intermod

In general, no. The number of IX complaints we have filed - 98% are maritime issues on 467.600 - now number about 190+ over five years. The FCC regional director here in the west has attempted to pursuade DC to issue a general notice to Maritime companies, but I don't think he has been successful yet. But the FCC requires us to do quite a bit of foot work in advance - and I can't when I get busy at work. The FCC did put us in touch with the Port Warfinger (yea, there is a maritime position with that strange name). This person can help identify which vessels have just arrived - and you can correlate this with the start and end of the IX. The FCC usually asks us to record the traffic and email it to them as well. However - the FCC has responded several times, but the offenders are only there for 1-3 days, so they miss them. And the FCC does not work weekends. In some cases, where the FCC could not respond but we needed the offender to immediate cease (as we were having an event, net or some such on our repeater), we would contact the offender direfctly on 467.600 using a remote base station we temporarily installed (set for the tone they were using); we were sometimes able to get them to change channels (all of them seen to understand english). But that is no longer permitted after the FCC has restricted GMRS network connections for conveying messages. So our problems are now going unresolved.

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.

You can with DMR Heck, I don't even say my callsign over the air. Same and callsign is just imbeded in the digital stream....

After you asked this, I re-read the rule section. Maybe the answer depends on the definition of "sharing". There is sharing through "use", but then there is also sharing through ownership and/or control. I am thinking they are referring to "use", in which case a written agreement appears to be needed, along with record retention. Having said this - I know 95% of repeater owners or groups do not comply..... G

I am not completely following what happened - but if its not in the rules or provided in writing, then its not not official and considered hearsay. Although it might be smart to work with the FCC and start a conversation. I hope they did not ask who else uses the repeater; this would be a bit agressive and would warrant a call to your elected represenative (hopefully republican) to have them suggest the FCC back off. But everyone seems to forget this rule: "§ 95.1705 Individual licenses required; eligibility; who may operate; cooperative use. (f) Cooperative use of GMRS stations. (4) All sharing arrangements must be conducted in accordance with a written agreement to be kept as part of the station records." Normally, the best policy in any organization is to keep a limited number (or no) records....but this rule requires something. This is why I have always said that open repeaters may not be permissible unless they meet this requirement.

I was unable to pass them.

Looks like about -119, which is low for VHF. If you have good coax then you are doing better than my area....

You may be one of the few. What does your SDR show for noise floor at 16 kHz bandwidth?

High noise floor, particularly in the metro and suburban areas, can be the controlling factor. This is primarily caused by microprocessors, associated clocks and switching power supplies in electronic products (including many LED light sources). This effectively deafens VHF receivers so that they are no longer as sensitive as they used to be. If you ever get a chance to use 700, 800 or 900 MHz, or even 1200 MHz, it will become immediately obvious. As was said above, while VHF propagates really well outdoors, in some cases the 700-1200 MHz bands can actually do better, except when the signal hits dirt (hill or mountain) or a dense foliage. Another factor to consider in VHF is portable antenna efficiency. Most portable radios are equipped with the 10" flexible helical antenna, versus something that more approximates a 1/4 wave length (18"). The 10" has an effective gain of -11 dBd. That takes a 2-watt MURS radio and degrades it to less than 0.2 watts. And it does the same to reception of signals......so VHF is really being hammered. UHF has become degraded but not as bad. But the antennas (for a given length) are more efficient.

IEEE TECH TALK: IS VHF DEAD? Date: 13 Feb 2024 Time: 05:30 PM to 06:50 PM Online Join link Join Zoom Meeting https://us06web.zoom.us/j/87613850683?pwd=VGhYQmxsU0dlbE5qRnMyS3o2Vmxqdz09 Meeting ID: 876 1385 0683 Passcode: IEEESEA https://events.vtools.ieee.org/m/401815

Linking repeaters through the Internet, or via a private broadband connection (private point-to-point microwave radio, like using Ubiquity radios) is not prohibited by the rules. The FCC rep's opinion in the video is “hearsay” and is not considered authoritative. The female rep even notes this earlier. Here is a brief tutorial on this matter. § 95.349 Network connection. Operation of Personal Radio Services stations connected with the public switched network is prohibited, unless otherwise allowed for a particular Personal Radio Service by rules in the subpart governing that specific service. See e.g., §§ 95.949 and 95.2749. Fact 1: The Internet is not a “public switched network”. § 47CFR § 9.3 - Definitions. Public Switched Network. Any common carrier switched network, whether by wire or radio, including local exchange carriers, interexchange carriers, and mobile service providers, that uses the North American Numbering Plan in connection with the provision of switched services. Fact 2: Internet Service Providers (ISPs) are not considered a “Common Carriers”. They were between 2015-2017, when Net Neutrality was in place. Net Neutrality was eliminated in 2017. § 95.1749 GMRS network connection. Operation of a GMRS station with a telephone connection is prohibited, as in § 95.349. GMRS repeater, base and fixed stations, however, may be connected to the public switched network or other networks for the sole purpose of operation by remote control pursuant to § 95.1745. § 95.303 Definitions. Remote control. Operation of a Personal Radio Services station from a location that is not in the immediate vicinity of the transmitter. Operation of a Personal Radio Services station from any location on the premises, vehicle or craft where the transmitter is located is not considered to be remote control. § 95.1745 GMRS remote control. Notwithstanding the prohibition in § 95.345, GMRS repeater, base and fixed stations may be operated by remote control. Fact 3: While “control” or “remote control” normally refers to the act of enabling or disabling the ability of a transmitter to “activate”, the term “operation by remote control” refers to people using the repeater remotely. Conclusion: Linking GMRS repeaters through the Internet is not prohibited. Linking through a private connection (not routing through the internet) is certainly fine as well. Just don't install an autopatch on GMRS. If anyone is aware of a formal case where a licensee received a formal NOV for linking after 2017, please let us know. I suspect one does not exist. What typically occurs is that an NOV is issued for harmful or destructive interference (IX). For example, if I operate a repeater in Boston, which activates a repeater in California, and the California repeater walks on top of another local repeater, then we have harmful IX. This is a violation. Not the linking.