The Motorola DTR

Posted: 11/05/2013 in Communications

Readers can find a short exchange of comments at the bottom of the blog regarding the Motorola DTR. I would like to thank the gentlemen for the information provided. A special thanks to Ticom, author of “Musings of a Man In Black: Prometheus”. Read and heed folks.

If you have followed my past articles, including those over at Mountain Guerrilla, you know that I am fond of the Motorola DTR. It is one of the few, rugged, MILSPEC radios that you can run without a license. I do include some caveats and they are:

1.  I would use this radio for inter-squad use only. Great for CQB. The DTR inherently has limited range due to it’s 1 watt power output and 900 MHz range.

2.  Use it in that application sparingly. When operating in a patrol, I prefer squad hand and arm signals to any radio. Why is that Dan?, you ask. Because I am highly allergic to JDAMs, 30mm Bushmaster rounds and Hellfire missiles. One advantage of the DTR is it’s frequency hopping capability. Motorola is very tight lipped regarding it’s hopset. I do know that it will run ten separate hopsets and will repeat hopsets every 50 cycles. I have no doubt that our buddies over at NSA already have those hopsets. If your dealing with Mosby’s Cannibalistic San Franciscan’s or local law dog’s, don’t worry about it. It can’t be intercepted with any commercial scanner. But, if you’ve managed to draw the ire of the big boys, don’t key any mic (unless you are running a deception). I don’t know how else to put it.

3. As per the comments at the end of the blog, I prefer the DTR-550. The 410 has a fixed stubby antenna which limits range. The 550 and the 650 have removable antennas that can greatly increase range if the proper antenna is constructed and used. The 410 and 650 have the infamous manager functions that can cause havoc if not properly administered.  And for you former 18Es, buy the keypads, they’re about $30.00. They can be used somewhat like a DMDG with the DTR.

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Comments
  1. […] The Motorola DTR. […]

  2. sparks31 says:

    Reblogged this on Signal Corps and commented:
    Good info from MSG Morgan.

  3. Kerodin says:

    Sir – I am as illiterate as it gets with comms. Please consider this scenario: remote mountainous area with a small town within a few miles. Local LEO is a 4-5 man “police department” and a Sheriff department ” of maybe as many.

    Is the channel-hoping feature of the Motorloa DTR likely to provide security between husband/wife/and a few neighbors (discounting a FedGov element) operating within a few square miles?

    Thanks,
    K

    • danmorgan76 says:

      K,

      If configured properly, the DTR will provide very secure comms against any civilian and local/ state law enforcement threat. I would not recommend the DTR for ranges beyond 1 kilometer, (6/10 mile), line of sight. And that’s when using a modified antenna to increase the range. It’s a great short range patrol radio for inter-team comms, for use around a small homestead/retreat and in buildings (CQB). The radio operates about the mid point of the UHF range 300-3000MHz. Anytime you see a radio spec’d in that band, it’s range becomes very dependent on power output in watts. Since the DTR only puts out 1 watt, it has very limited range. Also, since you operate in a mountainous area, as I do, when your other station is in the opposite shadow of a mountain, the probability for good comms drops off drastically. Remember that term, line of sight. If you can’t see it because of an obstruction, you probably won’t talk to it. The exception for this radio is in buildings. It is very good at talking through concrete. I always recommend that everyone practice now to see what your comms will do in your area, but the DTR is a fairly expensive HT radio to find out it has very limited applications in the arena you’ve asked about. If you don’t have your Amateur Technician License (first level of ham) I would go with a marine radio (go over to signal corps, he has a great article on these babies), gmrs or even CB-Single Side Band. The radios won’t set you back a fortune for testing purposes (except the CB/SSB) If you do decide to go one of these routes, you will need to come up with some system of brevity and authentication codes, since you will be open to interception by most good civilian scanners. I plan on covering that in a future article. One note, encryption, which would include brevity codes, is not legal on all amateur bands and not available on most of the free bands, except for MURS. Hope this helped, if not stay tuned for future posts that might give you some more insight.

