ohms) 50 50 Antenna Minimum Gain Maximum Gain Antenna Gain (dBi) 0 18 Minimum Separation Distance (cm) 39 305 RF EXPOSURE DISTANCE LIMITS r= P ⋅G = 4 ⋅π ⋅ S EIRP 4 ⋅π ⋅ S Sample calculation: S = 406.1/1500 mW/cm2 EIRP = 42 dBm = 1042/10 mW = 15849 mW (Worst Case for Quarter Wave antenna) (Minimum Safe Distance, r) = EIRP = 4 ⋅π ⋅ S 15849 ≈ 68cm 4 ⋅ π ⋅ (406.1 / 1500) WARNING: Changes or modifications not expressly approved by Microhard Systems Inc.
