Home > Surveying Technology > RTK radio users should prepare for FCC Part 90 narrowbanding

RTK radio users should prepare for FCC Part 90 narrowbanding

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Owners of RTK (Real Time Kinematic) GPS equipment using radios subject to federal Communications Commission (FCC) part 90 should  plan to migrate to narrowband in the next several months.  Since 1995 the FCC has been talking about narrowbanding and now the drop dead date is fast approaching.

RTK  GPS users of radios in the 150-512 MHz range have until January 1st, 2013, to comply with FCC part 90 narrowbanding mandate.  After that date, users still broadcasting on 25 KHz channel bandwidths will be subject to enforcement action by the FCC which could include monetary fines.  Since January 1, 2011, the FCC has not accepted applications for new licenses for new operators using 25 KHz band width.  According to the FCC narrowbanding website, the migration to narrower 12.5 KHz channel bandwidths will allow the use of additional channels and has been under way for two decades.

Legacy single voice analog broadcast technology required a band width of 25 HKz, but newer efficient technology allows the same voice or data transmission to be broadcast with only a 12.5 HKz band width.

My recent experience with a GPS equipment purchase showed that some manufactures still do not supply narrowband equipment.  Some new RTK rovers still come with 25 KHz receive only radios that may work with a narrowband base.   I learned from a phone call to Pacific Crest that some current 25 KHz rover radios will work with a 12.5 KHz (narrowband) base radio with some loss of performance.  Rover radios optimized for narrowband are available now, but may be a different physical configuration from the radios they replaced.  Some RTK base radio transmitters can be modified by the manufacturer to be narrowband compliant.

Many public agencies and emergency services are struggling to meet the deadline and have less funds than ever to change their equipment.  Most Land Surveyors have the same deadline and funding problems and many are still not aware of the mandate.  I’m surprised at how little mention of narrowbanding I see in Land Surveying publications.

Network RTK rovers with cellular modems and 900 MHz “spread spectrum” radios will not be affected by this mandate.

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