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There is a billiards club about 2 miles from my location and almost direct line of site and employees use GMRS/FRS on 462.725MHz simplex with DPL252. The little bit of chatter I've heard sounds like security and/or bouncers. What caught my attention was that D252 is one of the standard 104 DCS/DPL codes but is not one of Motorola's original set of 83 standard DPL codes which are a subset of the 104 codes. Most FRS radios advertise "121 codes" consisting of the 38 standard CTCSS/PL tones plus Motorola's original set of 83 DCS/DPL codes. It makes me wonder what equipment they are using, either Part 90 commercial gear or one of the newer FRS models advertising "142 codes" (38 CTCSS/PL + 104 DCS/DPL). http://onfreq.com/syntorx/dcs.html

This radio is Vaporware and not cheaper. The specs posted on Retevis' site contain many red flags (can you spot them all?) and contain conflicting and mutually exclusive information. The published specs resemble a hilarious copy and paste of specs from multiple sources. Epic FAIL. The minimum order quantity (MOQ) is 200 at $60 each ($12k total). I posted about this radio in the RadioReference.com forums. https://forums.radioreference.com/threads/retevis-900mhz-license-free-radio.413954/ I own a small fleet of Motorola DTR700 portables and a small fleet of DTR650 portables. I previously owned a small fleet of DLR1060 radios which I later sold to a friend of mine for his business. At first he wasn't sure what he was going to do with them except may use them for radio rentals. Now he and his employees use them all the time around the office and at job sites because they work so well. Don't underestimate a FHSS digital radio on 900MHz just because of the 1W transmitter power. My range record with a pair of 900MHz Motorola DTR650 FHSS digital portables transmitting at 890mW (+29.5dBm) stands at 12 miles from the Cocoa Beach Pier in Cocoa Beach FL to the top of the steps from the parking lot leading down to Hightower Beach in Satellite Beach FL. The top of the steps are about 30 ft or so above sea level. There is a bit of coastline in the way so it's not entirely line of site. Myself and a friend of mine who helped me test the DTRs also had 4W UHF Part 90 portables with us which we had on GMRS to compare to. (We are both GMRS licensed.) We were able to communicate on GMRS simplex but the received signal strength was noisy and scratchy and we each had to find a hot spot and stay there in order to communicate. The DTRs were crystal clear because of the digital modulation and overall was more reliable and finding a hot spot for them was less critical. Motorola DTRs on 900MHz are capable of outperforming VHF and UHF conventional portables on simplex. Where the DTRs beat VHF and UHF conventional portables is when operating inside buildings due to buildings being much more open at 900MHz compared to 150MHz and 450MHz. Where the 900MHz DTRs blow all others away on simplex is when operating aboard cruise ships. People who have used DTRs aboard cruise ships report having full ship coverage on all decks compared to a pair of 4W UHF portables on GMRS simplex which had trouble penetrating more than about 2 decks. When operating aboard a cruise ship, you are essentially operating inside a compartmentalized metal box. The shorter wavelength signals at 900MHz reflect in an out of the many nooks and crannies of the ship where longer wavelength signals at VHF and UHF won't. The many reflections actually help with the FHSS operation because individual hot spots and dead spots also hop around as the frequency hops. The FHSS operation effectively stirs the modes so to speak. I never got my DTRs to set any range records. I got them for reliable local on-site simplex type use with family and friends. They are my high quality professional digital replacement for GMRS/FRS and MURS for local simplex type use. They outperform UHF Part 90/95 conventional portables on simplex and totally blow FRS away. A coworker once asked me why not just use FRS? My answer was that I have already been doing that since FRS was created in 1996 and longer than that as a GMRS licensee since 1992 with Part 90/95 commercial gear. I want a secure, high quality digital solution that is higher quality and more professional than FRS. The fact that they are totally scanner proof comes as a bonus. They are not monitorable on any consumer grade receiver (scanner) so don't even bother trying. I hardly use GMRS/FRS at all any more because I migrated my local on-site simplex type use with family and friends to the DTR radios on 900MHz.

