Posts Tagged ‘D-Star’

Review – BTech AMP-25 series for Analog & DMR

by John ‘Miklor’
K3NXU

The  AMP-25  series  VHF / UHF Amplifiers

The recently announced BTech Digital and Analog amplifier series puts a whole new spin on mobile operation. It performs more like a mobile than it does a power amp. The D series are true TDMA Tier2 DMR amplifiers.

Note: This review was done using an Anytone D868UV on both DMR and analog.

In the Box

Included with the 40W Mobile Amp are:

–  Mounting Bracket
–  3′  Interface Control Cable (Kenwood K1 connectors)
–  3′  RF connect cable (SMA-M to SMA-F)
–  Microphone and Hanger
–  All necessary mounting hardware
–  User Guide

General Description
–  UHF or VHF Power Amplifier

–  2-6W  >  20-40W  Output

                         Modes of operation include:

             V25  U25             V25D   U25D
Analog (FM)
C4FM (Fusion)
P25  (Phase 1)
NXDN
IDAS
dPMR
MPT1327
 >  DMR Tier II (TDMA)
 >  P25  (Phase 2)
Analog (FM)
C4FM (Fusion)
P25  (Phase 1)
NXDN
IDAS
dPMR
MPT1327

A Different type of Mobile Amplifier

I found these to be much more than a typical power amplifier. Although they can function as a simple ‘In and Out’ power amp, this is about as close to a full mobile as you can get. Although the driving force was my DMR handheld sitting in my cup holder, the transmit audio was that of the included hand microphone and the receiver audio out was coming through the built in speaker driven by a four watt audio amplifier.

Transmit Power

I tested the power on two different models. The VHF V25 (non TDMA) and the U25D for UHF DMR.  The power was tested using the analog side of both into a calibrated Bird Termaline wattmeter. The maximum current drain from my 13.6V 30A power supply was just under 6A. This is low enough for the amp to be powered by the 10A accessory jack in your vehicle.

Enclosure

The basic frame measures 4.6″W x 1.3″H x 5.5″D (excluding the SO-239) and weighs in at 26oz.  I was curious to see the internal layout of the amp and to no surprise, there was a 5/8″ finned heat sink spanning the entire length and width of the case along with air vent along the back of the enclosure.

Operating Modes

These are single band amplifiers.
V25(D) = VHF 136-174MHz
U25(D) = UHF 400-480MHz.

Note: The V25D and U25D were designed to include DMR Tier II (TDMA) and P25 Phase 2 along with all other modes. Their operation varies slightly.

V25  /  U25
To operate VHF through the UHF (U25) amplifier, or UHF through the VHF (V25) amplifier, simply power off the amplifier. This will allow you to run straight through directly to the antenna without power amplification on that band.

V25D / U25D
These amplifiers will only operate within their specified VHF or UHF range. This is due to the circuit switching design of DMR Tier II and P25 Phase 2.

Hook Up

The simplest configuration is using the included RF cable to attach the radio to the amp. You could add a Spkr/Micr to the handheld, but you would still be bypassing some of the best features.

I use the two included cables. The 3′ RF cable to attach the radio to the amp, and the control cable. This allows me to use the full size hand microphone as well as connecting the four watt audio amp powering the speaker. The power included power cable is compatible with handhelds using the standard two pin Kenwood style connector, such as an MD380, D868, GD77, UV5R, F8HP, UV82, etc.

I use an Anytone D868 on DMR as well as analog with the hookup diagrammed below. Depending on your radios antenna jack, you may need to pickup an SMA-M to SMA-M adapter.

 

Convenience

All channel selection and volume adjustments are done using the handheld. No duplicate programming or code plugs are necessary. Whatever is in my handheld is what I operate in the mobile

Operating my handheld in the low power position, I still get 22W out on UHF and my handheld’s battery life remains excellent, but high power gives me a solid 39W.

Conclusion

I was glad to see someone finally develop what is a full featured mobile amplifier capable of  DMR as well as all other modes including C4FM and D-Star that is small enough to mount in the car, boat, and on top of your computer. This amplifier is Part 90 certified and definitely worth considering.

Available from Amazon:    V25     V25D     U25     U25D
and     

VHF /UHF
Digital / Analog
Mobile Power Amplifiers

 

The Cacophony of Digital Voice Continues (Part 2)

Digital transmissionThis post is a continuation of The Cacophony of Digital Voice Continues (Part 1), so you probably should read that one first.

