And Radio Technology

1 By: Firas Faham, Senior Engineer

Information modulating SIGNAL m(t) is Audio, Video, or Data.

RF modulated SIGNAL with carrier frequency f(c) helps the information travel.

The RF SIGNAL s(t) represents the f(c) carrier providing a ride to m(t) and enabling RF wireless or wired communication, cellular, or point to point.

S(t) = x(t) Cos (2π fo) t - y(t) Sin (2π fo) t

RF, Microwave, and Millimeter Wave.

• RF is less than 1 GHz.

• Microwave is between 1 GHz and 40 GHz.

• Millimeter wave is greater than 40 GHz.

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Wavelength [cm] = 30 / frequency [GHz]Frequency [GHz] = 30 / Wavelength [cm]1000 MHz = 1 GHzWavelength [mm] = 300 / Frequency [GHz] (for sub-mm)Wavelength [um] = 300,000 / Frequency [GHz] (for Scuba and others)

30-300 Hz 10-1Mm .....ELF (extremely low frequency) 300-3000 Hz .........................................1Mm-100 km 3-30 kHz 100-10 km ...........VLF (very low frequency) 30-300 kHz 10-1 km .....................LF (low frequency) 300-3000 kHz 1 km-100 m ....MF (medium frequency) 3-30 MHz 100-10 m ....................HF (high frequency) 30-300 MHz 10-1 m ..........VHF (very high frequency) 300-3000 MHz 1 m-10 cm ..UHF (ultra high frequency) 3-30 GHz 10-1 cm .............SHF (super high frequency) 30-300 GHz 1 cm-1 mm EHF(extremely high frequency)

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• Distance and power control, for wireless.

• Selection (Frequency selector networks and Time selector

networks.)

• Multi-users enhanced security (TDMA, DS or FH SS, and CDMA.)

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Logic Trunk: Network automatically assigns one channel from the pool of channels to one user.

TDMA: Time division multiple access.

FDMA: Frequency division multiple access.

Blue Tooth: an open standard for short-range transmission of digital voice and data between mobile devices (laptops, PDAs, phones) and desktop devices. It supports point-to-point and multipoint applications.

SS: Spread spectrum is a form of wireless communications in which the frequency of the transmitted signal is spread or varied over greater bandwidth than the un-spread signal.

Packet Networks: The fragments of the message are exchanged in sequence between terminals according to certain rules (protocols.)

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RZ

NRZ

PPM

PWM

0 1 1 0

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AM

Carrier: 540 TO 1700 KHz.

117 channels each of 10 KHz BW.

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DS SS

FM

Carrier: 88 to 108 MHz.

100 channels each of 200 KHz.

FH SS

~AMP

~

Power AMP

LNA AMPFilter

Filter

OSC

OSC

Filter

Mixer

Mixer

IF

INFO

INFO

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High performance, scalable, and back ward compatibility.

Standardization (ISM band, other manufacturers, IEEE, FCC)

Environment and interference (Location, close by systems…)

Security and integrity (multiple access, jamming, multi path interference…)

Speed and access media.

Network connectivity.

Technology (functionality, ease of use, Shared or dedicated channels, Wide or Narrow Band…)

Cost (upgrade, expand, or new system.)

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• RFID, Source tagging, EAS, Transponders, surveillance, and theft-prevention systems …

• CATV and MMDS.

• Remote monitoring and control.

• Wireless communication, Pagers and cellular phones ….

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Electronic Article Surveillance

According to AIM (Association of Automated Identification Manufacturers) over 80,000 EAS systems are installed world wide resulted in saving of millions of dollars for retail industry.

• Different exit/ Entrance aisle width.

• Consumer Products Manufacturers Association (CPMA) encourages manufacturers to produce compatible tags.

• Types are AM Acousto Magnetic, EM Electro Magnetic, Swept RF, and Microwave system.

• Acousto Magnetic AM system has the advantage of attaching tags directly on metal surface.

• System type and surveillance area width are function of operating frequency.

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Acousto Magnetic

Acousto systems: Physical vibration in the molecules of tag caused by RF pulses of 50.9 Hz (19.6 ms) carried by 58 KHz signal. When the transmitter pulse ends, the tag responds, emitting a single frequency signal like a tuning fork.

Bias Magnet: Reduces tags response from frequency 2F to F.

Magnetostrictive tag: Physical strain experienced in a material subjected to a polarizing magnetic flux, or reversibly, experiencing magnetic property changes to external mechanical stresses.

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Electro Magnetic

• Fundamental frequency = 70 Hz to 1 KHz.

• Tags generate harmonics due to abrupt change in its magnetic state.

• Receiver detects fundamental, harmonics, and timing to activate an alarm.

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• Transmitter produces signals between 7.4 to 8.8 MHz.

• Tag is LC tuned network.

• Receiver detects phase difference between transmitted and tag signals.

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• 2 transmitters, hi and low frequencies.

• Hi frequency A) North America 902 to 906 MHz make 50 hoped frequencies, and B) Europe 1 fixed frequency between 2402 and 2486 MHz.

• Low frequency 111.5 KHz.

• Tag is tuned circuit that will radiate the sum and difference of hi and low frequencies.

• Receiver detects the modulated hi frequency signal.

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16

MUX BPF PGA GAIN

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BPF

• Real Time Locating System (RTLS). If expensive item is moved outside the surveillance area closest exit is locked, alarm sounds, items located by 3 positioning antennas and the backend software performs a triangular calculation and displays the location of the asset.

• Proximity detectors (switch, IR, or RF) for stand by mode.

• Compliance, future and backward compatibility, and networkability.

• Tags used to enter restricted areas for added security against merchandise loss.

• Buried pedestal antennas for wider entrances and better feeling for some.

• Improved packaging and silicon-ink imprinted tags.

• System work with any tag, tags work with any system, + and -.

• Automatic VISA payment, automatic and customer self deactivation.

• If payment is made and tag sounds the alarm, customer can go back through pedestals, rescan to verify purchase, deactivate.

• System works if customer leaves but not enters.

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