intermod

Mistake #3: Fail to Communicate with Existing (Incumbent) Repeater Licensees You fail to coordinate access codes with the other repeater owners on your channel and install your repeater anyway. The incumbent(s) become unhinged and pissed off. You also fail to realize that some repeaters use multiple access codes (for different user groups), and may also be using unmatched code pairs on the repeater uplink and downlink (i.e., repeater access/uplink uses 141.3 Hz, but its downlink uses 85.4 Hz). While this can be closely related to Mistake #2 described earlier, it’s also possible you are using one of the incumbent's codes. You could have attempted to contact the incumbent and ask whether they were using any of your proposed codes (via mygmrs.com, over their repeater, or by reading their Morse code repeater ID and getting their address through the FCC website). Or - you could have researched the codes in use the traditional way: purchasing one of the essential tools used by repeaters owners for decades, called the "CTCSS/DCS decoder". Also, many new radio models will automatically decode and display downlink codes when set correctly.

Agree. Another question: As GMRS licnesees, are we obligated to accept interference by the rules, regardless of the shared channel environment? I believe that FRS users are obligated to not cause IX, and must accept IX.

SteveSHannon is correct. All of them were approved under FRS rules. However, there is no restriction on "continuous carrier" modes under the 95.3 (general) area or the FRS rules. This is a problem that needs resolution. This can be resolved with one sentance in the rules. We ordered several models of these to test a few years ago (thankfully Amazon has a Free Return policy...). At the time, we were searching for models operating on 467 MHz GMRS repeater uplink channels. There were some models that did this (we never found the model). However, their operation on 462.725 MHz regularly interfere with reception of licensed GMRS direct and repeater communications. They seem to propgage well, assuming they comply with the 2-watt requirement. I am going to look for a rule that restricts one-way communication in FRS.

Excellent idea, but somewhat inconvenient. But why not do real time-slicing? If the FCC would permit DMR technology, it would provide two discreet channels/time-slices (slots) - one for each user group - to use *at the same time*, and would only require half of the standard GMRS channel. Maybe I should not have mentioned DMR - it triggers some people.

Mistake #2: Ignore the 467 MHz "Uplink" Problem You choose a unique repeater CTCSS / DCS / PL / Privacy code, but other incumbent repeater owners become unhinged and pissed off. That is because signals from users trying to access your repeater are still being heard by the incumbent's repeater *receiver*. Those signals don't activate the incumbent's repeater - but they still exist and can block or walk on the incumbent's users, particularly when the incumbent’s users are operating handheld radios. CTCSS / DCS / PL / Privacy Codes, etc. only prevent inadvertent repeater activation - they cannot prevent uplink IX. Clue - your repeater's transmitter is not causing the interference; it’s your users' transmitters that are causing this type of interference. This cannot be fixed by making any adjustments to your repeater. Of course.

This is correct. After working with business frequency coordinators in the Part 90 bands (450-470 MHz) for many years, the same approach applies there - if you can't find a clear channel, you can still coordinate, license and install your repeater at the same site as another licensee operating on the same frequency (assumes neither is an FB8 class - centralized trunked). Just don't interfere. This often works out fine because the incumbent repeater is not being used (user moved on, or seasonal), or no longer exists, even though a license still exists. It really is the best way to fully utilize spectrum. However, the FCC's disservice was to lengthen the license term from five to ten years, resulting in tens of thousands to Peper" or non-existent repeaters.

Planning a new repeater? What are the most common mistakes a new repeater owner makes? Below is Mistake #1. Additional installments are forthcoming. Mistake #1: Using Mygmrs.com to Find a Clear Channel You pick a channel from the Mygmrs Repeater Database having the least number of repeaters, or nothing immediately close by. You end up causing interference (IX). Other co-channel repeater owners (e.g., incumbents) become unhinged and pissed off. Many existing repeaters, particularly those that have existed for decades, are not listed in Mygmrs.com. Often, these owners may not want the hassles of having multiple users, and prefer to avoid repeater kerchunker's, weak scratchy handheld radio users that are really annoying to listen to, and poorly performing radios (see Note 1 below). Also, radio signals can travel 150+ miles with no obstructions, even portable radio signals. There are possibly other repeaters just 50 miles away that are at a high elevation (or on a tall tower) that can hear your users just fine, causing IX. Notice I said “your users” and not “your repeater”. This will be discussed under Mistake #2. (Note 1: The current trend in Cheap Chinese Radios [CCR] are models with unresolvable low transmit audio/volume, very poor quality audio [includes poor quality speaker/microphones] and improper default settings, like Roger Beeps.)

