I posted something along the below lines in the suggestion forum some time ago, however here is something a little more upto date and taking into account Sandros comments.
I would leave the Advanced scanner with infinite range but give it certain downsides while offering certain benefits from using the other two scanners.
My thinking around changes to scanners is based loosely on Sonars and radars.
The Basic Scanner i would change into a Passive scanner similar to passive sonar. The main benefits of this would be that it is stealthy, in that ships using this scanner would be harder to detect, especially if combined with other low observability kit like clean drives and low emissions powerplant. Stealth gameplay elements would be built into using this type of scanner, for example you would be able to detect and lock onto interdictions in the locale This would allow bounty Hunters to quickly come to the assistance of players being attacked by pirates. The scanner would also allow players to identify specific engineering modifications thereby enabling better tactical judgement on if to attack a target or not. In addition it would also be excellent at revealing hidden assets such as pirate bases, loot caches, or other unauthorised activity. As it is a passive device it generates no heat penalty with only minimal power usage. The range for planetary scanning would be increased to 1000ls.
The Advanced Scanner. This is a fully active scanner. This lights you up like a christmas tree. Everyone human or otherwise can detect you throughout the star system when equipped with this scanner. Carry this scanner and if you enter lets say an area with hostile aliens in it, then you can expect a very hot reception. If in human space then you will stand out beautifully for pirates. Interdictions of ships equipped with advanced scanners become far easier. Torpedoes and other homing weapons love them as they lock onto the emissions and hunt you down., Gimballed and turreted weapons find you easier to track. The main benefit of this scanner however is its infinite range that reveals all planetary objects within a star system. The power of the system however drowns out low level emissions from hidden artifacts such as pirate bases, ships of the missing, loot caches and anything else frontier want to make hard to find. Fitting this scanner carries a significant power and heat penalty along with some mass penalty. It is of course excellent for those engaged in stellar mapping.
The intermediate Scanner. This represents a half way house between the Advanced Scanner and the Basic Scanner. One might say it is a semi active scanner. This does intermittently generate some noise which makes you visible to those around you so dont expect to be able to use this as a stealth ship. However you are not advertising your presence to all and sundry throughout a star system. Though you will be visible within a certain detection sphere. Hidden features may be visible but will be harder to detect than with the Basic scanner. The intermediate scanner comes with some heat and power penalties and some weight penalties. I would increase its range to 10,000 ls.
Each scanner would need to have its own signature sound to indicate its operation. The advanced would in my opinion retain the current foghorn like sound. I think that is appropriate. The Intermediate would have something like a classic pinging sound of sonar, while the passive would have a hissing noise to represent just the background radiation of the stars it is picking up.
The various scanners would reveal planets much as they do now. However for more forensic analysis there would be the option of opening up something akin to the SRV scanner that would emit various noises and wave patterns to indicate something unusual. This would be especially useful in a multicrew scenario as would allow someone to fly the ship while someone else sits examining the scan data. In multicrew through having a dedicated scanner screen the scanner operative would be able to drill down to specific noise segments to hone in on specific areas of interest quickly, and be able to plot courses and set markers in space or on planetary surfaces.