Most of mine are just NFM--far away, weak, very narrow signals. Just wanted 2.5 kHz as that seems to be what most are spaced at across 150-160 MHz. 153.3175, 153.320, 153.3225, 153.325, 153.3275, and so on for example.
Assuming we're talking about the US, the problem is that highband is not consistent, with different services (business, marine, rail, LoJack, paging, etc.), channel spacings, and older technology, and even apparent mistakes, having had to be grandfathered in at various times as technology evolved.
In general, 7.5 kHz spacing catches much of the range accurately, but the problem is that there are gaps, discontinuities, and special cases all over the place (both physically and frequency).
In your example, only 153.3200 and 153.3275 are valid channel center frequencies. The range you mentioned is part of a nice, contiguous 7.5kHz-spaced set at 152.8625–154.4525 (213 channels). It's business industrial at 152.8625–153.7325 (except (4) public-safety-shared channels), then public safety at 153.7400–154.4525. Then, it jumps to 154.45625 (
3.75 kHz diff). After that, there are (3) 7.5 kHz-spaced channels 154.46375, 154.47125, 154.47875. Then, there's another 3.75 kHz space to (4) more 7.5 kHz-spaced channels 154.4825–154.5050. Then, there's a 10 kHz gap to 154.5150, and a 12.5 kHz gap to 154.5275. After that, it
really gets messy, e.g., depending on whether you're in Alaska or not.
The Industrial/Business pool table is at
47 CFR 90.35(b)(3) and public safety is at
47 CFR 90.20(c)(3). There's other stuff in 47 CFR, like marine in
Part 80 Subpart H, broadcast remotes at
47 CFR 74.402, etc..
Also see my previous post
here, where I came up with (22) sub-bands (!) to cover most of the valid channels in 150–174 MHz.
