Frequency Coverage and RFI Observations at Effelsberg

Frequency Coverage and RFI Observations at Effelsberg

K. Grypstra, R. Keller, Max-Planck-Institut für Radioastronomie, Bonn, Germany

Wettzell;March 18-20, 2009

Frequency Coverage and RFI in EffelsbergK. Grypstra, R. Keller, MPIfR

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Overview

• Frequency coverage and protected bands

• RFI at low frequencies• Observations in an RFI polluted

environment



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Frequency coverage

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Protected Bands



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Frequency coverage

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zReceivers at Effelsberg



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Frequency coverage

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E-VLA RX



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RFI at 18cm

• RFI Signal

• Spectral Lines(same scale)



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RFI examples: TV

• Analogue– High level

carriers– Low spectral

density in between

• Digital– No carriers– High

spectral density

– Lower power level



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RFI by Radar Signals

• Radar Spectrum at Effelsberg

• 1.0 – 1.2 GHz • Setup:

Log Periodic+ 120K LNA+ Spectrum Analyzer



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RFI at 21cm

Setup:• 100m RT• 15K RX• 9x20MHz

Source:• PCs?• Media

Converters?• WebCam?• Radar?• ?



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RFI at 18cm

Setup:• 100m RT• 20K RX

Source:• PCs?• Media

Converters?• WebCam?



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RFI at 18cm

BackendArtefacts

Setup:• 100m RT• 20K RX• FFT-Spectr.



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Airplane Radar Altimeter

• Airplanes over Effelsberg

• 4.2-4.4GHz• 2hrs• Aaronia

Spectrum Analyzer(2k€)



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RFI examples: UMTS

• UMTS• On the field• Setup:

– LogPer– 200K LNA– R&S FSH6



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RFI examples: Wireless

• WLAN 2.4GHz• Spectrum

50MHz

• Setup:– LogPer– 200K LNA– R&S FSH6



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• WLAN 5.28GHz

SAPOS-GSM

WLAN



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• WLAN 5.28GHz• Time Series• OFDMA

Orthogonal Frequency Division Multiple Access

• Setup:– LogPer– 200K LNA– R&S FSH6



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RFI: Electric Fences

• Distances0,5-1km



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RFI: Electric Fences

• ‚Pulsar‘1.382sec

• Setup:– 100m RT– 20K L-Band RX– FFT Anal.



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Ultra Wide Band

• UWB Generator

• @ 0-5GHz• Spurious up to

18GHz



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RFI and Measurements

• GSM900• Setup:

– LogPer.– 120K LNA– 30dB

Gain– R&S FSH6



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Gain– R&S FSH6



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Gain– R&S FSH6– Pointed

to zenith



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Observations through RFI

• 3C28618.6Jy

• @21cm



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Usable Frequencies

• 50cm: 608-614MHz protected; TV band IV narrow BW

• 21cm: 1.4-1.427GHz protected, outside critical

• 13cm (S): 2.2-2.29GHz prot. (no observation / experience)

• 11cm: 2.69-2.7GHz protected, surrounded by radar

• 9cm: 3.26-3.267GHz & 3.332-3.339GHz narrow BW

– 4-4.2GHz Airplane Radar Altimeter

• 6cm: 4.8-5GHz prot.; free in wide bands

– 5.1-5.5GHz earth bound radar, WLAN



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Usable Frequencies

• 5cm: 5.7-6.7GHz nothing prot.; free in wide bands

• 3.6cm (X): 8.215-8.4GHz prot.; >9GHz classical radar

• 2.8cm: 10.6-10.7GHz; not usable in practice → TV-sat

• 1.9cm: 14.47-14.5 & 15.35-15.4GHz prot.; radar @ 16.7

• 1.3cm: 22.01-24GHz prot. with gaps; ptp comm. @ 24

• Above: more or less free (cloudsat @ 86)



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Usable Frequencies

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Don't use!



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Don‘t suppress!

Setup:

• 100m RT, 15K RX, 20MHz BW, 1420MHz CF.

Frequency Coverage and RFI Observations at Effelsberg

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