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BPSK
milstar: Missions not requiring a residual carrier and having modest data rates (20 ks/s - 200 ks/s) should consider BPSK/NRZ modulation first. ######################## nonreturn-to-zero (NRZ) to binary phase-shift keying It provides a good compromise between spectrum efficiency and simplicity of design. While data imbalance does not result in system losses as in the case of PCM/PM/NRZ modulation, the statistics of each application should be reviewed. Agencies employing a DTTL architecture in their symbol synchronizers, must ensure a sufficient transition density to acquire and maintain synchronization. Manchester encoding prior to BPSK modulation can ensure sufficient transitions. As with PCM/PM/Bi-N modulation, there is a 100% penalty in spectrum efficiency over the NRZ equivalent https://deepspace.jpl.nasa.gov/files/phase3.pdf https://deepspace.jpl.nasa.gov/dsndocs/810-005/208/208B.pdf
milstar: The relative telemetry performance of residual-carrier operation and suppressedcarrier operation depends strongly on the bit rate. One scheme is said to have better telemetry performance than the other when it has a smaller required PT/N0 for the support of a given bit rate at a given threshold FER. In general, residual carrier has the better telemetry performance for the very low bit rates and especially for low bit rates coupled with larger carrier loop bandwidths (as would be necessary in the presence of significant phase noise or uncompensated Doppler dynamics). For intermediate bit rates, suppressed carrier offers a significant telemetry performance advantage over residual carrier. For high bit rates, suppressed carrier offers a telemetry performance advantage, but it is only about 0.1 dB. Of course, there will be times in which the decision between residual carrier and suppressed carrier is made on grounds having nothing to do with telemetry performance. For example, a residual carrier is sometimes needed for a radio science experiment. Also, in some applications it will important to minimize acquisition time. Then, the choice of residual carrier or suppressed carrier will be based on whichever scheme offers the quicker acquisition https://deepspace.jpl.nasa.gov/dsndocs/810-005/207/207A.pdf
milstar: s. First, the carrier loop signal-to-noise ratio (rL, see paragraph 5.3) must be at least 10 dB if tracking a residual carrier or at least 17 dB if tracking a suppressed carrier. Second, the squarewave subcarrier loop signal-to-noise ratio (rSUB, see paragraph 5.4) must be at least 20 dB. Third, the symbol loop signal-to-noise ratio (rSYM, see paragraph 5.5) must be at least 15 dB. Fourth, the product hSYS ◊Eb/N0 must be at least 0.8 dB, where hSYS is system loss. For each residual-carrier performance curve, it is assumed that at each point on the curve the optimum modulation index is used. The subcarrier loop bandwidth and window factor are assumed to be 50 mHz and 0.25, respectively. The symbol loop bandwidth and window factor are assumed to be 50 mHz and 0.25, respectively. For the case represented in Figure 8 with BL = 0.5 Hz, residual carrier offers better telemetry performance than suppressed carrier for bit rates less than 20 bps, and suppressed carrier is better for bit rates greater than 20 bps. With BL = 1 Hz, the performances of residual carrier and suppressed carrier cross at 50 bps. With BL = 2 Hz, they cross at 100 bps
milstar: The reason residual carrier performs better than suppressed carrier at the low bit rates is because a residual-carrier loop is not subject to half-cycle slips. A suppressed-carrier loop, on the other hand, can slip a half-cycle and therefore requires a higher carrier loop signalto-noise ratio in order to guard against these damaging slips. (A residual-carrier loop can slip a whole cycle, but this is both less likely and less damaging than a half-cycle slip.) In order to get the best performance from residual-carrier operation, it is necessary that the modulation index be optimal or, at least, near optimal. Each residual-carrier performance curve of Figure 8 is based on the assumption that the modulation index is optimized at each point on the curve. Figure 9 shows what happens if this is not the case. In Figure 9, the lower curve (with the better telemetry performance) is the same as the residual-carrier curve with BL = 1 Hz of Figure 8, with an optimized modulation index at each point on the curve. The upper curve of Figure 9 represents residual-carrier performance with BL = 1 Hz under all the same circumstances except that the modulation index is not optimized at each point on the curve; instead, a single modulation index of 54° (the optimum modulation index for a bit rate of 10 bps) is used for the entire curve. The two curves of Figure 9 coalesce at RBIT = 10 bps but, for RBIT greater than 10 bps, a penalty is paid for not using the appropriate optimum modulation index. At RBIT = 1000 bps, the penalty is about 2 decibels.
