China's BeiDou Navigation Satellite System completes in-orbit upgrade

The BeiDou Navigation Satellite System has recently wrapped up an in-orbit upgrade to provide higher-quality services, according to the China Satellite Navigation Office.

While ensuring stable operations, the system will develop new navigation technologies in order to provide more reliable positioning, navigation and timing services for global users, the office said.

The upgrade took 140 days, running from March 13 to July 31, and involved all in-orbit satellites in the system. The satellite upgrade team described the upgrade as a task of unprecedented scale and complexity.

"The requirements for this upgrade are indeed demanding. For one, the coverage is extensive, and the task is to ensure the upgrade process remains seamless and imperceptible to users -- with absolutely zero margin for error -- so naturally we had greater pressure," said Mai Peng, a staff member of the Xi'an Satellite Control Center.

Ahead of the in-orbit upgrade, the team increased the frequency of health checks for the target satellites to ensure they were in optimal condition for the upgrade.

"We conduct satellite health checks basically every month, with a comprehensive review every six months. For satellites that tend to malfunction more frequently, the checks may be conducted even more often," said Liang Wenjie, another staff member.

To ensure a smooth system-wide upgrade, the team also prepared in advance by uploading relevant software and commands to a test satellite and closely monitoring its status.

After the test satellite successfully completed the upgrade and its status was verified as normal, the team replicated the same process on the remaining satellites in batches.

Then the team reconfigured the satellites' Pseudo Random Noise (PRN) codes to increase navigation's accuracy and stability.

"For users in general, assigning PRN codes from the higher-performance satellites to a wider range that most consumer devices can access can significantly improve accuracy and stability, especially in areas with signal obstruction such as mountainous regions," said Mai.

Following more than four months of efforts, the upgrade was completed successfully without virtual impact on users. The team reported substantial improvements in the system's navigation accuracy and stability.

"This upgrade has been successfully completed, but we will continue to carry out tasks such as in-orbit satellite management to ensure the satellites keep operating normally," said Wang Xingyu, another staff member.

As a mature, fully functional and high-performance global satellite navigation system, the BDS currently has 50 operational satellites in orbit. It offers a global positioning accuracy of better than 10 meters, velocity measurement accuracy better than 0.2 meters per second, and timing accuracy within 20 nanoseconds.

Through its Precise Point Positioning (PPP) service signal, it can realize horizontal positioning accuracy better than 0.3 meters and vertical accuracy better than 0.6 meters.

China's BeiDou Navigation Satellite System completes in-orbit upgrade

Civilians in Yemen continue to flee their homes amid the ongoing conflict, as the humanitarian crisis worsens by the day, UN humanitarians said Wednesday.

Since Aug. 1, more than 184,000 people have been displaced nationwide, including over 21,000 people in the past week alone, the UN Office for the Coordination of Humanitarian Affairs (OCHA) said, citing the International Organization for Migration.

According to OCHA, the United Nations and its humanitarian partners have reached more than 126,000 people with life-saving assistance. Nevertheless, it warned that needs continue to outpace the resources available.

The World Health Organization warned of major funding shortfalls as rising displacement, disease outbreaks and conflict put more pressure on an already fragile health system, OCHA said. "Cholera cases have tripled in recent weeks -- including in displacement camps -- while measles, dengue and malaria continue to spread."

Key roads connecting Taiz governorate with major surrounding cities, including Hodeidah, Aden and Sanaa, remain blocked, the office said, adding that the closure severely restricts the movement of civilians and commercial supplies, as well as humanitarian access.

Shortages of essential commodities and medical supplies are being reported, with sharp increases in food and fuel prices, and growing concerns over the availability of flour, cooking gas and medicines, OCHA said.

The office said it was alarmed by reports of civilian casualties, damage to civilian property and heightened risks from explosive hazards, which are further constraining humanitarian access and the safe movement of civilians.

"OCHA continues to assess the humanitarian impact and calls on all parties to protect civilians and facilitate humanitarians' efforts to safely and swiftly reach them with the support they need," it said.

Civilians in Yemen continue to flee homes amid insecurity: UN