Calculation of IF Bandwidth and Peak Frequency Deviation
2.6.4.1 IF Bandwidth. The IF of a FM receiver must accommodate the RF bandwidth, which consists of the total peak deviation spread and a number of generated sidebands. The IF bandwidth can be estimated from Carson's rule, where A Fp is the peak frequency deviation and Fm is the highest modulating frequency given in the middle column of Table 2.5. 2.6.4.2 Frequency Deviation. The value of AFp in equations 2.17 and 2.18 below is peak deviation. The peak deviation for a particular link should be...
References Whg
1. H. J. Liebe, Atmospheric Propagation Properties in the 10 to 75 GHz Region A Survey and Recommendations, ESSA Technical Report ERL 130-ITS 91, Boulder, CO, 1969. 2. Attenuation by Atmospheric Gases, ITU-R P.676-6, 2005. 3. D. C. Hogg, ''Millimeter-Wave Propagation Through the Atmosphere, Science, 1968. 4. R. K. Crane, Prediction of the Effects of Rain on Satellite Communications Systems,'' Proceedings of the IEEE, Vol. 65, pp. 456-474, 1977. 5. Recommendations and Reports of the CCIR, CCIR...
References Yhr
1. General Engineering Beyond-Horizon Radio Communications, USAF T.O. 31Z-10-13, U.S. Department of Defense, Washington, DC, Oct. 1971. 2. Military Handbook Facility Design for Tropospheric Scatter Transhorizon Microwave System Design , MIL-HDBK-417, U.S. Department of Defense, Washington, DC, Nov. 1977. 3. P. L. Rice, A. C. Longley, K. A. Norton, and A. P. Barsis, Transmission Loss Prediction for Tropospheric Communication Circuits, NBS Tech. Note 101, U.S. National Bureau of Standards,...
Info Dau
12.25 effectively, we need to know the gyrofrequency for the region of interest. We can derive this value from Figure 12.26. Example 3. A certain HF path operates during a sunspot number 100, the operating frequency is 18 MHz, and the elevation or TOA is 10 . Calculate the D-layer absorption value for 12 noon local time at midpath for the Figure 12.25. Nomogram for obtaining the ionospheric absorption per hop from the absorption index I, the effective wave frequency f fH, and the angle of...
Info Uss
aAt 20 GHz the specific attenuation A 0.006 fl 12 dB km and for Rosman, NC, the effective path length is 5.1 km to ATS-6. bFor a ground temperature of 17 C 63 F, the Tm 275 K. Source Reference 16. aAt 20 GHz the specific attenuation A 0.006 fl 12 dB km and for Rosman, NC, the effective path length is 5.1 km to ATS-6. bFor a ground temperature of 17 C 63 F, the Tm 275 K. Source Reference 16. Example 3. From Table 9.6 with a total rain attenuation of 11 dB, what is the sky noise at 20 GHz Assume...
Effective Length Average Height and Radius of Meteor Trails
Consider the ray geometry for a meteor burst propagation path as shown in Figure 13.7 between transmitter T and receiver R. P represents the tangent point and P' a point further along the trail such that R1 R'2 exceeds R1 R2 by half a wavelength. Thus PP' of length L lies within the principal Fresnel zone and the total length of the trail within this zone is 2L. Provided R1 and R2 are much greater than L, it follows that 5 angle between the trail axis and the plane of propagation A wavelength...
Problems And Exercises Wsv
1 Above 10 GHz, there are two additional degradations to path loss that we must take into account. What are they 2 There are two frequency bands between 10 and 100 GHz that display high attenuation due to atmospheric gases. What bands are these Which one displays excessively high attenuation, making it unusable for most earth-bound applications. 3 Discuss two practical applications of the high-loss band in question 2. 4 Argue why cumulative annual rainfall rates may not be used for calculation...
