WRAF213

Back to the original question. Are there people running DMR on GMRS? Yes. Does hearing DMR constitute illegal DMR use? Not really. There's other places that signal could have come from, such as intermod. I would expect DMR repeater outputs on GMRS interstitials to be quite uncommon, but still possible; ruling out interference sources should come first. Even in the event someone is running a DMR repeater on that channel, the FCC won't do anything about it because it's too difficult to prove equipment ownership or the presence of harmful interference. If you hear a repeater output on a 462.xxxx channel, check for TDMA on 467.xxxx. That would indicate there's a repeater on the standard frequency split. Some repeaters have inputs somewhere in the business band and hearing an input signal requires being pretty close to the other user. Pretty much all DMR radios transmit on just one timeslot, which sends short bursts. Baofeng's DM-5R is a notable exception and transmits on both timeslots with the same data, giving a continuous carrier.

I've had a NA-771 swept and posted about it here. If it's a real NA-771, it'll work a bit better than stock. If it's counterfeit, it won't really work at all. Topography is the main influence on how GMRS propagates. Since two similar radios didn't have similar performance, something else is at play. Is the channel clear? Are the adjacent channels clear? Try switching places. Try switching antennas. Try a slightly different site.

There's a local, open repeater that uses multiple PLs. There's no defined purpose to all the PLs, but it mainly allows the repeater to have travel tone and a separate local tone. The rest of the tones are mostly for sticking a group of people on the repeater without the other repeater users having to hear them. 67.0 Hz output tone is available to address FRS users for emcomm. Having a bunch of tones available makes the repeater really susceptible to interference, and all the radios need to be set up with busy-channel lockout (which works a lot better when the repeater has a short hangtime of 0.5-1.0 seconds). Things start getting nutty when there's more than 3 tones configured on a repeater.

Use promiscuous mode to ensure you have the right settings. One thing I've found is that CCRs won't unmute to DMR systems with RAS enabled, which is commonly set on public safety channels (who probably shouldn't be on DMR anyways). Since you are getting bits and pieces, it may not be the issue. Scrambling/encryption is a possibility as well, and SDR software can indicate what type of traffic is going across the system. I would expect any scrambling to be full-time, so it's probably not that. You can check by going into monitor mode when the receive LED is going, it'll sound like a bunch of weird noises. [Edit] RAS works by altering checksums and including some other types of CSBKs. Because the checksums are altered, radios that verify checksums won't recognize RAS data. This is the case for pretty much every commercial radio out there, since checksums ensure the right data is received. Scanners and SDR software know better, and will work with RAS traffic.

It's probably some ridiculous courtesy tone. SWR issue shouldn't affect that. If the repeater just sends its CWID all the time but nobody actually uses the repeater, there's probably nobody to talk to using it anyways; it wouldn't surprise me if the owner doesn't watch it either.

Businesses can use FRS all they want, we've discussed it to death on other threads. MURS radios are very difficult to find at the same price point anyways. Everyone, regardless of GMRS licensing, is limited to 1/2 watt on the 467 MHz interstitial channels (8-14) on an integrated antenna. It wouldn't surprise me if people were selling imported radios capable of more power or detachable antennas on 8-14, but the equipment shouldn't have type certification. FRS can use all the other channels (1-7, 15-22) at 2 watts and narrowband modulation. Even if the radio was sold as a FRS/GMRS combination radio under the old type acceptance rules, it was reclassified as a FRS radio during the rule change if it were compliant with those power limits. Selling GMRS radios without proof of license, or making licensing requirements difficult to locate on the consumer-visible packaging, was the bigger issue. Had the labeling and licensing requirements been made more rigorous, the GMRS radio manufacturers (Motorola, Midland, Uniden, Cobra, etc.) would have been under pressure to recall basically every FRS/GMRS radio on the market. Additionally, adding more barriers for equipment adoption and generating a lot of consumer confusion would have hurt sales significantly and made the FCC look bad to the public. It was easier to change the requirements for FRS, and recertify the radios for FRS. GMRS was screwed either way due to the need for more channel capacity on FRS with falling equipment prices.

