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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 benefits of frequency hopping spread spectrum (FHSS) are potentially neutralized by a repeater jammer (also known as a follower jammer), which has been investigated for more than ten years. The repeater jamming technique for FHSS has been used in both military communications and commercial communications [1]-[3]. In contrast to this, any power-effective jamming technique used in direct sequence spread spectrum (DSSS) has not been proposed in public literatures. Meanwhile, the current jamming types are ineffective at the current jamming power level when the processing gain is large enough. So it’s necessary to investigate a new power-effective jamming technique for the purpose of both commercial frequency surveillance and military countermeasures. The principal types of jamming on DSSS signals include broadband noise (BBN) jamming, partial-band noise (PBN) jamming, pulsed jamming and tone jamming. The last of these includes both single tone jamming and multiple tones (MT) jamming. The effectiveness of these jamming types is not good, because they are non-correlative jamming types which can not synchronize PN sequences. In order to achieve desired jamming effectiveness, the jammer has to increase power level of jamming signals. Unfortunately the victim receiver will countermine the strong jamming signals with adaptive notch filters, repeat coding and so on [4], [5]. https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4224679&tag=1
milstar: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=140456 BER 10 -6 SNR 56 db fading SNR 74 db shadowing with jamming worster SNR 11.5 db quasi ideal only Gaussian noise
milstar: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=544468 we obtained simulated estimates for the symbol error probabilities of synchronous and asynchronous FHSS-MA networks using MFSK modulation with noncoherent detection for M = 2,4,8,16,32, and 64 with and without independent Rayleigh fading. An appropriately normalized throughput measure was defined in order to make a fair comparison between the performance of systems employing different modulation orders. Modeling the channel as an Mary symmetric memoryless channel, it was found that there exists an optimum value of M that should be used to obtain the largest possible throughput. It was also observed that the anomalies caused by the (M - 1)/M-bound noticed in [l] for M = 2 are also present for the cases for M larger than two.
milstar: https://www.researchgate.net/publication/3161194_Maximum_throughput_of_FHSS_multiple-access_networks_using_MFSK_modulation
milstar: https://www.wirelessinnovation.org/assets/Proceedings/2011/2011-6a-harris%20chen.pdf
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