milstar: MRO communications has operated in three different frequency bands: 1) Most telecom in both directions has been with the Deep Space Network (DSN) at X-band (~8 GHz), and this band will continue to provide operational commanding, telemetry transmission, and radiometric tracking. 2) During cruise, the functional characteristics of a separate Ka-band (~32 GHz) downlink system were verified in preparation for an operational demonstration during orbit operations. After a Ka-band hardware anomaly in cruise, the project has elected not to initiate the originally planned operational demonstration (with yet-to-beused redundant Ka-band hardware). https://descanso.jpl.nasa.gov/monograph/series13/DeepCommo_Chapter6--141029.pdf
milstar: 6.3.1 X-Band: Cruise and Orbital Operations Uplinks to MRO and downlinks from MRO at X-band are the primary means of communication between the MRO and the DSN antennas in California, Spain, and Australia. The X-band communication system on the orbiter uses a 3-meter-diameter (10-foot) HGA and a 100-watt (W) X-band TWTA to transmit signals to Earth. Each of these devices is more than twice as capable as those used by previous Mars missions. As a result, MRO has been sending data back to Earth more than 10 times faster than previous missions. At a maximum distance from Earth (400 million km [250 million miles]), the orbiter is designed to send data at a rate of at least 500 kbps. At closer ranges, the signal strength can be greater, so higher data rates are possible. When the orbiter is at its closest ranges (about 100 million km [60 million miles]), for several months the orbiter will be able to send data to Earth at 3 to 4 megabits per second (Mbps). https://descanso.jpl.nasa.gov/monograph/series13/DeepCommo_Chapter6--141029.pdf
milstar: 2.2 Carrier Recovery For optimum reception of the transmitted data in a BPSK modulated signal, both the carrier as well as data clock signals must be available at the receiver. The extraction or regeneration of these signals from the noisy digitally modulated received waveform, is the task of the carrier recovery and clock and data recovery systems. This section focuses on the operating principles of the former. As previously discussed, to improve the power efficiency of the transmitter, most modern modulation techniques choose to fully suppress the carrier in the transmitted signal. This has the added benefit that now all the transmitted energy resides in the information carrying side-bands. Unfortunately, without the presence of a carrier, ordinary Phase Locked Loops (PLL) cannot be used for carrier recovery. This means that complex carrier recovery techniques are required. Many factors have to be considered during the selection and development of a carrier recovery system. Here, only the basic operating principles of these systems are surveyed. For the sake of simplicity, only BPSK modulation is considered. The task of carrier recovery in most telecommunication applications can be accomplished by one of the following three types of carrier recovery methods: multiplication loop (such as a squaring loop for BPSK), remodulator loop and Costas loop. Other types of carrier recovery schemes are extensions or modifications of these techniques [12]
milstar: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.472.8206&rep=rep1&type=pdf https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1367923&tag=1
milstar: https://gdmissionsystems.com/satcom-technologies/antennas/small-deployable-antennas
milstar: . Unfortunately, this is not completely possible since, for example, a squaring loop (or equivalently a binary phase-shift keying (BPSK) Costas loop) cannot track a quadrature phase-shift keying (QPSK) modulation and likewise a 4th power loop (or equivalently a QPSK Costas loop, sometimes referred to as an in-phase– quadrature (I-Q) loop) cannot properly track a BPSK signal.1 https://pdfs.semanticscholar.org/044d/e86040cbf778d2b4e2e2ecdeefd28e6f12f9.pdf
milstar: Telecommunications teams make use of separate (but coupled) link budgets for carrier, telemetry channel, and ranging channel, each having their own set of assumptions. In order to simplify the discussion, we will assume the case of no-ranging. The carrier channel threshold involves maintaining a minimum carrier tracking loop signal-to-noise ratio (SNR) required to maintain lock. The DSN Telecommunications Link Design Handbook, DSN No. 810- 005 [2] provides recommendations for minimum SNR for different link configurations. For residual carrier tracking involving binary phase-shift keying (BPSK) telemetry, a minimum loop-SNR of 10 dB is required, whereas for suppressed-carrier BPSK, it is 17 dB [2]. There are higher threshold carrier loop-SNR values required for quadrature phase-shift keying (QPSK) telemetry. The carrier link also takes into account transmitter phase noise and solar phase noise (significant at small solar elongation angles). Usually projects maintain a carrier link with 3 dB or higher margin above the SNR threshold. https://ipnpr.jpl.nasa.gov/progress_report/42-208/208B.pdf
milstar: https://deepspace.jpl.nasa.gov/dsndocs/810-005/207/207A.pdf Residual Carrier A residual-carrier signal can be tracked whether or not there is a subcarrier (squarewave or sinewave) present and whether the symbols are non-return-to-zero or Bi-phase.
