Telit Wireless Solutions LM940 Design Guide

LM940 Hardware Design Guide
1VV0301352 Rev. 18 Page 51 of 75 2022-01-04
Not Subject to NDA
Item
Value
VSWR recommended
≤ 2:1
Table 35: Antenna Diversity Requirements
The second Rx antenna should not be located in the close vicinity of main antenna. To
improve Diversity Gain, Isolation and reduce mutual interaction, the two antennas should
be located at the maximum reciprocal distance possible, taking into consideration the
available space into the application. For the same reason, the Rx antenna should also be
cross polarized with respect to the main antenna.
Isolation between main antenna and Rx antenna must be at least 10 dB in all uplink
frequency bands.
Envelope Correlation Coefficient (ECC) value should be as close as possible to zero, for
best diversity performance. ECC values below 0.5 on all frequency bands are
recommended.
GNSS Receiver
The LM940 integrates a GNSS receiver that could be used in Standalone mode and in A-
GPS (assisted GPS), according to the different configurations.
LM940 supports an active antenna.
Item
Value
Frequency range
• Wide-band GNSS:
1560–1606 MHz recommended
• Narrow-band GPS:
1575.42 MHz ± 2 MHz minimum
• Narrow-band Galileo:
1575.42 MHz ± 2 MHz minimum
• Narrow-band BeiDou:
1561.098 MHz ± 2 MHz minimum
• Narrow-band GLONASS:
1601.72 MHz ± 4.2 MHz minimum.
Gain
1.5 dBi < Gain < 3 dBi
Impedance
50 Ohm
Amplification
18 dB < Gain < 21 dB
Supply Voltage
3.1 V
Current consumption
20 mA Typical
Table 36: LM940 GNSS Receiver Requirements
7.4.1. GNSS RF Front End Design
The LM940 contains an integrated LNA, and pre-select SAW filter.

Telit Wireless Solutions LM940 Specifications

General

Brand	Telit Wireless Solutions
Model	LM940
Category	Wireless modules
Language	English