You get more fidelity at a given power level using a wider deviation. You need more power (a net change of 3dB in this case) to reproduce a transmitted signal with the same fidelity. So if you've got a receiver trying to receive your buddy down in the valley and you're in a theoretically perfect hilltop site, you'll have -130dBm of thermal noise coming in. If everything is wideband, your buddy needs to be received with some signal-to-noise ratio to achieve some level of fidelity. Let's arbitrarily set that threshold -122dBm to achieve a good-enough signal. If your buddy switches to a narrowband radio and you switch the repeater to a narrowband configuration, you'll have a narrower IF filter and thus less thermal noise within the IF passband: -133dBm. Passing the input signal at the same signal-to-noise ratio (which would be received at -125dBm) will not reproduce the input signal at the same degree of fidelity -- it'll sound worse. You're trying to do the same thing with less RF, it just doesn't work like that, or we'd have been 6.25 kHz compliant for a long time. The signal-to-noise ratio needs to improve by 6dB each time the bandwidth is halved to produce the same fidelity, and we gained 3dB from the narrower IF filter. To get the same fidelity, we'd need a received signal at -118dBm. The easy way out of the problem is to lowpass the audio so less noise is audible, and that's one of the reasons you'll hear a lot of people say narrowband sounds like junk. The audio loses fidelity in the process, but has less high-pitched hiss from FM noise. The problem is with reproducing the transmitted frequency range. More and more RF power is needed to allow the higher pitches to be demodulated with an audio SNR above a fixed threshold as IF bandwidth goes down. It's a property of FM.

You can't use analog RF linking on GMRS. There's nowhere to put the links anyways. Use point-to-point Wi-Fi for building networks. If the repeater's receive side is solid in all desired locations, try improving the repeater's sensitivity with more robust filtering and a LNA before trying to figure out where you're going to put a bunch of voting receivers. Simulcasting would be overkill. RTCMs don't take a 10 MHz clock directly, they require some PLL device to shift the frequency down to 9.6 MHz. There's plans to build such a device that are readily available, but there isn't an off-the-shelf solution. A 9.6 MHz OCXO would work for voting purposes as well. All of this is far more complicated than improving the repeater's receiver, since it turns a standard duplex repeater into a computer-controlled radio network.

Wideband has a slight advantage (3dB) over narrowband when it comes to sensitivity. Cutting the bandwidth in half requires 6dB more power to get the same signal-to-noise ratio, but 3dB comes from having the noise power on the narrower receive IF filter. On business radio systems, this may not matter; but on GMRS, the users tend to be dispersed further as operating area isn't constrained by the license and minimal frequency coordination takes place. This effect also causes mobile flutter to be more pronounced. On modern commercial radios designed for narrowband use, the strong-signal voice quality doesn't take much of a hit when moving to narrowband channels. We can't get any more pairs because FRS is already authorized for the 467 MHz interstitials. We'd need to go to 6.25 kHz ultra-narrowbanding (NXDN48 or dPMR) and use some odd channels (462.546875, 462.553125, 462.559375, ...), which won't happen anyways because digital voice isn't allowed. Adjacent ultra-narrowband channels would also interfere unless frequency accuracy is well-controlled, which raises equipment cost considerably (particularly for portables) and requires realignment during the equipment's service life. Additionally, wideband users would take interference from any of four ultra-narrowband channels, and narrowband users would take interference from any of two ultra-narrowband channels. The end result is even less voice capacity than before, unless everyone goes ultra-narrowband and maintains their equipment to high standards. The repeater operator always has the option to narrowband should they want to, but there's no benefit unless there's significant adjacent-channel interference, all of the radios are properly configured for narrowband (travelers are probably not), and the radios used on the system have proper 12.5 kHz IF filters (the GMRS-V1 does not). A narrowband mandate would also screw up equipment certifications and cause the FCC to get a big headache over something that is not really a problem at all.

That's just a short blip. The only analog STL is up at 947.00 MHz and doesn't come in particularly strong. There's a few FLEX pager signals bleeding in and they show up pretty weak on that spectrum display, but they're coming in around -60dBm just about 2 MHz up. All of the rest of that junk is real signal, and it's getting worse as the smart meter deployment continues. Here's a current look, with interference sources labeled:

There's a bunch of businesses using channel 1 in CSQ or 67.0 here. They've gotten used to kids trying to talk to them.