No special or "right equipment" is needed. If a radio has DPL capability, it already has inverted DPL capability. With one exception (D172N), every code in the table of 104 standard DCS codes has its inverse somewhere in the table. For example, codes 125 and 365 are inverses of each other. D125I is the same as D365N and vice versa. I've been using 411 (normal) (D411N) and its inverse is 226 (normal). D411I corresponds to D226N and vice versa. Normal and Inverted simply refers to the polarity of the DCS waveform. By convention, a logic 1 is represented by a positive carrier shift and a logic 0 is represented by a negative carrier shift. This is considered Normal polarity for a DCS waveform. A DPL word is a 23-bit cyclic Golay pattern with a 12 bit codeword (23,12). The 12 bit codeword is formed from the 12 least significant bits of the 23 bit DPL word. The 12 bit codeword consists of a fixed octal 4 (100 binary) followed by the 3 octal digits that you can program. Notice that the available DPL codes are octal (base 8) numbers. The 11 most significant bits are error correcting code bits generated by the Golay algorithm from the 12 codeword bits. The 23 bit DPL word is transmitted repeatedly over the air at 134.4 bits/second. The least significant bit is transmitted first, resulting in the DPL word being played out backwards over the air. Here is the best technical description of DCS/DPL operation that I've been able to find: http://www.onfreq.com/syntorx/dcs.html Also check out: https://wiki.radioreference.com/index.php/DCS In my case of dealing with a repeater jammer who didn't have DPL capability and didn't have a clue and thought he knew all there is to know about radio, DPL also stands for "Definitely Prevents Losers" LOL.

I used to use 141.3 on GMRS/FRS and MURS, having nothing to do with the travel tone concept. I moved away from 141.3 due to it being advocated as a travel tone on GMRS and I like 156.7 better anyway. I also like using DPL. What is it that makes 141.3 officially (and legally) the travel tone for GMRS? The FCC doesn't regulate the use of specific CTCSS tones for licensees. The only case I know of where the FCC has specified a particular CTCSS tone in its rules and required to be used is for public safety agencies on the nationwide public safety interop channels on VHF, UHF, 700MHz, and 800MHz. These are the LTAC, VTAC, UTAC, 7TAC, and 8TAC inter-agency TAC channels. I don't think we will be able to mandate a specific tone to be used as a travel tone, short of getting it written into the FCC rules for GMRS.

If FRS works for them and don't want to upgrade to business radios, then that's perfectly OK. I am OK with business use of FRS. Most business users of FRS are casual users of 2-way radio and don't need expensive business radios and the hassle with FCC licensing that goes with it. Given that business use of FRS is 100% legal, it helps fill this niche, sort of like what PMR446 does in Europe. Accommodating casual business users of 2-way radio as FRS does helps keep the Part 90 Industrial/Business (IB) pool frequencies more available for licensed users who really need those frequencies. I recently had a paving crew resurfacing one of the streets next to my house and the flaggers were using FRS. I saw them using FRS and I quickly found them on FRS channel 1 (462.5625). The flaggers were only about 100 feet or so apart and FRS worked fine for them. What was different about them was they behaved themselves and strictly used the radios for what they were meant for. They actually sounded professional, unlike the usual sewer mouth chatter you normally hear from flaggers on FRS.

I don't think it's a regional thing but maybe more popular in urban areas. There was a local REACT group on 675 in my area about 20 years ago and they're gone now. They used 675 w/PL167.9 for their local ops and also had 141.3 for traveler assistance. The 675 repeater they were using is also gone. I've heard REACT groups active on 675 in a few major urban areas of the country. This was around 20 years ago. 67.0Hz is a good tone to avoid due to it being the out of box default tone in Motorola Talkabout FRS bubble packs. I've found FRS users tend to use their radios right of the box at the factory default settings. If they change tones, they typically don't stray far from the default tone. The middle tones tend to rarely get used by FRS users. I narrowed my favorite tone range down based on a number of factors. Avoid all tones below 100.0Hz due to them being more susceptible to being false decoded by noise and adjacent tones.Avoid 100.0Hz because it's used a lot and I've had problems with noise from electronics having 100.0Hz modulation.Avoid tones that are harmonics of AC power line frequencies. Avoid 118.8 (close to 2nd harmonic at 120.0Hz) and 179.9 (3rd harmonic at 180.0). Avoid 100.0Hz in Europe due to 50Hz power.Avoid 131.8 and 136.5 due to the DPL kerchunk problem caused by the 134.4Hz DPL reverse burst.Avoid all tones above 167.9 due to them being more likely to be audible and annoying. Tones above 200Hz tend to be screamers. My favorite tones are 141.3 through 167.9, with 156.7 being in the middle of the range. They seem to work the best and aren't annoying to listen to. 156.7 is also the tone specified by FCC rule to be used on the nationwide public safety interop channels on VHF, UHF, 700MHz and 800MHz. These are the LTAC, VTAC, UTAC, 7TAC, and 8TAC inter-agency TAC channels. I've also heard of preppers liking to use PL156.7. When I use PL on GMRS/FRS and MURS, my favorite is 156.7.