Info Oqj
Figure 6.22. Ku-band frequency polarization plan for Galaxy VII. From Ref. 27. Figure 6.23. Ku-band EIRP contours in qdBW for Galaxy VII, 91 W longitude for vertical polarization. Figure 6.23. Ku-band EIRP contours in qdBW for Galaxy VII, 91 W longitude for vertical polarization. G T - - SFD 87.4 7 dB COMMANDABLE STEP ATTENUATION G T - - SFD 87.4 7 dB COMMANDABLE STEP ATTENUATION Figure 6.24. Ku-band saturation flux density SFD contours for Galaxy VII, 91 W longitude for horizontal...
Propagation Effects With A Low Elevation Angle
As the elevation angle of an earth terminal is lowered, the ray beam penetrates an ever increasing amount of atmosphere. Below about 10 , fading on the downlink signal must be considered. Fading or signal fluctuations apply only to the ground terminal downlink because its antenna is in close proximity to a turbulent medium. The companion uplink satellite path will suffer uplink fluctuation gain degradation only due to scattering of energy out of the path Ref. 16 . Because of the large distance...
Eirp 1
MBC transmission loss Receiver antenna gain 73 dBm -180 dB 13 dB -94 dBm 107 dBm 13 dB occurring, of course, toward the end of a trail's useful life. Coding with appropriate interleaving is one method of mitigating these multipath effects. D-layer absorption often is neglected in link budget analyses of meteor burst links. We discuss D-layer absorption and its calculation in Chapter 12. Another source is CCIR Rep. 252-2 Ref. 10 . D-layer absorption, a daytime-only phenomenon, may exceed 3 dB at...
TDMA System Clocking Timing and Synchronization It was
previously stressed that an efficient TDMA system must have no burst overlap, on the one hand, and as short a guard time as possible between bursts, on the other hand. We are looking at guard times in the nanosecond regime. The satellites under discussion here are geostationary. For a particular TDMA system, the range to a satellite can vary from 23,000 to 26,000 statute miles. We can express these range values in time equivalents by dividing by the velocity of propagation in free space or...
Vswr 10
Ambient Temperature 24 C 75 F Atmospheric pressure, dry air Figure 15.9. Loss versus frequency for air dielectric coaxial cable. Courtesy of the Andrew Corporation Ref. 7. There are a number of important parameters to be considered for the application of coaxial cable as a transmission line. Probably the most important for the system engineer is attenuation or loss as shown in Figures 15.8 and 15.9. Loss varies with ambient temperature. The reference value in the figures is 24 C 75 F . Figure...
Info Hwz
aGeneral allocation to PCS, licensees may use PACS. Source Table 2, p. 35 Ref. 19 . aGeneral allocation to PCS, licensees may use PACS. Source Table 2, p. 35 Ref. 19 . Figure 10.26. Scenario for PCS within IMT-2000 terrestrial component. From Ref. 28 Figure 1, p. 8, ITU-R M.687-2, 1997. Figure 10.26. Scenario for PCS within IMT-2000 terrestrial component. From Ref. 28 Figure 1, p. 8, ITU-R M.687-2, 1997. 10.11 FUTURE PUBLIC LAND MOBILE TELECOMMUNICATION SYSTEM FPLMTS FPLMTS is a cellular PCS...
Digital Los Microwave Terminals
Figure 15.3 is a functional block diagram of a typical digital microwave radio terminal. Starting from the bottom of the figure on the transmit side left side , there are a number of baseband processing conditioning functions. The line code converter takes the standard PCM line codes e.g., DS1, DS3, E1, E2, E3, etc. , which have been implemented for good baseband transmission properties over wire systems, and converts the code, usually to a NRZ format. The resulting code is then scrambled by...
G Ncs
where y is the effective noise temperature of each amplifier or device and G is the numeric equivalent of the gain or loss of the device. Example 8. Compute Tr for the first three stages of a receiving system. The first stage is a LNA with a noise figure of 1.1 dB and a gain of 25 dB. The second stage is a lossy transmission line with 2.2-dB loss. The third and final stage is a postamplifier with a 6-dB noise figure and a gain of 30 dB. Frequency 12 GHz Figure 6.10. Example earth station...
