Rice Lake MSI-9850 CellScale RF Digital Indicator - Operator Manual - Manual (Page 23)

MSI CellScale ® System • 9850 User Guide Page 23
MEASUREMENT SYSTEMS INTERNATIONAL
Firmware Version 5-XX for 2450 Modems
SECTION 2 – RF SCALE COMMUNICATIONS
The 9850 is a component of the MSI CellScale System. The CellScale system uses frequency hopping spread-
spectrum RF Modem technology transmitting in the 2.4 GHz ISM band.
RF Modems have been problematic as the RF bands are very hostile, corrupted by noise, path loss and inter-
fering transmission from other radios. Even in a pure interference-free environment, radio performance faces
serious degradation through a phenomenon known as multipath fading, a problem particularly prevalent for
indoor installations. Multipath fading results when two or more reflected rays of the transmitted signal arrive
at the receiving antenna with opposing phase, thereby partially or completely cancelling the desired signal.
Spread spectrum reduces the vulnerability of a radio system to both interference from jammers and multipath
fading by distributing the transmitted signal over a larger region of the frequency band than would otherwise
be necessary to send the information. This allows the signal to be reconstructed even though part of it may be
lost or corrupted in transit.
Spectrum has been set aside at 2.4 GHz in most countries for the purpose of allowing compliant spread spec-
trum systems to operate freely without the requirement of a site license. In the USA, there are absolutely no
site licensing requirements. The CellScale system is also programmable for use in most European countries.
Please contact MSI for worldwide compliance information.
FCC STATEMENT
FCC ID: HSW-2450M
Note: This unit has been tested and found to comply with the limits for a Class A digital device, pursuant
to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful
interference when the equipment is operated in a commercial environment. This equipment generates,
uses, and can radiate radio frequency energy and, if not installed and used in accordance with the
instruction manual, may cause harmful interference to radio communications. Operation of this equip-
ment in a residential area is likely to cause harmful interference in which case the user will be required
to correct the interference at their expense.
NETWORK DESCRIPTION
The CellScale system uses frequency hopping which is produced by transmitting the data signal as usual, but
varying the carrier frequency rapidly according to a pseudo-random pattern over a broad range of channels, in
this case 86 discreet frequencies. These 86 frequencies are combined in different “hopping patterns” to provide 64
(0-63) separate networks. The CellScale network uses a ‘Star’ network topology. One unit, usually the CellScale,
is designated a ‘Master’. The Master transmits a sync pulse on a regular basis, providing synchronization of all
remotes in the designated Network. Thus it forms the center of a cell. MSI provides five products capable of being
the master unit: the CellScale, the Smart CellModem 9000 (not 9020), the MSI-9260 ruggedized Crane Scale,
the MSI-9300 Porta-Weigh+ Crane Scale (with local display), or the MSI-6260CS Trans-Weigh CS Crane Scale.
Up to 15 slaves can access the master unit. The 9850 is always a ‘Slave’. Multiple 9850 units can coexist on one
network, or can be easily switched to other networks as required.
The CellScale system uses TDMA (Time Division Multiple Access) to arbitrate between multiple remotes. Each
remote is assigned a specific time slot thus guaranteeing data throughput. For more on setting up CellScale net-
works, please refer to the MSI-9000 CellScale User Guide.
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