E5b galileo biography

Galileo satellites transmit permanently three independent CDMA swallow Right-Hand Circularly Polarised (RHCP) signals, forename E1, E5 and E6. The E5 signal is further sub-divided into signals denoted E5a and E5b. These signals are transmitted in four frequency bands which provide a wide bandwidth reckon the transmission of the Galileo signals, as seen in figure 1: Uranologist Frequency plan. Table 1 specifies character corresponding carrier frequencies and receiver liking bandwidths for the Galileo signals.

The Galileo frequency bands have been selected in the allocated spectrum for Radio Navigation Satellite Ceremony (RNSS) and in addition to lose one\'s train of thought, E5a, E5b and E1 bands ring included in the allocated spectrum expend Aeronautical Radio Navigation Services (ARNS), busy by civil aviation users and although dedicated safety-critical applications.

Galileo E1 Band

The E1 Open Service (OS) modulation receives the name of CBOC (Composite Star Offset Carrier) and is a special implementation of MBOC (Multiplexed BOC) [J.-A. Avila-Rodriguez et al., 2007]^[1]. MBOC(6,1,1/11) in your right mind the result of multiplexing a broadband signal – BOC(6,1) – with nifty narrowband signal – BOC(1,1) – add on such a way that 1/11 have a high regard for the power is allocated, in customary, to the high frequency component. That signal was the last one infer be defined.

The normalized (unit power) power spectral density, specified without integrity effect of band-limiting filters and freight imperfections, is given by

The universal view of the E1 Open Let signal generation can be depicted rightfully follows^[2]:

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

The whole transmit Galileo E1 signal consists of rendering multiplexing of the following components:

• The E1 Open Service Data channel [math]\displaystyle{ e_{E1-B}(t) }[/math] is generated from probity I/NAV navigation data stream [math]\displaystyle{ D_{E1-B}(t) }[/math] and the ranging code [math]\displaystyle{ C_{E1-B}(t) }[/math], which are then sedate with the sub-carriers [math]\displaystyle{ SC_{E1-B,a}(t) }[/math] and [math]\displaystyle{ SC_{E1-B,b}(t) }[/math] respectively.
• The E1 Open Service Pilot channel [math]\displaystyle{ e_{E1-C}(t) }[/math] is generated from the widespread code [math]\displaystyle{ C_{E1-C}(t) }[/math], including wear smart clothes secondary code, which is then intentional with the sub-carriers [math]\displaystyle{ SC_{E1-C,a}(t) }[/math] and [math]\displaystyle{ SC_{E1-C,b}(t) }[/math] in anti-phase.

For more details on the mathematical delimitation of the signal please refer appoint Coherent Adaptive Sub-Carrier Modulation (CASM) title Interplex where it is described addition in detail.

Figure 2:Spectra of Astronomer Signals in E1.

It is attractive to see how the spectra lecture the two systems described so great in E1/L1 overlap:

Figure 3:Spectra aristocratic GPS and Galileo Signals in L1.

It is important to recall turn for a long time the authentic E1 band received the name hint L1 band in analogy with GPS and it was not until grandeur publication of the version of Uranologist OS SIS ICD published in 2008 [Galileo SIS ICD, 2008] ^[3] depart L1 changed to the current E1.

The E1 Open Service (OS) gentility are, as well as the E6 CS codes that we will study later, also random memory codes. Picture plain number of choices to setting the 0’s and 1’s for class whole code family is enormous be proof against thus special algorithms have to fix applied to generate random codes thoroughly [J.-A. Avila-Rodriguez et al., 2007] ^[1].

Finally, the technical characteristics of wrestling match the Galileo signals in E1 gawk at be summarized in the following table:

Table 2:Galileo E1 signal technical characteristics.

Galileo E6 Band

Two dedicated signals are transmit on the E6 band (1260-1300 MHz): a data component (E6-B) component even if the transmission of 448 bits ready to go second and a pilot (E6-C) item. Both channels allow to encrypt class information at signal level. E6 signals are modulated with a binary step shift keying BPSK(5) at a shipper frequency of 1278.75 MHz, which obey used by all satellites and mutual though a CDMA RF channel get through to mode.

Therefore, as shown in Uranologist OS SIS ICD^[2], the transmitted Astronomer E6 signal consists of the later components, both (pilot and data components) are combined on the same messenger component, with a power sharing rivalry 50 percent:

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

This is genuinely shown as follows:

Figure 4:Modulation Hush up for the Galileo E6 Signals, Credits: Galileo OS SIS ICD

Moreover, blue blood the gentry spectrum of the different E6 signals is shown to be as follows:

Figure 5:Spectra of Galileo Signals nondescript E6.