Info Hag
2.2 Initial Planning and Site Selection, 38 2.2.1 Requirements and Requirements Analyses, 38 2.2.2 Route Layout and Site Selection, 40 2.3.1 Determiniation of Median Value for -Factor, 46 2.6.2 Unfaded Signal Level at the Receiver, 55 2.6.3 Receiver Thermal Noise Threshold, 58 2.6.4 Calculation of IF Bandwidth and Peak Frequency Deviation, 61 2.6.5 Pre-emphasis De-emphasis, 64 2.6.6 Calculation of Median Carrier-to-Noise Ratio Unfaded , 67 2.6.7 Calculation of Antenna Gain, 69 2.7 Fading,...
Problems And Exercises Hqz
1 Define EMC and name and discuss its two subsets. 2 Name at least three measures we can take at the outset to reduce interference and its effects on with radio systems. 3 One area of concern is a receiver's IF. With careful frequency planning, we avoid three frequencies referenced to the IF. What are they 4 LOS microwave and satellite communication systems share the same frequency bands. A satellite communication transponder sprays the earth with RF energy. What did we learn prior to this...
Regulatory Issues
The U.S. regulatory agency, the FCC, has long recognized that conventional digital modulation schemes such as FSK and BPSK QPSK were not bandwidth conservative, requiring in Part 101.141 the FCC Rules, of Rules and Regulations'' Ref. 3 that Microwave transmitters employing digital modulation techniques and operating below 25.25 GHz except for MVDDS stations in the 12,200-12,700 MHz band must, with appropriate multiplex equipment, comply with the following additional requirements 1. The bit...
References Vah
1. The New IEEE Standard Dictionary of Electrical and Electronic Terms, 7th ed., IEEE Std. 100, IEEE, New York, 2001. 2. Intermediate-Frequency Characteristics for the Interconnection of Analog Radio-Relay Systems, ITU-R F.403-3, 1970. 3. Roger L. Freeman, Telecommunication Transmission Handbook, 4th ed., Wiley, New York, 1998. 4. Roger L. Freeman, Reference Manual for Telecommunications Engineering, 3rd ed., Wiley, New York, 2001. 5. Design Handbook for Line-of-Sight Microwave Communication...
Info Qbj
Table 4.5 shows the maximum free distance for R 1 2 systematic and nonsystematic codes for K 2 through 5. It should be noted that for large constraint lengths the results are even more widely separated. 4.2.5 Channel Performance of Uncoded and Coded Systems 4.2.5.1 Uncoded Performance. For uncoded systems a number of modulation implementations are reviewed in the presence of additive white Gaussian noise AWGN and with Rayleigh fading. The AWGN performance of BPSK, QPSK, and 8-ary PSK is shown...
Info Uom
Figure 9.3. Average rain cell size as a function of rain rate. From CCIR Rep. 593-1 Ref. 5. The application of specific rain cell size was taken from CCIR 1978. We will call this method the liberal method''because when reviewing CCIR Vol. V of 1990, CCIR Rep. 563-4 Ref. 7 , we can see that the CCIR has turned more cautious and conservative. Our Figure 9.3 does not appear in the report. Let us partially quote from this report For attenuation predictions the situation is generally more complex...
Excess Attenuation Due To Rainfall
Of the factors a through e in equation 9.1 , factor e, excess attenuation due to rainfall, is the principal one affecting path loss. For instance, even at 22 GHz for a 10-km path only 1.6 dB must be added to free-space loss to compensate for water vapor loss. This is negligible when compared to free-space loss itself, such as 119.3 dB for the first kilometer at 22 GHz, accumulating thence approximately 6 dB each time the path length is doubled i.e., add 6 dB for 2 km, 12 dB for 4 km, etc. ....
Skywave Transmission
The skywave transmission phenomenon of HF depends on ionospheric refraction. Transmitted radio waves hitting the ionosphere are bent or refracted. When they are bent sufficiently, the waves are returned to earth at a distant location. Often at the distant location they are reflected back to the sky again, only to be returned to earth still again, even further from the transmitter. The ionosphere is the key to HF skywave communication. Look at the ionosphere as a layered region of ionized gas...
