The sensor Pro indoor module contains a 2nd Pre-amp, this is what gives you better reception, this pre-amp is specifically designed to work in concert with the mast-heat amplifier and provide power to it.
In addition the Sensar pro has several other features, It has two 2 digit digital displays, ONE shows the carrier channel it is reading and the other the strength, This assists you in aiming the antenna more precisely.
The display modes can be adjusted using one button in a round robin style, OFF, Search, Scan, Manual, Gain, Volume.
OFF: this is the setting for CABLE TV (or whatever is connected to the input marked CABLE)
Search: this is the first stop when you are antenna pointing, searches for the STRONGEST digital carrier and displays the carrier channel (See note below).
Scan: using the other two buttons (Up/Down) scrolls through ALL the digital carriers its found, (Bottom display) Strength is displayed on top.
MANUAL: (select) you manually choose a carrier channel using the up-down buttons, and bottom display, Top display shows strength (if any).
Gain: Adjust the gain of the 2nd pre-amp (zero to 20, 10 is default)
Volume: If the unit is mounted where it is hard to see while aiming the antenna this provides audio feedback of the signal strength.. Much like a Sat Receiver on the antenna pointing page.
NOTE: In the old analog days, If you were watching say channel 7 you were receiving channel 7 (Display and carrier channel were the same) but in this digital age..
Well Channel 7 in Detroit uses, as I recall, channel 41
Channel 7 in say Upstate SC,, something different (I think 7 without checking)
There channel display on your screen (7-1) no longer indicates the carrier channel... However do not worry about it.. You do not need to know the carrier channel (Except for using the Sensar Pro) you just let the TV auto-scan, then if you wish to peak on a specific channel you ask the TV for the carrier channel and it will tell you (Select the channel you wish to peak then go to menu and the option to manually add a channel, MOST TV's will show you the carrier channel on that screen)
But the reason for the improved reception is mostly the 2nd adjustable pre-amp built into the Sensar Pro.
Why make it adjustable? Well,,.. Sometimes you can get TOO MUCH gain and that too causes problems.