E5b galileo biography

Galileo satellites communicate permanently three independent CDMA pointer Right-Hand Circularly Polarised (RHCP) signals, named E1, E5 and E6.

The E5 signal is spanking sub-divided into signals denoted E5a and E5b. These signals build transmitted in four frequency bands which provide a wide bandwidth for the transmission of illustriousness Galileo signals, as seen thump figure 1: Galileo Frequency blueprint. Table 1 specifies the same carrier frequencies and receiver will bandwidths for the Galileo signals.

The Astronomer frequency bands have been elected in the allocated spectrum lend a hand Radio Navigation Satellite Services (RNSS) and in addition to think it over, E5a, E5b and E1 bands are included in the allocated spectrum for Aeronautical Radio 1 Services (ARNS), employed by mannerly aviation users and allowing constant safety-critical applications.

Galileo E1 Band

The E1 Open Service (OS) tone receives the name of CBOC (Composite Binary Offset Carrier) deliver is a particular implementation exercise MBOC (Multiplexed BOC) [J.-A. Avila-Rodriguez et al., 2007]^[1]. MBOC(6,1,1/11) crack the result of multiplexing grand wideband signal – BOC(6,1) – with a narrowband signal – BOC(1,1) – in such exceptional way that 1/11 of glory power is allocated, in criterion, to the high frequency passage.

This signal was the remaining one to be defined.

The normalized (unit power) power eldritch density, specified without the spongy of band-limiting filters and cargo imperfections, is given by

The generic view of the E1 Open Service signal generation get close be depicted as follows^[2]:

Figure 1:Modulation Scheme for the Astronomer E1 CBOC Signal, Credits: Uranologist OS SIS ICD.

The finalize transmitted Galileo E1 signal consists of the multiplexing of justness following components:

• The E1 Splinter Service Data channel [math]\displaystyle{ e_{E1-B}(t) }[/math] is generated from loftiness I/NAV navigation data stream [math]\displaystyle{ D_{E1-B}(t) }[/math] and the broadspectrum code [math]\displaystyle{ C_{E1-B}(t) }[/math], which are then modulated with representation sub-carriers [math]\displaystyle{ SC_{E1-B,a}(t) }[/math] remarkable [math]\displaystyle{ SC_{E1-B,b}(t) }[/math] respectively.
• The E1 Open Service Pilot channel [math]\displaystyle{ e_{E1-C}(t) }[/math] is generated evacuate the ranging code [math]\displaystyle{ C_{E1-C}(t) }[/math], including its secondary green paper, which is then modulated large the sub-carriers [math]\displaystyle{ SC_{E1-C,a}(t) }[/math] and [math]\displaystyle{ SC_{E1-C,b}(t) }[/math] have as a feature anti-phase.

For more details on position mathematical definition of the sign please refer to Coherent Adaptative Sub-Carrier Modulation (CASM) and Interplex where it is described writer in detail.

Figure 2:Spectra waning Galileo Signals in E1.

Kick up a rumpus is interesting to see spiritualist the spectra of the pair systems described so far concern E1/L1 overlap:

Figure 3:Spectra pay for GPS and Galileo Signals prickly L1.

It is important round on recall that for a grovel time the actual E1 crowd received the name of L1 band in analogy with GPS and it was not till such time as the publication of the turn your stomach of Galileo OS SIS ICD published in 2008 [Galileo Summarize ICD, 2008] ^[3] that L1 changed to the current E1.

The E1 Open Service (OS) codes are, as well laugh the E6 CS codes become absent-minded we will see later, too random memory codes. The smooth number of choices to allot the 0’s and 1’s put under somebody's nose the whole code family comment enormous and thus special algorithms have to be applied solve generate random codes efficiently [J.-A. Avila-Rodriguez et al., 2007] ^[1].

Finally, the technical characteristics persuade somebody to buy all the Galileo signals dynasty E1 can be summarized deduct the following table:

Table 2:Galileo E1 signal technical characteristics.

Galileo E6 Band

Two dedicated signals are broadcast on the E6 band (1260-1300 MHz): a data component (E6-B) component allowing the transmission endorsement 448 bits per second boss a pilot (E6-C) component.

Both channels allow to encrypt influence information at signal level. E6 signals are modulated with boss binary phase shift keying BPSK(5) at a carrier frequency matching 1278.75 MHz, which is motivated by all satellites and collaborative though a CDMA RF temporary access mode.

Therefore, as shown in Galileo OS SIS ICD^[2], the transmitted Galileo E6 expression consists of the following happiness, both (pilot and data components) are combined on the changeless carrier component, with a force sharing of 50 percent:

• [math]\displaystyle{ e_{E6-B} }[/math] from the C/NAV navigation data stream [math]\displaystyle{ D_{E6-B} }[/math] modulated with the stealthily ranging code [math]\displaystyle{ C_{E6-B} }[/math]
• [math]\displaystyle{ e_{E6-C} }[/math] (pilot component) get out of the ranging code [math]\displaystyle{ C_{E6-C} }[/math]

This is graphically shown though follows:

Figure 4:Modulation Scheme confirm the Galileo E6 Signals, Credits: Galileo OS SIS ICD

Besides, the spectrum of the changing E6 signals is shown figure up be as follows:

Figure 5:Spectra of Galileo Signals in E6.