As your repeater existed first, ask the other repeater owner to move to a different channel. I think the other repeater is programmable, and a duplexer tuned for that particular channel would likely not require retuning as the frequency change is minor.

But we can get 25 mile range on this portable radio, right?

This is where many groups should really start. The organization can pay for one commercial (or public safety) license for ~$300 (for 10 years) and be assigned one callsign that everyone uses. As opposed to every member having to figure out CORES, FRNs, and pay $35 for a GMRS license. GMRS may have been used originally due to the low-cost radios, but Part 90 radios are just as low cost today. Eventually PII (Personally Identifiable Information) will be enforced for CERT and SAR organizations, and FCC rules permit encrypted transmissions on commercial and public safety channels. And they allow for digital for greater clarity and capacity. And they can be linked easily and without controversy. And have slightly greater protection from interference, particularly if the groups chooses to use public safety catagory channels. Downsides?

I thought I would start this thread as LScott noted elsewhere: "Hummm… This could be the topic for another thread. GMRS seems to be mutating into a hobbyist type service. It seems the original primary intent by the FCC was a radio service simple enough to be used by ordinary people with basically no background in radio communication technology for their personal use, and immediate family members." GMRS traditionally had been for personal use (family, small groups and very small business), in direct or repeater mode. Repeaters were stand-alone (not linked). Large business use was discouraged as the FCC saw this as incompatible with personal communications (which is the main reason the service requires individual licensing). But the number of users have risen dramatically over the past 5-6 years (particularly in the metro areas), and the service is experiencing some growing pains (busier channels, more IX from businesses, other repeaters, etc.). What are the top three causes of this? In no particular order, here is a potential list: General experimentation with repeaters (duplex or simplex), increasing interference in some areas FCC permitting unlicensed 2-watt direct-mode usage Unlicensed 2-watt users operating direct-mode digital (NXDN, DMR, etc.) Entry by new unsophisticated users Linking repeaters using input frequencies (467 MHz; causes interference (IX) to other co-channel repeaters) Low cost (primarily Chinese) user equipment and repeaters Some sporatic use of digital repeaters on GMRS Linking (e.g., Local, Regional, National) Low-cost / long-duration licensing Russia? Other ideas?

Fixed....thanks.

For those who care, MotoSol's current GTR8000 line of repeaters may be replaced with their new "DBR" line. This also means that we may start seeing some GTR8000's repeaters becoming available on ebay soon. Here it is: https://www.motorolasolutions.com/en_us/products/p25-products/astro/dbr-m12-site.html I think a set of two repeaters share a single common power amplifier; specs indicate it allows for two carriers to be spaced as close as 50 kHz. It looks like we are moving back to point-to-point wiring. Equipment staging for these photos must have been performed by an engineer or sales person (or maybe the Human Resources Dept.). Example of DEI? You be the judge.....

I vagely remember this article. Our numbers are a bit differnt - but I dissagree with Jay on the 6 dB degradation. If you reduce the receiver bandwidth by half (25 kHz to 12.5 kHz), the receiver noise floor should drop 3 dB (improving C/I by 3 dB), offsetting his 6 dB to 3 dB. But the rest seems right on the money.

In reality, narrowband effectively reduces coverage by about 3 dB (is this 1/3? 1-2 miles? who knows; depends on the situation). But I would agree its noticeable along the edges. This has the same effect as reducing your transmitter power by half. This was one reason to encourage digital - it can (but not always) replace what was lost with analog narrowbanding. However, the most significant problem with analog narrowbanding was not the coverage impact in an of itself. The interference susceptibility, or the effect of interference, increased by 6 dB. Said another way, interference using narrowband has a much greater impact than it did with analog wideband. With the increase in unlicensed low-power use on the 462 MHz channels, useable range will be reduced significantly in the GMRS service. Interference susceptibility of digital actually improved - this included DMR, NXDN, P25, etc. And, it is even even better than analog wideband (there are just few conditional exceptions). Public safety radio users may not have expereinced as much interference degradation since their channels have less co-channel interference. One Conclusion: if the FCC considers narrowbanding, they really need to permit digital - otherwise range will suffer.