I'm a little late to the party, but here's my thoughts: Most people are operating in close proximity (to other operators in the same building or within a few hundred feet), where the other party will overpower any other users on the channel except in dense areas. For FRS, that's fine. I use it to talk to my family members and my unlicensed friends, and neither of us wants to hear the other users on the channel. That's all undesirable for disaster communications, where I can use my higher power level to reach many users. Putting a proper emergency channel in FRS radios would end up the same as CB 9, full of false reports and interference. A licensed solution would improve the situation, but that's not possible anymore with 22-channel FRS (I would also prefer a solution under Part 90 or a similar setup, but that's a topic for another thread). FRS can be a tool but much of the hardware are toys and perform in RF-busy environments like you'd expect a $10 radio to perform. Motorola's Quiet-Talk enabled by default is stupid, it defeats the purpose of FRS's interoperability requirements. FRS 1 in CSQ should be the out-of-the-box channel for all radios, and mandating the radios be shipped in that mode would greatly assist emcomm. It wouldn't make much sense in reality where there's no distinction between calling and working channels and where it's impractical to attempt to train kids on that stuff. The FCC won't recommend a calling channel or tone for a reason. Agreed, LMR is not going anywhere. Infrastructure dependence is a real concern among the public and first responders alike, and those views can be seen in some cities' resistance to joining county/state trunked systems (see LA-RICS). Being able to communicate unit-to-unit effectively is an underrated feature of two-way radio that cell phones still can't provide, especially where interoperability is required. If you only remember two paragraphs in this post, I hit the "Post" button a bit early.

To my understanding, businesses can continue to use their existing business authorizations on any authorized with Part 90 equipment as if their license were never altered, and *all* unlicensed users must use Part 95 equipment. The language on what constitutes a grandfathered station is poorly written, but a Part 90 authorization for what is now a MURS station is required. Such licenses are uncommon now, eince nearly 20 years have passed since such a license could be obtained. No exemption is referenced in 95.335 for MURS, so I would not expect business equipment to be permissibly used in MURS. [edit] MURS is licensed by rule, like FRS and CBRS. If there's no type-certification, there's no rule for it to be licensed by. This is well-established in CBRS.

FRS is licensed by rule, they also have authority to operate. See 95.359, it's up to both parties to resolve interference issues. This also means that GMRS users cannot jam FRS users in an effort to clear the channel. There's no ownership of channels and they are shared between the services. If the other party is operating outside their authorizations, they lose these protections.

151.625 is under Part 90.35 as a business itinerant channel and isn't part of MURS.

That situation is different from what's going on here. WISCOM is a Wisconsin State asset, and the Wisconsin DOJ is protecting their state's system. The legal subscriber radios and the system key for the trunked system (while trivial to generate, such a key would probably not authenticate on the system) are most likely property of Wisconsin. I'm allowed to own Baofengs, but I'm not allowed to join trunked systems on stolen or cracked hardware/software.

Amazon is indeed responsible for the misleading descriptions, they would not be allowed to market the uncertified devices to Americans. Should the FCC do anything about it, I'd bet that Amazon would (successfully) try to shift the blame to the sellers, who would then claim they are outside the FCC's jurisdiction; the cycle would continue. The whole situation is a mess, and licensed GMRS and Part 90 (both Public Safety and Industrial/Business pools) users are receiving significant interference from users fully unaware that their radios aren't actually FRS radios. The sellers are desperate for sales and most will say anything to secure a sale. Keep digging around Amazon's site and you will find many sellers saying their radios are legal out-of-the-box and a handful of reviewers upset that they aren't. The FCC already fined one distributor a while back for selling UV-5Rs with an incomplete type certification. The internet was naïvely rejoicing, "The FCC made Baofengs illegal!" Yet this barely scratched the surface of the problems with illegal marketing. Over here, there's more activity on the BF-888S channels than on FRS channels, and a handful of commercial users on amateur simplex channels complete with profanity. Reports go nowhere. Users claim the sellers said the radios were legal, and tone squelch on the default channels makes the users unable to determine they are causing or receiving interference. Where is the Commission when you need them?

It's either an IF image (most likely), intermod, or a transmitter spur (highly unlikely). Most FRS radios I'm familiar with have IF frequencies above 20 MHz, but have pathetic frontends that easily unmute to mixed out-of-band signals. Another receiver with a different IF frequency and a stronger frontend, or a properly configured SDR, can determine the nature of the interference. That said, 60WPM is way too fast for legal Part 90 identification; Part 90 requires 20-25 WPM.

It's really fast (like 50wpm) CW for WQDK421, with carrier at 400 Hz.

160 miles is really, really long for a RF link. The speed-of-light delay alone (850us) is problematic for 802.11-based linking. An Internet link through Asterisk would be much easier and much more reliable. There's a lot of tutorials on how to set up private Asterisk links, and the final architecture will strongly resemble an AllStarLink node. Internet-based linking is permissible for operating a remote base per 2017 FCC rule update.