I used PL141.3 on GMRS for years and on my 462.625 repeaters I had back then, having nothing to do with the travel tone concept. 462.675 used to be reserved for emergency and traveler assistance prior to all-channel licensing which started in 1999. The reservation of 675 for emergency and traveler assistance went away when the FCC switched to all-channel licensing. Many local REACT groups used 675 and PL141.3 back in the day. I was using 141.3 on all GMRS/FRS channels. I got GMRS licensed back in 1992 and you had to pick any 2 of the available GMRS primary channels and you put them and the corresponding 467MHz repeater inputs on the license application. The license was issued showing the 4 frequencies and a note at the bottom saying that additional frequencies were authorized per rule section 95.29 and to refer to that section. 95.29 authorized the 7 12.5kHz "splinter" channels now shared with FRS 1-7 and authorized the use of 675 for emergency and traveler assistance if it wasn't already one of the 2 primaries you applied for. I purposely got licensed on 575 and 625 because of manufacturers starting to make cheap 10 channel radios containing the 7 splinters now shared with FRS plus 575, 625, and 675. These were the early cheap radios prior to the creation of FRS in 1996 and the ensuing bubble pack invasion which followed. I got away from 141.3 and have used DPL to help thwart a jammer I posted about in another thread. The jammer had antiquated equipment with only CTCSS capability and no DCS/DPL capability and didn't have a clue about DPL. I have a few favorite DPLs and my favorite PL tone is 156.7. PL156.7 is in the sweet spot of tones I like in the middle of the tone range. I'm sort of on the fence whether to use PL156.7 or DPL full time on GMRS/FRS and MURS. One thing for sure is I won't be using PL141.3 anymore because of too many people using it.

Hi, first post on myGMRS and long time lurker. Ham licensed since the 1980s and GMRS licensed since 1992. This brings back memories of some dealings I had with a jammer 15-20 years ago. I had a GMRS repeater at home for local area chit chat and the jammer liked to target myself and a friend of mine. We were the only users of the repeater. The repeater was on DPL instead of PL which annoyed the jammer to no end because his antiquated equipment only had CTCSS/PL and he didn't have a clue about DCS/DPL. He also liked to target us when on local simplex since he lived in my friend's neighborhood. I lived several miles away so the repeater was not local to the jammer. The jammer was legendary for jamming on GMRS, FRS, and CB19...wherever he could get attention and hold an audience. He mostly stayed on CB19 because he managed to hold the largest audience there. He was legendary in the local CB, ham and GMRS communities and the FCC also dealt with him a few times. We were largely successful at ignoring the jammer on GMRS but he persisted. We continued to use GMRS legally like the jammer was not there, never acknowledging his existence. We also brought the fight to him. The repeater was at home and I lived several miles away so I took the repeater mobile and my friend rode with me in the car while we chatted on the repeater with our portables. We were separated by the distance between us in the front seats and the repeater was on the back seat, powered by the car and with a UHF mobile antenna on the roof. The repeater all by itself worked excellent in the mobile installation. We were in my friend's neighborhood and the jammer was just down the street from us. We were so close to the repeater that the jammer couldn't make a dent in our communications, no matter how hard he tried. We were close enough to the jammer that he could hear the repeater on a scanner while transmitting to see if he was successful at jamming us (he wasn't). I was also listening on the repeater input and heard him try multiple CTCSS/PL tones to try to key the repeater (he couldn't). I also later heard him viciously ranting on CB19 about being unable to get into the repeater. He finally gave up trying to bother us on the repeater. What worked best was to never let him see us sweat and make him think he was having zero impact on us.