      • sparks31 says:

        I’m wondering how easy it would be to mate a simplex repeater to a DTR radio…

  4. Joseph Plumb Martin says:

    As usual MSG Morgan and Sparks31 are ratcheting up the level of comms awareness by the increased technical info you guys provide on your blogs. Seems that the next stage is possibly to develop a POI and offer some hands on practical training in things like tactical comms, SIGINT intercept, HF comms, clandestine comms/antenna , and antenna theory and construction, OTP use and practice, PSK31 etc . There are great shooting and patrolling classes out there by guys like Mosby and Max Velocity and wilderness survival courses. There are lots of people who can benefit from a course put together by MSG Dan, Sparks31 and TICOM and actually operate some of the equipment talked about. There are lots of older folks that would be helpful as support personnel that can get involved running the commo/SIGINT shop who are too old or broken to run around the woods but can be very useful nonetheless.

  5. Exl says:

    MSgt –

    There is a radio out recently to the market called the Kirisun S780 which operates in the clear as well as in FDMA mode. I do believe they’re priced around $90 a set and kick out 1W on low power and 4W on high power, have you had the chance to look these over as yet?

    • danmorgan76 says:

      Exl,

      I have no experience with the Kirisun. The frequency range it operates in is generally in all of the amateur 70cm band. It overlaps somewhat on the high end into the GMRS and FRS bands. So unless you have an amateur Technician ticket, you would be operating illegally on most of the freqs. available to you.

      It appears to use a Chinese vocoder codex as it’s encryption device, but I haven’t been able to pin that down. There’s a lot of conflicting info. published regarding that. FDMA is not an ecryption mode, it is a type of digital modulation. The following is a list of published digital modulation modes(not trying to be a smartass, but I don’t understand all of them); ASK, APSK, CPM, FSK, MFSK, MSK, OOK, PPM, PSK, QAM, SC-FDE, TCM. As you can see, every manufacturer has his pet mode and some are better than others.

      If you do some research into APCO Project 25 (P25) you will see where the government spent a lot of money to develop new transmission and encryption protocols for public safety radios. Most use FDMA and are known as “Trunking Radios”. It turns out that the radios, which are now widely used by law enforcement, are very vulnerable to jamming, and denial of service. The P25s have additional insecurities that allow anyone to see the unencrypted id portion of the transmission and capture and change the encrypted portion for retransmission as well as a vulnerability that causes a users radio to go “hot mic” without their knowledge, allowing them to be DF’d.

      I would say, as long as you have a license to operate them, understand their vulnerabilities and if they will help you accomplish your mission (METT-TC) then give them a try. I tend to stick with what I know, and always look for rugged radios with big, easy to use buttons, knobs and switches.

  6. Historian says:

    Are headsets/boom mics available?

  7. Deadmeat99 says:

    Old Nextel cell phones do the exact same thing as these radios for a fraction of the price. Put them in DirectTalk mode and they work exactly the same.

    • Kerodin says:

      Deadmeat: Do the Nextels frequency hop for security?

      • Deadmeat99 says:

        Yes, they do. I did this video http://www.youtube.com/watch?v=3bokUC06Nmo that shows it in action. Nearly all of the old Motorola Nextel phones have this feature built in, and they can do groups and individual device identifiers as well. Now that Nextel is dead, these used phones are very cheap. One caveat is that the DTR radios are not comaptible with the Nexetel phones.

  8. Zach N says:

    If anyone is interested, I just saw this site had DTR 6 packs for the cheapest I’ve found..

    http://www.talktwoway.com/two-way-6-packs

  9. Mike Mango says:

    A company named Crane has a repeater designed the Motorola DTR radios, if any one is interested;
    http://www.canewirelesspro.com/drx-repeater.html

    For close range, a mile or less the Motorola DTR radios are a reasonably secure radio system because of it’s frequency hopping abilities. Personally, I’d rather use a DTR radio for short range comms, instead of a high powered encrypted HT, because the typical linear/hertzian signal which is used in most HT’s can be DF’ed, direction finding, to locate the transmitters position. While the low power, frequency hopping DTR, is difficult to detect, even when using a spectrum analyzer. Although, I would strongly recommend setting up your own private group, instead of using public talk groups.

    Mike

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