All of the popular amateur digital voice (DV) systems (D-STAR, DMR and YSF) use the AMBE vocoder (voice codec) technology. This technology was developed by Digital Voice Systems, Inc. and is proprietary technology covered by various patents. The use of proprietary technology on the ham bands causes some folks to get worked up about it, especially proponents of an open source world. See my blog posting: Digital Voice at Pacificon and this presentation by Bruce Parens K6BP: AMBE Exposed. Codec2 is an alternative open voice codec developed by David Rowe, VK5DGR. David is doing some excellent work in this space, which has already produced an open codec that is being used on the ham bands. FreeDV is an umbrella term for this open codec work. Here’s a recent video of a presentation on FreeDV by VK5DGR.

It will be interesting to see if and how Codec2 gets adopted in a DV world already dominated by AMBE. After all, a new codec is another contributor to the digital cacophony. On the HF bands, it is easier to adopt a new mode if it can be implemented via a soundcard interface (which FreeDV can do). Any two hams can load up the right software and start having a QSO. The same is true for weak-signal VHF/UHF via simplex. (Note that Flexradio also supports FreeDV, showing how Software Defined Radio (SDR) has an advantage with adopting new technology.)  VHF/UHF repeaters are trickier because you must have a solution for both the infrastructure (repeaters and networks) as well as the user radios.

The vast majority of digital repeaters support just one digital format. For example, a D-STAR repeater does not usually repeat DMR or YSF transmissions. Interestingly, DMR and YSF repeaters often support analog FM via mixed mode operation for backward compatibility. It is definitely possible to support multiple digital formats in one repeater, but the question is will large numbers of repeater owners/operators choose to do that? With existing DV systems, the networking of repeaters is unique to each format which represents another barrier to interchangeability. In particular, most of the DMR infrastructure in the US is MOTOTRBO, which won’t ever support D-STAR or YSF.

In the case of a new vocoder, we can think of that as just a new format of bits being transported by the existing DV protocol. DMR, for example, does not actually specify a particular vocoder, it’s just that the manufacturers developing DMR equipment have chosen to use AMBE technology. So from a technical viewpoint, it is easy to imagine dropping in a new vocoder into the user radio and having it work with other identical radios. Of course, these radios would be incompatible with the existing installed base. Or would they? Perhaps we’d have a backwards compatibility mode that supports communication with the older radios. This is another example of putting more flexibility into the user radio to compensate for DV incompatibilities.

One objection to AMBE is the cost of the technology, especially when compared to free. When D-STAR radios first started using AMBE codec chips, the chip cost was rumored to be $25 to $50, but I don’t have a solid source on that. Now, I see that Tytera is selling a DMR handheld at around $100, including AMBE technology inside, so the codec can’t be very expensive. If a free codec starts to be a credible threat, it will put additional pricing pressure on the AMBE solution.

A potential advantage of Codec2 is superior performance at very low signal-to-noise ratio. We’ve all experienced the not-too-graceful breakup of existing DV transmissions when signals get weak. Some of the Codec2 implementations have shown significant improvement over AMBE at low signal levels.

Conclusions

Repeating a key conclusion from Part 1:

  • For the foreseeable future, we will have D-STAR, DMR and YSF technologies being used in amateur radio. I don’t see one of them dominating or any of them disappearing any time soon.

Adding in these conclusions for Part 2:

  • Codec2 will struggle to displace the proprietary AMBE vocoder, which is well-established and works. The open source folks will promote codec2 but it will take more than that to get it into widespread use. Perhaps superior performance at low signal levels will make the difference.
  • Repeater owner/operators will continue to deploy single-DV-format repeaters. This will make multiformat radios such as the DV4mobile be very attractive. In other words, we will deal with the digital cacophony by having more flexible user radios. This will come at a higher price initially but should drop over time.

Repeating this one from Part 1:

  • A wild card here is DMR. It benefits from being a commercial land mobile standard, so high quality infrastructure equipment is available (both new and used gear). And DMR is being embraced by both land mobile providers (i.e., Motorola, Hytera) and suppliers of low cost radios (i.e., Tytera, Connect Systems). This combination may prove to be very powerful.

Well, those are my thoughts on the topic. I wish the DV world was less fragmented but I don’t see that changing any time soon. What do you think is going to happen?