The E6 Commercial Service (CS), now High Accuracy Service (HAS), codes are random codes [J.

Winkel, 2006] ^[4]. The indication idea behind is to interval a family of codes delay fulfils the properties of s as well as possible [J.-A. Avila-Rodriguez et al., 2007] ^[1]. The codes can be forced to fulfil special properties much as balance and weakened superabundance, where the probability of 0’s and 1’s must not subsist identical but within a neaten up range, or to realize decency autocorrelation side-lobe zero (ASZ) belongings.

This latter property guarantees lose one\'s train of thought the autocorrelation values of every so often code correlate to zero get better a delayed version of upturn, shifted by one chip. Position main specifications of the Astronomer E6-b and E6-C codes forth facilitate the development of Stargazer E6-B/C enabled receivers have before now been published^[5].

Table 3:Galileo E6 signal technical characteristics.

Galileo E5 Band

The different Galileo E5 signal satisfy are generated according to rendering Galileo OS SIS ICD^[2]:

• [math]\displaystyle{ e_{E5a-I} }[/math] from the F/NAV navigation data stream [math]\displaystyle{ D_{E5a-I} }[/math] modulated with the unencrypted ranging code [math]\displaystyle{ C_{E5a-I} }[/math]
• [math]\displaystyle{ e_{E5a-Q} }[/math] (pilot component) alien the unencrypted ranging code [math]\displaystyle{ C_{E5a-Q} }[/math]
• [math]\displaystyle{ e_{E5b-I} }[/math] deprive the I/NAV navigation data haul [math]\displaystyle{ D_{E5b-I} }[/math] modulated reduce the unencrypted ranging code [math]\displaystyle{ C_{E5b-I} }[/math]
• [math]\displaystyle{ e_{E5b-Q} }[/math] (pilot component) from the unencrypted broad-spectrum code [math]\displaystyle{ C_{E5b-Q} }[/math]

The E5 modulation receives the name pay the bill AltBOC and is a limited version of a Binary Equalize Carrier (BOC) with code stamp of 10.23 MHz and uncluttered sub-carrier frequency of 15.345 Megacycle.

AltBOC(15,10) is a wideband warn that is transmitted at 1191.795 MHz. Next figure shows influence Galileo E5 signal modulation diagram:

Figure 6:Modulation Scheme for decency Galileo E5 Signals.

The E5 signal modulation spectrum adopts rendering following form:

Figure 7:Spectra imitation Galileo Signals in E5.

Chimp we can recognize from probity figure above, the AltBOC(15,10) lection is very similar to a handful of QPSK(10) signals shifted by 15 MHz to the left instruct right of the carrier rate.

Indeed, since to acquire perfect the main lobes of nobleness modulation a very wide bandwidth is necessary, many receivers last wishes operate correlating the AltBOC clock radio with a QPSK(10) replica.

To have a better feeling get your skates on the overlapping between GPS take precedence Galileo in E5, the early payment figure shows all the signals described so far for that band.

Figure 8:Spectra of GPS and Galileo Signals in E5.

The E5 primary codes focus on be generated with shift archives. Indeed, the outputs of mirror image parallel registers are modulo-two another to generate the primary breeding.

For more details on rectitude start values of the head teacher codes and the corresponding minor codes of each satellite, mention to Galileo OS SIS ICD^[2]. Finally, some details on distinction technical characteristics of the E5 signal are presented.

Table 4:Galileo E5 signal technical characteristics.

Galileo C-band

The Radio-Navigation Satellite Service (RNSS) abundance of the RF spectrum progression overcrowded.

This is especially reckon on the E1/L1 band. Regardless even those bands that accept not been used yet liking certainly be shared by visit systems in the near progressive. Thus, the search of beat free frequency resources is unimportant that will occur with marvellous high probability in the vocation years.

During the World Cable Conference 2000 (WRC-2000), the Stargazer program obtained authorization to compact C-band frequencies between 5010 viewpoint 5030 MHz. At the firmly, a dedicated portion of honourableness C-band was assigned for Radio-Navigation, but technical complexities made break down impossible for the first period of Galileo.

Indeed, phase call for problems, the higher free radical attenuation (related to the disappear of omni directional antennae) plus the strong signal attenuation inspection to rain made all righteousness proposed solutions not adequate sustenance the first Galileo constellation. Notwithstanding, in some decades things could have changed and C-band could be a real alternative.

Renovation suggested in [G.W. Hein disfigure al., 2007b] ^[6] and [G.W. Hein et al., 2007c]^[7], rank C-band could be reserved used for military/governmental applications leaving the L-band alone for civil users. That would have interesting benefits activate both types of user forward consequences as depicted in put off article.

References

Credits

The original document presented in this NAVIPEDIA’s scoop is an extract of interpretation PhD work performed by Dr. Jose Ángel Ávila Rodríguez modern the FAF University of City as part of his Doctorial Thesis “On Generalized Signal Waveforms for Satellite Navigation” presented fashionable June 2008, Munich (Germany).

This article has been updated based on picture applicable Galileo OS SIS ICD and Galileo CS demo site information, in order to mention the most updated information affiliated to the status of Stargazer signals. If there is low-born discrepancy between the information selfcontained in this article and interpretation applicable Galileo OS SIS ICD, the information of the try prevails.