ISSN:0737-2884    

DOI:10.1002/sat.4600070402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600070403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractAn increasing number of advanced signal processing techniques are being investigated in satellite communications systems as the ground and space segments require more and more sophisticated, light‐weight, low‐power‐consumption and cost‐effective equipment.RF signal processing techniques based on surface acoustic wave (SAW) devices can be suitably exploited in these systems, constituting a valid alternative to digital baseband processing.This paper aims at presenting the most recent applications of SAW devices to RF signal processing in satellite communication systems. They span the frequency range from about 10 MHz to 10 GHz. Interaction of SAWs with laser beams is also illu

ISSN:0737-2884    

DOI:10.1002/sat.4600070404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractMarket growth in the area of thin route satellite communications services has led to consideration of non‐traditional system architectures requiring sophisticated on‐board processing functions. Surface acoustic wave (SAW) technology exists today which can provide implementation of key on‐board processing subsystems by using multicarrier demodulators. This paper presents a review of this signal processing technology, along with a brief review of dispersive SAW device technology as applied to the implementation of multicarrier demodulators for on‐board signal pro

ISSN:0737-2884    

DOI:10.1002/sat.4600070405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper reports on the work done at ELAB‐RUNIT on surface acoustic wave (SAW) on‐board signal processing. The main processing is done by the analogue chirp Fourier transformer (CFT) and its inverse (ICFT). In a CFT, the input signal is transformed from an FDMA format to a TDM format and at the same time filtered by a filter bank. By multiplying and convolving the signal with chirp waveforms, the CFT is implemented by one bandpass cover filter and one chirp filter. The paper demonstrates that SAW reflector array compressors (RAC) built by ELAB‐RUNIT have suitable chirp responses and adequate precision for digital satellite communication. Two applications are described. An on‐board multicarrier demodulator (MCD) for 9·6 kb/s QPSK carriers and a processor for filtering, routeing and beam steering (FROBE) for flexible transparent repeaters. For MCDs the use of SAW CFTs leads to a power consumption for demultiplexing and A/D conversion of 15 mW per carrier with room for improvements. For transparent paylods, the FROBE leads to more flexibility and narrower guardbands than can be obtained by other analogue pr

ISSN:0737-2884    

DOI:10.1002/sat.4600070406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractOne key technology, for the implementation of future on‐board processing payloads, is the multicarrier demodulator (MCD). The MCD is instrumental in allowing FDMA/TDM access schemes which optimize the use of on‐board and ground resources in VSAT networks. This paper deals with the analogue and digital implementations of MCD, trying to assess the fields of application of each of the two technolog

ISSN:0737-2884    

DOI:10.1002/sat.4600070407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractSevere RF spectrum limitations imposed by international regulations make filtering, and principally channel filtering, a key parameter of the mobile satellite service. About 30 MHz is available atL‐band for maritime, aeronautical and land mobile users, and must be shared between all potential service providers! Furthermore, this band must also accommodate signals with characteristics as dissimilar as: data at low and high bit rates, digital and analogue voice. Even worse, the transmissions are to be done with different categories of users, having terminals withG/Tin the range of −4 to −24 dB/K.If the satellite payload provides a global earth coverage the RF spectrum will have to be channelized so that the various types of signals can be efficiently handled. This is what happens in the return transponder of the INMARSAT second‐generation satellite.If, as anticipated for future mobile satellite systems, spot beams are implemented, further channelization becomes necessary to provide the maximum of flexibility in the channel to beam allocation.In either case, a minimum of bandwidth can be wasted in the guardbands, while at the same time hardly any distortion is to be tolerated in the useful passband.The present article will illustrate, with two examples, how these drastic filtering requirements can be best fulfilled with surface acoustic wave tec

ISSN:0737-2884    

DOI:10.1002/sat.4600070408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe Japanese spacecraft ETS‐V implemented an experimental mobile satellite communication system via a transponder called AMEX (aeronautical maritime experimental transponder).L‐band was used for the mobile link andC‐band for the feeder link. For theL‐band two‐beam system routeing and filtering were performed through 12 SAW filters and four switches in the IF part. The effective frequency allocation plan was obtained considering the features of the links used and the characteristics of SAW filters. The filtering to prevent EMC problems was also studied for AMEX, which handles high‐ and low‐level signals simultaneously. AMEX shows good performance in orbit and is being used for a variety of mobile communication experiments by many organizations including the Communications Resear

ISSN:0737-2884    

DOI:10.1002/sat.4600070409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe present paper reports the design of a SAW filter bank consisting of 26 linear phase filters with bandwidths ranging from 60 to 2180 kHz, 0·5/40 dB transition width narrower than 30 kHz and stopband rejection as high as possible. Passbank amplitude and phase ripple limits are 1 dB and 4° peak‐to‐peak respectively. Three candidate filters of bandwidth 60 kHz, 400 kHz and 2·180 MHz were selected for detailed design, taking into account spurious effects such as acoustic regeneration and diffraction as well as technology limits. Since the physical length of a SAW filter—as any transversal (FIR) filter—is determined by (i) the required passband amplitude ripple, (ii) the stopband rejection level and (iii) the transition width, the steepness of the required passband‐to‐stop band transitions in these filters dictates their physical size to be unusually large, resulting in an overall size for each packaged filter of 360 × 38 × 17 mm, i.e. 14·2 × 1·5 × 0·7 inches. The electrical specifications are met by all but the 2180 kHz filter, whose shape factor, for a 30 kHz transition band, would be 1·027 : 1, beyond the state of the art. The filter bank has about 27 dB insertion loss per filter, plus roughly 14 dB (1

ISSN:0737-2884    

DOI:10.1002/sat.4600070410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractSAW oscillators can provide fundamental frequency operation to above 1·5 GHz, with stability and FM noise performance approaching that offered by bulk crystal oscillator technology. Their high fundamental frequency, small size and rugged construction gives SAW technology a unique capability at UHF and microwave frequencies.The low FM thermal noise floor associated with fundamental frequency operation can be combined with the stability and low close‐to‐carrier noise of multiplied bulk crystal oscillators by locking a high frequency SAW oscillator to a bulk crystal reference. SAW oscillator stability is compatible with conventional phase‐locked‐loop techniques and also with injection lock stabilization, and their own low close‐to‐carrier FM noise ensures that such locked sources exhibit minimum phase noise. Furthermore, locked oscillator phase noise is not significantly degraded when extreme operating conditions, such as those experienced in space applications, demand a reduced SAW deviceQfor reliable locking using either technique.Use of a PLL avoids any need for reference frequency multiplication, and provides additional design flexibility with respect to reference frequency selection and phase noise optimization. Injection locking offers design simplicity and uses fewer frequency control components, which can contribute additional noise in

ISSN:0737-2884    

DOI:10.1002/sat.4600070411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY