DTR radios

[garys]

A friend asked me what these are all about, and I know very little. I know that they are simplex only, use 900 Mhz, and have multiple channels. That's about it. I don't know if they use DMR or some sort of less expensive, probably proprietary form of modulation.

Can anyone give me a quick summary of frequencies and capabilities?

Thanks,

Gary

 

[BigDogg795]

Motorola DTR radios use the ISM 900 band for simplex communication. Designed for "on site" (aka non-repeated) use, they utilize DSS style encryption to prevent monitoring from consumer grade scanners. If a 3 letter agency wants to hear you, they supposedly can.

I had a set of them; and they were really great radios. Think Nextel without the cellular backhaul (in fact, DTR's could be readily compared to the DirectTalk function of the late model nextel phones). I ended up getting rid of them because I just didn't use them as much as I thought.

https://www.motorolasolutions.com/c...adios/dtr410/dtr550_and_dtr650_spec_sheet.pdf

Hope that helps.

A friend asked me what these are all about, and I know very little. I know that they are simplex only, use 900 Mhz, and have multiple channels. That's about it. I don't know if they use DMR or some sort of less expensive, probably proprietary form of modulation.

Can anyone give me a quick summary of frequencies and capabilities?

Thanks,

Gary

 

[PACNWDude]

Motorola DTR radios are great for site wide communications, if you do not want to get a license, and can handle the slight delay in transmission to reception (you will not notice this if you are far enough apart from another user to hear it), they are also rugged radios.

I have many of these in use in school campus locations, they work well for up to about a mile range, can be set for private channels, but do cost about $250 each.

If you are in an area saturated with FRS/GMRS users, these are perfect, as many people will not buy these for personnal use. As for someone listening to them, they are Frequency Hopping Spread Spectrum (FHSS) radios in the 900Mhz band, so as above, casual snoops will probably not hear you. Unless you use the default channel settings. They will work in large buildings and forested areas, but that maximum range is still about a mile.

School users seem to like the text messaging feature, and ability to communicate with one user or all users at once. Great series of radios. One of my profile pictures shows some DTR410's being programmed.

 

[garys]

Thanks to both of you. This confirms some of what I thought and adds more information. It seems like a good tool to use for on site communications with some amount of privacy.

 

[alcahuete]

Thanks to both of you. This confirms some of what I thought and adds more information. It seems like a good tool to use for on site communications with some amount of privacy.

Great radios for that. Great radios for cruise ships. Great radios for RF-dense environments. Just plain great radios. And while definitely not to be expected, out in the desert where I live, I have used them out to 25+ miles (ran out of road before I ran out of signal) with the 6" antennas. I routinely get full ship coverage on huge cruise ships (last was the Norwegian Epic...very big ship), and had no problem 2 terminals away at DFW airport last summer.

They are also crystal clear, and as was mentioned, if you program them to something other than the default frequencies, you are not going to be heard by anyone, scanners included.

Highly recommended.

 

[PCTEK]

I heard there was a problem with the PTT button failing. Have any of you experienced that? I am looking for non license radios for our company that is in a 10 floor building. Do you think they would work in a 10 story modern office building?

Thanks

 

[alcahuete]

I heard there was a problem with the PTT button failing. Have any of you experienced that? I am looking for non license radios for our company that is in a 10 floor building. Do you think they would work in a 10 story modern office building?

Thanks

I have over a dozen of them, and have never had an issue with the PTT failing, personally. Honestly, I've never even heard of that before.

As far as a 10 story building, I doubt you will have issues, but as with anything radio, it just depends. There are so many factors that it is almost impossible to say for certain whether it will work or not. My last foray in large building stuff was last year in Vegas. I had no issues with pretty much property-wide coverage at the Rio and Aria (SkySuites). My room was near the top at Aria, and my friend's room at the Rio was on floor 51 (which is really floor 41). I had no problem from there anywhere throughout the building. Your mileage may vary, but I've been very impressed.

 

[SCPD]

They should perform well. Our 2 level basement courthouse below and 3 floor above ground high court house has no issues. They are used as security, admin. They are pretty decent radios just don't forget to change the settings and not use the default privacy settings.

 

[n1das]

A friend asked me what these are all about, and I know very little. I know that they are simplex only, use 900 Mhz, and have multiple channels. That's about it. I don't know if they use DMR or some sort of less expensive, probably proprietary form of modulation.

Can anyone give me a quick summary of frequencies and capabilities?

Thanks,

Gary

These radios are all digital and operate in the 902-928MHz range using frequency-hopping spread spectrum (FHSS) modulation. An 8-level FSK modulation scheme is used on individual hopping channels. The vocoder used is VSELP, what NEXTEL DirectConnect phones used. I also recall early Motorola Astro radios not long before P25 Phase 1 (IMBE) used VSELP for a short time before IMBE took over with P25.

The FCC legal limit for a FHSS device in the 902-928MHz range under Part 15 is 1W (+30dBm) and must use a hopset consisting of a minimum of 50 frequencies. Actual FCC certified transmit power is 890mW (+29.5dBm). The 0.5dB under the legal limit is to have some margin to account for measurement uncertainty and unit to unit variation while staying FCC-legal. The 50 individual hopping frequencies are spread out over the entire 902-828 band. The radio uses the entire 902-928 band when transmitting. Forget about trying to monitor these on any consumer grade receiver (i.e., scanner) because you can't. They are not encrypted but can be made very secure.

The DTR radios have public and private groups that can be configured. DTRs can monitor and work with other DTRs on the public talkgroups. Private talkgroups can be configured so that only members of a group an communicate on that talkgroup. So while not encrypted, they can be made very secure by security through obscurity. The DTRs and the new DLR series will work with each other right out of the box with the factory default programming. Customization of programming and features requires Motorola's Business Radio CPS, a free download from Motorola. The programming cable is around $40 on Amazon. No programming is needed to use these radios right out of the box. If you acquire some used radios and they are programmed differently and won't work with each other, simply reset them to the factory default programming and then they will work.

The DTR radios are spec'd as a 10-channel radio. Each channel represents a hopset of 50 frequencies to hop on. The IDs for public and private talkgroups represent modifications to the hopping sequence etc. The new DLR series added a 4-digit Profile ID feature to further multiply the number of possible combinations in the hopping algorithm.

The DTR radios share a common design with the Motorola i325is iDEN phone used on NEXTEL and other iDEN networks (i.e., BOOST Mobile). They initially started out as part of the same design project and were the same radio and then later split apart as the unique models were created. Many NEXTEL phones back in the day had an off-network DirectTalk feature for local simplex phone to phone use when in range and network service was unavailable. My wife and I owned a pair of NEXTEL i355 phones back in the day and we used the DirectTalk feature a few times. It really came in handy when we were shopping at Walmart* where NEXTEL network coverage was spotty to nonexistent. DirectTalk mode solved that for us while we were inside the store.

Note that DirectTalk is not to be confused with NEXTEL DirectConnect which used the NEXTEL network. The DirectTalk feature is the same system the DTR and new DLR series radios use. The DirectTalk feature in NEXTEL phones was purposely coded differently than the DTRs and DLRs such that they are not compatible. It would have been wicked cool and wicked useful if they were compatible. The DirectTalk feature appears to be a simpler feature set of what the DTRs (and the DLRs) have. I believe the DirectTalk feature was also called MOTOTALK for a while. The simpler DirectTalk features was probably what forced them to be not compatible with the DTRs even though they use the exact same FHSS system.

DTR/DLR radios in the CheckCheckOneTwo forums:
Professional Radios
New DLR radios - compatible with DTR

RR forum threads:
https://forums.radioreference.com/gmrs-frs/346074-motorola-dtr-550-dmr-uhf-simplex-cruise-ship.html
https://forums.radioreference.com/gmrs-frs/345831-gmrs-exit-strategy-going-900mhz-dtrs-dlrs.html

Chickenhawk's DLR review:
NEW - Motorola DLR series - rugged, licence-free, high-quality digital radios - Two Way Radio Forum

My DTR650 audio test on YouTube:
https://www.youtube.com/watch?v=aaNdMWPmVZI

I own a fleet of DTR650 radios and a fleet of DLR1060 radios. I have a multi-unit charger (MUC) for each fleet.
These are great radios specifically designed for on-site small business type use. DLR = Digital Lightweight Radio, according to Motorola.

The DTR series is more than 10 years old but is still current product from Motorola. They have replaced my use of GMRS/FRS for local on-site simplex type use. I still have GMRS/FRS and MURS capabilities but these are no longer my go-to mode for local simplex ops. While on vacation in Florida over the holidays, my wife and I and friends used my fleet of DTR radios for our local simplex ops. We did not bother to use GMRS/FRS at all because the DTRs worked so well. We also wanted an all-digital solution that is higher quality and more professional than FRS.

 

[garys]

Thanks. It sounds that they would be very useful when walking around Deerfield during NEAR Fest. :wink:

Seriously though, this and the other answers are very helpful.

These radios are all digital and operate in the 902-928MHz range using frequency-hopping spread spectrum (FHSS) modulation. An 8-level FSK modulation scheme is used on individual hopping channels. The vocoder used is VSELP, what NEXTEL DirectConnect phones used. I also recall early Motorola Astro radios not long before P25 Phase 1 (IMBE) used VSELP for a short time before IMBE took over with P25.

The FCC legal limit for a FHSS device in the 902-928MHz range under Part 15 is 1W (+30dBm) and must use a hopset consisting of a minimum of 50 frequencies. Actual FCC certified transmit power is 890mW (+29.5dBm). The 0.5dB under the legal limit is to have some margin to account for measurement uncertainty and unit to unit variation while staying FCC-legal. The 50 individual hopping frequencies are spread out over the entire 902-828 band. The radio uses the entire 902-928 band when transmitting. Forget about trying to monitor these on any consumer grade receiver (i.e., scanner) because you can't. They are not encrypted but can be made very secure.

The DTR radios have public and private groups that can be configured. DTRs can monitor and work with other DTRs on the public talkgroups. Private talkgroups can be configured so that only members of a group an communicate on that talkgroup. So while not encrypted, they can be made very secure by security through obscurity. The DTRs and the new DLR series will work with each other right out of the box with the factory default programming. Customization of programming and features requires Motorola's Business Radio CPS, a free download from Motorola. The programming cable is around $40 on Amazon. No programming is needed to use these radios right out of the box. If you acquire some used radios and they are programmed differently and won't work with each other, simply reset them to the factory default programming and then they will work.

The DTR radios are spec'd as a 10-channel radio. Each channel represents a hopset of 50 frequencies to hop on. The IDs for public and private talkgroups represent modifications to the hopping sequence etc. The new DLR series added a 4-digit Profile ID feature to further multiply the number of possible combinations in the hopping algorithm.

The DTR radios share a common design with the Motorola i325is iDEN phone used on NEXTEL and other iDEN networks (i.e., BOOST Mobile). They initially started out as part of the same design project and were the same radio and then later split apart as the unique models were created. Many NEXTEL phones back in the day had an off-network DirectTalk feature for local simplex phone to phone use when in range and network service was unavailable. My wife and I owned a pair of NEXTEL i355 phones back in the day and we used the DirectTalk feature a few times. It really came in handy when we were shopping at Walmart* where NEXTEL network coverage was spotty to nonexistent. DirectTalk mode solved that for us while we were inside the store.

Note that DirectTalk is not to be confused with NEXTEL DirectConnect which used the NEXTEL network. The DirectTalk feature is the same system the DTR and new DLR series radios use. The DirectTalk feature in NEXTEL phones was purposely coded differently than the DTRs and DLRs such that they are not compatible. It would have been wicked cool and wicked useful if they were compatible. The DirectTalk feature appears to be a simpler feature set of what the DTRs (and the DLRs) have. I believe the DirectTalk feature was also called MOTOTALK for a while. The simpler DirectTalk features was probably what forced them to be not compatible with the DTRs even though they use the exact same FHSS system.

DTR/DLR radios in the CheckCheckOneTwo forums:
Professional Radios
New DLR radios - compatible with DTR

RR forum threads:
https://forums.radioreference.com/gmrs-frs/346074-motorola-dtr-550-dmr-uhf-simplex-cruise-ship.html
https://forums.radioreference.com/gmrs-frs/345831-gmrs-exit-strategy-going-900mhz-dtrs-dlrs.html

Chickenhawk's DLR review:
NEW - Motorola DLR series - rugged, licence-free, high-quality digital radios - Two Way Radio Forum

My DTR650 audio test on YouTube:
https://www.youtube.com/watch?v=aaNdMWPmVZI

I own a fleet of DTR650 radios and a fleet of DLR1060 radios. I have a multi-unit charger (MUC) for each fleet.
These are great radios specifically designed for on-site small business type use. DLR = Digital Lightweight Radio, according to Motorola.

The DTR series is more than 10 years old but is still current product from Motorola. They have replaced my use of GMRS/FRS for local on-site simplex type use. I still have GMRS/FRS and MURS capabilities but these are no longer my go-to mode for local simplex ops. While on vacation in Florida over the holidays, my wife and I and friends used my fleet of DTR radios for our local simplex ops. We did not bother to use GMRS/FRS at all because the DTRs worked so well. We also wanted an all-digital solution that is higher quality and more professional than FRS.

 

[n1das]

Thanks. It sounds that they would be very useful when walking around Deerfield during NEAR Fest. :wink:

Seriously though, this and the other answers are very helpful.

That is EXACTLY what my wife and I used at NEAR-fest last month. We were using my DLR1060 radios. The DLRs are extremely small and stealthy and convenient. DLR = Digital Lightweight Radio, according to Motorola.

At NEAR-fest during the previous year, my wife was by herself and talking to me on the radio and a guy at a table asked her what frequency we were on, thinking we were using plain old analog radios on UHF. We were using my DTR radios and had the 7" half wave 900MHz antenna. I was somewhere else on the fairgrounds at the time and that's why we were using the DTR radios. Since she had no idea what "frequency" we were on, she asked me over the air because somebody was asking her. I said we were on 902-928MHz using digital radios with FHSS. He then told her "OK so that's why I'm unable to see you on my spectrum analyzer!" The signal is actually not totally invisible on a spectrum analyzer if you have the right equipment and know what to look for. The radios spend no more than 90 ms on any given frequency in the hopset of 50 frequencies across the 902-928 band.

So now I've actually had a case where somebody (unsuccessfully) tried to find us so they could listen to us on the air.