Measurement of Antenna Performance in Analog LMR Systems Using PL Tone Analysis

We are interested in measuring the in situ antenna performance in analog land mobile radio (LMR) FM systems. The gain (efficiency and directivity) and self-impedance of an antenna sufficiently characterize its performance and a number of traditional methods exist to measure these quantities. However it is hard to do antenna gain measurements using these methods. Furthermore, it turns out that volumetric antenna gain measurements are not quite relevant for understanding in situ performance. In this thesis, we present a novel approach for directly measuring the in situ performance of antennas in analog LMR systems. The procedure involves receiving an FM signal simultaneously using the antenna under test (AUT) and a reference antenna. Both received signals are demodulated to audio using separate but identical receivers. Then a convenient method for characterizing the audio signal quality is to analyze the private line (PL) tone. The PL tone signal-to-noise ratio (SNR) is calculated by measuring the power of the tone relative to the sub-audio noise power. The PL tone SNR for both antenna systems is compared as it provides a ``bottom line'' evaluation of the antenna performance. The audio SNR can also be mapped to RF SNR using a theoretical method. From simulation and experimental studies, we conclude that the RF SNR estimated using this technique is within 0.5 dB of the actual value for RF SNR values between +3 and +36 dB. Finally, we demonstrate this procedure in actual in situ LMR antenna measurements.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Department dc:contributor.department

Electrical and Computer Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2012

Author dc:creator

• Kumar, Akshay

Chair dc:contributor.committeechair

• Ellingson, Steven W.

Committee members dc:contributor.committeemember

• Clancy, Thomas Charles III
• Beex, A. A. Louis

• Antennas
• Antenna performance
• in-situ measurements
• LMR systems
• RF SNR
• Public Safety Radio

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-12102012-171705

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/46188