Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Scott Helmke]

Just to start things off in a cheery fashion, neither Wireless Workbench nor IAS have up to date TV channel assignments.  This is apparently a problem with the publicly available databases that they use, and which are not up to date in many markets.  So this thread is about how to make sense of what should be, if you're not able to just scan locally.  Most of the TV markets in the USA are now through the repack, but things are generally not at all fully settled. TV stations may still be running on secondary transmitters and antennas, often at lower power than their primary transmitter would produce.

What IAS and WWB have is usually correct for the market before the 600MHz repack.  What is needed is some reliable source of how the various stations have changed during their repack phase, and that something is the "387 report" which can be found online at Rabbit Ears:
https://www.rabbitears.info/repack387.php
Generally you would search by TV market, which roughly corresponds to large cities. I haven't yet figured out a quick shortcut to finding a specific market by name, since they are sorted by number on this form.

The 387 report does not show stations that didn't have to move, so by itself the 387 report is not a complete list.  What I do is start with a standard zip code search in WWB or IAS, which gives me the pre-repack list of all TV stations.  From there I can use to 387 report to figure out which stations have moved, and adjust the TV station list in my software to match. At the end of this, I should have a reasonably accurate list of TV station channel assignments and so have a good starting point for doing coordinations for that market.

I also have to add exclusions to the software to make sure that I am not using the 600MHz regions that are now off limits.  Those should be 616-657MHz and 663-698MHz for unlicensed operators. Part 74 licensed operators may also use 653-657MHz.  Note that all transmitters will also need to be set to only produce 20mW in that 653-663MHz range.

Ideally you should start with a local scan, which is going to be the most accurate method.  However, my company rents out and sells wireless gear and often ships it to customers in other cities and sometimes on short notice.  Not only do we need to (at least try to) provide a working coordination, often we need to start with determining which frequency ranges will work in a given market.  This is the method we use when a local scan is not possible.

[Henry Cohen]

Try using Rabbitears' Search Map first (make sure you put in "1000" for the antenna height), then double check those results against the 387 status for the market in question.

As for finding the market name in the 387 database, first go to the Market Listings page, then use the browser's find (control F) find function to get to the market name, and note the market number.

It's not fast or elegant, but gets you 99% of the information needed.

[Pete Erskine]

Ideally you should start with a local scan, which is going to be the most accurate method.  However, my company rents out and sells wireless gear and often ships it to customers in other cities and sometimes on short notice.  Not only do we need to (at least try to) provide a working coordination, often we need to start with determining which frequency ranges will work in a given market.  This is the method we use when a local scan is not possible.

This is nothing new.  I have always found that the TV databases either have extra in-use channels or clear channels where they really are occupied.  If I don't have a recent local scan, I initially use the DB in the app to spec bands to use and initially do band planning.  I do post world wide scans on my website for free... (SCANS) Currently there are more than 88 scans done within the last 6 months.

When onsite, I always do an outside scan and then an inside scan.  Starting with the outside scan, (see below) I do My coord and only start using the inside if I can't get enough freqs.

[Scott Helmke]

Currently there are more than 88 scans done within the last 6 months.

This is the problem, though.  The Chicago repack happened in mid-October.  Are you checking the dates on those scans to make sure that they represent current data, depending on the market and repack phases?  Hopefully all these issues with stale databases will be sorted out soon (I'm quite certain that Shure is hoping so), but in the short term there's a *lot* of confusion.

[Pete Erskine]

This is the problem, though.  The Chicago repack happened in mid-October.  Are you checking the dates on those scans to make sure that they represent current data, depending on the market and repack phases?  Hopefully all these issues with stale databases will be sorted out soon (I'm quite certain that Shure is hoping so), but in the short term there's a *lot* of confusion.

No,  they're all dated and its up to the user to determine if they want to use it.  FCC db will never be correct due to poor management.  i.e., Do your own scan.

[Scott Helmke]

Definitely an onsite scan is the best option, as I mentioned originally.

This is sort of "wireless lab lounge" topic, though.  For the past couple of months I've been getting a fair number of house of worship types of calls, from people who didn't even know about the 600MHz auction and repack, and aren't going to be pulling out a TTi for a quick scan.  So this is about how to find this info and put it to use, during the period when the larger institutions haven't caught up yet.

[ProSoundWeb Community]