The method and simulation model for the synthesis of barker-like code sequences

Noise immunity is one of the essential characteristics of modern wireless data reception/transmission systems. In wireless systems such as Wi-Fi, HiperLan, or Bluetooth, the signal is propagated by electromagnetic oscillations in the environment. However, unlike wiring systems, these oscillations are unprotected from external influences. Noise immunity is one of the essential characteristics of modern wireless data reception/transmission systems. Moreover, if several wireless systems work close enough to each other, there is a possibility of overlapping waves, which will damage the information signal. It is determined that for the tasks of control of unmanned aerial vehicles and mobile robotic complexes increasing the noise immunity of data transmission channels is an urgent problem. It has been investigated that Barker-like code sequences based on ideal ring bundles provide an increase in the power of the obtained sequences by optimizing the parameters of the ideal ring bundles used. It is determined that the increase of noise immunity during data reception and transmission is achieved by choosing the optimal ratios of the parameters of the ideal ring bundle. It is shown that the advantages of Barker-like code sequences such as the optimal ratio between the length of the sequence and its correcting ability, the ability to change the length of the sequence depending on the level of interference are widely used in modern wireless communication and telecommunications systems. The method of synthesis of Barker-like code sequences with the use of ideal ring bundles has been improved, which, by taking into account the ratios of the parameters of ideal ring bundles, provides the choice of the minimum bit code sequence that takes into account the level of interference. A simulation model of synthesis of Barker-like code sequences, noise generation, and error correction has been developed on the basis of the improved method of synthesis of Barker-like code sequences. The developed simulation model is used to study the processes of coding, decoding, detection, and correction of errors in the obtained Barker-like code sequences. It has been investigated that the use of synthesized Barker-like code sequences based on ideal ring bundles provides data recovery of damaged no more than 25 % of the bits of each codeword, and detects up to 50 % of damaged bits in each codeword. Keywords: Barker-like code sequence; ideal ring bundle; noise-tolerant coding; simulation model.

Ventrolateral Compression of the Brain Stem in Essential Hypertension: MR Angiography Study

Our purpose was to evaluate neurovascular compression at the level of ventrolateral medulla and NVC with the IXth and the Xth cranial nerves in patients with essential hypertension and in healthy volunteers using high resoluted Spoiled Recalled Gradient Echo (SPGR) sequences, allowing the detection of stationary tissues and moving spins. Thirty patients (19 men and 11 women) with essential hypertension were examined. Patient's ages ranged from 24 to 64 years-old (mean age was 48 y.o.). Patients older than 65 were excluded. The average of systolic blood-pressure of hypertensive patients was 183 ± 10 mmHg, while the diastolic pressure was 98 ± 10.5 mmHg. In conclusion, we consider axial single partitions from a three-dimensional TOF MRA sequence ideal to demonstrate both vascular and neural components of NVC. NVC could explain essential hypertension disease in a significant percentage of patients, even though true idiopathic hypertension - probably less frequent than believed- exists.