73, Bob KØNR

The post The Cacophony of Digital Voice Continues (Part 2) appeared first on The KØNR Radio Site.

The Cacophony of Digital Voice Continues (Part 1)

Digital transmission

It wasn’t that long ago that I commented on the state of digital voice on the VHF/UHF ham bands: Digital Voice Balkanization. We have three main competing (incompatible) standards in the running: D-STAR, DMR and Yaesu System Fusion (YSF). At a high level, these three formats all do the same thing but there are significant differences in implementation (See Comparison of Amateur Radio DV by Roland Kraatz W9HPX.) All three of these are (arguably) open standards, allowing anyone to implement equipment that supports the standard. However, the reality is that D-STAR is still largely an ICOM system (with Kenwood joining the party), YSF is mostly a Yaesu system and DMR is…well, DMR is not deeply embraced by any large amateur radio equipment supplier. Instead, DMR is promoted heavily by Motorola for the commercial market via their MOTOTRBO product line. Another big factor is the availability of DMR radios from some of the low cost providers in the ham market: Connect Systems, Tytera MD-380. Baofeng has also announced a DMR radio but it has some potential shortcomings.

D-STAR has a clear head start versus the other DV standards and is well-entrenched across the US and around the world. DMR and YSF are the late comers that are quickly catching up. To put some numbers on the adoption of DV technology, I took at the digital repeater listings in the August issue of the SERA Repeater Journal. SERA is the coordinating body for Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia and West Virginia. This is a large region that includes rural and large urban areas, so perhaps it is a good proxy for the rest of the country. I just considered the listings for D-STAR, DMR and YSF repeaters, some of which are set up as mixed-mode analog and digital repeaters.

D-STAR   161    39%
DMR      136    33%
YSF      121    29%
Total:   418   100%
SERA Repeater Journal - August 2016

I was definitely surprised at how the DMR and YSF numbers are in the ballpark with D-STAR. Of course, we don’t know for sure how many of these repeaters are actually on the air or how many users are active on each one. Still, pretty impressive numbers. (And I did not bother to count the analog FM repeaters but those numbers are way higher, of course.)

It is the repeater clubs and repeater owners that drive the deployment of infrastructure for new technology. To some extent, they are driven by what their users want but also by their own technical interests and biases. One of the positive factors for DMR is that most of these systems are Motorola MOTOTRBO. Hams involved in commercial land mobile radio are exposed to that technology and naturally port it into the amateur radio world. MOTOTRBO is actually not that expensive and it’s built for commercial use. YSF received a big boost when Yaesu offered their repeater for $500 to clubs and owners that would put them on the air. By using Yaesu’s mixed analog/digital mode, it was an easy and attractive upgrade for aging repeater equipment.

Disruption From New Players

Early on in the world of D-STAR, the DV Dongle and DV Access Point by Robin AA4RC allowed hams to access the D-STAR network without needing a local repeater. This basic idea has continued and evolved in several different directions. For example, the DV4Mini is a cute little USB stick that implements a hot spot for…wait for it…D-STAR, DMR and YSF. This is very affordable technology (darnright cheap) that lets any ham develop his or her own local infrastructure. We don’t need no stinkin’ repeater. DV MEGA is another hot spot, supporting D-STAR, DMR and YSF. I guess somebody forgot to tell these guys they have to choose one format and religiously support only that one.

dv4-mobile-transceiver
DV4 Mobile Transceiver as shown in Dayton 2016

OK, so that’s one way to solve the babel fish problem…support all three formats in one device. And that’s what the DV4 mobile radio promises to do as well: “This DV4mobile is a tri-band VHF/UHF transceiver (2m, 1.25m and 70cm) that supports DMR, D-STAR and C4FM ( or “fusion”) all in one box.” Heck, let’s throw in LTE while we are at it, it’s only software. This site says the radio will be available Q4 2016. Well, it’s Q4, so maybe it will be here soon.

Conclusions

So let’s wrap up Part 1 of this story. What can we conclude?

  • For the foreseeable future, we will have D-STAR, DMR and YSF technologies being used in amateur radio. I don’t see one of them dominating or any of them disappearing any time soon.
  • Equipment that handles all three of those DV modes will be highly desirable. It is the most obvious way to deal with the multiple formats. Software-defined radios will play a key role here.
  • A wild card here is DMR. It benefits from being a commercial land mobile standard, so high quality infrastructure equipment is available (both new and used gear). And DMR is being embraced by suppliers of low cost radios as well. This combination may prove to be very powerful.

