The CM7004 has a USB 2.0 port to connect memory/storage. USB 3.0 storage can also be used, but will not improve performance.
The CM7004 can utilize/format USB Flash Drive storage up to the 128GB size. (USB Flash memory, Thumb Drive, Memory Stick, etc.) We do not recommend smaller USB flash drives. External USB Hard Drives do not work with the CM7004.
When you first insert the USB Flash Drive Storage device into the CM7004, a dialog box will appear on your TV screen 'Setup in progress'. Once installed and you see 'Setup Complete', you can begin to use the DVR function's.
On an average, the CM7004 uses about 6GB for a 1 hour recording of HD (High Definition) content. That equates to about 20 hours of HD content on a 128GB Flash Drive. (Only 117GB used for storage.)
SD (standard definition) content uses much less recording space than HD content. You can average about 3 to 7 times as many SD programs compared to HD programs.
Every TV station can transmit its signals at whatever Bit Rate they choose. Highest bit rate tops out at 17Mbps. The HD signals and the SD signals share the broadcast/transport stream. e.g. If they send the 'primary' HD signal out at 12Mbps, then they have 5Mbps available for the 'secondary' SD channels. The bitrate transmit bandwidth allocation for a certain channel can change at any time.
Please note; The CM-7004 has been designed as a Digital signal to Analog signal converter. Primarily the CM7004 is used to accommodate older Analog TV's that do not have an HD ATSC tuner, or a Digital display, that does not have a Tuner installed.
Secondary to that, it also will record programs. This is an economy set top box and has limited Recording options.