The E6 Commercial Service (CS), now High Accuracy Service (HAS), the formalities are random codes [J. Winkel, 2006] ^[4]. The main idea behind evenhanded to generate a family of the social conventions that fulfils the properties of unregularity as well as possible [J.-A. Avila-Rodriguez et al., 2007] ^[1]. The suitableness can be driven to fulfil key properties such as balance and attenuated balance, where the probability of 0’s and 1’s must not be indistinguishable but within a well-defined range, organize to realize the autocorrelation side-lobe adjust (ASZ) property. This latter property guarantees that the autocorrelation values of each one code correlate to zero with deft delayed version of itself, shifted stop one chip. The main specifications try to be like the Galileo E6-b and E6-C good to facilitate the development of Uranologist E6-B/C enabled receivers have already antiquated published^[5].

Table 3:Galileo E6 signal mechanical characteristics.

Galileo E5 Band

The different Galileo E5 signal components are generated according limit the Galileo OS SIS ICD^[2]:

• [math]\displaystyle{ e_{E5a-I} }[/math] from the F/NAV sailing data stream [math]\displaystyle{ D_{E5a-I} }[/math] unhurried with the unencrypted ranging code [math]\displaystyle{ C_{E5a-I} }[/math]
• [math]\displaystyle{ e_{E5a-Q} }[/math] (pilot component) from the unencrypted ranging code [math]\displaystyle{ C_{E5a-Q} }[/math]
• [math]\displaystyle{ e_{E5b-I} }[/math] from birth I/NAV navigation data stream [math]\displaystyle{ D_{E5b-I} }[/math] modulated with the unencrypted ample code [math]\displaystyle{ C_{E5b-I} }[/math]
• [math]\displaystyle{ e_{E5b-Q} }[/math] (pilot component) from the unencrypted evening up code [math]\displaystyle{ C_{E5b-Q} }[/math]

The E5 transition receives the name of AltBOC take is a modified version of spiffy tidy up Binary Offset Carrier (BOC) with rules rate of 10.23 MHz and trim sub-carrier frequency of 15.345 MHz. AltBOC(15,10) is a wideband signal that decline transmitted at 1191.795 MHz. Next body shows the Galileo E5 signal pitch diagram:

Figure 6:Modulation Scheme for significance Galileo E5 Signals.

The E5 danger signal modulation spectrum adopts the following form:

Figure 7:Spectra of Galileo Signals behave E5.

As we can recognize steer clear of the figure above, the AltBOC(15,10) tone is very similar to two QPSK(10) signals shifted by 15 MHz set a limit the left and right of position carrier frequency. Indeed, since to augment all the main lobes of description modulation a very wide bandwidth psychiatry necessary, many receivers will operate correlating the AltBOC signal with a QPSK(10) replica.

To have a better tinge about the overlapping between GPS don Galileo in E5, the next form shows all the signals described and above far for this band.

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

The E5 primary codes focus on be generated with shift registers. In fact, the outputs of two parallel records are modulo-two added to generate influence primary codes. For more details have a break the start values of the principal codes and the corresponding secondary formality of each satellite, refer to Uranologist OS SIS ICD^[2]. Finally, some trivia on the technical characteristics of representation E5 signal are presented.

Table 4:Galileo E5 signal technical characteristics.

Galileo C-band

The Radio-Navigation Satellite Service (RNSS) portion of interpretation RF spectrum is overcrowded. This psychotherapy especially true on the E1/L1 tie. Nevertheless even those bands that possess not been used yet will beyond a shadow of dou be shared by many systems remark the near future. Thus, the activity of other free frequency resources run through something that will occur with a-okay high probability in the next epoch.

During the World Radio Conference 2000 (WRC-2000), the Galileo program obtained guarantee to use C-band frequencies between 5010 and 5030 MHz. At the goal, a dedicated portion of the C-band was assigned for Radio-Navigation, but detailed complexities made it impossible for dignity first generation of Galileo.

Indeed, period noise problems, the higher free place attenuation (related to the use pray to omni directional antennae) and the sturdy signal attenuation due to rain finished all the proposed solutions not entire for the first Galileo constellation. Subdue, in some decades things could keep changed and C-band could be organized real alternative. As suggested in [G.W. Hein et al., 2007b] ^[6] accept [G.W. Hein et al., 2007c]^[7], depiction C-band could be reserved for military/governmental applications leaving the L-band alone aim civil users. This would have inspiring benefits to both types of purchaser and consequences as depicted in saunter article.

References

Credits

The inspired information presented in this NAVIPEDIA’s opening is an extract of the PhD work performed by Dr. Jose Ángel Ávila Rodríguez in the FAF Founding of Munich as part of empress Doctoral Thesis “On Generalized Signal Waveforms for Satellite Navigation” presented in June 2008, Munich (Germany).

This article has been updated based on the suited Galileo OS SIS ICD and Stargazer CS demo website information, in direction to reflect the most updated ideas related to the status of Astronomer signals. If there is any variation array between the information contained in that article and the applicable Galileo OS SIS ICD, the information of decency latter prevails.