The post The Cacophony of Digital Voice Continues (Part 1) appeared first on The KØNR Radio Site.

‘USA 1776′ DMR Talk Group

DMR-logoOne of the nice things of D-Star and DMR is the ability to talk all over the world without the need of an HF rig and a bunch of big antennas. While this largely reduces a radio to a simple Internet-driven communication tool – just like Skype or other VoIP apps – it’s definitely nice to use.

There are a few problems surrounding DMR, one of which is the lack of more than two time slots. For example, if hams are using the Dutch Hytera network and occupying talk group 204 on slot 1, World Wide (which uses the same time slot) will be unavailable. Because 204-1 is a busy place, world wide QSOs are often impossible. It’s one of the reasons I thought of dumping DMR all together — I can talk to the same Dutch guys on analog while enjoying a much better quality audio.

There are reasons to keep DMR too. DMR is maturing; there are more than enough possibilities to put less pressure on the nation-wide network by going local. Now if only hams would do that…. but most don’t. Another reason to keep DMR for now is the gateway we recently added, which connects D-Star to our DMR network.

Not available on the Motorola network, sorry — some people responsible for that network appear to be so scared of such innovations that they will ban a repeater from the network if such a gateway is detected.

Talk group ‘USA 1776′ could add to the appeal of DMR. It’s unclear on which network this talk group will reside, but my best guess is that it will be the Motorola network.  MITCON writes:

The “USA 1776″ (English preferred) Talk Group will be distributed worldwide to DMR networks upon request.  The spirit of “1776” is to continue the Amateur Radio tradition of international friendship and to push the boundaries of technology in the new frontier of digital communications.

USA 1776USA 1776 is intended to be a flexible, politically neutral, unrestricted Talk Group that can be used as Push-To-Talk (PTT) or Full-Time (FT) to meet the operating requirements of a DMR Network.  DMR subscribers are welcome to use 1776 as a universal meeting place to “Rag Chew” or as a jumping off point and QSY to an alternative Talk Group if desired.  To add USA 1776 to your DMR Network please contact us to schedule a time for configuration & testing.


‘USA 1776’ DMR Talk Group

DMR-logoOne of the nice things of D-Star and DMR is the ability to talk all over the world without the need of an HF rig and a bunch of big antennas. While this largely reduces a radio to a simple Internet-driven communication tool – just like Skype or other VoIP apps – it’s definitely nice to use.

There are a few problems surrounding DMR, one of which is the lack of more than two time slots. For example, if hams are using the Dutch Hytera network and occupying talk group 204 on slot 1, World Wide (which uses the same time slot) will be unavailable. Because 204-1 is a busy place, world wide QSOs are often impossible. It’s one of the reasons I thought of dumping DMR all together — I can talk to the same Dutch guys on analog while enjoying a much better quality audio.

There are reasons to keep DMR too. DMR is maturing; there are more than enough possibilities to put less pressure on the nation-wide network by going local. Now if only hams would do that…. but most don’t. Another reason to keep DMR for now is the gateway we recently added, which connects D-Star to our DMR network.

Not available on the Motorola network, sorry — some people responsible for that network appear to be so scared of such innovations that they will ban a repeater from the network if such a gateway is detected.

Talk group ‘USA 1776’ could add to the appeal of DMR. It’s unclear on which network this talk group will reside, but my best guess is that it will be the Motorola network.  MITCON writes:

The “USA 1776″ (English preferred) Talk Group will be distributed worldwide to DMR networks upon request.  The spirit of “1776” is to continue the Amateur Radio tradition of international friendship and to push the boundaries of technology in the new frontier of digital communications.

USA 1776USA 1776 is intended to be a flexible, politically neutral, unrestricted Talk Group that can be used as Push-To-Talk (PTT) or Full-Time (FT) to meet the operating requirements of a DMR Network.  DMR subscribers are welcome to use 1776 as a universal meeting place to “Rag Chew” or as a jumping off point and QSY to an alternative Talk Group if desired.  To add USA 1776 to your DMR Network please contact us to schedule a time for configuration & testing.


DVAP + Pi

I’ve owned my Raspberry Pi for a while now.  I purchased it around the time they were first introduced (early 2012).  Not having a lot of knowledge in the Linux OS, the most I ever really did with it was set it up and play around with it.  However, my reason for purchasing the RPI was to some how use it for amateur radio purposes. 