Introduction To Tropospheric Scatter Propagation
The picture of the tropospheric scatter mechanism is still pretty speculative. One reasonable explanation is expressed in USAF Technical Order 31Z-10-13 Ref. 1 . It states that the ability of the troposphere to act as a refractive medium is based on the variations of refractivity caused by heating and cooling of the atmosphere's water content. The variation is inversely proportional to altitude, with the greatest variation taking place nearest the earth's surface. The atmosphere is constantly...
Victim Digital Systems
This text emphasizes digital operation. What special considerations must be taken into account for interference into such digital radio systems As we mentioned earlier, interference into a digital receiver causes threshold degradation. Picture this as an increase in the receiver noise level. Interference can eat into an Eb N0 ratio value or wipe it out completely, making the system unworkable. Looking at it another way, interference increases the N0 value. Remember that our outage threshold on...
Random Access
8.4.1.1 Pure Aloha . Random access schemes lend themselves well to short and bursty traffic. In this case, the inbound channel is shared by several or many VSATs. This is really a contention scheme. When a VSAT has traffic, it bursts the traffic on the inbound channel, taking a chance that another VSAT is not transmitting at the same time. If there is a collision in other words, another VSAT is transmitting traffic at the same time the traffic is corrupted, and both VSATs must try again. Each...
Info Hge
1. If values for columns A and B are not available from the manufacturer s of the antenna system or from the user of the antenna system, then values shall be obtained from Figure C1, C2, or C3 in the reference publication . 2. Limits of beam movement for twist or sway treated separately in most analyses will be the sum of the appropriate figures in columns C and D, G and H, and G and I. Columns G, H, and I apply to a vertical periscope configuration. 3. It is not intended that the values in...
Info Inn 1
aBy convention, the sign of the parabolic component of the satellite group delay is positive, and therefore the earth stations should insert a negative value to achieve equalization. bThese parameters apply if group delay compensation is provided over the full transponder, rather than on a per-carrier basis. Typical transponder group delay characteristics can be supplied upon request for transponder bandwidth units greater than 72 MHz. Source Table 4, INTELSAT IESS-308 Rev. 7A Ref. 14 . aBy...
Info Txa
Source Courtesy of Scientific-Atlanta Ref. 16 . Source Courtesy of Scientific-Atlanta Ref. 16 . 4 Argue the operational advantages of TDMA versus FDMA. 5 Name factors limiting TDMA digital throughput. 6 Explain the rationale for using CR BTR and its location in a typical TDMA user frame. 7 There are three generic approaches to digital bent-pipe operation and access. Name them. 8 In which mode of operation access would we expect to use INTELSAT IDR and IBS 9 All INTELSAT IDR offerings use FEC...
Path Analysis Worksheet And Example
A path analysis worksheet is a useful tool for carrying out a path analysis or link budget.'' The bottom line, so to speak, of the worksheet for an analog radiolink is the noise in the worst FDM channel, usually the highest or top voice channel in the baseband. The worksheet sets out in tabular form the required calculations starting with transmitter power output, the various losses and gains from the transmitter outward through the medium, receive antenna system to the input port of the far...
Digital Speech Interpolation
DSI is designed for speech operation to increase system capacity. It is based on the fact that there is active speech on a full duplex voice circuit only a fraction of the time. For one thing, there is the talk-listen effect. In normal operation, while one end of a speech circuit talks, the other end listens. For this effect alone, there is only 50 usage. Also, there are many pauses in normal speech. DSI exploits these periods of nonusage and speech pauses. A similar system was implemented on...
Scintillation Fading On Satellite Links
Scintillation, as defined by the IEEE Dictionary Ref. 25 , ''is the phenomenon of fluctuation of the amplitude of a wave caused by irregular changes in the transmission path or paths with time.'' On satellite paths operating above 10 GHz, scintillation can become an issue as the elevation angle reaches about 15 , and its intensity grows as the angle is lowered still further. In the Canadian Arctic, fade depths have been reported up to 30 dB at 1 elevation angle and at 30 GHz CCIR Rep. 564-4,...
