This read-write UpstrmFreqKhz object sets the RF board's receive frequency in KHz, and the description warns that changing it causes a temporary service loss because the RX card must send a frequency-change message to every ComPort on that channel in turn. An admin uses this to retune an upstream channel, for example to resolve ingress noise at a particular frequency, understanding the operational cost of doing so. For example, after detecting persistent interference at the current frequency, staff schedule a maintenance window to change hcxRecvFrequency and accept the brief interruption while ComPorts retune.