Wideband equipment on GMRS allows 5ppm error, but stuff operating on the 467 interstitials requires 2.5ppm. I have seen ham gear off by 20ppm or more, and drifts of 10ppm per transmission. That's not really important since there is no type acceptance for Part 97; as long as the equipment stays in-band and doesn't have excessive out-of-band spurs. Running 30kHz deviation is fine. Running 4 kHz off-center is fine, but not optimal. That's not really why there's type acceptance. Ham gear can generate nearly every emission. Part 90 gear can generate a good number of emissions, like TDMA digital voice or packet data. Both services allow for transmit power above 5 or 50 watts. None of those are allowed on GMRS, which is why there are type acceptance procedures in place. It also establishes a set of guidelines for manufacturers to follow when designing and marketing equipment to ensure interoperability across manufacturers. Why there's a prohibition of having amateur and GMRS channels together on the same Part 90-certified and 'otherwise compliant' radio, I don't know. I would expect it to be a prohibition of marketing dual-service radios, given the difference in intended use and operational procedures between the two services.

There's no regulation of receivers in Part 95 ir 97; receivers are Part 15 devices, and receive that treatment when integrated into type-approved devices (aside from ensuring the receiver at least permits effective two-way operation, for Part 95). An Amateur station can listen to GMRS all day long, and vice-versa. Amateur operators can relay information to GMRS if the operator holds both respective licenses, and an Amateur operator can have a GMRS operator retransmit information and vice-versa. Interconnecting two transmitters between services is not allowed, be it by a direct interface, RF/TCP link, receiver monitoring the other service, remote base, or phone patch. It's an odd way of preventing unlicensed operators of transmitting on GMRS since license authorizations are mutually exclusive and callsigns (station identification procedure) is different between the services. Operator distress special operation under 97.405(a) appears to be the only case where a direct interconnection would be permitted; a GMRS license does not explicitly allow communication outside its service for emergency traffic. Grandfathered business GMRS licenses are probably why we don't see similar Part 90 restrictions.

A 16K0 mask is pretty typical for 5 kHz deviation, 300-3125 Hz modulated frequencies (see Carson's rule). There's probably a strong lowpass keeping modulated audio in that range, allowing a 16K0 mask. It's not narrowbanding, it's just muffled audio. Some manufacturers either fudge the numbers or obtain rather arbitrary numbers from testing (for an extreme example, look at the BF-888S) instead of using the commonly accepted emission masks for the modulations supported by the radio. I use an XTS3000 and XTS5000 myself, with AGC enabled. I wouldn't call the audio 'nice', but it remains clearly intelligible in all environments. The additional audio controls on the XTS5000 do make a difference. Being able to run full duplex with both radios on the hip is a nice touch.

[Note: following is my opinion, written on a phone] I have a pair of UV-82s, and have set up a pair of BF-888S. Audio is kinda okay (you can understand the other party as long as people talk at a proper distance from the mic), RF performance is atrocious. They completely desense when any 'nearby' transmitter is active, and thus are only really operable on the sad antennas provided with the radios. The RDA1846 those radios are built on are prone to desense, and the minimal filtering and isolation Baofeng is known for compounds the issue further. RDA1846 is found in most of the new dual-band or digivoice designs (just about all Baofeng, TYT, AnyTone, pretty much all CCR DMR radios, and the new Yaesu HTs like the 4XR and 70DR). Some designs have acceptable performance, others do not. But that front-end-on-a-chip is displacing less flexible but more durable architectures and taking over the handheld (and now mobile) market like a plague. So if you see comments to the tone of "they don't make them like they used to", this is likely why. At least they allow arbitrary CTCSS/DCS. The tiny mic hole is pretty standard for "commercial" (and almost certainly not Part 90 approved) CCRs designed to be used in industrial environments. It keeps background noise down and works fine if you're talking loudly into the radio. Our conversational needs aren't shouting contests, so drilling out the mic hole to a larger diameter does help at the expense of more wind noise and reduced pop filtering. For general ham use, the CCRs are fine. The DMR ones tend to be built a bit better (and with the DMR repeaters popping up everywhere, there's more people to talk to), just make sure there's a VFO and FPP. A meaningful programmable scan function is also standard in most DMR CCRs, something lacking in the Baofeng analog portables. Programming cable is a necessity for any digivoice radio. I'd recommend the AnyTone AT-D878UV. DMR/analog, FPP, GPS, has a VFO, and active firmware development adding new features -- $200ish. I do not have one myself (blew all my cash on Motorola XTS), but I hear plenty of users on BrandMeister. D868UV has fewer bells and whistles at a lower price point; both are Part 90 and have adjustable mic gain. As with the other DMR radios, a programming cable is essential. I do not know their desense resistance, but it's better than the Baofengs.

There's Motorola's MPL feature on the ASTRO25 radios and Spectra mobiles. Not exactly FPP-like support since the tones are entered in RSS/CPS, but it's good enough for most cases when combined with a PL Defeat switch.