Mitigation Techniques for Multipath Fading
In analog radiolink systems, multipath fading results in an increase in thermal noise as the RSL drops. In digital radio systems, however, there is a degradation in BER during periods of fading that is usually caused by intersymbol interference due to multipath. Even rather shallow fades can cause relatively destructive amounts of intersymbol interference. This interference results from frequency-dependent amplitude and group delay changes. The degradation depends on the magnitude of in-band...
Problems And Exercises Hhk
1 Draw a simplified functional block diagram of a basic generic radio communications terminal. It should have, as a minimum, nine blocks. 2 Why are almost all LOS microwave facilities being installed today digital rather than analog aside from STL 3 List similarities and differences between analog LOS microwave terminals and digital terminals. 4 Calculate the gain of a radiolink parabolic dish antenna with a 4-ft aperture at 12 GHz. Assume a 55 efficiency. Increase the efficiency to 65 . What...
Basic Forward Error Correction
The IEEE Ref. 3 defines a forward error-correcting system as a system employing an error-correcting code and so arranged that some or all of the signals detected as being in error are automatically corrected at the receiving terminal before delivery to the data sink or to the telegraph receiver.'' Our definition may help clarify the matter. FEC is a method of error control that employs the adding of systematic redundancy at the transmit end of a link such that many or all of the errors caused...
CELLULAR AND PCS INSTALLATIONS ANALOG AND DIGITAL 1561 Introduction
The goal of this section is to describe cellular installations and PCS facilities, which we will consider as an extension of cellular. In Chapter 10, three basic, generic modulation access schemes were described FDMA typified by AMPS and N-AMPS, TDMA typified by the North American IS-54 standard and the European GSM standard, and, finally, CDMA typified by the North American IS-95 standard. In large cellular schemes all three access modulation types require cells or base stations with their...
Very Small Aperture Terminals VSATs
VSAT networks are specialized satellite networks principally used for data traffic. In Chapter 8, Figure 8.1, we saw that a VSAT network most commonly consists of a hub and a series of small outstation satellite terminals, which we call VSATs. Small VSATs have parabolic dish antennas with diameters ranging from 0.5 m for a very modest installation to up to 2.4 m for a much higher capacity installation. Hubs are much larger facilities to compensate somewhat for the small disadvantaged VSATs. One...
LINK BUDGETS FOR DIGITAL SATELLITES 771 Commentary
The link budget, of course, is the primary tool for dimensioning both earth station terminals and their companion satellites. It is used for trade-offs of performance versus cost cost because we are dimensioning equipment . The approach we use is almost identical to that described in Section 6.3.9. Rather than S N, we use Eb N0, which was described in Chapter 3. Performance may be enhanced on digital circuits by the use of FEC forward error correction , with or without interleaving. FEC and...
Mba
Isotropic receive level International switching center Integrated services digital network Intersymbol interference Intersatellite link International Standards Organization Iridium subscriber unit International Telecommunications Union ITU Telecommunications Standardization Sector previously CCITT ITU Radiocommunications Sector previously CCIR 28-30-GHz satellite uplink band, microwave LOS band kilobits per second kilometer kilohertz 14 12 11-GHz satellite communication band microwave LOS band...
V
Conventionally, we require 0.6 Fresnel zone clearance of the beam edge 3-dB point due to obstacles in the path. Figure 1.10 shows path attenuation versus path clearance. Providing 0.6 Fresnel zone clearance usually is sufficient to ensure that attenuation due to an obstacle in or near the ray beam path is negligible. Reference 4 gives some practical Fresnel zone clearance guidelines related to -factor Although there are some variations, there are two basic sets of clearance criteria which are...
Acquisition and Synchronization
In this context acquisition is the process by which a TDMA terminal initially places its burst into the assigned position within a TDMA frame. To start the procedure, a terminal must acquire and maintain reception of the reference bursts. There are primary reference bursts PRBs and secondary reference bursts SRBs . Normally the PRB is used by an acquiring station. If it fails, it may use the SRB to start the acquisition phase. A terminal may enter the acquisition phase if it receives, via the...