As I have mentioned before on my blog, I also own a D-STAR Digital Access Point Dongle (DVAP).  I purchased it in 2011 and had been using it connected to an older Windows XP machine.  I wrote a “first look” post as well as one where I was experimenting on the DVAP range away from my QTH.   However, in following my own advice given in my podcast, The Practical Amateur Radio Podcast episode 64 about the Microsoft Windows XP End of Life, I decided it was time to explore how the DVAP might be used with the Raspberry Pi.

In most situations, Google truly is your friend.  Just doing a simple Google search for DVAP and Raspberry Pi led me to more information than I had time to read.  However, the very first search result happened to provide all the information I needed to setup my Raspberry Pi to work with my DVAP dongle.  Special thanks to Bill, AB4BJ who had blogged about his experience in setting up his Pi for DVAP purposes. 

If you have a Raspberry Pi, a DVAP Dongle and a D-STAR radio sitting around your ham shack, it’s very easy to set it all up just as I have done.  In the below picture, I have my ICOM ID92-AD, the DVAP Dongle and the Raspberry Pi setup.  Once configured, the Raspberry Pi will function stand-alone (without keyboard, mouse and monitor).  I can access the RPI via VNC from my iPad if needed. 

2013-11-24 13.39.52

Raspberry Pi running Debian Linux and the DVAPNODE and IRCDDB software.  DVAP is connected to REF001A in Aurora, Illinois.  Screenshot from iPad VNC session.

photo

For now, my setup will remain in my ham shack.  I know many build this setup for mobile/portable use.  At the present time I do not have wireless capabilities for the RPI.  I also want to see just how stable this setup is before making any additional changes.   I was pleased to wake up this morning and find the RPI was still running and the OS was stable.  Time will tell…

Until next time…

73 de KDØBIK

Digital Voice at Pacificon

Last weekend, I had the privilege of attending the Pacificon amateur radio convention in Santa Clara, something I have been trying to do for several years now. It is a great event, with good technical programs and a super venue.

The most interesting presentation I saw was the one on digital voice (DV) technology by Bruce Perens K6BP. The presentation was mostly about the digital voice known as FreeDV,  an open source approach to DV that uses the Codec 2 voice codec for digitally processing/compressing speech.

K6BP photo

Bruce Perens K6BP talking about FreeDV

I won’t cover all of the technical details here but you can follow the links above to go deeper on the topic. The initial FreeDV efforts are focused on the HF bands, using the sound card plus computer approach to implementing DV. This is a good approach since it is a relatively easy way to adopt this technology. (Compare this to VHF/UHF where you need to solve the repeater infrastructure problem to make progress.) FreeDV operates with a bandwidth of  1.25 kHz, narrower that the standard 3 kHz or so SSB signal. FreeDV also has the benefit of degrading gracefully as the  signal-to-noise ratio is decreased, with less of a digital dropoff that we see with D-STAR and other DV technologies.

Like many hams, Bruce pointed out the concerns and limitations of the proprietary AMBE chip used in D-STAR, DMR and now the new Yaesu DV system. I totally get this point and support the idea of a an open source codec. On the other hand, this work is coming more than a decade later than the creation of D-STAR. I like to refer to this phenomenon as ”our ideas are better than their products.”

Bruce introduced Chris Testa KB2BMH to talk about the “HT of the Future”. This is a handheld transceiver implemented using Software Defined Radio (SDR) and inspirations from the world of smartphones. As Bruce said, “Why isn’t your HT as smart as your smart phone?” This is similar to the Android HT idea that I blogged about a while back. See Chris’s blog and this HamRadioNow video for more information.

Another presentation that I attended was about D-STAR with several speakers, including Robin AA4RC. The innovation continues to happen in the D-STAR world with a strong theme of using Raspberry Pi computers to create D-STAR hotspots and repeaters. Robin described the “DV Pi” being developed…a DVAP-like daughter board that plugs into a Raspberry Pi. Jim Moen K6JM talked about the many ways you can implement a D-STAR Hotspot. For more info on that see his D-STAR Hotspot page.

There’s much innovation happening in the area of Digital Voice. It got me thinking about it again so I dug out my ICOM D-STAR HT and put my DVAP back on the air.

73, Bob K0NR


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