milstar: 3.3.3 Radio Frequency Subsystem 3.3.3.1 Receivers. The receiver is a narrow-band, double-conversion, superheterodyne, automatic-phase-control design. The receiver has a coherent Voyager Telecommunication 53 amplitude detector that detects and measures received-signal strength and provides the receiver with an automatic gain control (AGC) function. Receiver AGC is telemetered as a primary uplink performance parameter. https://voyager.gsfc.nasa.gov/Library/DeepCommo_Chapter3--141029.pdf
milstar: s. In the residual carrier mode, the X-band carrier Voyager Telecommunication 61 modulation index settings vary from 51 deg for the lowest data rate (10 bps) to 80 deg for the highest (115.2 kbps).1 ##################### 7 A modulation index of 90 deg puts all of the power in the sidebands and therefore produces a suppressed carrier mode. Suppressed carrier mode is used during VIM to extend Voyager 2 playback data rate capability. See Section 3.6, New Telecom Technology.
milstar: lation index be optimal or, at least, near optimal. Each residual-carrier performance curve of Figure 8 is based on the assumption that the modulation index is optimized at each point on the curve. Figure 9 shows what happens if this is not the case. In Figure 9, the lower curve (with the better telemetry performance) is the same as the residual-carrier curve with BL = 1 Hz of Figure 8, with an optimized modulation index at each point on the curve. The upper curve of Figure 9 represents residual-carrier performance with BL = 1 Hz under all the same circumstances except that the modulation index is not optimized at each point on the curve; instead, a single modulation index of 54° (the optimum modulation index for a bit rate of 10 bps) ################### is used for the entire curve. The two curves of Figure 9 coalesce at RBIT = 10 bps but, for RBIT greater than 10 bps, a penalty is paid for not using the appropriate optimum modulation index. At RBIT = 1000 bps, the penalty is about 2 decibels. https://deepspace.jpl.nasa.gov/dsndocs/810-005/207/207A.pdf
milstar: The curves of Figures 20 through 23 are defined by two constraints: rL should be greater than or equal to 10 dB and the product hRADIO ◊Eb/N0 should be greater than the threshold effective energy per bit to noise spectral density ratio. Moreover, for effective residual-carrier tracking the modulation index must be no larger than 80 degrees. ############ https://deepspace.jpl.nasa.gov/dsndocs/810-005/207/207A.pdf
milstar: Still further, if the modulation is known to be other than suppressed carrier, i.e., a modulation index less than π/2 rad, then it is still possible to exploit the power in both the data and residual carrier components for carrier-tracking purposes provided one has knowledge of the modulation index itself. Such knowledge could be derived noncoherently, i.e., in the absence of carrier synchronization, from a suitable modulation index estimator (to be discussed elsewhere in the monograph). Loops of this type have been referred to in the literature as hybrid carrier tracking loops and like their suppressed-carrier counterparts are motivated by the same MAP considerations.
milstar: https://apps.dtic.mil/dtic/tr/fulltext/u2/a286018.pdf A Costas loop may be used as a suppressed carrier receiver. In Eq. (70), the first term is the carrier while the second term is the data channel. Hence, the modulation index 13i has allocated the total power PT in the transmitted signal VT(t) to the carrier and to the data channel, w' >•re the carrier power and the data power are given respectively as, PC = PT cos^ 2 beta , PD = PT sin^ 2 beta .beta = angle of modulation 45° nositel i dannie mopschnost odinakowa
milstar: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900010954.pdf RF 20 ghz 1 IF 3.373 ghz
milstar: https://pdfs.semanticscholar.org/f032/bc3474cc45d2e4cb7612549916b9caa99ec8.pdf
milstar: https://deepspace.jpl.nasa.gov/dsndocs/810-005/205/205C.pdf carrier modulation for high gain antenna 1.2 radian 68.75 °
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