DMR <-> SIP Translation

When I first got interested in D-Star, there were some discussions on building a D-Star to SIP bridge.

This was back in 2011, now DMR seems to be taking off as I just wrote in my last blog entry titled AMBE proxy.  Once again that nasty AMBE problem?

However Trbonet (http://trbonet.com/) software dispatch thingy does allow you to dispatch from a PC.  So unless this software has some DVSI/AMBE licenseed code in it, there must be a way to address both sides of the AMBE vocoder in the Mototrbo repeater and or radio.  If there is a way to address the input side of the AMBE+2 vocoder in the radio, then you can jack the audio in that way, instead of through a bastardized speaker mic (as an analog hack)

There are a number of interesting DMR related projects on gihub.    The first we stated to play with locally was KD8EYF's TRBO-NET perl scripts:



Showing some interactive text based commands sent from a DMR portable, and the replies from the KD8EYF powered information gateway. Weather reports, sending APRS messages, last heard status of a station, etc.

DMR does actually seem more well suited for a SIP to private call bridge.  D-Star really has no way to know when the call ended to be able to tear down the SIP connection.  It also has no real way to know if a particular D-Star radio is even on.  DMR on the other hand can do all this.

Other ideas:   When mobile it might be nice to have the various responses to the quick texted queries  actually spoken with a text to speech engine.  And since your radio affiliates when you turn it on, maybe even custom repeater greetings/reminders.

When you try and send a text to someone who doesn't have their radio on, obliviously that times out.  In theory it should be possible to see there isn't a reply happening and have server accept the message on their behalf, and when that server sees the user next affiliate, send the message to them then.  (Much like how it works in the cellular world)

The same could apply to a private call that isn't being acknowledged.  The server recognizes this and asks using a text to speech voice if you'd like to leave them a message.  Again playing the message to the user it was original intended for when they next turn on their radio and it phones home to the repeater.

This one seems to incorporate some audio related things:

https://github.com/n0mjs710/DMRlink:

 playback.py: As of this writing, a large multi-national ham radio group has deployed this on TGID 9998 and dubbed it the "parrot". This application can listen to group and/or private voice transmissions and if you trasmit to the group and/or private IDs it's programmed to use, it will record the digital packet stream and then re-play it back. Handy for listening to your audio to see what you actually sound like on the air

Interesting:

Tutorial for Setup of Hytera Phone Patch via SIP:

Yaesu Digital?

Back in September 2011 at the Tokyo Ham Fair Yaesu presented a new line of digital ham radios. Then a short time later in late 2011, a new page on the Yaesu website titled "The Dawn of Digital Communications in the Amateur Radio World" appeared.


So here it is, a FT-1DR:


Their PDF talked a lot about C4FM. So many hoped they'd use IMBE and let it work with P25 gear.

They also talked about DMR (compatible with MotoTRBO), and we know the Vertex Standard branch does have DMR radios like the VXD-720 DMR HT.

However, there are 3 tiers in the DMR standard (described in ETSI technical standard TS102 361):

DMR Tier I products are for license-free use in the 446MHz band.

Under Tier I, ETSI has also defined two Tier-1 protocols:

DMR Tier-1 protocol utilizes 12.5kHz FDMA <---- br=""> dPMR protocol utilizes 6.25kHz FDMA

Both protocols provide for consumer applications and low-power commercial applications, using a maximum of 0.5 watt RF power. With a limited number of channels and no use of repeaters, no use of telephone interconnects, and fixed/integrated antennas, Tier-1 DMR/dPMR devices are best suited for personal use, recreation, small retail and other settings that don’t require wide area coverage and advanced features.

DMR Tier II covers hand portables, mobiles and base stations operating in the VHF and UHF allocations for PMR.

The ETSI DMR Tier-2 standard is targeted to those users who need spectral efficiency, advanced voice features and integrated IP data services in licensed bands for high-power communications. ETSI DMR Tier-2 calls for two slot TDMA in 12.5 kHz channels.

DMR Tier III products will support trunking operation.

Most savvy hams are familiar with Tier-2. This is what the above mentioned Vertex/Standard VXD-720 uses, as well as MotoTRBO.

According to a Yeasu FT1D sales flier picked up at Dayton :

C4FM 12.5 KHz FDMA.

Peak data transfer rate 9.6 kbps.

It can send a 320x240 pixel picture using a camera speaker mic. (as eluded to on the universal radio page)

It takes 20 seconds to send the picture over the air at 320x240, and 4 seconds at 160x120.

Because of display limitations, it can only save it in JPEG format to the Micro SD card slot on the camera. It can't display it on the radio itself.

What is interesting is the radio has a USB connector. This is for accessing the camera speaker mic as a webcam, and for firmware updates.

So in effect it's not really compatible with anything other than the cheesy radios designed for the license free PMR 446 band in Europe. But never fear, keep your anticipating eyes open for the Yaesu radio that will be compatible with Tier-2 DMR:

---From Page 14 of the Yaesu PDF---

At this point in time, Vertex Standard believes the C4FM (4-level FSK) FDMA or TDMA are the most suitable selections for Amateur radio applications. In early 2012, we will release a C4FM (4-level FSK) FDMA Handy-Talky and a Mobile transceiver into the Amateur radio market.

After our initial introduction, we plan to introduce a C4FM (4-level FSK) TDMA (2 slots) or TDMA Handy and Mobile transceiver into the Amateur market.

This is from page 15 of the Yaesu pdf.   The receiver audio output is the same as the IC-92.  And that is my biggest grumble with the IC-92.  In digital mode you better be in a quiet room, close to your radio.  In analog, however the audio out is okay.