This is a feature request for new classes for sensor and for port types.

New classes:

sensors class=distance (in meters)

I think it would be great to have a new class for distance.
I was faced with the need for a new class when I was preparing a patch for BDCOM in OBS-3648.
This patch is for EPON OLT that can report the distance to the client device.
Track is useful for monitoring unauthorized line lengthening or diagnostics of signal strength problems.
Distance can also be obtained from many switches (on copper ports) that support cable diagnostics.
For example on snr-switch (DCN like):

mtivi@tlife-hs:/opt/observium$ snmpbulkwalk -v2c -c *** -Pud -Ih -OQUsb <hostname> SNR-SWITCH-MIB::vctLastStatus.8

vctLastStatus.8 = "

Interface Ethernet1/0/8:

-----------------------------------------------

Cable pairs     Cable status    Length (meters)

-----------     ------------    ---------------

(1, 2)          open            5

(3, 6)          open            5

(4, 5)          open            5

(7, 8)          open            6

"

index 8 = ifIndex
In future we can discover distance for this port. I don't know how to discover that now.

sensors class=bitrate

I found digital decoder PBI DCH-4000P, I am working on patch for this device...
This device is used for decode signal from satellite (DVB-S) to cable (DVB-C) or to multicast for IPTV.
It have a metric for bitrate of signal , for example (in bps):

snmpbulkwalk -v2c -c *** <hostname> PBI-4000P-5000P-MIB::tunerValidBitrate

PBI-4000P-5000P-MIB::tunerValidBitrate.0 = INTEGER: 54602688

sensors class=frequency

this class is already exists, but I found a problem for save this metric when I prepare a patch for digital decoder PBI DCH-4000P.

snmpbulkwalk -v2c -c *** <hostname> PBI-4000P-5000P-MIB::tuner-sInput

PBI-4000P-5000P-MIB::lnbFrequency.0 = INTEGER: 9750

PBI-4000P-5000P-MIB::satFrequency.0 = INTEGER: 11880

...

lnbFrequency and satFrequency in MHz.
When I use

'scale'               => 1000000,

I have SQL WARNINGS : Out of range value for column 'sensor_value' at row 1, and Observium shows 1000MHz.
So we need a new class (something like frequency in MHz) or we need to change limit in DB for sensor_value.