Metso D200137 shortwave communication

Description

Metso D200137 shortwave communication

Metso D200137 shortwave communication

The frequency selection of shortwave communication mainly goes through three main stages:
(1) Long term frequency prediction. Predict the highest available frequency MUF of the circuit based on the number of sunspots and seasonal time. This method is based on the concept of mid month values, making it difficult to track changes in the ionosphere at operating frequencies, thus affecting the effectiveness of high-frequency communication.
(2) Real time frequency prediction. Since the 1960s, countries such as the United States and Canada have developed real-time frequency selection technology, and specialized real-time frequency selection systems such as CURTS, CHEC, and Chirp have emerged. Real time frequency selection technology plays a significant role in ensuring high-quality shortwave trunk communication. In recent years, Chirp frequency selection systems have undergone significant development. In 1994, ITURecommendation 720 recommended FM/CW “Chirp” detection technology as the standard for dynamic frequency management. The United States, Britain and other countries have conducted on-site scientific experiments on the Chirp system and achieved good practical results in the Gulf War.
(3) Adaptive communication technology. This is a new technology developed in the 1980s, which integrates frequency selection and communication, and can automatically communicate circuits on the optimal channel. Due to the integration of frequency selection and communication, and the focus on communication, the quality of frequency selection is lower than the frequency quality provided by dedicated real-time frequency selection systems. The future development direction should be to combine dedicated frequency selection systems with adaptive communication systems to further improve the quality of shortwave communication. At present, the third-generation adaptive high-frequency system proposed by the United States has reflected the combination of Chirp frequency selection system and shortwave communication system.

BAUMER UNDK30P3712/S14
BAUMER BUR622-16-2
BAUMER BKF12/120/400/2002
BAUTZ E642B-MGB
BBC 10QT01
BBC DT680E
BBC DT602
BBC ZT372a-E
BBC LT9673a
BEARING AVS-1700-ACX
BEI H25E-F1-SS-10
BEI H38D-1800-ABZC-8830-LED-SC-UL
BENDER 9604-1121
BENTLY 3500/20