I've confirmed the frequency was being used by DHS HQ personnel that were in the NY area for about a week...and for testing purposes only.
By DHS HQ personnel, i assume you mean the US Department of Homeland security, which from the web shows as having these agencies below under it.
DHS | Department Subcomponents and Agencies
Department Components
The
Directorate for National Protection and Programs works to advance the Department's risk-reduction mission. Reducing risk requires an integrated approach that encompasses both physical and virtual threats and their associated human elements.
The
Directorate for Science and Technology is the primary research and development arm of the Department. It provides federal, state and local officials with the technology and capabilities to protect the homeland.
The
Directorate for Management is responsible for Department budgets and appropriations, expenditure of funds, accounting and finance, procurement; human resources, information technology systems, facilities and equipment, and the identification and tracking of performance measurements.
The
Office of Policy is the primary policy formulation and coordination component for the Department of Homeland Security. It provides a centralized, coordinated focus to the development of Department-wide, long-range planning to protect the United States.
The
Office of Health Affairs coordinates all medical activities of the Department of Homeland Security to ensure appropriate preparation for and response to incidents having medical significance.
The
Office of Intelligence and Analysis is responsible for using information and intelligence from multiple sources to identify and assess current and future threats to the United States.
The
Office of Operations Coordination is responsible for monitoring the security of the United States on a daily basis and coordinating activities within the Department and with governors, Homeland Security Advisors, law enforcement partners, and critical infrastructure operators in all 50 states and more than 50 major urban areas nationwide.
The
Federal Law Enforcement Training Center provides career-long training to law enforcement professionals to help them fulfill their responsibilities safely and proficiently.
The
Domestic Nuclear Detection Office works to enhance the nuclear detection efforts of federal, state, territorial, tribal, and local governments, and the private sector and to ensure a coordinated response to such threats.
The
Transportation Security Administration (TSA) protects the nation's transportation systems to ensure freedom of movement for people and commerce.
United States
Customs and Border Protection (CBP) is responsible for protecting our nation’s borders in order to prevent terrorists and terrorist weapons from entering the United States, while facilitating the flow of legitimate trade and travel.
United States
Citizenship and Immigration Services (CIS) is responsible for the administration of immigration and naturalization adjudication functions and establishing immigration services policies and priorities.
United States
Immigration and Customs Enforcement (ICE), the largest investigative arm of the Department of Homeland Security, is responsible for identifying and shutting down vulnerabilities in the nation’s border, economic, transportation and infrastructure security.
The
United States Coast Guard protects the public, the environment, and U.S. economic interests—in the nation’s ports and waterways, along the coast, on international waters, or in any maritime region as required to support national security.
The
Federal Emergency Management Agency (FEMA) prepares the nation for hazards, manages Federal response and recovery efforts following any national incident, and administers the National Flood Insurance Program.
The
United States Secret Service protects the President and other high-level officials and investigates counterfeiting and other financial crimes, including financial institution fraud, identity theft, computer fraud; and computer-based attacks on our nation’s financial, banking, and telecommunications infrastructure.
