FM IBOC Coverage Prediction

transcript

FM-IBOC Coverage Prediction

Doris Camiré

Radio Broadcast Systems & TransmissionCommunications Research Centre Canada

Ottawa

Western Association Broadcast Engineers (WABE)Annual Convention – Victoria, B.C., Dec 1, 2008

FM-IBOC Coverage Prediction in CRC-COVLAB

• As a result of CRC’s extensive laboratory tests on the performance of the FM-IBOC system, we were able to develop an advanced module to predict the coverage in CRC-COVLAB software.

• One essential consideration in predicting FM-IBOC coverage is interference from adjacent analog FM stations.

• Interference from 1st adjacent analog stations is most disruptive, especially when in the presence of both upper and lower 1st adjacent stations.

• In CRC-COVLAB we consider interference from the 1st, 2nd and 3rd adjacent stations, all having a compound effect on the FM-IBOC coverage.

FM-IBOC Module Accuracy

Does the module perform?

Let’s take it for a test drive!

Need field measurement data to compare with the simulation.

Thanks to our friendly neighbors South of the border, we were to have access to FM-IBOC field measurements…

National Public Radio FM-IBOC Field Measurements

• NPR developed a field test unit which was shipped to dozens of public radio stations to gather field measurement data on the performance of FM-IBOC

• CRC was provided measurements from three cities:– Chicago, Illinois: where the coverage is mostly noise limited

(not very affected by interference)– Oxford, Ohio: where the coverage is moderately affected by

interference– North Highlands, California: where the coverage is

significantly affected by interference• This offers a nice variety of interference situations to compare

coverage predictions.

Simulations Parameters

• Propagation model: CRC-PREDICT 2.08• Terrain elevation database: Computamaps 250 m resolution• Terrain type database: Computamaps 250 m resolution

• Transmitter parameters taken from FCC broadcast stations database.

• Receiver performance derived from CRC lab measurements.

Note: In all simulations, the default parameters of CRC-COVLAB were used, there was no fine tuning or adjusting the simulation to fit the measurements.

WBEZ Chicago, Illinois

WMUB Oxford, Ohio

KQEI North Highlands, California

Observations on Measurements vs Simulation

• Results show a good correlation between NPR measurements and the performance/accuracy of the FM-IBOC module in CRC-COVLAB.

• Exception of the North-East sector of the WMUB Oxford, Ohio, simulation. – There could be a discrepancy between the parameters

recorded in the FCC database and the actual system, example the antenna radiation pattern.

– Simulation may be considering an interferer N-E that is not actually operating…needs further investigation.

• From report: FM HD RadioTM System Performance At Elevated Carrier Levels, iBiquity Digital Corportion, December 2007

• Field tests done by iBiquity on the FM HD RadioTM system to assess the system’s performance with an increase in the ratio of digital power to analog power.

• Tests compare the performance at current power levels (digital power 20 dB below analog power) with elevated power levels (digital power 10 dB below analog).

• Presented simulation vs measurement results for:– Point Pleasant, New Jersey– Detroit, Michigan

FM-IBOC iBiquity Field Measurements

WRAT Point Pleasant, New Jersey

WRAT Point Pleasant, NJ: Digital Power 20 dB Below Analog Power

WRAT Point Pleasant, NJ: Digital Power 10 dB Below Analog Power

WCSX Detroit, Michigan

WCSX Detroit, Michigan: Digital Power 20 dB Below Analog Power

WCSX Detroit, Michigan: Digital Power 10 dB Below Analog Power

Conclusion

We consider the FM-IBOC module of high accuracy and are confident in the use of CRC-COVLAB for FM-IBOC system planning and interference analysis.

CRC will continue to contribute with partners worldwide to the advancement of radio broadcast technologies and the evaluation of existing technologies: DAB+, DMB, IBOC, DRM,…

CRC will continue to provide expert advice to the Canadian Industry and Government.

We often present these kinds of results to the Digital Radio Coordinating Group (DRCG).

Acknowledgements

Barry McLarnon, BDMComm

Martin-Pierre Lussier, CRC

Patrick Pilon, CRC

Measurements from: NPR Labs & iBiquity

For more information on

Radio broadcast technologies research

or coverage simulation software,

come to visit us…

www.crc.ca/crc-covlabThank you!

Doris CamiréSenior Research EngineerRadio Broadcast Systems

Communications Research Centredoris.camire@crc.ca

FM IBOC Coverage Prediction

Technology