2. Chi è?
Heinrich Rudolf Hertz
(22 febbraio 1857 – 1 gennaio 1894)
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3. SRD (Short Range Devices)
SISTEMI A RADIOFREQUENZA, CON NORMATIVA
DEFINITA IN AMBITO EUROPEO PER LIBERO UTILIZZO
Bande disponibili per libero utilizzo:
433.05 ÷ 434.79 Mhz Utilizzo Generico
863 ÷ 865 Mhz Audio
868 ÷ 870 Mhz Sotto Bande specializzate
2.4 ÷ 2.5 Ghz Dati,Video, Reti Lan, BlueTooth,
WiFi, Zig Bee…
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4. Scelta della banda in funzione delle
esigenze del prodotto
• Quanta strada devo fare?
• Cosa devo trasmettere?
• Quanto posso consumare?
• E’ una soluzione semplice?
• Quanto spazio ho?
• Quanto costa?
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5. Utilizzo tipico delle bande
434 MHz Telecomandi codificati
Telemetria dati low speed
863 MHz Audio con normativa specifica
868 MHz Telecomandi codificati
Telemetria dati low speed
Specializzazione bande sia come duty cycle che come
potenza
2.4 GHz Possibile ampia banda passante per reti dati.
Massima complessità del sistema RF sia come hardware
(tecniche di modulazione), sia come software (reti
complesse).
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6. Short Range Devices: CEPT
(Conférence européenne des administrations des postes et des télécommunications)
Reserved Frequencies (434 Mhz)
10 mW ERP
10 mW ERP
1 mW ERP
433.05 434.04 434.79
433.0 434.0 435.0
Duty Cycle up to 100%, No channel spacing. Power density limited to -13dBm/10Khz
for wideband channels with a bandwidth greater than 250Khz.
Max Duty Cycle 100% , channel spacing up to 25Khz
Max Duty Cycle 10% , No channel spacing
Telemetry, Telecommand, Alarms, Data in general and other similar applications.
The band is also designed for industrial, scientific and medical (ISM) application as defined in ITU Radio Regulation.
Audio and voice signals should be avoided in the band 433.050÷434.79 Mhz.
Antenna Type: integral or dedicated
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7. Audio Short Range Devices: Reserved
Frequencies (863÷865 Mhz)
Allowed antenna type integral or dedicated
10 mW ERP
10 mW ERP
863 864 865
Wireless Audio Applications – Duty cycle up to 100%, No channel spacing. In case of
analogue systems the max occupied bandwidth should not exceed 300 Khz. Narrow band
analogue voice devices (such as baby voice monitors, door entry systems etc ) should
only use the band 864.8-865 MHz with duty cycle up to 100% and 50 Khz channel
spacing.
Radio microphones – Duty cycle up to 100%, 200 Khz channel spacing.
In case of analogue systems the maximum occupied bandwidth should not exceed 300 kHz
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8. Short Range Devices: CEPT Reserved Frequencies (868Mhz)
ERP
500 mW
Antenna type: integral or dedicated
25 mW
10 mW
5 mW
ERP 869.2 869.3 869.4 869.65
869.0
868.0 868.6 868.7
Telecommand, Alarms, Data,…)
869.25 869.7
Non-specific SRD (Telemetry,
Max duty cycle 1%, No channel spacing. Below 868.5 Mhz the usage of a dedicated frequency channel is avoided and a
technology that allows automatic channel selection of a free channel within the band should be used.
Max duty cycle 0.1%, No channel spacing.
Channel spacing 25Khz. An appropriate access protocol should be used (EN XXX XXX). No restriction on duty cycle
Max duty cycle 10%, 25 Khz channel spacing. The whole band may also be used as 1 channel for high speed data
transmission.
Duty cycle up to 100%. No channel spacing. The adjacent frequency band above this band has been designated for use by
the high powered TETRA service. Manufacturers should take this into account in the design of the e.i.r.p.
Max duty cycle 0.1%, 25Khz channel spacing. May also be used as 1 channel for high speed data
and for security)
Alarms (general
transmissions
Max duty cycle 0.1%, 25Khz channel spacing. Frequency band 869.20 ÷ 869.25 is for social alarms
Max duty cycle 10%, 25Khz channel spacing.
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9. CEPT Reserved Frequencies 2.4 GHz
500 mW EIRP
100 mW EIRP
10/25 mW EIRP
MHz
2440
2400 2483.5
2446 2454
No restrinction on duty cycle. No channel spacing.
10 mW EIRP Telemetry, Telecommand, Alarms, Data in general. Video applications. Industrial, scientific and
medical (ISM) application as defined in ITU Radio Regulation.
25 mW EIRP Equipment for Detecting Movement and Equipment for Alert.
No restriction on duty cycle. No channel spacing. Wideband data transmission systems: Radio Local Area
Networks. For direct sequence spread spectrum the maximum spectrum power density is limited to -20 dBW/1
MHz. For FHSS the maximum spectrum power density is limited to –10 dBW/100 kHz.
Railways applications (Automatic Vehicle Identification). No restriction on duty cycle.Transmitting only in presence of
trains. 5 channels, each 1.5 MHz wide.
RFID applications (Frequency Hopping Spread Spectrum (FHSS) techniques should be used
as means of mitigation when more than 500 mW EIRP is used.):
500 mW EIRP, duty cycle up to 100%. No channel spacing.
4 W EIRP, duty cycle < 15 %. Power levels above 500 mW are restricted to use inside the
boundaries of a building and the duty cycle shall in this case be <= 15 % in any 200 ms
period (30 ms on /170 ms off). 9
12. Protocollo e applicazioni
Tecnologia Bluetooth
E’ stata pensata per:
•Comunicazioni a corto raggio
•Essere utilizzata da dispositivi dotati di batterie
•Supportare sia traffico voce che dati
•Essere utilizzata in tutto il mondo (banda ISM)
E’ caratterizzata da:
•Basso costo
•Basso consumo di potenza
•Affidabilità
•Specifice aperte
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13. Modulazione: Frequency hopping pseudocasuale
79 canali da 1MHz
Slot temporali da 625us
Piconet: Due o più dispositivi (max 7 attivi)
Architettura a stella
Profili: definiscono i requisiti necessari per
Permettere l’interoperabilità fra le applicazioni.
Sicurezza del canale: Pairing, autenticazione, cifratura
Autorizzazione
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