Miniaturizing Hybrid GPSLoranCEurofix Receivers

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Miniaturizing HybridGPS/Loran-C/Eurofix Receivers

• Wouter J. Pelgrum,
• TU-Delft Reelektronika b.v.
• René Kellenbach Prof.dr. Durk van
  Willigen,Reelektronika b.v. / Reeuwijk / The
  Netherlands
• 3rd International Symposium on Integration
  ofLORAN-C / EUROFIX and EGNOS / Galileo
• Munich, Germany, 11-12 June 2002

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Integrated Loran-C GPS Receiver of the Future

• Integrated GPS-Loran-C receiver promising concept
• Current interest of industry depends on
  capabilities of (near) future Loran-C receiver
• Different applications demands different
  specifications

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GPS Receiver

• Wealth of miniature OEM GPS receiver chips or
  PCBs widely available
• GPS receiver must output raw range and velocity
  (Doppler) data
• Tight coupling
• DGPS

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Applications vs Demands

• Applications
• Business
• Timing
• Aviation
• Maritime
• Rail
• Land Mobile
• Personal
• Public
• Land Mobile
• Personal (e.g. E112)

• Demands
• Size / weight
• cost
• Integrity
• Availability
• Accuracy
• Continuity

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Size Effort?

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Loran-C receiver
battery
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Antenna E-field

• Excellent performance in open field in absence
  of precipitation statics
• Omni-directional radiation pattern with
  single-channel receiver
• Excellent noise performance
• Very small size (5-10 cm)
• - Signal ground required
• - Basically broad-band structure causes
  out-of-band interference susceptibility
• - E-field signal attenuation in urban canyons
• - Precipitation statics susceptibility

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Antenna H-field

• Excellent performance in urban canyons
• No signal ground required
• Excellent noise performance with relative small
  size
• Excellent with precipitation statics
• Band-pass response gives some out-of-band
  interference rejection
• - Omni-directional radiation pattern requires
  dual-loop structure and dual-channel receiver

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Antenna SNR

• Ideal Decrease antenna-size until receiver noise
  dominant (Note depends on interference rejection
  receiver)
• Miniaturization Decrease antenna-size further

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Antenna vs Amplifier

• Smaller antenna
• ? antenna gain ?
• ? receiver noise ?

Better amplifier design ? receiver noise ?
? smaller antenna possible !
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Antenna Gain vs Size
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Amplifier Noise
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How to beat the Graphs?

• Better ferrite materials
• Smaller bandwidth
• Multiple rods / other rod geometries

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Multiple Rods
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Multiple Rods

• Multiple rods
• save space for electronics save weight (without
  losing much performance)

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Antenna SNR

• SNR too low? -gt more signal -gt
• More TX power / more sticks in the fix

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Reelektronika / TU-Delft Antenna

• Reduction of E-field susceptibility
• Range error due to E-field now down to lt 30cm
• Not noticeable sensitive to E-field interference
• Build prototype (140x140x24 mm)
• In progress
• Automatic calibration
• Miniature combined Loran-C / GPS antenna
  (55x55x12 mm)

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Electronics size

• No limit in miniaturization?

POWER!
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Electronics power

• Better batteries / fuel cells
• Reduce power consumption
• Future chip technology
• More efficient algorithms
• Reduce sample rate

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Electronics Power
Software radio concept maximum flexibility with
minimal number of components
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Downsampling
48 kHz stereo audio ADC!

• Problem analogue bandpass

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Applications vs Demands

• Applications
• Business
• Timing
• Aviation
• Maritime
• Rail
• Land Mobile
• Personal
• Public
• Land Mobile
• personal

• Demands
• Size / weight
• cost
• Integrity
• Availability
• Accuracy
• Continuity

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Miniaturizing

• Antenna size ? noise performance
• Power consumption ? DSP level ofx-rate and CW
  interference rejection
• More Loran-C transmitters / more TX power