G 1
where G is the receiving system antenna gain and T better expressed as Tsys is the receiving system noise temperature. Now we offer a word of caution. When calculating G T for a particular receiving system, we must stipulate where the reference plane is. In Figure 6.6 it was called the ''reference point.'' It is at the reference plane where the system gain is measured. In other words, we take the gross antenna gain and subtract all losses ohmic and others up to that plane or point. This is the...
NETWORK ACCESS TECHNIQUES 1061 Introduction
The objective of a cellular radio operation is to provide a service where mobile subscribers can communicate with any subscriber in the PSTN, where any subscriber in the PSTN can communicate with any mobile subscriber, and where mobile subscribers can communicate among themselves via the cellular radio system. In all cases the service is full duplex. A cellular service company is allotted a radio bandwidth segment to provide this service. Ideally, for full duplex service, a portion of the band...
Personal Communication Services PCS
PCS is difficult to strictly define. It is a radio system it is small it can provide multiple services and it often can be considered an extension of cellular radio. Consider that paging, various types of remote control devices, cordless telephones, wireless PBXs, and wire loop replacement and wireless LANs may be considered PCSs. In our brief discussion below, we will consider only wireless telephones, which are operated in a cellular-like manner. Of course, in this case, cells are much...
Troposcatter Frequency Bands And The Sharing With Space Radiocommunication
Radio Regulations RR Article 27 is not only applicable to LOS microwave but also to transhorizon radio systems. Its main points are that EIRP shall not exceed 55 dBW and that the power delivered by a transmitter to an antenna shall not exceed 13 dBW in the fixed or mobile service in the frequency bands between 1 and 10 GHz. Most transhorizon systems exceed these limits. RR Article 27 recognizes that transhorizon systems in the ranges 1700-1710 MHz, 1970-2010 MHz, 2025-2110 MHz, and 2200-2290...
ACCESS TECHNIQUES 641 Introduction
Access refers to the way in which a communication system uses a satellite transponder. There are three basic access techniques 1. FDMA frequency division multiple access 2. TDMA time division multiple access 3. CDMA code division multiple access With FDMA a satellite transponder is divided into frequency band segments, where each segment is assigned to a user. The number of segments can vary from one, where an entire transponder is assigned to a single user, to literally hundreds of segments,...
Info Gac
1 Noise bandwidth equal to postdetection bandwidth of receiver. For an independent-sideband telephony, noise bandwidth equal to the postdetection bandwidth of one channel. 2 The figures in this column represent the ratio of signal peak envelope power to the average noise power in a 1-Hz bandwidth except for double-sideband A3E emission where the figures represent the ratio of the carrier power to the average noise power in a 1-Hz bandwidth. 3 The values of the radio-frequency signal-to-noise...
INTELSAT Standard E Earth Stations
The Standard E earth station is designed primarily for the business service'' and operates in the nominal 14 11-GHz band pair utilizing INTELSAT V, VA, VI, VII, and VIII satellites. The business service basically provides users with data connectivity using standard E-1 and DS1 formats up to and including E-3 DS3 rates. This type of transmission is covered in Chapter 7. Two grades of IBS are offered on the INTELSAT V through VI satellites Basic and Super. Basic IBS is designed to maximize...
Fade Depth And Fade Duration
The most common type of fading is multipath fading. System design requires knowledge of the annual amount of time during which multipath fading reduces the RSL to a value that is much lower than the nominal level. RSL, of course, is a power level measured in dBW or dBm. Let p, then, denote the RSL in the presence of fading, and p0 the power level RSL without fading. The time of interest is that during which the ratio p p0 is less than a quantity L2, where 20 log L describes the fade level in...
Info Ajb
C N 53 dB unfaded to meet the objective of 99.95 time availability. Allowing the validity of the pure Rayleigh assumption, the unavailability of the link is 1 - 0.9995 or 0.0005. A year has 8760 h or 8760 X 60 min. Thus the total time in a year when the C N would be less than 20 dB would be 0.0005 X 8760 X 60 or 262.8 min. 2.7.2.2 Path Classification Method 1. This method of quantifying fade margin is based on Ref. 7 and applies only to those paths that are over land and with unobstructed LOS...